Research On Virtual Inertia Control Strategy Of Temperature Control Load

Due to the increasing demand of electricity for production and living as well as the excessive depletion of fossil fuels,Wind,photovoltaic and other new kinds of energy generation get increasing proportion of electricity generation.However,since most centralized renewable energy generation devices are connected to the grid through power electronics devices,they are usually lack of inertia.Therefore,high penetrations of renewable energy sources will lead to a significant reduction in power system inertia.A large power disturbance,because of the lack of inertia of the power system,may lead to a particularly large deviation amplitude of system frequency.Therefore,how to adjust the system inertia by designing effective control strategy is of great importance for the safe and stable operation of the power system,and also provides security assurance when the large amounts of renewable energy generation participate in the power generation.This paper takes this as an opportunity to carry out the research on the virtual inertia control strategy of thermostatically controlled loads,so as to adjust the inertia of power system and improve system stability.The main work of this paper includes:(1)The research background and significance is introduced and the influence of high penetrations of renewable energy generation on power system inertia is analyzed.The advantages of using a large number of aggregated thermostatically controlled loads to participate in the frequency control of power system are discussed.The domestic and foreign research status is introduced from three aspects,namely,the strategy of improving the power system inertia,the modeling of thermostatically controlled loads and the participation of thermostatically controlled loads in frequency modulation and dispatching.(2)Based on the equivalent thermal parameter model and considering the fact that the operating states of thermostatically control loads cannot be switched continuously,the improved simulation model of thermostatically controlled loads is established.The dynamic equivalent energy storage model of aggregated thermostatically controlled loads is deduced considering parametric heterogeneity of a large number of thermostatically controlled loads.The influence of high penetrations of renewable energy generation on the parameters of power system frequency response model is analyzed.After studying the derivation process of power system frequency response model in detail,the correction scheme of power system frequency response model's parameters is proposed.(3)According to the kinematic equation of generator's rotor,the influence of demand response strategy based on differential controller on power system inertia is explored,and the control structure and control means of aggregated thermostatically controlled loads participating in demand response are determined.Based on equivalent energy storage model of aggregated thermostatically controlled loads,the relationship between thermal energy stored in the rooms and actual electric energy is analyzed,and the conversion coefficient between thermal energy and equivalent electric quantity is given.Combined with the above two research results,the real-time adjustment scheme of virtual inertia controller parameters is designed.(4)Based on the improved simulation model established in this paper and the corrected power system frequency response model,the simulation is accomplished by selecting reasonable value of parameters.Firstly,the simulation considering differential controller verifies that the thermostatically controlled load demand response strategy based on differential controller benefits for improving the power system inertia.Secondly the simulation considering PI based tracking controller verifies that the uncertainties of power consumption of aggregated thermostatically controlled loads are restrained by establishing PI based feedback loop.The last simulation by choosing the proper temperature value of the thermostatically controlled load verifies the effectiveness of real-time adjustment scheme of virtual inertia controller' s parameters.