Study On Hybrid Energy Storage Control Strategies For Microgrid Including Wind Power

With the development of the national economyand the electricity demand rapid growth,distributed generation technology has gotten much more attention under the multiplepressures such as environmental protection, energy exhaustion.Distributed generation accessto grid in the form of a microgrid, which is not only can reduce the impact on the safeoperation of the distributionnetwork, but also achieve the distributed generation “plug andplay”.At the same time, it can make the best use of distributed generation. The randomness ofthe intermittent energy sources power output such as wind farm and uncertainty of the loadwill cause the exchange power fluctuating and influence the power distribution whenmicrogrid works in grid-connecting mode.The energy storage system applied in the microgridcan provide short-time power supply, electric power peak shaving and improve microgridpower quality and micro sources’performance. Meanwhile,it is effective means to restrain thefluctuations of the intermittent power supply because of its great technical and economicadvantages.This paper sets the microgrid including wind power and hybrid energy storage system asthe research object and studies the control strategy of hybrid energy storage system (HESS)while microgrid works in grid-connecting mode.Firstly, the operating model and control of wind generation are discussed. Smallpermanent magnet direct drive wind generation system representing intermittent micro source,the dual PWM converters circuit control strategy are studied: motor-side converter usesspeed-current double closed-loop control, and has improved variable step size climbingmethod to maximize wind power; grid-side converter employs voltage-current doubleclosed-loop control to achieve power decoupling control and the stability of DC voltage.Next, the operating model and control of HESS including battery and supercapacitor arediscussed. HESS is introduced on the basis of the battery DC/DC converter、 thesupercapacitor DC/DC converter and DC/AC converter structure. HESS power managementstrategy is proposed based on variable moving average filtering method.The voltage-currentdouble closed-loop controller of the bi-directional DC/DC converter is showed to stabilize theDC voltage and control battery and supercapacitor charge and discharge. The PQ control ofDC/AC converter is demonstrated to accelerate follow output power instructions change.Then, the active and reactive power control strategy of hybrid energy storage inmicrogrid is proposed based on the hierarchical control methodto inhibitthe exchange power fluctuations between microgrid and power grids and reduce the impact on the power flowdistribution when microgrid works in grid-connecting mode.Finally, the simulation test models of small permanent magnet direct drive windgeneration system and hybrid energy storage system are established and thier performancesare tested based on Matlab/Simulink simulation software. A simulation experiment platformof microgrid has been constructed. The operation condition has been simulated ingrid-connecting mode. Simulation results show that the proposed control strategies canachieve good performance of the microgrid.