| High-permeability renewable energy generation has added new difficulties to power system frequency modulation.The uncertainty of its output has led to an increase in the requirements for frequency modulation capacity and frequency modulation speed of the system,and the demand for rapid frequency modulation resources has risen sharply,which in turn has led to an increase in the cost of conventional power generation side frequency modulation.On the demand side,the proportion of small and medium-sized loads(such as temperature-controlled appliances,electric vehicles,etc.)with energy storage characteristics is gradually increasing.Such equipment can change the state in a short time without affecting the user's experience.Through the control and aggregation of load aggregators,it can be put into the electricity market as secondary frequency modulation reserve,and relieve the economic pressure of generation side frequency modulation.Therefore,after studying the domestic and international status of demand-side resources participating in FM,this paper starts from the three levels of power system,load aggregator and demand response equipment.The source-charge coordinated frequency modulation strategy at the power system level,the frequency modulation control strategy of the demand response group,and the AGC power dynamic allocation strategy at the load aggregator level are mainly studied.Firstly,this paper introduces the basic theory of predictive control model and designs a source-charge coordinated frequency modulation control framework based on this theory.Aiming at the minimum frequency modulation cost and the minimum output deviation of the traditional generator set.A source-charge co-modulation strategy based on hierarchical predictive control model is proposed.The model is divided into power generation planning layer,secondary frequency modulation upper layer and secondary frequency modulation lower layer 3 layers according to the time scale.The upper layer serves as the reference trajectory of the lower layer,continuously rolling optimization and correction.The example is based on the IEEE14 node system to prove the feasibility of the model in the quadratic frequency modulation scene.Secondly,this paper chooses air conditioner and electric vehicle as the typical equipment for demand side secondary frequency modulation,and studies the demand response group secondary frequency modulation control strategy.In the aspect of air conditioning,the working principle of air conditioner is introduced based on the first-order equivalent thermal parameter model.Based on this,a secondary frequency modulation control strategy for air conditioning group with air conditioning state transition time as the priority sequence is proposed.The feasibility of the strategy in tracking AGC signals and ensuring user comfort is proved by simulation analysis.In the aspect of electric vehicles,the charging/discharging model and travel rules of electric vehicles are introduced.Based on this,a second frequency modulation control strategy for electric vehicle group based on the user's travel demand and battery priority state is proposed.The feasibility of this strategy in secondary frequency modulation and meeting the user's travel needs is proved by an example.Finally,based on the introduction of discrete first-order consistency algorithm,the incremental consistency model of frequency modulation cost in demand response group is established in this paper.Based on this,a dynamic allocation strategy of load aggregator AGC power is proposed.The single-time example analysis proves the superiority of the strategy in optimization time,the adaptability to the communication network topology and the stability in the case of intelligent signal interruption.The feasibility of the strategy in the 1 min AGC power dynamic allocation scenario is illustrated by a multi-period calculation.It is concluded that the average FM cost of the load aggregator mainly depends on the AGC power ratio of the controlled agent and its incremental cost. |
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