Dynamic Vulnerability Assessment and Intelligent Control

Chapter 15Enhancement of Transmission System Voltage Stability through Local Control of Distribution Networks

Dr. Gustavo Valverde¹, Dr. Petros Aristidou² and Prof. Thierry Van Cutsem³

^1>School of Electrical Engineering, University of Costa Rica, Costa Rica

²School of Electronic and Electrical Engineering, University of Leeds, United Kingdom

³Dept. of Electrical Engineering and Computer Science, University of Liege, Belgium

15.1 Introduction

The most noticeable developments foreseen in power systems involve Distribution Networks (DNs). Future DNs are expected to host a large percentage of renewable energy sources [1], and small Dispersed Generation Units (DGUs) at distribution level are expected to supply a growing percentage of demand [2]. This proliferation of DGUs and the advances in infocommunications are key drivers of the transformations seen today in DNs.

The increased penetration of DGUs has given rise to new operational problems in DNs, such as over-voltages and thermal overloads at times of high DG production and low load. In response to these problems, several DN control schemes have been proposed to dispatch the DGUs and ensure secure network operation [3]. For instance, in [4], two coordinated voltage control algorithms are proposed. The first is based on simple control rules in which the Load Tap Changer (LTC) of the main transformer is used to control voltages. If this action is unable to restore all network voltages within limits, the resource with the highest ...