PSSC 500 PSSE Introduction to Power Flow and Steady State Analysis_PV QV analyses

PSSC 500 PSS®E Introduction to Power Flow and Steady State Analysis.The PSS®E Power Flow and Steady State Analysis courseis designed to familiarize new users with the Power Flowand Fault Analysis features of the PSS®E program.Participants gain experience through handson exercises.

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Tab 12 – PV & QV Analyses

V

PV Curves

Investigate relationship between power transfer and

voltages

As transfer (or load) increases, system reactive

consumption increases and voltages fall

Find maximum power transfer level before voltage

collapse – knee of the curve

Perform many power flow solutions and plot results

Knee of the Curve

Transfer Limit

PV Analysis Procedures

Prepare power flow base case

Run DFAX to input subsystem, monitored element and

contingency description files

Select PV analysis options

Initiate calculations

View graphical results

PV Analysis Run Options

Power

Flow

Solution

Transfer

Dispatch

Method

Stopping Criteria

Input & Output Files

Subsystem Selection Transfer Increment

Solution engine – FDNS, FNSL, optimized FDNS

Automatic adjustments options for base case &

contingency case – taps, area interchange, switched

shunts, etc

Generator var limit

Mismatch tolerance

PV Analysis – Power Flow Solution

Options

PV Analysis: Transfer Dispatch Methods

Subsystems - source &

sink (from DFX file)

Dispatch methods:

DFAX generation

and/or load

Scale by machines

MW, MBASE, reserve

(PMAX-PGEN)

Observe MW Limits

Economic dispatch

(ECDI) file

Initial transfer increment - Adjust “dispatch” in source &

sink by normal step size

Tolerance - If solution at normal step fails to converge,

retry from last converged point using binary search

technique

Negative minimum incremental transfer allowed - Extend

PV curve below zero transfer level

PV Analysis: Transfer Increments

PV Analysis – Stopping Criteria

“Transfer increment tolerance” reached

“Maximum incremental transfer” reached

“Minimum monitored bus voltage” reached (optional)

List of buses defined in MON file Note: Does not use

voltage limits in MON file

“Branch loading threshold” reached (optional) List of

branches defined in MON file

Select

Graph

Type

Select Base & Cont Cases

Select Bus

or

Generator

PV Analysis - Graphical Output

Data Points for Curve Selected

More Graphics for PV / QV Analysis

For multi-graph

Curves can be displayed singularly or together

Exporting PV/QV Results to Excel

Select data/results to

export:

PV or QV Solution Results

Define data/results file

Define Excel workbook

file

Select quantities to

export

Select Contingencies

Retrieving PV Analysis Results from a File

All run options retrieved from

Model a Given Transfer Level

Use transfer adjustments similar to those in PV analysis Choose a desired incremental transfer level

Changes will be applied to base case to create a new

power flow at desired transfer level

Suitable for detailed investigations after PV analysis

QV Curves

Useful tool for analyzing voltage collapse

Develop curves for critical buses by running a series of

power flows

Model synchronous condenser and vary voltage

setpoint

Solve power flow and observe MVar output

Reactive reserve is difference between reactive supply

(Q=0) and minimum point on QV curve

QV Analysis Procedures

Prepare power flow base case

Run DFAX to input subsystem, monitored element and

contingency description files

Select QV analysis options

Begin calculations

View graphical results

QV Analysis Run Options

Power

Flow

Solution

Options

Select

Study Bus

Input &

Output

Files

QV Analysis – Starting and Stopping

Sets study bus voltage at VHI and solves power flow

Decreases voltage setpoint in steps of DLTAV and

resolves

Stops when solution fails to converge or voltage setpoint reaches VLO

QV Analysis Output Options

Select Base &

Cont Cases

Display Q-V Data Points

Y-axis Elements Selected

Problem 12-1 Q-V Analysis

Determine the minimum reactive compensation needed to maintain converged

power flow solution at Bus 205 when generator at Bus 206 is outaged.

1 Pick up case EXER12-1.SAV.

2 Use Q-V Analysis to create Q-V curve at bus 205.

Use EXER12-1.SUB, EXER12-1.MON, EXER12-1.CON to create DFX file.

Select VHI=1.05, VLO=0.7, and DLTAV=0.01.

Select Fixed Slope Decoupled Newton Solution method, applying var limits immediately.

Leave other solution options at default settings.

Change plot range for V-axis to 0.7 and 1.1.

Change plot range for Q-axis to 600 and 1000, with Grid Step of 50 Make sure “Axis (grid start) place” is at “Bottom.”

3 Based on the curve, what is the minimum shunt compensation required to prevent

voltage collapse at Bus 205 during outage of generator at Bus 206 (the only

contingency defined in EXER12-1.CON)?

Problem 12-1 Q-V Analysis (continued)

Contingency of this generator