Contents 1. Introduction
Reactive power planning of complex transmission grid requires an intimate knowledge of the voltage instability and collapse mechanism. Voltage stability and reactive power-related system restrictions have become an increasingly growing concern for electric utilities following adoption of FERC open access and deregulation policies creating functional unbundling of generation and transmission systems. Electric utilities are faced with additional challenges in a deregulated environment when load centers are geographically remote from generation resources, connected through often heavily loaded weak transmission corridors. There are many considerations in planning an adequate dynamic reactive capability, most of them requiring practical knowledge rather than an analytical procedure. This intimate knowledge spans a wide range of equipment behavior from third party owned generator excitation protection to distribution LTCs and down to customer's load devices. Only with this complete knowledge can transmission planners assess the risk and deal with the challenge of providing adequate and optimum mix of static and (costly) dynamic reactive supply to protect against reactive deficiency. Utilities have also cost effectively applied appropriate undervoltage load shedding schemes along with adequate reactive supply to minimize the risk of voltage instability in the grid.
