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This paper presents a new computation method to determine simultaneously the optimal parameters of several voltage regulators such as the load-ratio control transformer (LRT) and step voltage regulator (SVR) installed in a radial distribution network. The proposed method determines a combination of their control parameters by minimizing the weighted sum of deviations of line voltage from the upper and lower voltage limits and the amounts of voltage violations by referring to the stored data measured by IT switches, which are sectionalizing switches with sensors installed in the distribution feeder. The optimization algorithm is based on particle swarm optimization (PSO), which is one of the nonlinear optimization methods, by using the concept of swarm intelligence. In order to confirm the validity of the proposed method, numerical simulations are carried out on a distribution network model. 

Abstract. This paper describes and verifies a voltage control for a loop distribution system. The proposed method adopts SCADA system based on voltage data from IT switches, which are sectionalizing switches with sensor installed at 6.6kV distribution line. The proposed voltage control combines centralized control of a LRT and autonomous control of decentrally-allocated RESs. The tap change control of LRT takes the major role of the proposed voltage control. It is the extended type of LDC method which is generally adopted, and minimizes voltage deviations based on voltage data from each IT switch. The output power control of RES additionally and autonomously supports the voltage control when the voltage violation from the upper limit is unavoidable. The reactive power control in the vacant capacity of RES's inverter mainly works, and the active power control works when not enough. In order to check the validity of the method, the experimental simulations using an analog distribution system simulator are carried out. This study is supported by a specially-promoted research grant of Power Academy in 2009 from the Federation of Electric Power Companies of Japan.

The line voltage control in a distribution network is one of the most important issues for a penetration of Renewable Energy Sources (RES). A loop distribution network configuration is an effective solution to resolve voltage and distribution loss issues concerned about a penetration of RES. In this paper, for a loop distribution network, the authors propose a voltage control method based on tap change control of LRT and active/reactive power control of RES. The tap change control of LRT takes a major role of the proposed voltage control. Additionally the active/reactive power control of RES supports the voltage control when voltage deviation from the upper or lower voltage limit is unavoidable. The proposed method adopts SCADA system based on measured data from IT switches, which are sectionalizing switch with sensor installed in distribution feeder. In order to check the validity of the proposed voltage control method, experimental simulations using a distribution system analog simulator "ANSWER" are carried out. In the simulations, the voltage maintenance capability in the normal and the emergency is evaluated.

Keywords: wind turbine generation system, acceptable maximum output, distribution system, power quality Recently, the total number of Wind Turbine Generation System (WTGS) connected to distribution network has been increased drastically. Installation of WTGS can reduce the distribution loss and emission of CO 2 . However, the distribution network with WTGS must be operated keeping reliability of power supply and power quality. The WTGS's effects to distribution network depend on its structure. In order to accomplish both the stable operation of distribution network and the progress of WTGS's prevalence, it is necessary to evaluate the acceptable output of WTGS quantitatively. In this paper, the authors evaluate several WTGSs connected to (a) Type 1 (Squirrel-cage induction generator, AC-link system) (b) Type 2 (Wound-rotor induction generator, AC-link system) (c) Type 3 (Synchronous generator, DC-link system)Recently, the total number of Wind Turbine Generation System (WTGS) connected to distribution network has been increased drastically. Installation of WTGS can reduce the distribution loss and emission of CO 2 . However, the distribution network with WTGS must be operated keeping reliability of power supply and power quality. The WTGS's effects to distribution network depend on its structure. In order to accomplish both the stable operation of distribution network and the progress of WTGS's prevalence, it is necessary to evaluate the acceptable output of WTGS quantitatively. In this paper, the authors evaluate several WTGSs connected to distribution network from viewpoint of Acceptable Maximum Output (AMO). The operational constrains to calculate the AMO of a WTGS are the following, (1) voltage limit, (2) line current capacity, (3) no reverse flow to distribution transformer, (4) short circuit capacity, and (5) voltage dip by inrush current. In order to evaluate the WTGS from viewpoint of AMO, numerical simulations are accomplished for a distribution system model. Furthermore, characteristics of AMO of a WTGS connected to distribution feeder are analyzed by several numerical examples.