Research On Power Imbalance Response Strategy For AC/DC Hybrid Substation Based On Energy Routing Networking

In the construction process of new power systems,the randomness and intermittency of new energy can cause an imbalance between active power supply and demand,leading to frequency fluctuations.In addition to conventional start-up of frequency modulation power plants and increasing the backup capacity of synchronous machines,the potential for regulating user side resources represented by electrolysis systems and air conditioning can also be fully explored,thereby constructing an optimized control plan for multi energy coordination between grid side and load side equipment,effectively alleviating the frequency modulation pressure of frequency modulation units.This paper takes the future-oriented AC/DC hybrid station area based on energy router as the research object,and the main research contents are as follows:Firstly,in order to meet the requirements of future highly integrated substation applications,an AC/DC hybrid substation was built based on the multi-port modular multi-level converter energy router topology,and the control methods of the rectifier and inverter sides were analyzed.PV,energy storage,fuel cell,industrial load electrolytic cell and residential load air conditioning are connected to the low-voltage DC port.Their working principles are analyzed,mathematical models are established and corresponding control strategies are designed,and the power balance characteristics of the substation area are further analyzed.Secondly,combined with the electrolytic load and air conditioning load in the AC/DC mixed station area,the constraint characteristics of the electrical response of the underlying equipment were analyzed.The response time and efficiency characteristics of the industrial load electrolysis system were analyzed,and the boundary of the optimal operating economic zone in response to the power grid was obtained.Aiming at residential air conditioning load,a potential calculation model is established,and a climbing control strategy considering comfort level is proposed for the bottom equipment converter of air conditioning load,which can not only respond to the power grid,but also avoid excessive temperature changes affecting the comfort level.Then,based on the response characteristics of the underlying equipment and the regulation characteristics of the remote power grid,a dynamic response strategy for grid load coordination based on AC/DC hybrid substation area was designed.Based on the basic control of HVDC transmission,a control strategy incorporating frequency variation is proposed to respond to the primary frequency regulation of the power grid;Furthermore,a response to secondary frequency regulation control scheme was proposed,where the upper level dispatch center coordinated the output of HVDC transmission,local generator units,electrolysis system,and air conditioning loads by issuing instructions to cope with power shortages.At the same time,the software and hardware for communication between the underlying devices and the upper dispatch center were designed to achieve frequency change detection.Finally,a demand response inverter for air conditioning load is designed,and through the RTDS-SPS platform,the information interaction between the variable frequency air conditioning load and the platform area is realized in the form of hardware in the loop,and the working conditions of the bottom equipment responding to the primary and secondary frequency regulation of the power grid are simulated.The experimental results verify the feasibility and effectiveness of the proposed method.