Power Application Software UPDEA - Workshop

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Power Application SoftwareUPDEA - Workshop
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What are Power Application Tools?

• Name as many of the Power Application Tools as
  you can

• Power Application Software (1)
• State Estimator (SE)
• Operator Load Flow (OLF)
• Optimal Power Flow (OPF)
• Contingency Analysis (CA)
• Short Circuit Analysis (SCA)
• Automatic Generation Control (AGC)
• Historical Information System (HIS)

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Power Application Tools (2)

• Power Application Software (2)
• SCADA Topology Determination
• Plausibility Check of Measurements
• Power System Model Adaptation
• Power System Security Analysis
• Study Base Case Initialisation
• Transient Stability Analysis (TSA)
• Voltage Stability Analysis (VSA)
• Available Transmission Capacity
• Complete Model Estimator (CME)
• Dynamic Security Assessment (DSA)
• Dynamic Stability Analysis

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PAS Applications

• The PAS subsystem consists of applications that
  support
• Real-time and study mode network analysis
• Determining the state of a power system network
• Level of security,
• How the security and economics of the network
  might be improved.
• The PAS applications run automatically using data
  originating from SCADA
• Study applications are run by the operator or
  planning engineers, to study the effects of
  changes in the power system.
• Study data can be initialized from a real-time
  network solution, or from archive files.

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PAS Tool Data flow

• Where do the Power Application tools get their
  data?
• What is data path from the substation to the PAS
  tools

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PAS Applications
What are the two primary sub tasks of the State
Estimator?
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State Estimation

• Real-Time Network State Estimation - (RTNET)
• Performs topology processing
• Estimation the network state
• Includes busload forecast and transmission loss
  sensitivities calculation

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State Estimator

• Produce valid topology and real time network
  solutions for all network apps.
• More reliable and more accurate than raw SCADA

When and how often will the State Estimator run?
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State Estimation

• Runs on a periodic basis, i.e.
• Usually every 5 minutes
• Each time a switching device such as a breaker or
  isolator changes state

1. What is the output of a State Estimator run ?
2. What is the output used for?

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State Estimation

• RTNET produces an Estimated State of the power
  system based on SCADA measurements using a least
  squares fit algorithm.
• Once RTNET has run to completion the following
  applications can run
• Power Flow (PWRFLOW)
• Optimal Power Flow (OPF)
• Contingency Analysis (RTCA)
• Dynamic Stability Analysis (VSAT / TSAT)
• Voltage VAR Dispatch (VVD)
• Short Circuit Analysis (RTSCT)
• Security Enhancement Analysis (SENH)

1. What is the purpose of Study Power Flow?

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Power Flow

• Allows control staff and planners to study the
  steady-state operation of the power network under
  hypothetical and postulated conditions
• Study how the power flows through the network
  before taking lines out for maintenance and what
  - if future scenarios

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Power Flow
The solution is a MWs and Mvar balance of Load
against Generation.

1. How do control staff make changes Study Power
   Flow?
2. How are the results of the study seen?

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• Changes to the network topology can be made by
  changing the status of circuit breakers on
  one-line diagrams or tabular displays.
• Results of Power Flow analysis can be displayed
  either on one-line diagrams or in tabular form.

What PAS tool makes recommendations on how to
optimise the grid?
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Optimal Power Flow

• Optimal Power flow -
• The primary purpose of optimal power is to
  provide control staff with network configuration
  recommendations that will eliminate or reduce
  violations and/or move the network to a more
  economical operating state.
• The primary function of OPF is to determine and
  present optimal, feasible device settings.
• These settings are calculated based on the
  network model, control model, objective function
  model, and operating limits.
• The presented control settings should correct
  (or, if not possible, reduce) any violations of
  operating limits and optimize the objective
  function while maintaining feasibility.

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Contingency Analysis
400 kV Line Outages Avon Mersy1 Mustrun Avon
Mersy Mustrun Mersy_Rabbit Mustrun Avon_Illov Must
run Illovo_ Mersy Mustrun 400 kV Load
Outages Mersy Load 1 Mustrun Rabbit Load
2 Mustrun Rabbit Load 3 Mustrun

• Contingency Analysis -
• Assesses the impact of potential changes in the
  network, such as equipment outages, on the state
  of the power system.
• The application runs in the real time and study
  environments.

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Outage Scheduler

• Outage Scheduler
• The Outage Scheduler provides the capability to
  schedule equipment outages or derations.
• The outage schedules are used by the study
  applications to study system conditions at a
  particular time, taking into account the
  necessary topological or rating changes.

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Security Enhancement

• Security Enhancement -
• A set of optimization algorithms that recommend
  operator actions for moving the system to the
  most secure and efficient operating point given
  the specified constraints. It includes
  Constrained Dispatch, Contingency Planning, and
  Preventive Action.
• The application runs in the real-time and study
  environments.

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Voltage-Var Dispatch

• Voltage-Var Dispatch
• Runs as part of the real-time sequence.
• Recommends reactive/voltage control changes to
  minimize MW losses, or to correct voltage
  violations.

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Voltage-Var Dispatch

• Voltage-Var Dispatch (VVD) is a real-time version
  of the study Optimal Power Flow application.
• It runs as part of the real-time network
  sequence, uses only reactive power and voltage
  controls, and is initialized from the results of
  the state estimator.
• If the state estimator found voltage violations,
  VVD will attempt to correct the violations with
  minimal reactive power control changes.
• If no voltage violations were found, then VVD
  will attempt to minimize MW losses using reactive
  power controls.
• Resulting control change recommendations are
  presented to the dispatcher as advisory
  recommendations.

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Short Circuit Analysis

• Short Circuit Analysis
• Calculates short circuit currents that result
  from specified faults.
• The Short Circuit analysis program requires a set
  of fault definitions in the FAULTS database
  before execution can begin.

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Study Network Sequence

• Study Network Sequence -
• The Study Network Sequence is an integrated
  environment for in-depth studies.
• It includes Economic Dispatch, Power Flow,
  Optimal Power Flow, and Contingency Analysis
  functions that can run in sequence.
• The Study Network Sequence is initialized either
  from the real-time system, from other study mode
  functions, or from archive.

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Online Dynamic Security

• VSAT
• Voltage Security Assessment Tool
• TSAT
• Transient Stability Assessment Tool

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VSAT Purpose

• VSAT is a tool to assess power system voltage
  stability
• It allows the user to specify multiple scenarios
  on the network to analyze
• Inputs are power flow data, contingency
  definitions, security limits, transfer
  definitions.
• The outputs are MW transfer limits, critical
  contingencies, PV curves

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VSAT Features

• Part of an automatic run sequence to cater for
  changing loads
• High speed analysis on a dedicated server
• Event driven such as change of system state
  (equipment failure, generator redispatch)
• Manual such as on instruction from an operator
• Transfer limit or base-case security analysis
  using the following criteria
• Voltage stability margin
• Voltage decline
• Reactive power reserves
• Thermal overloads

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TSAT Purpose

• TSAT is a tool to assess power system transient
  stability
• It allows full time-domain simulations of large,
  complex power systems
• Inputs
• Powerflow data
• Contingency definitions
• Transfer definitions
• Security criteria
• Analysis and solution options
• Outputs
• Transient stability index
• Damping Index
• Voltage duration index
• Frequency duration index
• Relay margin index

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TSAT Features

• Quick screening of contingencies, in order to
  minimize number of contingencies to be analyzed
  in detail
• Security analysis using the following criteria
• Transient stability
• Damping
• Transient voltage
• Transient frequency
• Relay margins

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VSAT and TSAT Uses

• Helping the operator in deciding whether or not
  to run a power station in Emergency Level 1 due
  to its impact on the transfer limit
• Deciding on the next worst contingency that could
  lead to a voltage collapse during an outage and
  the amount of load that must be shed to mitigate
  this after implementation of all remedial
  measures.
• Determining safe generation limits due to an
  outage of a line at a power station

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State Estimator Problem

• Problem
• Due to the way in which the topology model is
  evaluated, the line was seen to be in service
• It was carrying Mvars only and thus deemed to be
  in service even though the breaker was open.
• Lesson add logic that can differentiate between
  open lines and Mvar only states

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Principles of Automatic Generation Control
Dead Bands Hz 49.85 50.15 ACE /-
70 Spinning 1000 MW 10 minute 500 MW
Error Desired - Instantaneous
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Questions