Download Power Application Software

Power Application Software
UPDEA - Workshop
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)
1
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
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.
2
PAS Tool Data flow
•
•
Where do the Power Application tools get their data?
What is data path from the substation to the PAS tools
RTU
Live
SCADA
Data
Host I/O
Network
connectivity
models
State
Estimator
Power
Flow
Short
Circuit
Analysis
Contingency
Analysis
500
280
Power Application Software
PAS Applications
Real
Time
SCADA
Load
Forecast
Alarm
Processing
AGC
SCADA Data
Base
CA
State
Estimator
Rear Projection
System
Control Staff Workstations
HMI x 8 + 40
SC
Export to
Dispatcher
Training
Simulator
Power
Flow
Voltage VAR
Dispatch
Voltage
Security
Security
Enhancement
Power Application
Software
Fire
Wall
Transient
Security
Export data
to
Corporate Users
What are the two primary sub tasks of the State Estimator?
3
State Estimation
Real-Time Network State Estimation - (RTNET)
1. Performs topology processing
2. Estimation the network state
Includes busload forecast and transmission loss sensitivities calculation
State Estimator
Avon
Z = 100 ohms
1
160
Mersy
300 MW
2
160
400 kV
Σ
• Produce valid topology and real
time network solutions for all
network apps.
• More reliable and more accurate
than raw SCADA
395 kV
Loads at a bus = 0
When and how often will the State Estimator run?
Instantaneous SCADA values
Bus kV, Line MWs and MVAr
limit values exceeded
Estimated values based on
Kirchoff’s and Ohm’s Laws
4
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?
State Estimation
1. RTNET produces an Estimated State of the power system based on
SCADA measurements using a least squares fit algorithm.
2. 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?
5
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
Avon
Z = 100 ohms
Mersy
Load
Gen
1
150
300
300 MW
300 MW
2
0
150
400 kV
395 kV
Load
Generation
Power Flow
The solution is a MWs and Mvar balance of Load against Generation.
Gen
Mvar
MW
Solved
System
Generation
Gen
MW
Load
Mvar
Load
MW
Load
MVAr
MVAr
Load
MW
Fixed
Instantaneous
System Load
Error
Iterations
1. How do control staff make changes Study Power Flow?
2. How are the results of the study seen?
6
• 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?
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.
7
Contingency Analysis
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.
400 kV Line Outages
Avon – Mersy1
Avon – Mersy
Mersy_Rabbit
Avon_Illov
Illovo_ Mersy
Mustrun
Mustrun
Mustrun
Mustrun
Mustrun
400 kV Load Outages
Mersy Load 1
Rabbit Load 2
Rabbit Load 3
Mustrun
Mustrun
Mustrun
Mersy
150 MW
Avon
Rabbit
Load 2
Load 1
Gen
1
450 MW
2
140 MW
250
160 MW
200
Load 3
300 MW
400 kV
397 kV
395 kV
Illovo
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.
8
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.
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.
9
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.
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.
10
Study Network Sequence
Study Network Sequence – The Study Network Sequence is an integrated environment for indepth 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 realtime system, from other study mode functions, or from archive.
Online Dynamic Security
•
•
VSAT
– Voltage Security Assessment Tool
TSAT
– Transient Stability Assessment Tool
11
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
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
12
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
•
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
13
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
State Estimator Problem
On Load – caring MWs and Mvars
Off Load – caring Mars only
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
Unit Control System
Control
Plate
Set point
600
580
High
550
Low
Auto/Man
Normal speed is
50 revolutions
a second (+/-)
Power sent to Transmission
Steam flow
Steam
flow
valve
Turbine
CPU
GEN
AGC
ERTU
49.875
Memory
12 v
New set point target
sent to Generator
HV yard
ERTU
CPU
Memory
12 v
Instantaneous
Output & Hz
readings
Dead Bands
Hz
: 49.85 – 50.15
ACE : +/- 70
Spinning :1000 MW
10 minute : 500 MW
TEMSE AGC
Error = Desired - Instantaneous
Questions
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