tso-dso interaction in power systems with high res...

TSO-DSO interaction in power systems with high RES penetration

ISGAN & IEA PVPS workshopVienna 18/05/2015

Sébastien Grenard

Context

DSO-TSO cooperation has become high on the EC agen da priorities

Series of internal TSO-DSO knowledge sharing worksh ops planned during the first half of 2015 between ENTSO-E and t he 4 DSOs’ associations

Topics: Flexibility, Active and Reactive Power Management, Data management

Development of European Grid Codes/Guidelines by EN TSO-E Connection codes: RfG (Requirements for Generators), DCC (Demand Connection Code),

HVDC (High Voltage DC)

Operational codes: OS (Operational Security), OPS (Operational Planning and Scheduling), LFCR (Load Frequency Control and reserves), E&R (Emergency and Restoration)

Market codes: EB (Energy Balancing), CACM (Capacity Allocation and Congestion Management), FCR (Forward Capacity Allocation)

“Technical” interface between TN and DN throughout Europe

Source: Eurelectric

Distribution Grids operated by DSOs vary throughout Europe

“Technical” interface between TN and DN throughout Europe

�Limit between transmission and distribution in term s of operated voltage level covers a wide range (20kV – 150kV)

�Distribution networks of larger DSOs are usually di rectly connected to the Transmission grid

�Many small DSOs are only connected indirectly to th e Transmission grid via Distribution grids of the larger DSOs

�Some member States have a large number of DSOs with many DSO-DSO interfaces

The DSO landscape is diverse

Source: Eurelectric

Main current technical missions (non exhaustive)

Transmission network

Distribution network



Interconnexions

TSO

Dispatching Control Center

DSOs

Control Center

System missions

• Balancing generation and load in the LFC area (real-time + reserves)

Network development and operation missions• Planning / New Connections• Network operation (operational security)

• Operational planning• Real time operation• Emergency and Restoration

Network development and operation missions

• Planning / Grant access to their network• Network operation (operational security)

• Operational planning• Real time operation• Emergency and Restoration

Final customers “metering” missions

Future coordination required for Balancing





InterconnexionsDispatching Dispatching

dispatching

Balancing will require a suitable coordination betw een TSO and DSOs• Presence of a high share of production connected to distribution networks• New load types/behaviour• In the future: use of flexibilities from distribution network users

Real-time observability

• Improved Distributed Generation observability

Development of new forecast

tools

• Renewable power production forecast (PV, wind, ..)

• « Local » Consumption forecast

Scheduling• Exchange of information on market

scheduling

Example on next slide

French Example on improved PV and wind farmmonitoring: « IPES »

Distribution control Centre

Wind Farm

P (ACR)

CharacteristicsAgregationsarchivesForecasts,…Wind farms file

MV feeder dedicated to Wind generation (CEI 104 protocol)

HV/MV primarysubstation

*DEIE: DER dedicated RTU

A platform has been developed by RTE (TSO) with ERDF (DSO) in order to help the TSO reach an adequate

observability level of DG connected to the MV network:• Active power of MV dedicated feeders (derived on a 1 minute basis)

• Data used by the TSO for real-time operation and to feed in a power production forecast model

• Results of power production forecast are sent back to the DSO

Work is undergoing by ERDF in order to develop its own local power production forecast (for wind farms and

PV plants connected to its network). • Such new development could lead to an improvement of the existing scheme.

TSO-DSO Coordination for « Flexibility » procurement

More and more intermittent resources in the electri c systems � new needs for energy balancing could be required in the power system

New type of resources/flexibilities will be enabled by the rise of new technologies� Demand flexibility, Distributed Energy resources flexibility, storage

A large part of this flexibility will be connected to Distribution networks� a major role will be played by DSOs in future balancing activities

This flexibility connected to distribution networks could be either used for– TSO's balancing actions, – For local management of transmission networks (grid constraints) and/or for local management of

distribution networks.

� The use of these balancing flexibilities should not add risks to DSOs and TSOs missions (operational security of their network)

Therefore, an improved TSO/DSO coordination will be required for the use of this flexibility in both cases:

i. use of flexibility for TSO's balancing or for transmission network management action will impact distribution networks operation (--> TSO/DSO coordination required)

ii. use of flexibility by DSOs for local network management could impact the global system balancing (--> DSO/TSO coordination required)

Network development and planning

Based on maximum loading assessment (max consumptio n assessment on Transmission and Distribution Networks) and associa ted power factor:

� Leads to transmission and distribution network investment : existing coordination between TSO and DSO for interface substations development/reinforcement

� Leads to reactive power means investment : existing coordination between TSO and DSO usually based on contractual/financial incentives at the interface and based on historical requirements





Interconnexions

Better knowledge of the network available capacity at the interface can help/speed up DG connections

However, several new trends will require new coordi nation and information exchange between TSO and DSOs:

1) Connection of Distributed Generators to Distribution networks � lead to local connection investment� for high penetration, impact on the network capacity of upper voltage levels� Availability of reactive power capacities depending on technologies

2) MV and LV underground cables (impact Q transits and Voltage profiles)

• Voltage rise issues arising on both Distribution & Transmission networks• Improved exchanged of information between TSO and DSO will help investment decisions (example: length of MV underground cables)

TSO-DSO Coordination and network capacityinformation

French Example: « Capareseau »

• The French TSO (RTE) and the French DSO (ERDF) have worked together in order to develop a

public website: http://capareseau.fr/

• Objective: illustrating the existing and future network capacity of both transmission and

distribution networks (at the HV/MV substations level) for distributed generation connection.

• Anyone can access the information on the available hosting capacity of the network before

launching a new generation plant development project.

• This tool has been developed for high-level informative purposes: it does not replace any of the

steps within the existing official process for network connection granting.

Transmission and distribution systems operation (1/2)

TSOs and DSOs must have the suitable information to ensure the operational security of their own networks. To do s o, each network operator:

- develops its protection & automation schemes- monitors and controls their own network and their own Grid Users

� Direct actions from TSOs on distribution network users could jeopardize the operational security of distribution networks� Interactions between DSO and TSO are essential (before activation of any flexibility on the distribution network)

Secured telecommunication channels required between the TSO and the DSOs’ control centers for the activation of any acti ons in real-time





Interconnexions Dispatching Dispatching

dispatching

Transmission and distribution systems operation (2/2)

Operational planning

•Exchange of information and coordination on Significant Grid Users availablities / schedules and on network maintenance periods

•Exchange of information on consumption and generation forecast•DSOs will require information to perform constraint detection, including operation schedule and activation (in energy balancing market, ancillary services market, capacity market,…) of generators and/or customers connected to the distribution network and offering market offers.

« Real-time » operation

•Exchange of information to ensure operational security•Example for TSOs: P and Q transits at the interface / Reactive power compensation on DN•Example for DSOs: short circuit current and voltage angle on HV busbars of primary substation for real-time MV network reconfiguration studies,

Emergency and

Restoration

• Coordination between TSOs and DSOs has historically been a cornerstone for the implementation of system defence plan as a large number of defence actions are taking place in DSOs network

•With the growth of distributed generation connected to distribution systems, existing emergency actions would need to evolve and new emergency actions could be required in the future (LFDD, interface protection,...)





Interconnexions Dispatching Dispatching

dispatching

Improved coordination through information exchange

� The TSO and DSOs exchange relevant technical data f or current distribution and transmission system operation, however the in crease of DG and flexibility market players requires further informa tion exchange between operators. � Operationnal planning coordination at different time s frames will be key

� Three main stages for the coordination:

Network development

Operational planning

Real-time operation

� Three types of information for coordination :• Type 1: information used for a coordinated operation and control of the networks,

close to real time• Type 2: information used for medium term or long term purposes: management of

connection requests, planning,…• Type 3: information regarding market operation: energy market, ancillary services

markets, load shedding market, capacity market, …

DSO(s)TSO DSO(s)TSO DSO(s)TSO

Conclusion

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