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Techniques for distributed generations (DGs) have attracted increasing attention due to considerations of environmental sustainability. Wind farms are one of the DGs, and they have intermittent characteristics. This paper presents a method using wind generator voltages, static compensators, and transformer taps as controllers to regulate the voltage profile for operation planning in a distribution system. Wind power generations and bus loads are modeled with random variables. Through gray-based genetic algorithms (GAs), the MW loss in the system is minimized and the operational constraints are fulfilled. Moreover, this paper uses the cumulant method to calculate the bus voltage fluctuation by using the algebraic addition and multiplication to avoid convolution. The probability density function of the voltage fluctuation can be further expressed by the Gram--Charlier series expansion. Applicability of the proposed method is verified through simulation by using a 17-bus system and an autonomous 24-bus (Penghu) system. Index Terms--Cumulant, genetic algorithm (GA), gray code, reactive power control, wind farm.

The transient caused by capacitor switching is one of the important power quality (PQ) problems. In particular, switching on the capacitor may result in an overvoltage to a sensitive load, serious disturbance to an adjustable-speed drive or a resonance in the system. This paper presents a new method to locate the positions of the transient sources with the help of the PQ monitoring system. The discrete wavelet transform is used to extract the features of transients caused by capacitor switching. The fuzzy-c-means is then used to determine the placement of PQ measurement facilities. The signal energies attained by wavelet coefficients serve as inputs to the hybrid principal component analysis neural network for locating the transient sources. The simulation results obtained from an 18-bus distribution system show the applicability of the proposed method. Index Terms--Capacitor switching, fuzzy-c-means, locating, principal component analysis neural network, wavelet transform.

The installed transformer capacity can be reduced when the transformer connects intermittent loads with low duty cycles. This paper proposes a new method based on genetic algorithms to determine the transformer capacities for intermittent loads. The costs of transformers are minimized while the voltage fluctuations (drops) satisfy relevant standards. The duration of the voltage drop can be derived from the Markov Process. The intermittent loads are modeled with discrete stochastic distribution; therefore, the generating function is used for aggregating multi-intermittent loads at a bus. Two practical factories with grinders and welders are used to show the applicability of the proposed method. Index Terms--Discrete random variable, genetic algorithms, intermittent load, Markov process, transformer capacity.

The power quality in distribution systems becomes deteriorated due to an increase in nonlinear loads. This paper presents a new method, based on interactive multiobjective nonlinear programming (MONLP), using genetic algorithms (GAs) to study passive filter planning. The short-circuit capacity of the point of common coupling (PCC) and the individual bus loads are modeled with the fuzzy sets. The harmonic voltages and the filter cost are minimized while satisfying the harmonic standard and harmonic power plow equations with the harmonic Y-matrix. An 18-bus system is used as a test system for showing the applicability of the proposed method. Index Terms--Fuzzy parameters, genetic algorithms, harmonic, multiobjective, passive filter.

Energy loss (kWh) estimation of distribution systems is an important task for the system operation and planning. Because the losses are obtained through estimation, providing a fuzzy range of losses to engineers is essential. A new method based on fuzzy-c-number (FCN) and cluster-wise fuzzy regression (CWFR) analysis is proposed for developing loss formulas to estimate losses in this paper. A realistic distribution system is used for illustrating the applicability of the proposed method. Index Terms--Distribution systems, fuzzy clustering, fuzzy regression, loss formula.

A new Optimal Harmonic Power Flow (OHPF) method is proposed in this paper. This new OHPF is designed to minimize the MW losses and the total harmonic voltage distortion while satisfying the power flow equations, harmonic power flow equations, security constraints and harmonic standard, etc. A two-level algorithm is used to solve the problem: the master level determines the settings of compensators and taps; the slave level includes subproblems which involve cases of fundamental and harmonic frequencies separately. The test results for two power systems show the applicability of the proposed method. Keywords: Optimization, Power Flow, Harmonics, Two-level Algorithm.

The APLC (Active Power Line Conditioner) is a type of active power filter that compensates the voltage waveform distortion caused by harmonics in power systems. This paper presents a new approach based on an optimization theory to investigate the determination of locations and sizes of APLCs. The objective is to minimize the new APLC injection currents and the voltage distortion while satisfying the harmonic standard. The test result for an 18-bus distribution system shows the applicability of the proposed method.

A novel approach using the Y-matrix for analyzing voltage-flicker power flow is presented in this paper. Stochastic theory is incorporated with the power flow method to obtain the equivalent 10 Hz voltage fluctuation ([Delta][V.sub.10]) at each bus. The proposed method helps examine the impact of voltage flicker sources (e.g., arc furnaces) on system voltages. Simulation and experimental results show the applicability of the proposed method. Index Terms--Power flow, stochastic, voltage flicker.