A simple computation and visualization of voltage stability power margins in real-time

Abstract

Abstract-This paper introduces a simple method to monitor power system voltage stability conditions in real-time. The method is based on the concept of Voltage Instability Predictor (VIP). The essence of the method is a simple computation of a voltage stability boundary based on VIP derived quantities. The stability boundary is assumed as a parabolic equation in the P-Q plane identified using measurements collected at a specific substation, transmission path, or load center. The computed stability boundary is further visualized in a P-Q plane, together with a point representing the current operating conditions, and generally re-computed as soon as the new set of measurements is collected (preferably at high rates using phasor measurement units). Simplicity and easy interpretation of the results brings this method as a useful tool to increase system operator situational awareness. Supporting results are provided using relatively big test system (52 bus Nordic test system) and a reallife system (a portion of the North-West USA system).

Determination of the Thevenin equivalent in power grids using real records based on short circuit power

“…Step 2.1: m i , m i+1 , S S0 i , S S0 i+1 , A i , A i+1 , n i and n i+1 applying (2), (11), (13) and 14 21Step 2.3: Increase loading factor x and go to step 2.1.…”

Loadability analysis based on short‐circuit power

“…VPSI S is obtained by replacing V S from (10) into (17), which results as For the sake of simplicity, one can define a term A as…”

“…The use of PMUs in the voltage stability problem is explained in [14]. The Thevenin impedance match criterion is still used as an extension for multiport systems [15], for example, TE is applied for flowgates [16] or the visualisation of voltage stability margins using PMU data [17].…”

A Methodology for Determining Permissible Operating Region of Power Systems According to Conditions of Static Stability Limit

“…For determining the visual characteristics of the voltage stability limit and the operating region for the system, a P-Q curve [7,[17][18][19][20] is very useful. On a power plane, the operating region indicates both the possible active and reactive power in which the load bus of the system can operate normally.…”

“…In [17], the curve is assumed to follow a circle. In [7,[18][19][20], the P-Q curve is defined by a parabolic equation. Those assumptions about the shape of the curve are not realistic and may lead to the over-estimation of the reactive power limit.…”