Research On Coordinated Control Of Air Conditioning Load Based Virtual Energy Storage System And Distributed Photovoltaic Power Generation

With the continuous improvement of living conditions brought by technological progress,air conditioning has become a necessary equipment for adjusting the internal environment of buildings.The continuous increase in the scale of the air conditioning load in the low-voltage distribution network and the concentrated use have caused the peak-to-valley difference in power consumption to increase,which brings challenges to the stable operation of the distribution network.Increased environmental awareness and policy promotion have brought about the gradual application of distributed photovoltaics(PV).However,the intermittent and random nature of photovoltaics has also led to a series of voltage problems.The development of smart grid technology has brought more new solutions to the above problems,and the potential of air conditioning load in the demand side response is gradually emerging.The virtual energy storage system(VESS)based on air-conditioned buildings demonstrates a certain dispatch capability.Its thermal energy storage characteristics can be used to buffer the fluctuations of distributed photovoltaic power generation and reduce the centralized use of air conditioning loads.In view of the above problems and solutions,this thesis first reviews and analyzes the existing research work.In the modeling of VESS,most of the existing research work chooses simplified models with insufficient accuracy to simplify the work.Due to the high R/X value of the low-voltage distribution network,the intermittent nature of photovoltaics and the high cost of battery energy storage systems,the use of VESSs to participate in the voltage management of the low-voltage distribution network can improve the regulation efficiency as well as increase the PV penetration rate.Compared with the traditional voltage regulation method,it has the advantages of stronger flexibility and economy.At the same time,the coordinated optimization control scheme of VESSs,photovoltaic power generation and battery energy storage system can improve the peak-valley difference of power consumption and increase the penetration rate of photovoltaic,and comprehensively optimize the power utilization of the distribution network.Firstly,in terms of the modeling of the VESS based on air conditioning load,an improved two-parameter thermal model is proposed.The model adopts a more complex and more accurate two-parameter thermal model.Based on this,indoor heating elements and air conditioner coefficient of performance(COP)are considered.Meanwhile,it can ensure that the thermal comfort requirements of end users are not affected during the control of the air conditioners.In addition,a load aggregator method is adopted to manage large-scale VESSs.Aiming at the ability of aggregators to participate in scheduling,an evaluation method based on the maximum controllable active power is proposed,and the differential evolution algorithm is used to solve the model.Simulation experiment shows that this method can obtain the maximum controllable active power of each aggregator at each moment based on data such as building parameters,temperature,and thermal comfort requirements under the premise of ensuring the thermal comfort requirements of users.Secondly,this thesis studies the scheme of VESSs participating in distribution network voltage management.A hierarchical scheduling framework is proposed.The bottom layer is the local control of the VESSs by the aggregator,and the top layer is the distributed control of the coordinated voltage adjustment between the aggregators.The voltage management is realized by adjusting the active power consumption of the VESSs.A distributed control strategy based on the consensus algorithm is adopted to realize the coordinated voltage regulation of multiple aggregators under a limited communication link.The operation simulation experiments based on IEEE 15-node distribution network show that the proposed scheme can improve the problems of undervoltage and overvoltage caused by peak power consumption and photovoltaic power generation peaks,and the voltage regulation maintains good results under different photovoltaic penetration rates.Comparative experiments show that the voltage regulation under different communication network topologies is still effective,and the distributed control scheme has flexibility and robustness.Finally,the coordinated optimization control research of VESSs and distributed photovoltaic and battery energy storage system is carried out.A two-stage optimization control strategy is proposed: 1)A system optimization model based on mixed integer linear programming has been established at the day-ahead optimization scheduling level,which aims at optimizing the operating cost of the local distribution network;2)Moreover,the real-time optimization scheduling level considers the forecast errors of data such as temperature,photovoltaic power generation,and electricity prices.And rolling horizon optimization algorithm is used to reduce the influence of forecast errors on control accuracy.The simulation experiment results show that the scheme can minimize the overall operating cost and achieve the optimal utilization of electricity,while smoothing the power demand.The photovoltaic power is basically consumed locally,which can increase the photovoltaic penetration rate.In addition,due to the use of the mentioned VESS model,the user’s thermal comfort requirements have not been affected.