Islanding Research Articles

A Sampling Approach for Intentional Islanding of Distributed Generation

This paper proposes an innovative way of making a decision to island (or synchronize) distributed generators when operating conditions of a distribution system are varied. Islanding decisions are made when a network undergoes disturbances. In this approach, there is a decision-making mechanism, which samples states of the network operating condition to either synchronize or island in an identified period of time. Decision making is achieved through extended sequential sampling, which manages generator states within specific time periods. The approach can minimize the duration of islanded operation and manage generators' re-connection to the grid. Use of the proposed mechanism and sampling approach offer benefits over conventional relays; incorrect operations due to errors in measurements are reduced because the operational actions are not based on a single decision sample, but instead rely on extended sequential sampling over a number of samples. A case study is investigated using the IEEE 30-bus test system and the results are presented for this new approach

Impact Study on Intentional Islanding of Distributed Generation Connected to a Radial Subtransmission System in Thailand's Electric Power System

Traditional interconnection standards avoid the islanding operation of distributed generators (DGs) because of concerns of equipment failure and safety. However, in some cases, allowing the islanding operation of DGs in a radial subtransmission system could improve system reliability and decrease outage cost during power outages or a scheduled maintenance. This paper presents an impact study on a DG connected to a radial subtransmission system. The dynamic study is conducted to show how to manage DGs and electric power systems for the proper intentional islanding in specific cases.

Impact of intentional islanding of distributed generation on electricity market prices

The battle for electricity customers in an increasingly competitive and deregulated market environment is one of the challenges facing the electric power utilities of today. Customers expect a reliable and efficient supply of power from their utilities. One of the advantages that a distributed generator (DG) can provide to the electric utility and to customers is the possibility of improving the continuity of supply by implementing safe intentional islands in the event of upstream utility supply outage. Implementing intentional islanding of DG in a deregulated era will have an impact on electricity market prices. This problem is considered in this paper by solving the optimal power flow problem while accounting for islanded operation.

A scheme for controlled islanding to prevent subsequent blackout

The power systems operated by the utilities in developing countries suffer from a large gap between demand and generation, inadequate transmission capacity, and nonuniform location of the load centers and generating stations. Occurrences of faults in such systems, in most of the cases, end up with the worst consequences (i.e., complete blackout). This paper illustrates the way a blackout can be prevented in real time through controlled segregation of a system into a number of viable islands together with generation and/or load shedding. The nature and location of any fault that warrants such islanding can be ascertained in real time through monitoring the active-power (megawatt) flows at both ends of a number of prespecified lines. The blackout of June 20, 1998 in the Bangladesh Power Development Board system has been used as an example in the illustration. The philosophy of the proposed islanding scheme may be considered for implementation in other power systems also.