Research On Application Of Battery Energy Storage System In Power System Frequency Regulation

Renewable energies like wind power and PV come with great fluctuation anduncertainties, and their penetration into power system has brought great challenges tothe security and stability of the grid. Meanwhile, the slow reaction and low rampingrate of traditional generations fail to meet the needs of power system`s fastdevelopment and absorb new energy. As a result, to safeguard frequency stability ofpower system in high permeability of renewable energy`s generation is one of the newchallenges for Chinese grid.In recent years, the rapid advancement of energy storage technologies has shed anew light on the solutions of these issues. Battery energy storage(BES), awell-developed and widely used form in the energy storage family, possesses theability to track power accurately with nearly no delay, which makes it capable ofproviding frequency regulation services of high quality. Being more efficient thantraditional generations, it may serve as a new solution to problems in the field offrequency regulation.The paper first introduced the basic mechanism and conception of primary andsecondary frequency regulations in power system; carry out systematic summary ofarea equivalent method based on the physical structure and operational modes ofactual grid; each parts of regular frequency regulation of power system is modeledand modified compared to the traditional model, thus creating a new model with theability to consider generator constraints, limitation on tie-line power flow, decouplingand time delay of primary and secondary frequency control; Then, on the basis ofanalysis of operational principles, internal structure and previous models, majorcharacteristic parameters of batter energy storage system(BESS) are found out toestablish a modified equivalent circuit model oriented from the BESS unit.A three-area interconnected system of Changsha, Zhuzhou and Xiangtan isestablished based on the winter operation data of Hunan grid to verify the descriptiveability of the modeling method. Then, simulations are carried out to analyzefrequency regulation characteristics of regional grid and traditional generations. Inthis way, the characteristics and shortcomings of traditional frequency regulationtechnologies is explored to find out potential applications of BESS in the field.At last, the BESS model is used to perfect the traditional method for K confirmation in primary frequency control, and a variable-K control strategy isproposed and tested in classic two-area interconnected model, showing betterperformance than the traditional one. For secondary frequency control, a coordinatedfrequency regulation control system for BESS and traditional generations isconstructed based on model predictive control theory (MPC) to handle thecoordination problems. And simulations are carried out based on the space-stateequations of the three interconnected system model to validate the value of the controlsystem. Then, efficiency indexes are proposed to evaluate BESS`s performance infrequency regulation and tested through simulations of different grid situations in thethree interconnected system model established in chapt er three with detailed analysis.