special report-s3

C I R E D 20th International Conference on Electricity Distribution Prague, 8-11 June 2009

CIRED2009 Session 3: Operation, Control and Protection / 20

Special Report - Session 3 OPERATION, CONTROL AND PROTECTION

Theodor CONNOR Chairman - Germany

[email protected]

Markus ZDRALLEK Special Rapporteur - Germany

[email protected]

Ignaz HÜBL Special Rapporteur - Austria

[email protected]

Introduction

The interest in Session 3 -like the interest in Cired at all- is still and constantly growing. The number of 261 abstracts received for Session 3 underlines this growing interest impressively. Since the number of different countries submitting papers is increasing, too, Session 3 is even getting more international as it already was. Due to the extreme high number of abstracts received for Session 3 Chairman and Rapporteurs had to be once again quite strict in rejecting papers in order to keep quality and a manageable number of papers during the conference.

Therefore 142 abstracts were accepted by National Committees and Technical Committee (TC) and the authors were called to submit a full paper. Finally 124 full papers have been accepted for Session 3. An overview of the review process gives Figure 1.

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Fig. 1: Overview of the review process

All authors are asked for a poster presentation, 28 of them will be additionally present their paper in the Main Session and 16 more academic papers are allocated to two Research and Innovation Forums (RIF).

Traditionally and according to the topics of the papers submitted Session 3 is still structured into three blocks:

Block 1 Operation

− Condition Assessment

− Distribution Management

Block 2 Control

− Distribution Management Systems / SCADA

− Distribution Automation

− Communication/ IEC 61850

− Cyber Security

Block 3 Protection

− Fault Location

− Neutral Grounding

− Distributed Generation / Simulation

− Practical Implementation

In the area of grid operation lots of papers have been received dealing with the problem how to derive the technical condition of grid components correctly. This task still seems not solved sufficiently enough, although it is a major problem since many maintenance and renewal strategies are fundamentally based on a correct assessment of the equipment condition. All papers dealing with this matter are discussed in a separate block.

In the area of grid control two trends can still and clearly be observed: Firstly –in most cases driven by the quality standards of grid regulators- more and more automation of MV-grids or even of LV-grids can be considered. This comes along with a higher demand on communication and corresponding techniques and infrastructure. Since there is a lot of work spent on this tasks it was addressed especially in the call for papers and 14 papers covering communication matters are finally accepted.

Secondly grid control is increasing its efficiency due to more and more powerful SCADA-Systems. These systems can handle much larger grids than in the past and offer


CIRED2009 Session 3 : Operation, Control and Protection / 20

additional possibilities. Furthermore systems which in the past have been solely used for SCADA-purposes develop towards integrated Distribution Management Systems (DMS).

New in the control part is cyber security task. Including SCADA-systems more into the office IT-infrastructure of grid operators leads to an increasing risk for cyber threats.

The main focus of protection is the location of several types of faults and the neutral grounding in MV networks. Both theoretical examination and practical application are shown. A lot of papers being a part of protection are examining the location of earth faults in isolated and compensated networks. Of course there exists no universal method which would be applicable to all types of networks and ground faults and would be able to localize the ground faults in MV network safely.

Practical experiments try to attest the function of new algorithm and fault detectors implemented in protecting systems.

An overview of the number of papers related to the different blocks and sub blocks is given in Figure 2.

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Fig. 2: Overview of the accepted papers

The majority of papers is prepared by groups of authors. In some cases these groups are composed of authors from different countries and even continents. The authors are from grid operating companies, vendors, universities and other research associations. So Session 3 of Cired 2009 truly reflects the ‘state of art’ of the grid operation community in case of Operation, Control and Protection.

Operation

Condition Assessment All papers of this sub-block describe methods or case studies to determine the condition of the grid–equipment as exact as possible. Some methods are more theoretical or in experimental stage, while others are well used and implemented in grid operating companies.

The papers 146, 530 (both U.K.) and 195 (Netherlands) present the experiences with different condition assessment systems based on partial discharge monitoring systems.

Paper 403 from the U.S. focuses especially on the condition assessment of XLPE-insulated Cables. The proposed method is based on the analyses of radio frequency pulses.

Paper 234 shows a very practical application of a special inspection program in Brazil for the condition assessment of MV porcelain pin insulators in order to replace the bad ones. Due to this program the number of outages could be reduced significantly. In contrast to this the theoretical paper 466 (Russia) confirms a life time model of technical components to answer the still unsolved question of the ageing of grid components. Unfortunately only the theory is presented without showing any calculation results.

Another practical application is given in paper 525 (U.K.) about condition assessment of the foundation of steal towers. As an enhancement to the measurement of polarisation current a transient dynamic response method is used.

Still on experimental stage is a laser based scanning system for high voltage power lines from Italy presented in paper 784. The measuring system given in Figure 3 is adequate to monitor the ice accretion on conductors as well as conductors’ sags.

Fig. 3: Schematic description of the measuring system

Paper 540 from Italy introduces a condition based maintenance strategy of MV circuit breakers. Depending on several failure models from different concrete measurements like opening/closing duration condition information of the circuit breaker is derived.

Paper 448 (Italy) touches a security problem faced by many grid operators that is protection against housebreaking and vandalism. A video monitoring application developed and installed in many 110-kV-substations of Enel Distribuzione is presented.

A concrete and practically used condition assessment method of MV-transformes is given in paper 686 from Malaysia. Different diagnostic techniques as well as their influence on the calculation of the overall condition index are presented.



Fig. 4: Transformer health index according to age

Figure 4 actually shows the condition assessment results for a population of about 700 transformers and Figure 5 gives the according mitigation decisions for transformers in bad condition.

Fig. 5: Mitigating actions on problematic transformers

Distribution Management Paper 45 from a Romanian grid operator discusses the reliability of substation equipment during its lifetime focused on transmission level. The goal is to take sufficient decisions for operation and modernisation of substations

Paper 65 from U.K. proposes to use lithium-ion batteries for the back up power of substations in order to overcome the drawbacks of conventional lead-aced batteries. These are to big and require to much regular maintenance according to the paper.

In Cired 2009 only three papers deal with introduction of workforce management (WFM) systems although this is a major task for many grid operating companies worldwide. Paper 691 presents the implementation of a WFM-system at a large German grid operating company. An overview of the project and the new WFM-processes as well as the principal IT-architecture, the central and mobile equipment is given. Paper 326 from Sweden gives the results of a study about structure and robustness of the IT-architecture of WFM-systems. The last WFM-paper (559, Portugal) describes a system configured specially to optimize grid management and operation in the very dense distribution grid of Lisbon.

Paper 874 from the Netherlands is about organizational changes which are necessary since the lifecycles of substation automation systems are getting and shorter and shorter and the systems themselves are getting more and more integrated.

Two papers deal with risk assessment in distribution grids: A technical assessment management systems developed at EDP in Portugal based on risk assessment and condition assessment is presented in paper 914, while paper 171 (Norway) shows maintenance strategies based on qualitative and quantitative risk assessment.

Beside the papers presented in the condition assessment block two more papers deal with new, more sophisticated maintenance or refurbishment strategies: Paper 611 gives the experience of replacing Static Var compensators (SVC) feeding a coal train haulage grid in Australia before they reach the end of their service lifetime. Paper 472 presents a practical approach of an Austrian Grid operator to support the decision of maintaining MV- and LV- Overhead lines or replacing them by cables.

Fig. 6: Cost drivers of low voltage overhead lines

The different cost drivers of overhead line maintenance are analyzed in detail (Figure 6) and aerial views showing for example the vegetation (Figure 7) are used to support the concrete planning decisions.

Fig. 7: Visualized result for the low voltage grid

Paper 1036 gives details of an interruption reporting system developed and implemented in a Malaysian grid operating company.

The quit impressive paper 119 is about the icing catastrophy



in China in the beginning of 2008, causing a lot of large blackouts (see Figures 8 und 9).

Fig. 8: 110kV central conductor icing scene

It is shown, how the weather conditions could damage the grid so much and therefore affect the power supply so extensive. Finally countermeasures to prevent such black outs in the future are given.

Fig. 9: Icing phenomena on a pole of distribution line

Many customers facing longer lasting interruptions of supply complain about a lack of information about the re-supply process. To overcome this problem in Finland (paper 478) and Germany (paper 919) information platforms for 3rd-parties like police and fire-service and of course for the customers concerned have been developed.

Paper 697 (U.K.) describes the features of modern reclosers designed for self-controlled switching of load and fault current.

Paper 331 from China presents an analysis of switching time and capacities to compensate the reactive power of substations in a 35-kV-grid more accurate. Another analysis of reactive power compensation is given in paper 179 from Brazil.

In Paper 68 a method to plan and optimise own resources of a grid operating company (field service personnel, agency staff, tools etc.) and to define an optimal outsourcing strategy is introduced. An example of the optimisation of the operation of a high voltage grid is given. A similar model is presented in paper 818 in Session 6.

Paper 408 from Austria deals with the problem of stable island operation of grids. Grid restoration strategies in a 110-kV-grid are proved with dynamic simulations taking grid and feeding power stations into account.

Potential scope of discussion − Condition assessment of grid components: Why is it so

difficult to solve the problem? Is there a general solution trend? How about the ageing phenomenon?

− WFM-systems: Are they well introduced in the companies or are they still an experiment? How do they affect the whole processes of a grid operation company?

− Maintenance strategies: To simple or to sophisticated? How to manage the balance between data collection afford benefits?

− Can large blackouts due to extreme weather conditions be prevented? Will the frequency increase in the future?

Table 1: Papers of Block 1 Operation assigned to Session 3

Paper No. Title MS a.m.

MS p.m.

RIF PS

No.: 0045 Use of Information Generated by Remotely Controlled Medium-Voltage Distribution System Components

X

No.: 0065 The Utilisation of Lithium-Ion Batteries in Substations X

No.: 0068 Reducing Network Operation Costs by Optimal Resource Planning X X

No.: 0119 Analysis of Icing Accident in South China Power Grids in 2008 and Its Countermeasures

X X

No.: 0146 Experience of Mobile Web-Based Condition-Monitoring Technology for Partial Discharge Detection and Analysis

X

No.: 0171 Experiences Using Quantitative Risk Assessment in Distribution System Maintenance Management

X



Block 2 Control

Distribution Management Systems / SCADA All eight papers of this sub-block deal with the


MS p.m.

RIF PS

No.: 0179 Determination of Optimal Point for Reactive Power Compensation in Distribution Systems

X X

No.: 0195 Partial Discharge On-Line Measurements with Continuous Monitoring as Invaluable Tool for Assessing Insulation Quality and Maintenance Planning

X

No.: 0234 The Influence of the Weather Parameters on the Results of the Inspection of Pin Insulators in Distribution Medium Voltage Lines

X

No.: 0326 Assessing the Quality of Service of Workforce Management Tools X X

No.: 0331 The Reactive Power Compensation Analysis System of Substation Based on Typical Day Load Curve

X X

No.: 0403 Condition Based Maintenance Strategy Tools for Power Cable Systems X

No.: 0408 Dynamic Simulation of a 110-kV-Network During Grid Restoration X X

No.: 0448 Video Monitoring Application to Primary Power Stations X X

No.: 0466 Operation of Electrical Equipment in Distribution Networks on the Basis of its Technical Life Assessment

X

No.: 0472 Developing a Maintenance and Replacement Cabling Strategy for Medium and Low Voltage Overhead Lines - A Practical Approach

X X

No.: 0478 Innovative System Integration for Outage Communication X X

No.: 0525 Non Intrusive Assessment of Steel Tower Foundations X

No.: 0530 Use of Web Based Partial Discharge Monitoring to Extend Asset Life X

No.: 0540 Condition Based Maintenance on MV Circuit Breakers X

No.: 0559 Optimizing Management and Operation in very High Density Distribution Networks

X X

No.: 0611 SVC Refurbishment Experience for Critical Coal Train Haulage Network X

No.: 0686 TNB Experience in Condition Assessment and Life Management of Distribution Power Transformers

X X

No.: 0691 Benefits of Highly Integrated Workforce Management Concepts X

No.: 0697 Application of Recloser for Reliable Supply in Rural Overhead Distribution Networks

X X

No.: 0784 Laser Based Scanning System for Voltage Power Lines Conductors Monitoring

X

No.: 0874 Challenge of Managing the change Imposed on the Organisation by Digital Secondary Technology

X

No.: 0914 M2M - Developing and Implementing a Technical Asset Management System in EDP Distribuição (Portugal)

X

No.: 0919 Information and Communication Platform for Crisis Management (IKK) X

No.: 1036 Development of Distribution Outage and Interruption Reporting System on the Intranet to Facilitate Asset Management

X



improvement or refurbishment of existing Distribution Management Systems (DMS). Paper 142 presents the (long) way from a stand alone HV-SCADA-System in Serbia to an enhanced and integrated DMS for HV- and MV-grids. A similar project is given Paper 519 from Slovenia ending up in the system configuration shown in Figure 10.

Fig. 10: SCADA/DMS system configuration

Even more management and control information is aggregated in the ‘vision’ of new control centres in Switzerland (paper 587) and Italy. In paper 365 a so called ‘supervision dashboard’ is presented which gives an overview of the supply situation of the whole Enel-distribution grid. As shown in Figure 11 the user can zoom into each local control system to see its daily operation activities.

Fig. 11: Local and national ‘supervision dashboard’

Paper 73 from Egypt is abaut a practical project to increase the life time of the DMS of the city of Alexandria while paper 687 (Finland) presents Helsinki’s new DMS for the MV grid and in paper 699 an existing DMS in Serbia is improved by including optimal voltage control. Paper 396 gives another SCADA-application to control the 110-kV-grid for railway power grid in Germany.

Paper 328 from China promotes a new state estimation method for distribution grids which combines historical and remote data using six data rules to improve data quality.

Four more prospective papers deal with future requirements for DMS of all voltage levels which have to manage more and more ‘smart’ components. In paper 76 (U.K.) the idea of a ‘third generation DMS’ is introduced to cover these future requirements including the management of Smart Grids. Likewise papers 722 and 841 both from Germany focus on the growing needs for new, more intelligent DMS caused by more and more smart components connected to the grid. Paper 770 gives a 3-phases path (see Fig. 12) from today’s DMS towards future ‘Smart Grid’-DMS.

Fig. 12: Path towards DMS for Smart Grids

Paper 636 from Sweden is about integration of the different IT-system which are used in an grid operating company which special regard to the SCADA-systems

Distribution Automation Several papers in this block deal with more or less automatic re-supply switching actions carried through in MV-grids. While the goal is always the same –to reduce customers' duration of supply interruptions- the methods to achieve this goal are different. First papers 453 (Denmark) and 635 (France) introduce the ‘self healing MV-distribution grid’. In case of a MV-fault, several main switching and re-supply actions are carried though automatically by local automated MV-substations (Figure 13) before field staff arrives.



Fig. 13: Local automated MV-substation – general architecture

A similar target is presented by French grid operator ERDF in paper 496, who decided to add a set of advanced distribution management functions to its MV-remote control system with the ultimate aim to achieve an automatic network restoration. Paper 558 presents comparable ideas developed in the U.S. Paper 744 (Czech Republic) deals with several methods of utilization of data transmitted from remote-controlled components to the control centre.

Fig. 14: ‘Pulse closer’ for overheadline protection

Finally paper 1028 from the U.S. introduces ‘pulse closing’ as a new technology for overhead distribution system protection. It uses a new method for verifying that a power line has cleared a fault before initiating a closing operation. The authors state that pulse closing is an alternative to conventional re-closing. It is expected to significantly reduce stress on system components as well as improve power quality experienced by customers upstream of a fault (equipment see Figure 14). In some countries automation of LV-grids is in the scope of the grid operators, too. For example paper 439 from Italy presents a pilot project of Enel Distibuzione for the remote control of LV-grids. The goal is to reduce the duration of customer supply interruptions and number of workmen interventions in case of LV-faults. About 1000 remote controlled LV-circuit breakers have already been installed successfully. Paper 942 (Canada) describes a simulation tool that allows

to compare various levels of automation for distribution grids relating the improvements in customers reliability of supply and the corresponding costs. Paper 681 from the Czech Republic deals with the advantages of Phasor Measurement Units (PMU) to improve power systems performance and reliability.

Fig. 15: Coupling of MV-grids

Paper 739 (the Netherlands) handles the problem of safe coupling of MV-grids fed by different 110-kV/MV-substations (Figure 15). It discusses several aspects of equalizing currents and describes the system that has been built for predicting these currents reliable.

Communication/ IEC 61850 In this sub-block several papers deal with the utilisation of modern communication methods or standards for distribution grids. Three papers propose Ethernet communication: Paper 47 compares four ways of implementing an Ethernet/IP WAN network, with the aim of assuring the delivery of all the new generation services with Ethernet interfaces, with adequate quality of service and bandwidth, using the existing fibre optic network of EDP, the distribution company in Portugal. In paper 242 (Canada) key issues and considerations when designing hybrid networks involving serial and Ethernet Networks are defined and the characteristics of an environmentally robust hybrid network for substation automation applications are described. Paper 244 (Canada) looks at considerations when designing an Ethernet network for substation automation applications which may include IEC61850 station or process bus or a combination of both, with focus on redundancy. Three papers investigate how wireless communication can be used in distribution grids: Paper 619 from Spain discusses the state of art as well as advantages and disadvantages of using wireless communication. Paper 856 (U.K.) proposes the ‘WiMax-technology’ to deliver a wireless internet protocol service for distribution grids automation. A coverage study for Northern Ireland and border countries of Republic of Ireland is presented. In paper 174 (U.K.) the influence of characteristic radio frequency impulsive noises with a view to assess its impact on wireless network technologies is investigated. Therefore the measurement equipment shown in Figure 16 is installed



in a typical HV-substation.

Fig. 16: Measurement of radio frequency impulse noises

And many papers deal with the implementation of the (new) communication standards IEC 60870-5 (for SCADA-systems) and IEC 61850 (for substation communication): Paper 322 from Portugal states, that Engineering of substation automation systems according to IEC 61850 is a non-trivial task and describes different approaches to overcome the difficulties. Paper 372 presents the new design of the communication network of a Belgian grid operating company implemented to improve control and protection stepping into the new generation protocols IEC 60870-5-104 and IEC 61850. Paper 356 describes how the communication standard IEC 60870-5-104, which covers transmission over TCP/IP, is implemented at EDP Distribution a Portuguese distribution grid operator. In paper 421 from Sweden the use of a waveguide for IEC61850 communication with particular attention on the communication latency is studied. Paper 741 (Finland) looks in particular at how horizontal communication within IEC 61850, commonly known as GOOSE communication, between protection and control devices can be used to improve the reliability and performance of the system. Paper 843 from Germany gives requirements and accuracy definitions for a digital interface according to IEC 61850.

The goal of paper 368 (Spain) is to define and build a new communication architecture, in parallel to the electrical grid especially to support the demand management.

Finally Paper 641 (Spain) presents some general rules and criteria necessary to design a communication network over distributions grids correctly. The paper also collects main communication requirements needed for Smart Grids.

Cyber Security The lack of cyber security resilience endangers the reliability of the overall energy supply which is part of the critical infrastructure. So the protection of the IT-systems but in particular of the SCADA-systems against cyber attacks becomes more and more important for grid operators. Paper 247 (Germany) describes the new cyber security challenges for energy automation systems from the vendors point of view and proposes solutions on how to resolve them. Paper 473 from Austria asks the provocative question ‘how

to intrude a substation’ and of course gives answers how to establish a practical and secure IT-architecture in grid operating companies protecting all principal domains given in Figure 17.

Fig. 17: Logical domains dealing with information security

Paper 650 (Italy) presents results from real experimental cyber attacks on grid control systems. Attack processes are simulated and deployed in a laboratory test bed given in Figure 18. and their impact is evaluated by observing the application behaviour during ordinary maintenance and operation activities, as well as during the execution of highly critical defence actions.

Fig. 18: Attacked SCADA-system configuration

Paper 838 defines zoning principles for electricity distribution and energy production environments based on a Zone model given in Figure 19 designed to mitigate the risk of cyber attacks and to enable the secure integration

Fig. 19: Zone model for protection against cyber attacks

Paper 917 explores the evolution of SCADA-systems and



of critical infrastructures management under the perspective of the growing concerns with information assurance, security and reliability at EDP in Portugal. Paper 969 (Sweden) tries to understand the weaknesses of SCADA-systems by analyses based on appropriate graphical models of the system architecture. Potential scope of discussion − SCADA-systems are getting larger and larger and more

complicated. Is their a natural dead end for the systems and their operators?

− More MV and even LV-equipment means more secondary equipment to be maintained in the grids. Are the pros and cons really balanced?

− How much and which kind of communication is required by Smart Grids?

− Are cyber attacks on SCADA-systems a real danger or just a hip subject?

Table 2: Papers of Block 2 Control assigned to Session 3


MS p.m.

RIF PS

No.: 0047 Implementation Models of an IP/Ethernet Network to Allow the Delivery of New Generation Services in Substations

X

No.: 0073 Strategy and Planning to Improve Distribution Automation Assets Performance

X

No.: 0076 Third Generation Monitoring Systems for Electric Power Distribution Networks Lay the Foundation for Future Smartgrids

X

No.: 0142 Evolutions in the Elektrovojvodina Scada System for MV Network X

No.: 0144 Process of Simulating Novel Control Room Scenarios for Future Active Networks

X

No.: 0174 Detection of Ultra-Wide-Band Impulsive Noise in 400 kV Air Insulated Substation

X

No.: 0242 The Migration of Serial to Ethernet Communications – Why bother? X

No.: 0244 Ethernet Networks Redundancy with Focus on IEC 61850 Applications X X

No.: 0247 Cyber Security for Energy Automation Systems - New Challenges for Vendors

X

No.: 0322 Advanced Engineering Tools for Next Generation Substation Automation Systems – The Added Value of IEC 61850 and the Inpact Project

X

No.: 0328 A Novel State Estimation Method Based on Quality Tag for Distribution Networks

X

No.: 0356 IEC 60870-5-104 as a Driver to Evolution of Substation and Distribution Automation at EDP

X

No.: 0365 Supervision Dashboards to Monitor System and Network Performances at Local and National Level

X

No.: 0368 Demand Management Communications Architecture X

No.: 0372 Belgian Walloon Electricity Distribution Network : Turning Control and Protection into the Future

X

No.: 0396 New Technological Challenges Operating the 110 kV, 16.7 Hz Grid for Railway Power Supply in Germany

X

No.: 0421 Evaluation of a Waveguide System for IEC61850 Communication X

No.: 0439 Reduction of Supply Interruptions Duration by Means of Low Voltage Network Remote Control: First Results of Enel Distribuzione Experimentation

X X

No.: 0453 A Real Case of Self Healing Distribution Network X X



Block 3 Protection

Fault Location

The submitted papers deal with the fault location in case of short circuit as well as in case of earth fault. There exists no universal method which would be applicable to all types of networks and ground faults and would be able to localize the ground faults in MV network safely.


MS p.m.

RIF PS

No.: 0473 Intruding a Substation? - IT Network Security in Power Systems / Guide for Practical IT Based Architectures

X

No.: 0496 Towards MV Networks Automation X X

No.: 0519 Revitalization of Remote Control Centre at Elektro Primorska (Slovenia) X

No.: 0558 Distribution Automation for Back-Feed Network Power Restoration X

No.: 0587 Facing Challenges for Energy & Network Control Center X

No.: 0619 Applicability of Wireless Communication Technologies to Measurement on DENISE Electrical Distribution Network

X

No.: 0635 On the Field Autonomous Automatism: A Complementary Way for Network Automation

X

No.: 0636 Analysis of Asset Management System Integration Maturity at Distribution System Operators

X X

No.: 0641 How to Design a Communication Network over Distribution Networks X X

No.: 0650 Assessment of Power Control Systems Communications through Testbed Experiments

X X

No.: 0681 The Monitoring of Power System Events on Transmission and Distribution Level by the use of Phasor Measurement Units (PMU)

X

No.: 0687 A Comprehensive Secondary Substation Monitoring System X

No.: 0699 Real-Time Voltage Control Integrated in DMS X X

No.: 0722 Smart Substation and Feeder Automation for a Smart Distribution Grid X

No.: 0739 Safe Sitching in the Medium Voltage Grid between Substations X

No.: 0741 Utilizing Possibilities of IEC 61850 and Goose X

No.: 0744 Use of Information Generated by Remotely Controlled Medium-Voltage Distribution System Components

X

No.: 0770 From DA to SmartGrids - Evolution or Revolution? A Path to Improve the Utility Efficiency

X

No.: 0838 Zoning Principles in Distribution and Energy Production Enviroments X

No.: 0841 New Principles of Operating Electrical Distribution Networks with a High Degree of Decentralized Generation

X

No.: 0843 Digital Interface for IEC 61850. Requirements and Accuracy Definitions X X

No.: 0856 Wireless Telecoms for Distribution Networks based on WiMax X X

No.: 0912 Electric Grid Versus Data Network Architectures and Standards – Smartgrid as Plug&Play

X

No.: 0917 Security and Reliability over Critical Utility Infrastructures X

No.: 0942 Justifying Distribution Automation X X

No.: 0969 Issues of Cyber Security in Scada-Systems - On the Importance of Awareness

X X

No.: 1028 Applications Assessment of Pulse Closing Technology X



In Paper 161 from France a new generation of directional fault indicators used in MV underground networks is presented. The upgrade of the neutral point system in the MV system of ERDF demands a new detection algorithm.

Paper 293 from Spain describes a PLC Fault Location System used in underground cables of a MV network. The Communication is supported by a narrow Band PLC built in modems that couples the signal to the ground shield of the power cable. In case of short circuit and trip by the protective relay the master detector send the status of each detector in the system to the SCADA System.

Paper 299 from CZ discusses the detection of individual types of ground faults according to the analysis of electromagnetic fields of MV Lines using statical and dynamical methods. By using the telecommunication it will read out the data from individual indicators automatically and collect them into a database according to the requirements of the operator. When a complex data base will be available, it will be possible to evaluate the places with the most frequent occurrence of failures.

Paper 398 from Italy presents new developments in outdoor fault detectors.

Fig. 20: Fault detector complete equipment This detector for outdoor applications has been tested and is showing excellent results applied to both isolated and compensated distribution networks. In Paper 447 from Italy another outdoor fault detector with integrated current and voltage sensor is described. Including Overcurrent, cross country faults detection beside a directional phase to earth fault detection for insulated MV networks. Many thousands have been purchased by ENEL and are being installed, both in Italy and in Romania.

Fig. 21: Installation of cable fault detector Paper 464 from China describes transient current based earth fault locations in non-effectively earthed distribution networks. It is based on comparing the similarities of zero mode transient currents of faulty feeder, which is measured by the correlation coefficient. It does not require the measurement of zero mode voltage. The algorithm was tested in simulation using field data from an artificial fault with DAS of a 10 kV railway distribution network in Ganzhou, Jiangxi province, China. Paper 527 from The Netherlands derives from practical experience with fault location in MV networks. The Dutch grid operator Alliander puts effort in faster location of faults in this network. A fault location system was implemented in 10 substations equipped with the SASensor protection and control system. The search algorithm uses the momentary samples instead of FFT signals. Preliminary tests of this algorithm show promising results as is shown in Figure 22.



Fig. 22: Calculation of the fault impedance

Another way of detecting low- and high ohmic faults is presented in Paper 631 from Germany. The basics of the qu-algorithm where presented at CIRED 2003. There are some disadvantages of the standard qu-algorithm therefore the new qu2-algorithm was developed. The sensitivity against phase-splitting and the crosstalk from parallel systems are general problems of all protection relay. Field results show the effectiveness of this new concept for transient relays based on the qu2-algorithm.

In Paper 642 from Norway an efficient fault management using remote fault indicators is shown. The review in both traditional Fault Passage Indicators (FPIs) and the new methods supports the advantages by going from local indication to a remote indication. The interpretation of results is moved to the system operator who gets the complete overview during the fault situation.

Fig. 23: Downed conductor detection

Paper 675 from Croatia with the theme “Determination of earth faulted line with transient method” is a proven method based on the qu-algorithm. This paper shows examples based on earth fault tests that have been conducted in resonant grounded networks. This method can detect lowohmic earth faults selectively without any special demands on measuring transducers but its not reliable for highohmic and restriking earth faults.

Paper 973 from USA provides an update on the work performed to date with various utilities and fault location systems. Several different systems were evaluated. The Hydro Quebec system results indicate that the voltage-only fault location is also possible.

Paper 193 from China describes the simulation of a new method of single phase grounding fault location of distribution networks which are proven through lots of simulation results.

Neutral Grounding This part starts with paper 132 from China. Determining the 10 kV power grid developed rapidly in Shanghai Shinan. Based on the actual grid situation and the measured capacitive current of nine substations, a basic criterion has been concluded for adjusting the neutral point grounding mode from grounding through arc suppression coil to grounding through low resistance after having it analyzed technically. The criterion is instructive for selecting the neutral point grounding mode of newly built substations and the rebuilt ones.

Paper 305 from Austria describes a new improved algorithm which has been developed. Earth fault distance protection with distance protection relays is common practice in solidly grounded networks. The simulation shows, that this improved distance calculation provides very good accuracy up to earth fault transitions impedances of 1 kOhm and can be used in 2-phase networks as well. In Paper 345 from Austria the effects of the capacitive and inductive interference between parallel high voltage power lines depending on the neural point treatment of this grid is presented. Examples are given, practical investigations and an approach for optimization in a typical 220/110 kV grid is shown.

Paper 375 from Finland has studied earth fault protection based on neutral admittance. The results show that Y0 protection is a respectable alternative to traditional earth fault protection functions.

Fig. 24: Evaluation of the I0 cos(φ) criterion



Based on the theory and field tests, the admittance calculation should be based on changes in the zero-sequence quantities due to a fault, the novel Y0 characteristic should be used and the parallel resistor should be permanently connected.

Paper 397 from China describes an experimental study on extinguishing arc performance in different types of Arc Suppression Coils (ASC). The experiments show that the four kinds of ASC have are better able to extinct the grounding arc compared to that of electric network without ASC. In Paper 554 from Italy the neutral compensation and network monitoring is discussed. The latest experiences in the test application of the pulse injection techniques for determining the tuning conditioning compensated networks. This technique allows very simple and performing implementation for Petersen coil systems, independent from the coil type.

Paper 620 from Croatia evaluates a system on protection performance in resonantly earthed MV networks. An overview of the procedure implemented before putting Peterson coils in operation is given, with emphasis on the earthing system evaluation, which has proved to be rather important.

Fig. 25: Recorded transmission lines and transformer phase currents during single phase earth fault test

Paper 1004 from Portugal shows Artificial Neutral Points (ANPs) made by oil-immersed reactors which can be overstressed both mechanically and thermally. A number of failures have been reported, particularly in overhead line networks.

Fig. 26: 15 kV zigzag reactor with straight tank walls

The last paper in this sub block paper 1034 from Czech Republic, the influence of fault type on fault current in MV compensated network is discussed. There were damaged concrete towers in E.ON Czech Republic distribution network; the aim of an experiment was to measure electrical values during the fault. The first results of fault current and voltage analysis show that the longer operation of earth fault on unearthed console of concrete tower is very dangerous for the lifecycle of the towers.

Distributed Generation / Simulation This sub block contains four papers. Paper 649 from Finland describes the effects of the distributed generation on the earth fault protection of a MV feeder and protection coordination. Neutral isolated and compensated systems were considered.

Fig. 27: Model of MV system and DG unit The behaviour of the generator during the high speed automatic reclosing of the feeder is an important matter relating to electrical safety and protection coordination. In the second Paper 759 from Finland applications of modern communication technology to loss-of-mains (LOM) protection are discussed. In applications where the communication infrastructure and primary circuit lay-out supports the use of line differential protection of the interconnecting feeder, LOM protection can be realised in



a fast, reliable and selective way by utilizing the communication link of the line differential protection scheme for binary signal transfer signalling. The conventional passive techniques for LOM protection can be utilized as back-up or stand-by protection in case any abnormalities should be detected in the communication chain. In Paper 257 from UK the impact of wind farms on electromagnetic transients in 132 kV network, with particular reference to fault detection, was simulated in a number of cases. Results show that adaptive autoreclosing schemes may need particular attention when designed for DFIG connected lines, although the traditional approach of signal processing and AI is validated since the effect of fault parameters have far more significance then the generating technology concerned. In Paper 746 from UK the Prony method for the estimation of dominant inter-area oscillations modes in large power systems is presented. The main goal of this paper is to compare the dominant oscillations modes extracted by the Prony method with those obtained by Eigen-value analysis.

Fig. 28: Inter-area oscillation modes in a large system with a FSWF

Practical Implementation

The sub block practical implementation contains 23 Papers and show a big variety of practical experience.

Paper 36 from the USA compares operating characteristics of non-conventional current sensors, Rogowski Coils, and conventional iron-core current transformers for protective relaying applications.

Fig. 29: Current Transformer Connection to Relays

Fig. 30: Rogowski Coil Connections to Relays

Paper 56 from Egypt assesses the performance of over-current protective relays when a decaying DC component exists in the current signal. The Paper depicts how the characteristics of the relay can deviate more than expected. From those characteristics, three new performance indices are proposed. The method used for the assessment could be used in an analysis of protective system performance during system faults and also for selecting the proper relay for a specific application that requires the relay operation to be more independent of decaying DC components.

Paper 100 from India presents a fiber optics based sensing network applicable for fault detection in power system using PLC/SCADA technology. Paper 104 from Portugal presents a distributed generation protection scheme to permit “ride-through fault”.

Fig. 31: Voltage versus time profile



Fig. 32: Phase-to-Phase Voltage recorded

The main conclusions are that Distribution Utilities have to reduce their fault clearance time under 500 milliseconds at least when phase-to-phase voltage drops to 20% of the nominal voltage. This ride-through fault voltage profile has to substitute the current under voltage relay settings. In order to be user friendly the ride-through fault voltage profile must be included onto the digital protective relay.

Paper 168 from Czech Republic describes protection structures in MV networks, mainly the connection of instrument transformers (both inductive and electronic) and the measuring equipment used to analyze their signals. It summarizes the current situation and explains the way in which this structure could be optimized and the design of its components simplified.

Paper 199 from Brazil shows a protection system for the Co-Generation of methane gas connected to COPEL´s Distribution grid.

Fig. 33: Phase-Ground short-circuit test

After lab test results were approved, a panel with protection equipment was installed at Granja Colombari and short-circuit tests as real simulations were done on COPEL´s distribution system at the point of connection, as shown in Figure 33.

Paper 320 from France describes a modern SF6 RMU with circuit-breakers and integral self powered electronic relays. The main advantage for using RMU with fixed integral CB function is that it allows improved transformer protection.

Paper 347 from Japan shows a protection system for

Autonomous Demand Area Power System (ADAPS). In this paper an uninterrupted power supply method of 6,6 kV non-fault section using the LPC targeting 6,6 kV distribution line is proposed and demonstrates the fault operation method of the protection system for ADAPS.

Fig. 34: Expected future power system

Paper 360 from Italy describes the integration of DSO control system and TSO automatic load shedding system to improve the security of the national grid.

Fig. 35: Integrated remote and control system

The maximal delay time between a critical event on the national grid and the real load reduction is lower than 800 milliseconds. The positive results of the pilot project lead to an application plan to extend the application over the whole Italian territory.

Paper 504 from Austria describes the measurement of line impedance and mutual coupling of parallel lines to improve the protection system. Power lines are far from being symmetrical. The logical consequence of this seems to be that upcoming generations of protective relays will have individual impedance setting for all possible fault loops.

In Paper 623 from Czech Republic the interaction of



transmission and distribution systems is presented. The discussion points are protection settings and voltage control. The comparison between measurement and simulation shows the correctness of the used dynamic models.

Korea Electric Power Corporation (KEPCO) covers all power distribution lines in Korea. In Paper 629 from Korea the distribution protection coordination program using GIS schematics diagram is presented.

Paper 728 from Germany presents a network protection security assessment. This becomes particular necessary in case of networks with DG infeeds. The systematic protection security assessment includes variants of network and protection configuration and is feasible with restricted operating expenses.

Paper 729 from China describes an application of an in service setting of Micro-Processor based relays in China. The supporting system of in service settings for different kinds of substations is introduced. The technical and management measures to ensure the security of in service setting are presented.

Paper 733 from the UK describes how dynamic line rating is applied for load management and protection of the 132kV double-circuit line Skegness and Boston (North East of England) thereby enabling a larger penetration of wind generation. The rating of the line is calculated dynamically from local weather measurements.

Fig. 36: Measuring the conductor temperature

Fig. 37: Overview of weather station measurements

A protection relay has been developed which co-ordinates with E.ON Central Networks´ control system and provides backup in case the latter fails.

Paper 743 from Norway deals with the localization of phase-to-phase short circuits on a medium voltage feeder with distributed generation (DG). The methods are not meant for protection, only for fault localization. Thus, communication speed is not critical. Only current and voltage magnitudes need to be communicated. Measurements from the DG-node during fault can be utilized for deciding the most probable fault location when more than one candidate location is found.

Fig. 38: Two fault locations 20 km from the substation

Paper 764 from Finland describes the increasing cost-efficiency of substation automation systems by centralized protection functions. Technology developed and prototyped by ABB facilitates new centralized protection and control functionality for substations.

Paper 769 from Germany gives the criteria to operate the 20 kV networks of East Bavaria (Germany) with arc suppression coils according to standards. The investigation showed that for the tolerable touch voltage as well as for the earthing conditions at the sites, the decisive current has to be considered.



Paper 774 from the UK describes a new, economic and modernized version of the well known Cleveland protection / Time Limited Fuse (TLF) principle. The protection diagram has been redesigned and can now be used on all modern types of Medium Voltage Ring Main Unit switchgears with far less energy needed compared to the conventional TLF scheme.

Fig. 39: The new TLF protection scheme

Fig. 40: TLF protection accessible behind the front cover

Utility customers in the UK are working with TLF protection for several technical and economical reasons and are having good experience with this principle since the 1970´s. A modern version based on state-of-the-art components has been developed to improve the TLF protection.

Paper 903 from Germany describes a practical determination of protection settings for the utility Hof. In this paper the steps to perform a full revision of the protection settings of all protection devices in the medium voltage network from the utility Hof are detailed. This revision was caused by the change of the neutral treatment. Because of the complexity of the problem it is illustrated how software tools can support the planners during the

determination of protection settings and help to improve the documentation quality in the complete project.

The Paper 993 from Brazil presents performance analyses of distance protection and differential protection applied on 4 short transmission lines of ISA CTEEP, a Brazilian power transmission utility. The use of the Real Time Digital Simulation to evaluate the performance of distance protection and differential protection applied to short transmission lines demonstrates to be a very powerful tool, making the simulation of several situations on the power transmission system possible.

Paper 1064 from the USA presents the testing of multifunctional distribution protection relays. Testing of these devices requires good understanding of their functionality, the available tools and the purpose of the test.

Fig. 41: Distribution protection block diagram

IEC 61850 introduces new requirements for the testing tools – ability to simulate GOOSE messages from IEDs in a distribution protection scheme and to subscribe and monitor GOOSE messages published by the tested devises.

Fig. 42: IEC 61850 GSSE based IED functional testing

Paper 1065 from India examines the process of replacing the conventional high impedance (HiZ) busbar protection systems in substations with modern low impedance (LI) numeric busbar protection schemes. The study draws on



IEEE and CIGRE reports on deployment of numeric busbar protection, manufacturers´ literature, and National Grid´s own reliability studies, assessment of their policy for deployment of numeric busbar protection and operational experience of the operating personal. The paper also highlights some of the key issues, resulting from this study, which should be considered by National Grid before full commissioning of the modern busbar protection.

Potential scope of discussion − New algorithms and new generations of fault detectors

are designed. Is a new generation of protection systems required?

− Protection systems are interconnected with operation and control systems. How do the protection devices depend on the other systems?

− Combining protection, control and communication is a very powerful technique. What happens if one of these units is faulty?

− Distributed generation become more important in the future. How must DG and protection system work together?

Table 3: Papers of Block 3 Protection assigned to Session 3


MS p.m.

RIF PS

No.: 36 Comparative Performance Characteristics of Current Transformers and Non-Conventional Current Sensors

X

No.: 56 Impact of Decaying DC Component on the Characteristics of Over- Current Protective Relays

X X

No.: 100 Detection and Signalling System of High Impedance Faults in Transmission Lines Using Fiber Optic Sensing Network and PLC/SCADA Technology

X

No.: 104 Wind Park Protection Scheme to Permit “Ride-Through Fault” X X

No.: 132 Neutral Point Grounding Modes for 10 kV Grids in Shanghai Shinnan Area

X X

No.: 161 A New Generation of Directional Fault Passage Indicators for the ERDF Distribution Network

X

No.: 168 Protection of MV Networks Using Electronic Instrument Transformers

X

No.: 193 A New Method about Location for Line-to-Ground Fault in Small Current Neutral Grounding System

X

No.: 199 Protection System for the Co-Generation of Methane Gas Connected to Copel’s Distribution System Network – Tests and Procedures

X X

No.: 257 Impact of Wind Farms on Electro-Magnetic Transients on 132kV Network, with Particular Reference to Fault Detection

X

No.: 293 Underground Network Fault Location System Through Narrow Band PLC Technology

X

No.: 299 Identification of Ground Faults According to the Analysis of Electromagnetic Fields of MV Lines

X

No.: 305 Earth Fault Distance Protection X

No.: 320 Circuit-Breaker RMU Improves MV/LV Transformer Protection X

No.: 345 Displacement Voltages in Resonant Grounded Grids Caused by Capacitive Coupling

X

No.: 347 Development of Protection System for Autonomous Demand Area Power System - Demonstration Test of Isolated Operation Methods for Non-fault Section in Distribution Line Fault

X



Paper No. Title MS

a.m. MS p.m.

RIF PS

No.: 360 Integration of DSO Control Systems and TSO Automatic Load Shedding System to Improve the Security of the National Grid

X X

No.: 375 Performance of Novel Neutral Admittance Criterion in MV-Feeder Earth Fault Protection

X

No.: 397 Experimental Study on Extinguishing Arc Performance in Different Types of Arc Suppressing Coil

X X

No.: 398 Fault Isolation in Overhead Distribution Networks: New Developments in Outdoor Fault Detectors

X

No.: 447 An Innovative Integrated Current/Voltage Sensor for Outdoor Fault Detectors

X X

No.: 464 Earth Fault Location for Distribution Automation Based on Zero Mode Transient Current Correlation

X X

No.: 504 Measurement of Line Impedance and Mutual Coupling of Parallel Lines to Improve the Protection System

X

No.: 527 Practical Experience with Fault Location in MV Cable Networks X

No.: 554 Neutral Compensation and Network Monitoring – Test Field Experience in Determining Resonant Point and Homopolar Parameters with Active and Passive Pulse Injection

X

No.: 620 Earthing System Evaluation and Influence on Protection Performance in Resonantly Earthed MV Networks

X X

No.: 623 Interaction of Transmission and Distribution Systems from Voltage Control and Protection Settings Point of View

X

No.: 629 Distribution Protection Coordination Program using GIS X X

No.: 631 New Adaptive Algorithm for Detecting Low- and High Ohmic Faults in Meshed Networks

X X

No.: 642 Efficient Fault Management using Remote Fault Indicators X X

No.: 649 Improving the Operational Reliability of MV Distribution Network including DG Units applying different Protection Applications

X X

No.: 675 Determination of Earth Faulted Line with Transient Method X

No.: 728 Network Security Assessment – An important task in Distribution Systems with Dispersed Generation

X X

No.: 729 Application of in Service Setting of Micro-Processor Based Relays in China

X

No.: 733 Dynamic Line Rating Protection for Wind Farm Connections X X

No.: 743 Location of Short-Circuit Faults on a Medium Voltage Feeder with Distributed Generation

X X

No.: 746 Monitoring of Inter-Area Oscillations in Power Systems with Renewable Energy Resources Using Prony Method

X X

No.: 759 Applying Modern Communication Technology on the Loss-of- Mains Protection

X

No.: 764 Increasing Cost-Efficiency of Substation Automation Systems by Centralised Protection Functions

X

No.: 769 Definition of Criteria to Operate 20kv-Networks with Arc Suppression Coils According to Standards

X X




MS p.m.

RIF PS

No.: 774 Modern Redesigned Time limit Fuse Protection for Medium Voltage Distribution Circuit-Breakers in Ring Main Units

X

No.: 903 Protection Setting Simuation and Documentation within the Network Planning Tool PSS(R)Sincal

X

No.: 973 Update on Distribution System Fault Location Technologies and Effectiveness

X X

No.: 993 The use of Real Time Digital Simulation for Performance Analysis of Distance Protection and Differential Protection in Short Transmission Lines

X

No.: 1004 Neutral Earthing Through Reactors in Aerial Distribution Networks X X

No.: 1034 The Influence of Affected Phase on Fault Current in MV Compensated Networks

X X

No.: 1064 Testing of Multifunctional Distribution Protection Relays X

No.: 1065 A Survey on Performance Evaluation of Low Impedance Numeric and High Impedance Busbar Protection Schemes

X X

special report-s3

Education