Power Quality Impact of Distributed Generation: Effect on Steady State Voltage Regulation

With the advent of deregulation, distributed generation will play an increasing role in electric distribution systems. Various new types of Distributed Generation (DG), such as micro-turbines and fuel cells, are now being developed in addition to the more traditional solar and wind power. A common belief among developers is that DR will improve power quality, and this potential for better quality is cited as one of the value attributes of installing distributed generators. In some cases distributed generation and storage are being promoted as an answer to the premium-quality power requirements of high technology or sensitive end-use customers. Whether or not this value-attribute of DG is valid will depend on the specific technologies, site conditions and potential interaction with the existing electric power system.

The objective of this paper is to provide a technical assessment of the impact of distributed generation technologies on the power quality of the power distribution system. Power quality is a broad term covering a wide range of operating parameters including both steady state and dynamic conditions. The full range of power quality conditions are described in IEEE Std. 1159-1995 Recommended Practice for Monitoring Electric Power Quality. This paper focuses on steady-state voltage regulation impacts of DG and is the first of several papers covering the various power quality impacts of DG. The guidelines provided in this paper will help utility engineers evaluate the impact of distributed generation on voltage regulation and identify methods to mitigate problems that arise. The paper also makes recommendations for voltage trip thresholds to be used for DG interconnection that will help reduce the susceptibility of DG to nuisance trips but still provide utility system protection against sustained overvoltage.

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