| In the context of"double carbon",the vigorous development of wind and solar power and other clean energy generation has become an important energy strategy for China.Wind and solar energy are intermittent and volatile,and when used as the main power source or connected to the grid,they are prone to frequency oscillations,affecting the stability of power supply.In order to consume more wind and solar power,it is common to build micro-grid systems using the rapid response of hydropower units and the flexible and efficient compensation of energy storage batteries.Due to the multiple uncertainties in the constructed system,one of the difficult points affecting its stability is frequency control.To address this problem,this paper designs a hybrid H2/H∞robust controller based on multi-objective H∞theory,with the main objective of suppressing frequency oscillations in the transient state of the microgrid.The empirical method of parameter rectification for traditional robust H2/H∞control has certain limitations and cannot optimize the controller performance.In order to improve the control performance of the controller,an intelligent algorithm is applied to optimise the controller parameters in this paper.The specific work done in this paper is as follows:（1）A linear model of wind-light-water-storage microgrid load frequency control with perturbation signals is first established,and a joint frequency regulation design for hydroelectric units and energy storage batteries is carried out.A state-space equation reflecting the characteristics of the microgrid system is derived.Afterwards,according to the robust multi-objective H∞theory,the performance indicators for maintaining the stability of the microgrid system are obtained,and the satisfied performance indicators are transformed into the conditions for solving the H2/H∞multi-objective output feedback robust controller,and the solution conditions are transformed using the LMI tool to derive the relevant evaluation matrix and the parametric weights affecting the system control performance.（2）An Improved Seagull Optimisation Algorithm（ISOA）is obtained by introducing Logistics chaos and adaptive perturbation into the basic Seagull Optimisation Algorithm（SOA）and changing the relevant parameters in the algorithm’s search process,which improves the initialisation efficiency and search accuracy relative to the original algorithm.The ISOA is used to optimise the H2/H∞robust load frequency controller in the established microgrid,taking the minimisation of the absolute value of the time integral number of the system frequency deviation as the optimisation objective function of the algorithm,and selecting the relevant weight matrix reflecting the system performance and output robustness while making comprehensive use of the robustness expressed by the two H2/H∞parametrizers,so that the controller is optimised while satisfying the constraints The proposed method is validated by simulation.Finally,the effectiveness of the proposed method is verified by simulation.The simulation results show that the designed ISOA-H2/H∞robust controller is able to control the power output of hydropower units and storage batteries to compensate for the fluctuation of scenery output and load variation.On the basis of satisfying the system robustness,the microgrid is guaranteed to be frequency stable and have satisfactory dynamic characteristics under power disturbance and system parameter uptake. |
