Optimal Placement of Dynamic Var Sources by Using Empirical Controllability Covariance

TL;DR

This paper introduces an optimal dynamic var source placement method using empirical controllability covariance to improve voltage stability and address FIDVR issues more effectively than existing methods.

Contribution

It formulates a new optimization approach based on ECC maximization for dynamic var placement, enhancing FIDVR mitigation and voltage stability in power systems.

Findings

Fewer dynamic var sources are needed compared to VSI-based methods.

The ECC-based method effectively mitigates FIDVR caused by severe contingencies.

The method can address more FIDVR issues regardless of specific faults.

Abstract

In this paper, the empirical controllability covariance (ECC), which is calculated around the considered operating condition of a power system, is applied to quantify the degree of controllability of system voltages under specific dynamic var source locations. An optimal dynamic var source placement method addressing fault-induced delayed voltage recovery (FIDVR) issues is further formulated as an optimization problem that maximizes the determinant of ECC. The optimization problem is effectively solved by the NOMAD solver, which implements the Mesh Adaptive Direct Search algorithm. The proposed method is tested on an NPCC 140-bus system and the results show that the proposed method with fault specified ECC can solve the FIDVR issue caused by the most severe contingency with fewer dynamic var sources than the Voltage Sensitivity Index (VSI) based method. The proposed method with fault unspecified ECC does not depend on the settings of the contingency and can address more FIDVR issues than VSI method when placing the same number of SVCs under different fault durations. It is also shown that the proposed method can help mitigate voltage collapse.