Studies Of Coordiated AGC Control Strategy And Mining Technology For Secondary Frequency Regulation Capacity Of Interconnected Power System

In recent years,with fast development of wind power,“the three norths”area has a special power structure with high permeability of wind power and high proportion of combined heat and power(CHP)units.This causes a huge challenge for interconnected power system frequency control.On the one hand,the existing AGC control technology has severely limit the frequency regulation ability.On the other hand,high proportion of CHP units squeezes frequency regulation resources in heating period,which aggravates frequency regulation ability.Then,according to the potential frequency regulation resources of “the three norths” area,this paper has a deep discussion about two parts: AGC optimal coordination control technology based on multi-area frequency regulation capacity and CHP frequency regulation ability mining by electric heat combined system scheduling.(1)On optimal coordination control of multi-area frequency regulation capacity,a layered AGC control strategy based on static ARMC coordination controller is proposed.First,based on the characteristics of dynamic interconnected power system(IPS)model with the existing AGC control,the dynamic model of IPS which is suitable for the coordination of multi-area AGC control is proposed.Secondly,the flexibility of traditional AGC frequency regulation control standards is analyzed and summarized.Based on this,the principle of coordination control for IPS under layered AGC control model is established.Thirdly,by using the original dual gradient algorithm to transform the model and the linear transformation method,the optimal coordination control mechanism of multi-area is revealed.Finally,based on the above mechanism,the layered AGC control strategy based on static ARMC coordination controller is designed,by which AGC interval frequency regulation responsibility management and interval frequency regulation autonomous optimal coordination control in layered AGC control model is realized.Test results show that effect of system frequency control,control cost and performance of CHP are significantly improved.(2)A distributed AGC control strategy considering the fluctuation constraint of tie-line support and the optimal coordination frequency control scheme of AGC is proposed.First of all,based on characteristics of distributed AGC control model,analyze the tie-line security issues of multi-area frequency regulation,and improve the dynamic model of multi-area integrated system.Then,using saddle point theory analyze the multi-area frequency coordination regulation model with tie-line security constraint.And the mechanism of tie-line support security control and optimal coordination control of dynamic ARMC multi-area frequency regulation is obtained.Based on the above control mechanism,a distributed AGC optimal coordinated control strategy is proposed.Finally,the stability,security and optimality of the closed-loop control system based on the proposed control strategy is analyzed.Simulation results of test system show that the effectiveness of proposed strategy.(3)the frequency regulation capability excavation of CHP units in multi-time scale operation is studied: coordination mechanism of CHP units and thermal energy storage of thermal network in multi-time scale is investigated,and a method based on combined heat and power decentralized coordination dispatch for excavation of flexible frequency regulation reserve is proposed.Firstly,the flexibility of CHP units in power dispatch and frequency control is analyzed,and flexible reserve of CHP units for frequency regulation is defined.Secondly,coordination model of CHP units and heat system in multi-time scale is established and frequency regulation support level of heat system is effectively measured.Thirdly,a framework for combined heat and power decentralized coordination scheduling is proposed: robust interval scheduling of thermal system determines the maximum flexible coordination boundary of CHP units frequency regulation;dispatch and extraction of flexible reserve of CHP units for frequency regulation is realized by power scheduling based on thermal system scheduling.Finally,test results analyzes the influents of flexible reserve for frequency regulation on the operation of combined heat and power system.(4)The frequency regulation capability excavation of CHP unit in steam extraction control mode is covered.The coordination mechanism of CHP unit and building level thermal energy storage for frequency regulation is studied,and a heat and power optimal dispatch is established to excavate frequency regulation capability of CHP units.Firstly,the frequency response characteristic of CHP unit under steam extraction regulation mode is studied.Secondly,the complementarity of building level thermal energy storage to the fluctuation of CHP thermal output due to frequency regulation is analyzed,and the control parameters of the building level thermal reserve are set up.Based on this,the coordinated control strategy between CHP units and buildings in direct heating connection or indirect heating connection mode is established,and the coordination space of frequency regulation is quantified.Finally,based on the above coordination strategy,a frequency regulation reserve excavation method is proposed,which is realized by scheduling of combined heat and power system.Simulation results show the effectiveness of the proposed method.At the end of the paper,the main achievements and conclusions are summarized,and expectation on future work is given.