With increasing penetration of rooftop photovoltaic ( PV ) systems in the low voltage distribution systems, over voltage problem has become ubiquitous. Abnormal voltage profile not only deteriorates the life of various equipments connected to the network but also increases the chances of fire leading to financial losses and life threatening hazards. Therefore, it is important to keep the voltage profile within acceptable limits. Recently, the reducing cost of battery energy systems ( BES s) has made it possible to deploy them for voltage control purposes. The excess energy produced by PVs during the day can be stored in BES and used in the night. Using the coordinated control of PV and BES , that is, the reactive capability of the PV inverter and the charging/discharging of BES , both overvoltage and voltage dip problems can be alleviated. However, the high resistive characteristic of the distribution feeder limits the effectiveness of reactive power for voltage control purposes. Moreover, there is a need of effective coordination of different PV and BES in the system to achieve this goal. Hence, a coordinated communication system is proposed which requires communication network protocol for all the PV system and BES in the network. This article discusses the feasibility of utilizing the existing power line communication ( PLC ) for improving the voltage profile of the distribution network.

Grid frequency deviation caused by wind power fluctuations has been a potential issue with increase penetration of wind energy conversion systems. To assess grid frequency deviation, in this paper a new method is proposed employing timefrequency distribution technique. The proposed time-frequency distribution method provides simultaneous time and variable frequency information, and estimates the fundamental frequency deviation caused by wind energy conversion system. The efficacy of the proposed technique has been justified by employing it to assess the grid frequency deviation caused by a ramp wind speed, a wind gust and a random wind speed. The results of three different wind speeds show that the proposed method can be employed effectively for the estimation of fundamental frequency deviation caused by wind power fluctuations.

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