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A battery Energy storage system (BESS) based voltage and frequency controller (VFC), for an Autonomous Asynchronous Generator (ASG) driven by an uncontrolled pico hydro turbine used in constant power mode, is presented in this paper. Excitation of the asynchronous generator with capacitor bank enables it to generate rated voltage at no load. The additional reactive power demand of the ASG on load and that for the load itself is provided by the VFC. The proposed controller has the capability of harmonic reduction, load balancing and load leveling along with voltage and frequency control. The VFC has been realized using an IGBT based current controlled voltage source converter (CC-VSC) having a battery at its DC link. A simple and effective linear control scheme using SPWM control has been used to control the CC-VSC. This control scheme is easier to implement on hardware than the other reported schemes, as it involves only linear PI controllers. The effectiveness of the proposed controller for an autonomous generator is demonstrated by simulation on MATLAB platform. [ABSTRACT FROM AUTHOR]

Large inductive loads require larger rating of DSTATCOM to generate the required reactive power of the load. Larger the rating of the DSTATCOM higher is the cost. Most distribution system has a base reactive power requirement. The reactive power demand at any instant varies around the base value. A window operation of the DSTATCOM is proposed in this paper. The base reactive power is provided by the TSCs and the DSTATCOM operates within a window (comprising of both inductive and capacitive reactive power) beyond the base reactive power provided by the TSCs. Thus the range of the reactive power compensation of the system is enhanced without the system being limited by the steps in which the TSCs operate. Within the window range, the DSTATCOM provides a continuous and smooth variation in the reactive power generation and can track the change in the VAr requirement very fast. To obtain optimal performance of the combined system, the TSCs are switched through a Fuzzy Logic controller. In this paper, window operation of the DSTATCOM along with Fuzzy Logic Controller operated TSCs is demonstrated for an autonomous asynchronous generator. The entire system has been simulated on MATLAB platform. [ABSTRACT FROM AUTHOR]