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This paper proposes a voltage control method in cooperation with a tap changer, such as a step voltage regulator, for power distribution lines using power conditioning systems. Generally, a town which plays a role of a virtual power plant has an energy management system and consists of a lot of power conditioning systems in houses. In this paper, it is clarifies that the method is able to control the voltage at the connecting point of the distribution system properly cooperating with the step voltage regulator under several voltage fluctuation conditions. Furthermore, it is shown that a communication between the energy management system and power conditioning systems enables the system to resolve unevenness output of reactive power of the power conditioners.

This paper aims at proposing novel methods for multi-terminal VSC HVDC system design and operation with large-scale wind farms. The paper is based on the hierarchical optimal power flow with small-signal stability constraint. Multi-terminal VSC HVDC (MTDC) system reinforcements are designed in the first step. The reinforcement capacities of the HVDC systems are designed by optimization process. Economic load dispatch in the reinforced system with MTDC is carried out in the next step. By the proposed method, multi-terminal VSC HVDC systems can be utilized more effectively even when wind production is not high. Several multi-terminal configurations are designed. Wind power hosting capacities, net present value, and profitability index of the systems are analyzed.

This paper proposes a decentralized charging control method of a battery energy storage system (BESS) that can prevent the over-capacity of a pole transformer in low-voltage (LV) distribution systems due to reverse power flow from the photovoltaic generation system. The distribution system operator provides the charging parameters defined as the relationship between the state-of-charge (SoC) and the charging threshold determined by using only the LV-distribution system configuration and the demand-side information to customers. Each BESS charges the power according to the provided parameters. A high charging amount can be maintained by automatically changing the charging mode based on the change in SoC. Results of the numerical simulation demonstrate that the proposed method can prevent the over-capacity of PTr and maintain the high charging amount of a BESS in LV-distribution systems. Further, the maximum power flow at the distribution substation and the distribution losses in MV-distribution system can be reduced.

This paper proposes a fast and robust load flow method for balanced power distribution systems with distributed generation sources. The method formulates the power flow equations in PQ decoupled form with polar coordinates. Second-order terms are included in the active power mismatch iteration, and resistances are fully modeled without any simplifications. The impacts of zero-impedance branches are explicitly modeled through reconfiguring of the adjacent branches with impedances. Typical distribution generation models and distribution load models are included. A hybrid direct and indirect solution technique is used to achieve efficiency and robustness of the algorithm. Active power correction is solved by means of a sparse LU decomposition algorithm with partial pivoting, and the reactive power correction is solved by means of restarted Generalized Minimal Residual algorithm with incomplete LU preconditioner. The numerical examples on a sample distribution system with widespread Photovoltaic installations are given to demonstrate the effectiveness of the proposed method.

This paper presents the development and maintenance of intelligent 'switching sequence generation' systems. The author's have developed a new framework which can construct and update its knowledge base without external influence. This paper proposes an automatic knowledge acquisition method, a key part of the intelligent system architecture, which is realized by means of the machine learning paradigm. This paper introduces a new knowledge acquisition method and discusses the evaluation and the extension for the purpose of its practical use. >