Research On Fault Caiculation For Distributed Systems Containing Distributed Generation

In recent years, with the circumstances of aggravating energy crisis, distributed generation is developed rapaidly. And the access of distributed generation takes different kinds of effects in the the distributed system. The study on the impact of the distributed system injected with distributed generation rapidly becomes a new energy research hot field. The impact of the relays is one of the effects, the contents studied in this paper is the research on fault calculation for distributed systems containing distributed generation, where is the base to analyze the impact of the relay.Wind power is clean and reliable, so this paper typically chooses the mainstream model-doubly fed wind generator (DFIG). At the beginning of the basic study of the doubly fed induction generator, this paper builds the simulation model and fault calculation model of the doubly fed wind generator, the DFIG wind farm equivalent model considering the wake effect in fault calculation is researched and constructed in this paper. low voltage ride through(LVRT) is an essential part of wind power, according to the requirements of LVRT. the operation of wind power generation system under the failure in the distributed system is provided in detail, and the Crowbar protection circuit is the key of the doubly fed wind generator’s LVRT. Crowbar protection circuit is developed from passive to active protection circuit, this paper selects mainstream Crowbar protection circuit structure. analysis the selection of the Crowbar protection circuit bypass resistance. Based on the complete simulation model of doubly fed wind turbine, this paper simulated the voltage drop of the access point when Crowbar protection circuit is activated with different operating conditions. the paper proposes the operation criterion of the external electrical quantity whether the crowbar protection circuit is activated or not, the influence on the DFIG which the Crowbar protection circuit is in action is embodied in the fault calculation of the distributed system. This paper summarizes the theoretical analysis of the previous section, makes use of the superposition method combined with the back/forward sweep method and the failure compensation circuit to achieve the fault calculation for distributed systems containing the DFIG wind farm. Finally, the paper implements the algorithm by programming matlab codes, and compares with the simulation results of the PSCAD model to verify the feasibility and correctness of the algorithm.