Transient Analysis of Power Systems

7 Applications of Power Electronic Devices in Distribution Systems

Arindam Ghosh and Farhad Shahnia

7.1 Introduction

One of the main concerns in any electric power distribution system is the reliability of the supply. Usually the supply reliability pertains to maintaining the continuity of power supply. Indices such as system average interruption frequency index (SAIFI), customer average interruption frequency index (CAIFI), system average interruption duration index (SAIDI) and customer average interruption duration index (CAIDI) are used for quantifying the system reliability [1, 2]. By calculating these indices, distribution systems engineers can determine whether yearly interruptions affect one group of customers more than the others so that corrective measures can be taken. Generally, the organizational ability of a particular distributor can be determined by these indices and sometimes system regulators can ask the company to improve their scheduled maintenance process for better reliability.

However, reliability is not the only major concern these days – power quality is equally important. Power quality is defined as having a supply voltage that is a pure sinewave of rated magnitude and frequency (50 or 60 Hz), even though ± 5% variation in these quantities are often acceptable. The quality of power is said to have deteriorated when the supply voltage fails to attain the ideal specifications mentioned above. Unfortunately, the actual AC line supply that we receive every ...