Voltage Stability

Manu Parashar, Vijay Sukhavasi (Alstom)

Dino Lelic, Guorui Zhang (Quanta Technology)

Ron Markham, Vahid Madani (PG&E)

WECC JSIS Meeting

Salt Lake City, June 12th, 2013

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EMS & Online-DSA Applications

VSAT

CA

RAS

A Hybrid Approach to Voltage Stability Assessment An integrated “measurement-based” and “model-based “ approach

Real-Time Voltage Instability Indicator (RVII) Detect WHEN in danger!

PMU measurements

Estimate equivalent parameters in real-time

PMUs Real-Time Voltage Instability Indicator (RVII)

Predict HOW to respond….

Bus Voltage (V) Equivalent Impedance (Zeq) Reactive Margin (Qmargin)

Predict Qmargin changes under “worst case” contingency.

Provide recommendations on corrective actions.

MEAS

UREM

ENT-B

ASED

MO

DEL-B

ASDE

D

Measurement-based voltage stability monitoring applicable to the following scenarios:

- Bus (with measurements at the local bus)

- Corridor (with measurements at both ends

- Load Center (with measurements on all tie lines)

Real-Time Voltage Instability Indicator (RVII)

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Bus

Corridor

Load Center

Validating RVII at PG&E’s Proof-of-Concept (PoC) lab

Impact of PMU observability on tracking Qmargin using RVII: - CASE 1: PMUs at both sending & receiving ends (--)

- CASE 2: PMU at sending end only (--).

- CASE 3: PMU at receiving end only (--).

Consistent results!

RVII Engineering User Interface (UI)

Monitored Corridors

Monitored Busses

Real Time PQ Curve and P,Q Operating Point

Real Time Voltage(kV)

Real Time Equivalent Impedance and Load Impedance(p.u)

Real Time Active Power(MW)

Real Time Reactive Power(MVAR)

Input Frame Rate Display Duration

Monitored Bus or Corridor Status/Alarms

Historical Data Settings

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Real Time Chart Display

Real Time Bus and Corridor Status Monitor

Real Time Status/Alarms Status bar

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Other Functionalities

Sub Second Zoom

Cursor Point Display

Comprehensive Voltage Stability Alarms Linking WAMS “Wide-Area” Low Voltage Alarms to Operator Guides in EMS

PMU Voltage Stability Indicators

WAMS indicate the simultaneous occurrence of Low Voltage over a broad region.

AND

Operator Guides in EMS

Reactive Reserve Monitoring in EMS Decision making: Operator Guides (e.g. “Switch On Capacitor Banks”). Arm Special Protection Schemes

Reactive Reserve (MVAR) monitoring for user-defined areas in EMS.

Detect WHEN to Take Action... and HOW to Respond!

Voltage Stability Assessment in e-terravision Voltage Contours, MW Margins, Weak Elements, Remedial Actions

Identify weak elements (i.e. regions most

prone

to voltage instability)

MW Transfer Margins

Control

Recommendations