| With the large-scale grid connection of wind power and the wide application of wind power frequency modulation control technology,how to consider the role of wind power frequency modulation in the optimal dispatching of power grid considering frequency constraints is of great significance to ensure the safe and stable operation of frequency and guide the planning and construction of wind power grid connection.Therefore,this paper studies the frequency response characteristics of power system including the virtual inertia response and primary frequency modulation response of wind power,deduces the dynamic frequency constraints and the steady-state frequency constraints of power system including the role of wind power frequency modulation,establishes the optimal scheduling model of power system including wind power plant considering the frequency safety constraints,and proposes a solution method of scheduling model based on Benders Decomposition.The detailed method is arranged as follows:Firstly,combined with the process of power system frequency response,the paper introduces the calculation formula of traditional power system frequency response technical indexes and the range of system frequency safety constraints.Based on the differential inertia control method,the virtual inertia time constant of wind turbine is used to represent the virtual inertia response of wind power.Combined with the frequency safety constraints of the system,the influence of the virtual inertia of wind power participating in the system frequency modulation on the frequency safety constraints of the system is analyzed.At the same time,based on the control method of primary frequency modulation,the transfer function is used to describe the response of primary frequency modulation of wind turbine.Combined with the system frequency safety constraints,the influence of primary frequency modulation of wind power on the system frequency safety is analyzed.Secondly,the equivalent model of power system frequency response analysis with wind power frequency modulation response is established,which can be used to analyze and calculate the frequency response characteristics of power grid including wind power virtual inertial response and primary frequency modulation.The equivalent virtual inertia time constant is used to quantitatively represent the inertia response of wind farm.The transfer function model is used to describe the primary frequency modulation response of wind farm.Combined with the prime mover governor model of reheat thermal power unit and hydro power unit,the improved analytical calculation equivalent model of power system frequency response is obtained。 It provides a theoretical basis for the objective evaluation of power system frequency stable operation under high wind power penetration.Finally,based on the calculation model of system frequency response characteristics including wind power virtual inertia and primary frequency modulation,the maximum change rate of system frequency and the lowest point of system frequency are derived to ensure that the system has sufficient dynamic frequency response capability in case of sudden disturbance in the process of optimal scheduling;the maximum and minimum of system are calculated according to the reserved frequency modulation reserve for load shedding operation of fan and the requirements of system steady-state frequency deviation Frequency modulation standby is used to ensure the steady-state frequency safety of the system in the optimization process.Taking the minimum cost of power generation as the goal,the wind power frequency modulation is considered in the system frequency modulation response,and the optimal scheduling model of the wind power system with frequency security constraints is established.Through the transformation of ieee10 machine 39 node system,the optimization model is solved by benders algorithm,and the economy and security of the model are verified. |
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