The research of wind power optimized capacity configuration in hydraulic power system

Abstract

Buerjin power grid of Xinjiang province in China is an alone hydraulic-wind power mutual compensation system, which is composed of two hydraulic generators with capacity of 2000 KW and one with 2500 KW and seven wind generators with capacity of 150 KW, the wind power capacity account for almost 13.0 percent of total power system capacity. In order to study the optimal capacity scheme of wind power in the system, based on Buerjin real power grid topology, its simplified mathematical model was built by the methods of eliminating partial nodes of the whole power network and of removing power loss and merging into power load. The mathematical model of seven order differential equation for wind power generator considering variable wind speed is given in this paper, the emulation models for the synchronous wind generator with excitation system and frequency-modulation system and the asynchronous wind generator accompanying wind speed variation are built as well. The dynamic stability of wind-hydraulic power mutual compensation system were simulated and analyzed in these cases: wind generators cut-in one by one, wind generators cut-in simultaneously, wind generators cut-in when wind speed leaps. The simulation result is indicated as follow: the power system will be dynamic stable when generators cut-in one by one; the power system dynamic stability will be influenced a little when wind speed leaps from 10 m/s to 20 m/s; the power system frequency will fluctuate between 49 Hz to 52 Hz when seven generators cut-in simultaneously, finally all the generators will be cut off by its control system thus wind power cut-in will be failed. Furthermore, the simulation result also shown that the power system frequency could not be ignored when large-scale wind generators are switched into power grid, frequency should be paid more attention to do research on power system stability. The simulation result also fit the real measurement very well, which verify the correctness of the emulation model. The optimized mathematical model based on genetic algorithm was built in the paper, and the fitness function with punish item was created, so the genetic algorithm was utilized to calculate optimal wind power capacity, the calculation result demonstrated that when the wind penetration capacity exceed 15.25 percent of its rated wind capacity, which reaching its maximum limit, the stability of alone wind-hydraulic mutual compensation system would be destroyed, the conclusion also match its simulation result, which verify the rationality of mathematical model and the feasibility of genetic algorithm application on the calculation of the wind penetration power. In addition, the simulation result also show that the wind generators need to install VAr compensation capacitor with certain of capacity, and the simulation model need to be further improved.