PMU Communication Network Analysiswhat - why - how <=> with PMU existence

CS620: New Trends in Information TechnologyCourse Seminar Presentation

ByGelli Ravikumar & Kedar Khandeparkar

Roll No. 114070015 & 114076011

Course InstructorsProf. Krithi Ramamritham & Prof. Purushottam Kulkarni

Department of Electrical EngineeringIndian Institute of Technology Bombay

February 10, 2013

Outline

Talk by Gelli

PMU basics in nutshellPMU Communication Network Analysis - Discussing 2 papers

Talk by Kedar

PMU Communication Network Analysis - Discussing 2 papers

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PMU Exam (Quiz)? [PMU basics in nutshell]

What do I (PMU) do ?

How am I (PMU) exactly connected to power system network ?

Can I (PMU) measure current phasor of two different lines ?

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Key [PMU basics in nutshell]

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Gelli’s Discussion on 2 papers

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Abstract view of papers

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Analysis of communication network infrastructure to meet thebandwidth and latency requirements of Power System Applications

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Glanse of delay requirements

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Types of traffic considered

All the Substation (S/S) to Control Center (CC).CC to Control Substation (Generating station and substation havingcontrol units like transformers and reactors).Special Protection Scheme (SPS) substation to SPS.Generating substation to Generating substation.SPSs to CC.CC to CCPMU Communication Network Analysis Gelli Ravikumar 9 / 31

Inputs and Outcomes

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Methodlogies in nutshell

Created simulation scenarios for WAMS applications individually

Communication infrastructure is common for all scenarios

A hybrid scenario is simulated in which all the applications runsimultaneously on the same network infrastructure

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Communication infrastructure for the simulation inOMNET

120 PMUs placed in eastern USgrid.

Two PMUs, relays, and circuitbreakers over a 100Mbps Ethernet.

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Outcomes

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Kedar’s Discussion on 2 papers

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Purpose of the paper:

To provide illustrations on PMU communication networks with a specialfocus on centralized applications, which envisages and supports thetransmission system operators (TSO) while deploying physical PMUcommunication networks.

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Paper Contributions:

A brief review on WAMC architectures and its components, andvarious delays incur to the control center applications is presented.

As a case study, an equivalent model of Swedish TSO is consideredThe model includes geographical distances between PMUs, routers,etc.

The model is simulated in OPNET for two scenarios: (i) with and (ii)without considering PDC sorting and timeout concepts.

Briefed the PDC timeout concept

Lastly, the paper has presented the End-to-End delays of all PMUsand control commands for different channels.

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Snapshot of swedish Network TSO

The octagons on the maprepresent subnets (logicalgrouping ofcommunication networks).

The core subnets, core1and core2 represent anetwork of meshed routers

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Result 1:End-to-End delays of all PMUs and controlcommands for different channels

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Time outs in PDC

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Result 2: Illustrations of delays and timeouts

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Purpose of the paper:

To demonstrate the consequence of delayed input data in WAMC systemsand the performance requirements this poses on time available for decisionmaking and control actuation.

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Paper Contributions:

A brief review on the possible delays occur in a complex data transferis presented

In order to detect its maximum tolerated delay, a few simulations arecarried out iteratively by importing delayed Phasor measurements tothe set up made with Static Var Compensator (SVC).

From the simulation results, an analysis on the performancerequirements of applications for the centralized computation andcontrol actuation is presented.

Moreover, a feasibility study on compensations used in Power SystemStablizers (PSS) in situations with much phasor data delay ispresented.

Lastly, the authors have suggested a ICT architecture for WAMCsystems aiming to improve its robustness.

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Possible Delays

1. Data propagation time

It is the time after full message has been sent from the sender, until it hasreached the receiving node.The propagation speed depends on the physical medium of the link (thatis, fiber optics, twisted-pair copper wire, etc.) and is in the range of 2 ∗ 108

meters/sec for copper wires and 3 ∗ 108 for wireless communication.Propagation time = Distance / propagation speed

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Possible Delays

2. Transmission time

It is the amount of time from the beginning until the end of a messagetransmission.In the case of a digital message, it is the time from the first bit until thelast bit of a message has left the transmitting node.Packet transmission time = Packet size / Bit rate

3. PDC sorting time

It is the time required to sort all the received PMU data packets accordingto the specified configuration.

End to End Time delay

TETE = TWAN +Min(Max(TWAN )|TTO)

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Test Bed Implementation

Considered network for the test bed is,

The network model (from the famous Kundur book) consists oftwo fully symmetrical areas that are connected by two parallel 230 kVtransmission lines.two identical round rotor generators are located in each arearespectively

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Remote signal based SVC

The goal of the set up is to maintain the voltage stability of theconsidered network by monitoring the signals speed (ω) andaccelerated power (Pa).

The rotor speed ω and acceleration power Pa are monitored by PMUplaced at each generator bus.

The data is used to provide a supervisory controlling action on theSVC deployed at a bus.

A Static Var Compensator (SVC) controls the reactive powerinjections in order to maintain good voltage regulation profile.

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What happens if delayed phasors are present ?

Observations: the oscillation grows as the delay increases.When the 69ms time delay reaches: the oscillation can not becontrolled even by the SVC.

Therefore, for this specific network and WAMC system, the maximumtime for the decision making computation and control actuationshould be around 21.5ms (assumed value by all the communicationnetwork delays is: 47.5 ms).

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simulation result with PSS

Applied the same simulation scenario with the largest tolerated delayof 69ms.

With the power system stabilizer (PSS), the system is stabled withdelayed phasors of 69ms.

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Future work

Generalized methodology to compute latency and bandwidthparameters.

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Thank You...

Any Queries:gravikumar@iitb.ac.inkedar.khandeparkar@gmail.com

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