Research On Optimal Control Strategy Of Active Distribution Network With Aggregated Loads Demand Response

In recent years,energy shortages and environmental protection issues have become increasingly prominent,the proportion of renewable energy in the power grid increased year by year.However,when connecting to the power grid,due to the renewable energy has features of strong randomness,volatility and intermittent,it may cause problems like the power quality,power supply and demand balance and power system security issues.On the other hand,as the power system loads have rich diversities and larger scale,the percent of resource with characteristics of good interactive adjustment,adjustable,controllable increase steadily.In addition,with the continuous upgrading of communication and control technology,demand side controllable flexible load percent is also increasing.One of the core technologies of ADN(Active Distribution Network)is to use DSCL(Demand Side Controllable Load),achieving synergies with renewable energy,providing wave stabilization,load tracking and other ancillary services for the power grid.This thesis focuses on the demand side controllable load participating in the research of related technologies of renewable energy integration,including the demand side controllable load modeling,regulation and participation in grid auxiliary service,and so on.Main work of the thesis is as follows.(1)A "bottom-up" refined modeling method is proposed in the thsis,which can consider the physical characteristics and dynamic mechanism.A so-called "nonelectricity & electricity" model is developed for DSCL.Some DSCL's characteristics,such as thermostatical dynamic,charging and discharging are properly considered.Further,The method is applied to three typical DCSL: HP(Heat Pump),CAC(Central Air Conditioning)and EV(Electric Vehicle).The proposed method can provide model support to design control strategy and DSCL participating into renewable resource integration.(2)Based on generalized control strategy-parameter serialization method,appropriate strategies and disscussion of HP,CAC and EV are made:(1)HP: using "indoor temperature " as the serialization parameter,temperature priority list method is used to control HP;(2)CAC: Taking the main device as the study object,the indoor temperature was used as the serialization parameter.A control strategy based on adjustment of load rate is presented to avoid the disadvantages of traditional method which controls terminal devices frequently;(3)EV: The energy state is selected as a serialization parameter to regulate charge and discharge behaviors,to avoid overcharging negative impact and to achieve the controlling of EV.(3)A hierarchical collaborative control framework based on region information for "renewable energy-distribution network-demand side controllable load" is put up in the thesis.In the upper level,controlling center uses DPFT(Distribution Power Flow Tracing)method to propose a regional aggregated optimization control strategy for demand response.Based on power flow information,this strategy can take the "sourcegrid-load" coupling characteristic into account.Load regions closely related to the renewable energy will be determined.And,the power fluctuation distribution will be determined and dispatched.In the lower layer,power grid constraints,different beneficiaries and regional load control costs are considered at the same time.Various sources of load demand response are optimized to smooth the power flow fluctuation on the ADN's tie lines.