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In this paper, dead band control algorithms using a performance index of the load tap changing (LTC) tap position are proposed to reduce the tap changing operation times. The performance index is defined as the customer voltage quality with the tap position of LTC transformer. In addition, dead band control algorithms using the load diversity values of the feeders are proposed. The mathematical formulations of the proposed dead band control algorithms are introduced. A sample case study is shown to verify the effectiveness of the proposed dead band control algorithms. Index Terms--Dead band control, distribution substation, fine drop compensation (LDC), load diversity, load tap changing (LTC) transformer, voltage control.

This paper presents a new method regarding fault distribution modeling for the stochastic prediction study of voltage sags in the distribution system. 2-D stochastic models for fault modeling make it possible to obtain the fault performance for the whole system of interest, which helps to obtain not only sag performance at individual locations but also system sag performance through system indices of voltage sag. By using the bivariate normal distribution for fault distribution modeling, this paper estimates the influence of model parameters on system voltage sag performance. The paper also develops the modified SARFIx regarding phase loads that create better estimation for voltage sag performance for the distribution system. Index Terms--Bivariate normal distribution, distribution system, fault distribution modeling, phase loads, power quality (PQ), stochastic prediction, voltage sag frequency.

This paper presents a monitor positioning algorithm to determine the optimal number of power quality monitors and to decide the locations for a given distribution system. From graph theory, the system topology is formulated into a coverage matrix. The weighting factors of each component are newly defined from the guidelines of monitor positioning suggested. Weighting factors represent the degree of importance in the system topology. Ambiguity indices are suggested to evaluate the monitor locations in terms of topological ambiguity. The optimal number and locations are determined from the optimization routine utilizing the weighting factor and the ambiguity indices. The proposed approach can realize the expert's knowledge on monitor positioning into a sophisticated automatic computing algorithm. Index Terms--Ambiguity, distribution system, event, optimization, power quality, power quality monitor, topology, weighting factor.

The exhaustion of fossil fuel and the greenhouse gas emission are one of the most significant energy and environmental issues, respectively. Photovoltaic (PV) generators and battery energy storage systems (BESSs) have been significantly increased for recent years. The BESSs are mainly used for smoothing active power fluctuation of the PV. In this paper, PV–BESSs integration of two DC/DC converters and one AC/DC converter is investigated and DC-link voltage control to compensate the AC voltage deviation is proposed for the PV‒BESS system in low-voltage (LV) networks.

This paper presents a systematic algorithm to locate the power-quality (PQ) event source in the distributed monitoring system. Firstly, this paper proposes an improved realization of a distributed monitoring scheme for PQ diagnosis. The algorithm utilizes the topology of power system and the direction of PQ events. As a result, the coverage matrix and the direction matrix are constructed. The algorithm determines the candidate areas for an event source by manipulating these two matrices. For more accurate results, it calculates the distance from the PQ monitor to the location of the PQ event source. It is explained with an illustrative example and is applied to IEEE test feeder in order to validate the accuracy. The proposed algorithm can replace the expert's analysis on the PQ event source with an automated computer program. Index Terms--Fault diagnosis, fault location, monitoring, power distribution, power quality, power system harmonics.

This paper newly defines a voltage sag duration considering the voltage tolerance characteristics of individual electrical device for power quality (PQ) diagnosis. The conventional sag characterizing method has the possibility to overestimate voltage sag in case of nonrectangular sag. Furthermore, it cannot take the voltage tolerance characteristics of individual device into account. The proposed method utilizes the monitored parameters ([V.sub.sag], [V.sub.avg], d) at PQ monitor and the minimum voltage ([V.sub.min]) of voltage tolerance curve. The voltage sag profile is approximated using [k.sup.th] order radical root function and finally the sag duration is modified from this function. The proposed method is applied to the nonrectangular sag due to induction motor reacceleration. It effectively evaluates the actual effects of voltage sag on the customer equipments whether the sag is rectangular or not. Index Terms--Diagnosis, event, monitoring, nonrectangular sag, power quality, voltage sag, voltage tolerance curve.

This paper presents an inverter-interfaced distributed generation (DG) device, dubbed the premium power supply (PPS), which is designed to provide reliable electric power, and to improve power quality. This paper proposes an effective configuration for the PPS, using inverters, an inter-tie breaker, and a small generating unit. When the DGs are operated in parallel with the utility systems, some problems occur due to interconnections on such categories as reverse power flow and island protection. This paper advances both an operating strategy and a control scheme for the PPS, with respect to the interconnection standard, IEEE Standard 1547. Simulation results demonstrate the efficacy of the PPS. Index Terms--Distributed generation (DG), interconnection, inverters, power quality, premium power supply (PPS), PSCAD/EMTDC.