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Network reconfiguration results in voltage deviations because of the time-varying nature of loads. Nowadays, with the integration of renewable energy sources with the power grid, the optimal configuration should be determined taking into account the variations in loads and distributed generations. In this study, a long-term reconfiguration method named the long-term extended flow algorithm, which improves the timeliness of configuration behavior on time-varying loads, is proposed to substitute for the previous short-term ones. Moreover, optimal reconfiguration instants are achieved by a novel approach of optimal daily schedule called accumulation of unbalanced load distribution based on the trade-off between switching operations costs and reduction in voltage deviations. The proposed methods were tested by case studies of two test distribution systems under real-time measured data with the interconnection of photovoltaic generators in the MATLAB environment. By applying the proposed methods, the total operating cost of the network is reduced significantly within reasonable computation time, and its efficiency is also improved compared to fixed configuration, online reconfiguration policies, and daily schedule proposed by previous authors. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

The supervisory control and data acquisition (SCADA) system is used in power systems worldwide because of its maturity and capability. However, the SCADA system is vulnerable to fast system changes. Wide area monitoring system (WAMS) based on phasor measurement units (PMUs), which requires high investment, is being thought of as one of the solutions in recent power systems. This paper proposes a procedure to upgrade SCADA into WAMS by installing sufficient numbers of additional PMUs without removing conventional measurements from the existing SCADA system. The WAMS hybrid configuration is focused on the optimal PMU placement and state estimation strategy for hybrid PMU-SCADA measurements. The optimal placement of PMUs is subject to the improvement in estimation accuracy. For guaranteeing secure operation, line contingencies and some important buses are considered as subproblems of PMU placement. The state estimation procedure manages the initial state variable and modifies the weighting factor strategy that is suitable for the hybrid system especially during fast system changes. The results show that the proposed WAMS hybrid guarantees better estimation accuracy and faster state estimation process than SCADA in both non-contingency and contingency conditions. In addition, the WAMS hybrid has the capability to perform preventive strategy for securing voltage stability, which was previously applied in the PMU-based WAMS system. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

The high degree of penetration of residential rooftop photovoltaic systems causes the overvoltage problem in power distribution systems. This paper aims to introduce demand-side management for a distribution system for overvoltage prevention. A real-time overvoltage prevention coordination scheme between an on-load tap changer ( OLTC) and multi-community energy management systems (multi- CEMSs) is proposed. The main objectives of this control are to relieve the stress in the OLTC tap operation using household schedulable loads and to maximize customer profit in each CEMS. The load scheduling performed by each CEMS is formulated as a combinatorial, nonlinear, time-series scheduling optimization problem and is solved by a sequential search method named voltage-ranking-based load combination search algorithm. The effectiveness of the proposed method is validated in a model distribution system with1800 customers. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]