A Novel Tuning Method for Advanced Line Drop Compensator and Its Application to Response Coordination of Distributed Generation With Voltage Regulating Devices

Nowadays, the integration of small-scale electricity generators, known as distributed generation (DG), into distribution networks has become increasingly popular. This tendency, together with the falling price of DG units, has a great potential in giving the DG a better chance to participate in the voltage regulation process, in parallel with other regulating devices already available in the distribution systems. The voltage control issue turns out to be a very challenging problem for distribution engineers since existing control coordination schemes need to be reconsidered to take into account the DG operation. In this paper, a new tuning method for the line drop compensator has been proposed, and it is applied for the control coordination of DG with other regulating devices in the network, which is able to utilize the ability of the DG as a voltage regulator and, at the same time, minimize the interaction of DG with another DG or other active devices such as the on-load tap changing transformer (OLTC). The proposed coordination technique has been developed based on the concepts of protection principles (magnitude grading and time grading) for the response coordination of OLTC, DG unit, and other regulating devices. A distribution feeder with a tap changing transformer and DG unit has been extracted from a practical system to test the proposed control technique. The results show that the proposed method provides an effective solution for coordination between OLTC and DG, DG-DG, or DG and voltage regulating devices, and the integration of protection principles has considerably reduced the control interaction to achieve the desired voltage correction.

I. Introduction

The increasing importance of reducing greenhouse gas emissions has been the key drive for a number of Australian government programs which aim to facilitate new generation projects with lower gas emissions than the pool average [1]. These generators are normally intended to operate while electrically connected to the distribution network, and they utilize renewable energy (hydro, solar, wind, and biomass) or low greenhouse emission fuels (natural gas). They are known as distributed generation (DG) resources. The connection and operation of the DG not only can reduce environmental emissions but also offer a number of benefits compared to the conventional ones, such as lower capital cost of generation, generation capacity to more closely match the demand, and higher potential for enhanced security of supplies and improved power quality [2]. For these reasons, interest for the installation of DG has been growing rapidly worldwide in the last decade.