| Building a new power system with new energy as the main body is an important measure to realize "carbon peaking and carbon neutralization".However,the output of new energy represented by photovoltaic has volatility,randomness and anti peak regulation,which is bound to bring severe challenges to the power balance,security and stability of the power grid.In order to deal with these problems,this paper considers the participation of photovoltaic units in inertia support and primary frequency regulation process and the installation of energy storage devices,so as to improve the safety and stability of the system and the consumption level of new energy from different time scales.Firstly,the necessary conditions for maintaining voltage stability after photovoltaic units replace conventional power supply are deduced theoretically.At the same time,the frequency response model of conventional synchronous machine system is established,and the frequency response expression of the system after power disturbance is obtained.InDIgSILIENT/PowerFactory15.1,a three machine nine node system simulation model with photovoltaic units is built,and the influence of photovoltaic permeability on system voltage stability and frequency stability is observed by setting short-circuit fault and load disturbance.Secondly,in order to improve the impact of high proportion photovoltaic access on the frequency stability of the system,the scheme of virtual inertia support and primary frequency modulation control is adopted by configuring energy storage of photovoltaic units.The frequency response model of power system considering the inertia support and primary frequency modulation capability of photovoltaic units is established.Three indexes of maximum frequency deviation,quasi steady state frequency deviation and frequency change rate amplitude are introduced to quantitatively evaluate the frequency characteristics under different photovoltaic permeability scenarios.In addition,in order to quantitatively analyze the influence of key control parameters on system frequency stability,a feasible region calculation method of PV unit inertia and primary frequency regulation control parameters considering frequency index constraints is proposed,which can provide a reference basis for the selection of PV unit frequency regulation control parameters in high permeability scenarios.Finally,in order to meet the needs of flexible operation of the system after large-scale photovoltaic units are connected to the grid,the configuration of energy storage capacity is considered from the medium and long-term scale.Considering the peak valley difference,up/down climbing ratio and the maximum/minimum output limit of synchronous unit,a calculation method of energy storage capacity is proposed.By predicting the typical daily load and photovoltaic data from 2030 to 2060,the net load curve under different permeability is obtained.Based on the proposed calculation method,the energy storage capacity under different permeability scenarios is calculated,which can provide guiding suggestions for power planning and dispatching operation of local power grid. |
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