Modeling of Isolated Photovoltaic-Battery-Diesel Generator Hybrid System
Pradeep Kumar Dadhich, Ph.D, 05
Supervisor(s): Rangan Banerjee
Abstract PV-Battery-DG hybrid systems can play an important role in the decentralized based power generation especially in remote locations. The first part of this thesis deals with the modeling of PV-battery-DG hybrid system for decentralized power generation based on an actual hybrid system located at The Energy and Resources Institute (TERIs) Executive Residential Training Complex, located in Gurgaon near Delhi. A detailed component based model was prepared in MATLAB/ simulink and validated against the manufacturers specifications. The various modules that were prepared for this model are (a) the solar radiation module, (b) photovoltaic module, (c) the maximum power point tracker module, (d) array module, (e) load module, (f) dispatch module, (g) battery discharge module, (h) battery charge module (i) DG set and (j) the economic module. The power dispatch module was modeled incorporating operating capacity constraints and specifications of the inverter, the DG set and the battery charging current limits and the operating voltages as provided by the manufacturers. The operating strategy in this module can be changed as required. The economic module was prepared to calculate the cost of energy supplied by the hybrid system based on life cycle analysis. The second part of the thesis is to carry out parametric tests to identify criteria for sizing of the hybrid system using different operating strategies. The model was simulated using the existing dispatch strategy using the actual annual load curve and a load curve based on average daily demand. It was found that the hybrid system performance is very sensitive to the load curve. The model was also simulated using an alternative operating strategy. It was found that the total monthly average system losses in existing dispatch strategy were around 20 percent whereas in the alternative dispatch strategy the hybrid system losses were 4 percent. The model was also used to simulate the standalone PV system without the DG set. It was found that the hybrid system was not only cost-effective but also had significantly lower losses than the PV-SAS. The simulations show that using the average daily energy requirement basis for designing the hybrid system would result in a sub-optimal system design. The future work in this area would be to develop a search algorithm for arriving at an optimal system design for a given LOLP. The optimal system design is also very closely link to the operating strategy, which should be the part of the search algorithm.