New Method for Assessment of Distributed Generation Impact on Distribution System Reliability: Islanded Operation

Abstract

Distributed Generation “DG” is an emerging technology which is receiving mush attention and studies. One of the most important aspects of DG is reliability. Reliability is defined as the ability of the system to deliver electrical power to the customers within various limits. These limits include limits on continuity of supply, voltage drop, sag, regulation and other limits which are mentioned in various standards. This paper focuses on solving some problems with the reliability modeling of DGs [1]. Existing algorithms which deal with DG are very complex due to the nature of the model of the DG itself [1]. Some of the protection algorithms have to be complex so that they do not to count the DG twice [2]. In this paper protection algorithms and set of equations are proposed to accurately model the DG and calculate its effect on Load point indices. Then the method is applied to a study case to illustrate the steps needed to calculate the load point indices [3]. A load flow result will be used to determine the size of the DG needed. The system which will be studied is a system where the DG serves an island or what is known as islanded operation of DG [4]. The method only applies to islanded operation and cannot be used for other modes of operation of the DG. The results show that a very accurate method could be used to model the DG without the need for complex, time consuming algorithms which a characteristic of the existing algorithms. This paper presents the role of the DG in improving the system reliability by proposing a new method for calculation of load point indices in the case of DG presence in the system. The method is then applied to a study case.