Advanced Reactive Power Control at Individual Residences to Smooth Energy Loss Fluctuation for a Clustered Grid-Interconnected PV System

Reactive power control can control voltage within the proper range from the power network side or from the distribution generation （PV （photovoltaic）） side. Reactive power control from the power network side is simpler because little controlled object apparatus, such as STATCOM, is required. However, it is difficult to optimize the individual voltages of residential consumers because few data have been obtained by the power network side as compared with the power generation side. Energy loss at each residence with PV is different due to the difference in the grid-interconnection condition, such as distribution line impedance when the same operating voltage is set at all residences. Therefore, in this paper, the authors propose an advanced reactive power control method for residential PV systems in order to optimally control the voltage at individual residences so as to minimize energy loss fluctuation. The effectiveness of the proposed reactive power control is demonstrated by numerical simulation.

A Parameter Determination Method of Distribution Voltage Regulators Considering Tap Change and Voltage Profile

This paper proposes a parameter determination method of distribution voltage regulators load ratio control transformers （LRT） and step voltage regulators （SVR） considering the tap change and voltage profile. The method takes two procedures in order to simplify the optimization problem and to reduce calculation time. One is to simultaneously determine the control parameters of LRT and SVR minimizing voltage violations and voltage variations. The algorithm is based on particle swarm optimization （PSO）, which is one of non-linear optimization methods by using a concept of swarm intelligence. Another is to determine the dead-band width of LRT and SVR on the basis of bi-evaluation of tap change and voltage margin. The concept of a Pareto optimal solution is used for the decision of the best dead-band width. As the results of numerical simulations using distribution network model, the validity of the proposed method has been affirmed.

Effectiveness of Optimal Arrangement of the Residences Operated by Reactive Power Control for a Clustered Grid-Interconnected PV System

There is a danger of power generation efficiency decreasing due to voltage increase when clustered residential PV systems are grid-interconnected to a single distribution line. As a countermeasure, installation of the reactive power control of an inverter at each residence has been considered. However, there are not many types of inverters that can operate reactive power control because there are insufficient effects on a low voltage distribution line with low penetration PV with reactive power control. Therefore, it is necessary to consider how to increase generation efficiency with a lower number of inverters. In this paper, four Japanese standard distribution line structures, for example of a residential area on ＂C1＂, where 2,160 residential PV systems are grid-interconnected, are selected. The optimal setting of reactive power control at each residence is computed on the distribution lines with a greedy method.