US 6,249,719 B1 · Applications and methods for voltage instability predictor (VIP)

Abstract

A Voltage Instability Predictor (VIP) estimates the proximity of a power system to voltage collapse in real time. The VIP can be implemented in a microprocessor-based relay whose settings are changed adaptively to reflect system changes. Only local measurements (voltage and current) at the bus terminal are required. The VIP detects the proximity to collapse by monitoring the relationship between the apparent impedance {overscore (Z)}app and the Thévenin-impedance. In addition, we disclose: (1) that the VIP may be used in connection with non-radial topologies; (2) a new, more robust method to track voltage collapse in terms of impedance using rolling sums; and (3) a new method for representing distance to voltage collapse in terms of power margins.

Claims18

Dependent claims

A method for protecting an electrical power system, comprising the acts of:

(a) measuring current and voltage phasors at a point on the system;
(b) based on the current and voltage phasors, determining an apparent impedance ({overscore (Z)}app) associated with a load region and a Thévenin impedance ({overscore (Z)}Thev) associated with a source region, wherein {overscore (Z)}Thev is tracked using a ratio of a rolling sum of voltage (Trek(V)) to a rolling sum of current (Trek(I));
(c) comparing the Thévenin impedance and apparent impedances;
and
(d) deciding whether to initiate a prescribed action based on the relationship of the apparent impedance to the Thévenin impedance.

2 more elements

Dependencies are inferred from the claim text.

Applications and methods for voltage instability predictor (VIP)

Life of this patent

Applications and methods for voltage instability predictor (VIP)

Life of this patent

Abstract

Claims18