Study On Primary Frequency Modulation Characteristics Of Varuable Speed Pumped Storage Unit Under Power Generation Conditions

With the large-scale development of new energy sources,due to the uncertainties such as randomness,intermittentness and volatility of new energy sources,higher requirements are imposed on the frequency modulation capability of the power grid.Due to th,e action of the water hammer,there is a reverse adjustment phenomenon in the initial stage of the hydroelectric generating unit regulation,which seriously affects the quick-acting and primary frequency-adjusting characteristics of the regulating system of the generator set,and limits the peaking and frequency-modulating ability of the hydro-generator set.The variable speed pumped storage unit solves the problem of slow peaking and frequency response due to the initial back--adjustment of the unit due to its own adjustable speed.This paper mainly studies the power response and primary frequency modulation characteristics of variable speed pumped storage units during power generation,(1)Set up a simulation model of variable-speed pumped-storage generator set under power generation conditions,including AC excitation motor,network side and machine side control of AC excitation motor,frequency regulator,power regulator,speed regulator,water diversion system,nonlinear turbine,speed optimization module,etc.(2)Firstly,the variable-speed pumped-storage unit adopts PI active power controller,analyzes the influence of proportional gain and integral gain on the power response,and sets a set of drunkenness parameters to optimize the power response.Then,on this basis,the influence of the frequency regulator parameters on the primary frequency modulation characteristics is studied.Finally,additional power feed forward control is introduced in the speed regulator.It is found that for power response,power feedforward control is introduced to make the vane opening speed faster,the mechanical torque of the unit increases faster,and the unit speed decreases.The power response time is shor-tened.And no additional power feedforward control to study,due to increased power feedf-orward control,the vane opening speed is faster,the un it mechanical torque increases faster,the unit speed rises faster,the unit output increases,the unit is stable The time is shortened;then the active power controller of the variable speed pumped storage unit is studied;according to the influence of the active power regulator parameters on the power response,a set of optimal parameters is set,and the influence of the frequency regulator parameters on the primary frequency modulation characteristics is studied;finally,A set of optimal parameters is set by the influence of the frequency regulator parameters on the primary frequency modulation characteristics,and the primary frequency modulation characteristics of the variable speed unit are evaluated according to national standards.(3)Introducing additional power feedforward control in the speed regulator,and based on the selection of the optimal parameters of the active power regulator,the parameters of the frequency regulator are optimized by analysis and optimal parameter tuning,and refer to the latest" Standards such as the grid operation guidelines evaluate the primary frequency modulation of the variable speed unit.The results show that the reaction lag time is 0.3s when the variable frequency pumped storage unit is used for power generation,and the unit takes 90%to adjust the load for 5s.The average output power of the unit and the unit response target power deviation are average.The value should be within 7.5s of the theoretically calculated adjustment range of 7.5s,all of which are better than the requirements of the standard,and the use of the kinetic energy to eliminate the initial adjustment of the initial frequency modulation is completely eliminated,greatly improving the quickness of the adjustment system.The fast power regulation of the variable speed unit improves the primary integrated power of the frequency modulation.The qualified rate of the primary frequency integral power generation under the power generation condition reaches 94.20%,which is better than the requirements of the relevant standards.