Search

Islanding detection is important for the protection of any distribution system supported by distributed energy resources. In this work, a number of islanding and non-islanding events are simulated to prioritise 16 different passive parameters on the basis of performance analysis. Among the parameters tested, the rate of change of frequency over reactive power (df/dq) attains the highest accuracy and consequently, a new passive technique is proposed that employs df/dq as discriminative feature. An extended study is carried out to further test the ability of the technique to differentiate the islanding from the non-islanding events of similar signatures, such as load variation, capacitor switching, faults and induction motor starting. The simulation results confirm that the technique is proficient enough to identify islanding from non-islanding events that cause minute disturbances in the power supply network. [ABSTRACT FROM AUTHOR]

This paper presents a load shedding scheme for a distribution network connected to mini hydro generations. The proposed scheme uses the rate of change of frequency ( ROCOF) to estimate the power imbalance and voltage stability ( VS) to prioritize the load that is to be shed. The load with the most critical voltage stability (which is based on a special index) is given the first priority to be disconnected from the network in order to avoid voltage collapse. By performing load shedding based on the combination of the ROCOF and VS techniques, a better system frequency and enhanced voltage magnitudes can be achieved. The performance of the proposed scheme is validated on existing Malaysian network interconnected with a mini hydro generator. Simulation results show that the proposed scheme not only successfully stabilizes system frequency, but also simultaneously stabilizes the voltage magnitude of the buses within an acceptable limit. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

Mini hydro power plants (MHPP) are gaining attraction as a cost effective source for rural electrification in developing countries due to its environmental friendly operation. These MHPP plants suffer from the speed control problem due to continuous load variation. PID controllers fail to provide optimum speed control due to its limitation of parameter tuning. Alternatively, Fuzzy logic control is commonly used for implementing intelligent control for the nonlinear system. This paper presents a new fuzzy logic based governor for frequency/speed regulation of MHPP for implementation in distribution network. For verification, the response of load frequency control using fuzzy based governor and PID based governor is compared. The simulation results show that fuzzy based governor ensures robust control by improving the frequency response as well as dynamic response in comparison to PID based governor. Furthermore, fuzzy based governor enables the generator to continuously supply power even at 25% load variation whereas generator with PID based governor fails to supply power even at 20% load variation. [ABSTRACT FROM AUTHOR]

Research and development of fault location techniques for distribution system have been given a great emphasis to enhance reliability and quality of power supply. In a recent work, a comprehensive fault location method based on voltage sag profile has been proposed. In relation with this method, this paper presents a further test to evaluate the method performance by using a non-homogenous and unbalanced distribution network. A focus is given more on the influence of voltage sags patterns to the performance of the method. The test results present the strength and limitation of the method when applied for different fault resistances, loading variation and load models. [ABSTRACT FROM AUTHOR]

An improvement in service continuity of power supply in distribution system could be achieved through a fast fault location. In line with this objective, a fault location method for a distribution network is proposed in this paper. The method uses non-linear voltage sag profile equations as a means to locate a fault. Considering the possibility of having non-homogeneity of line impedances in distribution network, the voltage sag profile equations are constructed for each section. The possible fault location is estimated by incorporating the measured voltage magnitude and its corresponding phase angle into equation of voltage sag as a function of fault distance. The uncertainty of fault resistance is also considered in this method by constructing the voltage sag equations based on different fault resistance values. The performance of the algorithm is presented using an actual distribution network. [ABSTRACT FROM AUTHOR]

This paper describes an improvement of a faulted section identification method. The improvement has made the method not only able to identify a faulted section, but at the same time calculate fault distance from one-end of the faulted section. By having this new feature, the locating fault time can be further reduced. The method has been tested on an actual underground rural distribution network feeder with all type of fault. The results show that most faults can be located by the first attempt and with high accuracy of fault distance. Only few faulted sections found by the second attempt. Since the proposed method is using only voltage sag data, monitored at the primary substation, the method is considers economical to be implemented for a rural distribution network. [ABSTRACT FROM AUTHOR]