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This paper proposes a network splitting strategy following critical line outages based on N-1 contingency analysis. Network splitting is the best option for certain critical outages when the tendency of severe cascading failures is very high. Network splitting is executed by splitting the power system network into feasible set of islands. Thus, it is essential to identify the optimal splitting solution (in terms of minimal power flow disruption) that satisfies certain constraints. This paper determines the optimal splitting solution for each of the critical line outage using discrete evolutionary programming (DEP) optimization technique assisted by heuristic initialization approach. Heuristic initialization provides the best initial cutsets which will guide the optimization technique to find the optimal splitting solution. Generation-load balance and transmission line overloading analysis are carried out in each island to ensure the steady state stability is achieved. Load shedding scheme is initiated if the power balance criterion is violated in any island to sustain the generation-load balance. The proposed technique is validated on the IEEE 118 bus system. Results show that the proposed approach produces an optimal splitting solution with lower power flow disruption during network splitting execution. [ABSTRACT FROM AUTHOR]

In this paper, a fuzzy logic controller (FLC) is proposed to overcome the problems of the existing unified power flow controllers (UPFCs) and to provide the dynamic power flow control through transmission lines. Although many studies have been focusing on developing UPFC control strategies for power flow control through simulation, there is a lack of experimental validation of different UPFC controller and its performance in real-time operation. In order to investigate the performance of the proposed FLC based UPFC, a laboratory prototype has been developed using two 6-pulse converters. The six-bus power system network model is chosen as test system. The shunt and series controller for both PI and FLC-based UPFC prototype are designed in MATLAB/Simulink using Speedgoat performance real-time target machine. The UPFC prototype is tested on six-bus power system network model to verify its capability. The results revealed that the UPFC prototype had successfully controlled the power flow dynamically in transmission line with enhanced accuracy. In addition, other power system parameters have been improved significantly. [ABSTRACT FROM AUTHOR]

The benefits of distributed generation (DG) based on renewable energy sources leads to its high integration in the distribution network (DN). Despite its well-known benefits, mainly in improving the distribution system reliability and security, there are challenges encountered from a protection system perspective. Traditionally, the design and operation of the protection system are based on a unidirectional power flow in the distribution network. However, the integration of distributed generation causes multidirectional power flows in the system. Therefore, the existing protection systems require some improvement or modification to address this new feature. Various protection strategies for distribution system have been proposed so that the benefits of distributed generation can be fully utilized. This paper reviews the current progress in protection strategies to mitigate the impact of distributed generation in the distribution network. In general, the reviewed strategies in this paper are divided into: (1) conventional protection systems and (2) modifications of the protection systems. A comparative study is presented in terms of the respective benefits, shortcomings and implementation cost. Future directions for research in this area are also presented. [ABSTRACT FROM AUTHOR]

Common power system restoration planning strategy is based on a 'build up' approach, where a blackout system is sectionalized among several islands for parallel restoration prior to resynchronization. In order to speed up the resynchronization of the islands, each island must have similar energizing times. However, there is a huge number of possible combinations of islands that can be formed. Thus, this paper proposes a method to determine optimal islands that have similar energizing times. The method involves identifying transmission lines that should not be connected to form the islands. The proposed method is based on the combination of heuristic and discrete optimization methods. The heuristic technique is proposed to find initial solution that is close to the optimal solution. This solution will guide the optimization technique, which is the discrete Artificial Bee Colony optimization method, to find the optimum solution. The proposed method also considers restoration constraints including black start generator availability, load-generation balance, and the maintenance of acceptable voltage magnitude within each island. The proposed method is validated via simulation using IEEE 39, 118-bus and 89-bus European systems. The advantage of the proposed method in terms of restoration time is demonstrated through a comparison with other literature. [ABSTRACT FROM AUTHOR]

A correction is presented to the article "A Power System Network Splitting Strategy Based on Contingency Analysis."