Voltage Stability Index Using New Single-Port Equivalent Based on Component Peculiarity and Sensitivity Persistence

Muhammad Shoaib Bhutta,Jamshed Ali Shaikh,Zain Ul Abidin Jaffri,Larisa Ivascu,Muddassar Sarfraz,Hui Li,Ghulam Rasool,Umer Farooq,Muhammad Shahzad Nazir

doi:10.3390/pr9101849

Abstract

A voltage stability index is proposed using a new single-port equivalent depending on component peculiarity representation and sensitivity persistence to locate and determine long-term voltage instability in transmission and distribution power networks. The suggested single-port equivalent effectively represents the equivalence of various component types and assures the consistency of sensitivity information before and after the equivalence which is compulsory for the equivalent accuracy in estimating the voltage stability analysis. The stability index is derived from the new single-port equivalent to determine the system voltage instability. The proposed stability index is compared with indices based on virtual impedance and Thevenin impedance models. This new stability index shows more accuracy and effectiveness as compared to the indices based on virtual and Thevenin equivalent models. The index also determines the weak buses, where an improvement or functional measure can be used to reduce the system voltage instability. The validity of the proposed equivalent approach and stability index is presented by utilizing two radial systems, four IEEE systems and an actual system having bus size from five to 1010 buses.

Highlights

Voltage instability has become a major concern for the power sector as many major blackouts, and voltage collapses have occurred across the world in recent years [1–3]
The results of system voltage fluctuations determined by the new method are consistent with those attained by continuation power flow (CPF), indicating that the new index can efficiently determine the system voltage stability problems for the four IEEE systems and the actual utility system of 1010-bus, as shown in the columns of ‘system index’ below the ‘original system’ of Table 6
Enhanced SystemSystem Index Identified by CPF 4.01

Summary

Introduction

Voltage instability has become a major concern for the power sector as many major blackouts, and voltage collapses have occurred across the world in recent years [1–3]. A wide range of stability indices are developed to assess the longer-term voltage stability of the power network and highlight the critical buses [5–8]. The system indexes which utilize the continuation power flow (CPF) [9,10] and optimization techniques [11], e.g., system load margin, do not require network equivalence and can accurately assess the voltage instability and the stability margin of the power system. To evaluate the instability of system voltage, local bus-based indices have been suggested, and these indices utilize local bus-based equivalent systems to identify vulnerable buses [12–14]. The currently established local equivalent systems lack the characteristics of various elements in equivalence and the persistence of sensitivity information before and after the equivalent. The lack of characteristics of system components and persistence of sensitivity information within the local equivalent create inconsistencies in local indicators which can produce imprecise estimations of voltage stability

Objectives

Results

Conclusion