| With the rapid expansion of industrial scale,the power load continues to grow,and the peak valley difference rises steadily,which makes the high-quality power demand surge.Under the background of green energy development and deepening reform of energy structure,large-scale access to power grid of wind power and photovoltaic power generation will bring great challenges to power grid peak regulation and power generation quality due to its characteristics of randomness,intermittence and uncontrollability,as well as serious threats to power grid operation control and safety.Pumped storage power station can effectively make up for the impact of energy such as wind power and photoelectric on the power grid,and improve the capacity of large-scale access to renewable energy.Therefore,it is of great significance for the safe and stable operation of the power system and the maintenance of power quality to establish the fine coupling model of the regulation system of the pumped storage unit and to carry out the research on its optimal control.In the process of operation of pumped storage units,the complexity of each component system,the huge inertia of water flow,the complexity of water diversion system and the coupling among hydraulic,mechanical and electrical factors make the operation of pumped storage units have strong coupling,complex time-varying and nonlinear dynamic characteristics,which increases the difficulty of fine modeling and control of pumped storage units.Therefore,based on the comprehensive analysis of the hydraulic,mechanical and electrical characteristics of the pumped storage unit,this paper establishes the electromechanical coupling model of the pumped storage unit,carries out the Optimization Research on the control parameters of the speed control system of the pumped storage unit and the excitation control system of the synchronous generator based on the intelligent optimization algorithm,improves the primary frequency regulation performance and the excitation control performance,and ensures the safety and stability of the system function.The main work and innovative achievements are as follows:(1)Considering the calculation accuracy of the existing model and the internal coupling characteristics of the unit,a refined model of the Water-Machine-Electric coupling regulation system of the pumped storage unit is established,which makes the model simulation closer to the real situation of the actual work site.Considering the principle of water hammer and hydraulic loss,considering the influence of surge chamber,the water diversion system is modeled with reference to the actual pipeline layout of hydropower station;based on the projection method of logarithmic curve,the full characteristic curve of pump turbine is numerically transformed,and the nonlinear model of pump turbine is constructed to ensure the solution accuracy of the model under the full working condition;the internal electromechanical effect of unit operation is considered With electromagnetic influence,transient and sub transient processes,the seven order model of synchronous generator and potential source rectifier excitation system model are established to make the simulation model more close to the actual unit.(2)Based on the refined model of Water-Machine-Electric coupling regulation system of pumped storage unit,the performance of primary frequency modulation is studied.It is concluded that in the low head area,the regulation system of pumped storage unit is easy to enter into the unstable area under the condition of small load and large frequency disturbance,and the system produces violent oscillation.In order to solve the problem of optimal operation under this condition,the fractional order PID(FOPID)controller is adopted,and an improved gravity search algorithm(BCGSA)is choosed to optimize the control parameters,which effectively improves the frequency modulation control performance of pumped storage units under low water head,small load and large frequency disturbance conditions.(3)The excitation control system of synchronous generator is simulated and optimized when the unit enters into low frequency oscillation with the condition of low head and no load.By introducing the fuzzy control theory,the fuzzy FOPID controller is established for the excitation control system of the synchronous generator of the pumped storage unit.The BCGSA algorithm is used to optimize the control parameters,which effectively suppresses the problem of violent low frequency oscillation of the excitation system of the pumped storage unit when it enters the unstable area under the condition of low head and no load,and improves the excitation control efficiency. |
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