Power Quality Control in Wind/Fuel Cell/Battery/Hydrogen Electrolyzer Hybrid Micro-grid Power System

Generally, such as bio-fuels, wind, solar, small hydropower, marine and geothermal energy, etc. have been defined as new renewable energy. Photovoltaic and wind power generation have been in rapid growth, but they have characteristics of randomness, intermittent, uncontrollable. Although the idea of effective renewable energy use as a means of coping with environmental and resource problems, especially of reducing CO2 emissions, is globally attractive, inappropriate application of distributed renewable power generation systems can be a cause of insecure power supply. That is, the widespread use of various kinds of distributed renewable power sources which would impact the quality of the power supply within a micro-grid power system, causing many control problems (Li et al., 2008). Micro-grid is one such system, consisting of distributed generators, loads, power storage devices and heat recovery equipment, among other components. The main advantages of the micro-grid system are that (1) it can be operated independently from conventional utility grids, (2) it can make use of power and heat sources collectively, (3) it can be interconnected to the utility grids at one point (Lasseter et al., 2002; Lasseter & Paigi., 2004; Li et al., 2008). A micro-grid system (see Fig. 1) comprised of a control and monitoring system, a housing load, a 1MW load-controllable electrolyzer system to manufacture hydrogen, a hydrogen tank and renewable-energy-utilizing generators such as 3MW wind power generation system (WPGS), 500kW proton exchange membrane fuel cell (FC), 1MWh battery energy storage system (BESS), and others, is considered in this chapter. The power supply-demand balance control of the micro-grid system is performed by the control and monitoring system through a Control Area Network (CAN) composed communication network. Moreover, the electricity of electrolyzer system is supplied mainly by the wind power energy source and the hydrogen produced by the electrolyzer system is stored in the hydrogen tank to be converted back to electricity in the proton exchange membrane fuel cells. The wind power is considered as primary source in this chapter. However, when the lack of power supply from renewable power sources is occured, the missing power will be provided via utility grid (Li et al., 2007; Li et al., 2008).