Azah Mohamed

Application of binary firefly algorithm for optimal power quality monitor positioning

This study suggests the utilization of binary firefly algorithm (BFA) in getting the optimal power quality monitor(PQM) position in the power system. A multi-objective function is used in the optimization procedure with the system observability constraint which is determined by the concept of topological monitor reach area. The multi-objective function is made up of three functions, which are the number of monitors needed, monitor coverage index and sag propagation index. The usefulness of the proposed method has been confirmed by applying the algorithm on the IEEE 118-bus transmission system. The results prove that BFA is suitable to use in PQM positioning problem.

SVC damping controller design based on firefly optimization algorithm in multi machine power system

Power system stability is a great concern in todays interconnected power system especially when the system is subjected to a fault. These faults occasionally lead to Low Frequency Oscillation (LFO). Therefore, Shunt Flexible AC Transmission System (FACTS) devices for example, SVC are employed to provide damping to attain system stability. The performance of SVC is totally dependent on proper tuning of its controller and usually heuristic optimization techniques are used to search the best controller parameters. In this paper, a popular metaheuristic optimization technique known as Firefly Algorithm (FA) is presented for optimal design of SVC controller in multi machine power system. In the simulation, the linearized model of power system and conventional lead-lag controller as SVC damping controller are used. The performance of obtained results using Firefly Algorithm (FA) is compared with the results obtained from Particle Swarm Optimization (PSO) Algorithm. The comparison of attained results show that FA can find more optimal parameter values of SVC damping controller and subsequently enhance power system stability.

Optimum APC Placement and Sizing in Radial Distribution Systems Using Discrete Firefly Algorithm for Power Quality Improvement

This paper presents an improved solution to determine simultaneously the optimal location and size of active power conditioners (APCs) in distribution systems using the discrete firefly algorithm (DFA) for power quality enhancement. A multi-criterion objective function is defined to enhance voltage profile of the system, to minimize voltage total harmonic distortion and total investment cost. The performance analysis of the proposed DFA is performed in the Matlab software on the radial IEEE 34-bus test system to demonstrate its effectiveness. The DFA results are then compared with the standard firefly algorithm, standard particle swarm optimization (PSO), genetic algorithm, and discrete PSO. The simulation and comparison of results prove that the DFA can accurately determine the optimal location and size of the APCs in radial distribution systems.

Identification of relative location voltage sag source using phase space technique

This paper introduces an alternative method for voltage sag source location based on phase space based disturbance powers. It is done to avoid the wrong and inconclusive detection of conventional disturbance power method proposed in the literature. Unlike in the case of the traditional method, the proposed method first transforms the recorded voltage and current during the sag event to obtain some special features before calculating the new version of disturbance powers. The effectiveness of the proposed method has been verified through simulation. The studies show that the presented method can correctly detect the location of voltage sag source.

Voltage Sag Mitigation by Network Reconfiguration

The electric power distribution system must be designed to operate and supply acceptable level of electrical energy to customers. Power utilities must ensure that the power supply to customers is with voltage magnitude within standard levels. Other features like minimal interruptions and minimal system power loss also must be considered. Hence, the quality and reliability of supply must be maintained in an acceptable level even during contingencies. Voltage magnitude is one of the parameters that determine the quality of power supply. A decrease in voltage magnitude may result in voltage sag which is currently considered as one of the main power quality problems. Voltage sag is defined as a decrease in magnitude between 0.1 and 0.9 pu in rms voltage at a power frequency of duration from 0.5 cycle to 1 min (IEEE Std 1159, 1995). Voltage sag may cause sensitive equipment to malfunction and process interruption and therefore are highly undesirable for some sensitive loads, especially in high-tech industries. However, loads at distribution level are usually subjected to frequent voltage sags due to various reasons. Voltage sag can be treated as a compatibility problem between equipment and power supply. When installing a new piece of equipment, a customer needs to compare the equipment sensitivity with the performance of the supply. There are various engineering solutions available to eliminate, correct or reduce the effects of power quality problems (Kusko &Thomson, 2007). Currently, a lot of research works are under way to solve the problem of voltage sag in distribution systems. Most of these research works focus on installing voltage sag mitigation devices (Sensarma et al., 2000). Other researchers focus on improving the immunity level of customer equipment by installing custom power devices to improve the voltage sag ride through capability (Shareef et al., 2010). Some other research works focus on utility efforts in finding feasible solutions to mitigate voltage sag problem. Since system faults are considered as main causes of voltage sags, utilities try to prevent faults and modify the available fault clearing practice in power systems. Normally, voltage sag assessment at a particular site in the network consists of determining the frequency of sags of specified sag magnitude and duration over a period of interest (Conrad & Bollen, 1997). It is also dependent on the utility fault performances, the way the fault affects propagation of disturbance in the system, and the customer’s service quality requirements (Shen et al., 2007). For voltage sag assessment, voltage sag characteristics has to be

Voltage Sags and Equipment Sensitivity: a Practical Investigation

In recent years, interruption of manufacturing processes due to power quality degradation has become a major focal point for many power utilities. The most prominent power quality issue plaguing utility customers is voltage sag or dip. It is a sudden decrease in voltage amplitude followed by a return to its initial level after a short time. The use of automation and energy efficient equipment with electronic control would greatly improve industrial production. However, since these new devices are more sensitive to supply voltage deviations, characteristics of the power system that were previously ignored are now becoming a nuisance. To evaluate the technical aspects and economic issues related to voltage sags, the process and equipment immunity level has to be known. However, there is little available information related to equipment sensitivity due to voltage sags. Studies assessing sensitivity of voltage sags on customer loads are divided into practical and theoretical approaches. The practical approaches investigate the effects of voltage sag by monitoring and conducting experiments on customers’ sensitive loads, as well as by performing pertinent surveys (Bollen, 2000). Equipment sensitivity to voltage sag can also be considered and presented in the form of power acceptability curves. These curves are plots of bus voltage deviation versus time duration which separate the bus voltage deviation time duration plane into two regions namely, “acceptable” and “unacceptable” regions. The lower limb of the power acceptability curve relates to voltage sags and momentary outages. The latest power acceptability standards are the SEMI F47 issued by the Semiconductor Equipment and Materials International (SEMI) in the year 2000 (Djokic et al., 2005) and ITIC curve of the Information Technology Industry Council (ITIC) (Kyei et al., 2002). The SEMI F47 specification simply states that semiconductor processing, metrology, and automated test equipment must be designed and built to confirm to the voltage sag ride-through capability as per the defined curve. Equipment must continue to operate without interruption during conditions identified in the area above the defined acceptable region (Institute of Electrical and Electronics Engineers Inc, 2005). As an effort to understand the voltage immunity level of sensitive equipment, some works have been reported in the past. The categories of sensitive equipment commonly evaluated for voltage sags are personal computers (PCs) that control the on line and off line processes, 2