Frequency Characteristics Analysis And Coordinated Control Strategy With Demand Response

The traditional frequency modeling method mainly starts with power supply and performs power dispatching,which includes primary frequency regulation,automatic generation control and pumped storage.However,as more and more distributed generations access to distribution network,the randomness and uncertainty of distributed generations aggravate the task of Grid frequency modulation.Besides,in recent years,the development of EHV transmission brought several major Grid accidents which greatly affected the Grid frequency.As a consequence,only using conventional frequency modulation of power supply can't adapt to the development of new situation.In recent years,the improvement of power market makes partial sources of load side can also participate in Grid frequency modulation.The paper studied modeling method based on two types of typical loads and analyzed controlling strategies as well as the impact of the loads on parameters of power system frequency modulation control.Firstly,the paper introduces two power system frequency models which are time-domain simulation and equivalent model method.Secondly,this paper describes the necessity and feasibility of demand response participating in system frequency modulation.Also,based on the analysis of power system primary and secondary frequency modulation,this paper chooses two types of typical loads as research objects,which is as the groundwork of next part.Firstly,from the perspective of primary frequency modulation,this paper takes electric boiler as a typical example and analyses its running characteristic as well as the dynamic relation between temperature regulation and heating power based on its basic structure and operating principle.Based on the analysis,this paper deduces the maximum response capacity of the electric heating boiler up-regulated and down-regulated after comprehensive consideration of the running characteristic and parameters limitation.Lastly,considering the otherness of electric boiler response characteristics,the cluster optimization sequencing control strategy based on variable threshold is designed for balancing individual response potential and response priority in an electro thermal boiler group.With simulation,the electric boiler in specific area can response the signal of primary frequency modulation in order,which avoids the secondary damage to Grid caused by frequency overshoot caused by unreasonable response capacity as well as sudden load switching.Secondly,from the perspective of secondary frequency modulation,this paper took air conditioner as a typical example and proposed a linearized air conditioning thermal equivalent parameter model,based on the working principle of air conditioning load and its dynamic model.By analyzing this model,this paper made a conclusion that the controlling method that the on-off stated is controlled by changing temperature has some delay and inertia and is not easy to realize the transient breaking function.Therefore,this kind of controlling method can be classified in the area of power system secondary frequency modulation on time scale.Then,based on the control strategy of temperature regulation with air conditioner grouping,this paper analyzed the running characteristic of regional air conditioner cluster.At last,after considering the control strategy of air conditioning cluster frequency modulation,the simulation in this paper demonstrated that air conditioning load can cooperate with the secondary frequency modulation of generating set.Lastly,on the basis of fore study,this paper thoroughly analyzed the primary and secondary frequency modulation characteristic of traditional generator set,the primary frequency modulation response characteristic of electric boiler load and the secondary frequency modulation response characteristic of air conditioning load.This paper took the actual load fluctuation data as the sample and chose 12 kinds of load fluctuation scenes by risk quantification index.Considering the overall power system frequency response framework of demand response,this paper transferred the performance evaluation index ITAE to the multi-objective problem and took particle swarm algorithm to optimize the control parameters of system frequency modulation.An example of an interconnected power network in this paper simulated and verified the above control strategy and optimization method.