Coordinated Frequency Control Strategy Of Power System Source And Load Considering Communication Influence

Under the background of energy transformation and peaking carbon dioxide emissions and achieving carbon neutrality,the penetration rate of new energy is increasing.The traditional power system has gradually evolved into a new type of dominated by new energy sources.However,the frequency problem of new energy high-permeability power system is becoming more and more serious because of its low moment of inertia and strong randomness of wind and photovoltaic output.Moreover,the rotor units are gradually replaced by new energy sources,which leads to the shortage of power system regulation capacity and reserve capacity,and the traditional frequency regulation means can be inadequate to meet the frequency regulation requirements under the new situation.In recent years,with the large-scale access of distributed resources such as thermostatically controlled loads and energy storage,along with development of coordinated dispatching technology on both sides of source and load,fully tapping and mobilizing the regulation potential of demand-side flexible resources to support power balance has become an important direction for the future development of power system.Additionally,the power system is a highly coupled system of information and physics,where the frequency control depends on the communication network to transmit measurement signals and send control instructions.However,problems such as bandwidth limitation,network congestion and communication failure easily lead to uncertainties such as communication delay,thereby affecting the real-time control of the physical system and even leading to system instability.Hence,in view of the frequency regulation demand of power system under the new situation,fully tap the regulation potential of demand side,explore the source-load interaction of power system considering the influence of communication,realize the power balance between supply and demand through effective and rational control strategies,and ensure the frequency stability,which is of great significance for maintaining the safe and stable operation of power system and improving its reliability and flexibility.Based on the idea of networking and cooperation,this thesis investigates the coordinated frequency control strategy of power system source and load considering the influence of communication from two aspects:aggregated flexible loads and synchronous generators in centralized control and multi-source load resources on load side in distributed control.The main research content is as follows:1.The stability analysis of source-load cooperative frequency control in power system considering communication delay is studied.Firstly,the cooperative frequency control framework of the traditional synchronous generators on the source side and the inverter air conditioners(IACs)on the load side is constructed.Secondly,under this control framework,considering the influence of communication delay in the signal transmission process of IACs control loop,a cooperative frequency control model of source and load in time-delay power system is established.Furthermore,based on Lyapunov theory,a delay-dependent stability criterion is established,which takes into account the accuracy and computational efficiency of obtaining frequency control stability margin.Finally,the interaction between frequency control stability margin and controller gain in different scenarios is discussed,and the accuracy and effectiveness of the proposed criterion are verified.2.The frequency control of source-load cooperative model prediction considering communication delay is studied.Firstly,under the framework of source-load cooperative frequency control,a power system frequency control model with load dynamics of IACs is established.Secondly,in order to cope with the negative impact of communication delay in load control,a regional source-load cooperative model predictive frequency control strategy is designed.Based on this,a delay prediction compensation mechanism is designed,which ensures the effective implementation of cooperative frequency control method under the influence of communication delay.Finally,the simulation results show that the proposed coordinated control strategy and delay compensation mechanism have the characteristics of fast response and good robustness when dealing with the influence of uncertain factors such as communication delay.3.The source-load cooperative robust control considering communication delay under wind power integration is studied.Robust control strategy of source-load coordination under wind power integration.Firstly,considering the operation characteristics of large-scale wind power on the source side and IACs on the load side,a source-load cooperative control architecture is constructed,which includes primary frequency control of Doubly-Fed Induction Generator-based Wind Farms(DFIG-WFs)and secondary frequency control of IACs.Secondly,by introducing the virtual state of charge model,the uncertainty of response capacity of IACs is described,and at the same time,considering the uncertain factors such as communication delay on the load side,inertia reduction and fluctuation enhancement caused by high wind power penetration,a linear system model with uncertainty and time-varying delay is constructed.Furthermore,to solve the problem of frequency regulation under the influence of uncertainty of information and physical coupling,based on Lyapunov theory,the stability criterion of source-load cooperative frequency control is proposed,and a robust H_∞controller is designed.Finally,the simulation results show that the proposed control strategy has good control performance in different scenarios and effectively improves the frequency adjustment performance.4.The distributed cooperative control of load and storage oriented to load side frequency modulation instruction is studied.Firstly,the hierarchical control architecture of source-load cooperation is constructed,and the distributed interaction mode of IACs and hydrogen energy storage system(HESS)cooperation is established.Secondly,in response to the frequency command on the load side,consistent allocation strategies are proposed to realize the rational utilization of IACs and HESS.Furthermore,considering the network environment with limited communication bandwidth,a distributed dynamic event-triggered cooperative control strategy based on multi-agent leader-follower is designed,which realizes the on-demand transmission of power information and keeps close tracking of upper frequency instructions.Finally,the simulation results demonstrate that the proposed cooperative control strategy ensures the effectiveness and rapidity of frequency adjustment while reducing the communication burden.