| The rapid development of science and technology and the growing demand for electricity have imposed severe requirements on the transmission of electrical energy in transmission channels.Traditional transmission technology uses dynamic transmission grid planning to construct new transmission channels to meet load requirements.Although the dynamic grid planning technology can meet the power supply requirements,it is extremely easy to cause the grid structure to be complicated and occupy more transmission corridors.At the same time,the unbalanced power supply of the transmission line is extremely easy to cause transmission congestion on the one hand,and the line power supply capacity cannot be fully Give play to it and cause a waste of investment.Modern transmission technology represented by UHV transmission has the ability to realize a wider range of power resource allocation,and has been rapidly applied in the development of power.UHV transmission technology can not only realize the cross-regional flow of power resources,but also reduce the construction of new power grids,which has attracted widespread attention from power grid companies.However,the ultra-high-capacity transmission possessed by UHV technology has a great impact on the UHV drop point.If the grid structure near the drop point is relatively weak and the balance is poor,it is extremely easy to cause transmission congestion and voltage drop problems.The step-by-step update of the Flexible AC Transmission System(FACTS)provides new ideas for solving such problems.The FACTS technology adjusts the embedded parameters of the power network,thus unfolding the adjustment of the trend of the power flow and the distribution of the power flow to achieve a more balanced resource allocation of power resources.It not only reduces the transmission congestion and voltage drop problems near the UHV drop point,but also avoids the drawbacks of investing in new lines to meet the needs of UHV,and ensures the simplicity of the grid structure.Distributed Power Flow Controller(DPFC),as the most efficient member of the FACTS family,the extension of the United Power Flow Controller(UPFC),not only has the power flow control ability of UPFC,but also adapts to new requirements in the technical transformation of transmission.Based on consulting a large number of relevant literatures and materials at home and abroad,this paper conducts a lot of modeling,analysis and simulation verification.It mainly conducts an in-depth study on the optimal configuration of grid-connected distributed modeling of distributed power flow controllers,focusing on considering distribution The in-depth technical research has been carried out on the optimal configuration of grid-connected power flow controller and the optimal configuration of distributed power flow controller adapted to multi-form power grid.The main research contents and results are as follows:(1)By sorting out and discussing the principles of series and parallel power flow regulation,the mathematical models of STATCOM,SSSC,and UPFC are introduced,and the topology of DPFC is derived from the principle of FACTS power flow regulation.Based on the working characteristics of DPFC,Fourier transform is used for the fundamental and third harmonic power inside DPFC,which reveals the working principle of DPFC power exchange.In the power characteristic analysis of DPFC,the superposition theorem and the PQ decoupling method are used to analyze the fundamental power control characteristics,third harmonic power control characteristics,active power and reactive power,and the control range of DPFC,which lays the foundation for the full text research.The basis of the ability to regulate and control tidal currents.(2)The system power flow control efficiency attached to the DPFC grid connection determines the DPFC’s adjustment effect on the system power flow balance,transmission reliability and system operation economy.This paper focuses on the DPFC grid connection performance based on the power flow balance and economy.The concept of weighted power flow entropy is introduced in the study of power flow balance to distinguish the order of the network load rate;the life cycle theory is introduced in the economic study to quantify the economic behavior of the optimal configuration after the annual value of DPFC grid-connected operation.In order to reduce the dimension of the optimization calculation,based on the difference of the system power flow control objectives,the DPFC equivalent power injection model was introduced to enter the power flow calculation model.Using the sensitivity analysis method,the DPFC single-point optimization configuration model based on multi-index performance analysis and the DPFC single-site location optimization model based on differentiated economic evaluation are proposed.The particle swarm optimization algorithm is used to solve the problem,and the DPFC is simulated and verified The effect of grid connection on the improvement of tidal current performance.(3)Based on DPFC’s power flow control capability,the equivalent power injection model of DPFC is constructed,combined with the uncertainty of load,the method of probability statistics is used to realize the deterministic processing of load scenarios,and the AC power flow safety constraints are introduced.The DPFC multi-point location selection and capacity optimization configuration model of the equivalent power injection model is converted into a two-stage problem by the Benders decomposition method.The equivalent reactance model of the DPFC is used in the main problem,and the large-M method is used for linear relaxation to construct DPFC’s point selection and unit output plan,combined withprobability statistical models and AC power flow safety constraints in the sub-problems,optimize the DPFC grid-connected capacity,and modify the feasible solution of the main problem.(4)Aiming at the reactive power compensation capability of DPFC,combined with the grid connection point voltage problem caused by new energy grid connection,the equivalent reactance model of DPFC is constructed.For the uncertainty of new energy and load,the sampling clustering method is used to establish the scene set,A DPFC multi-point random optimal configuration model based on equivalent reactance model is proposed.Since the optimal configuration models are all mixed integer nonlinear programming problems(Mixed Integer Nonlinear Programming,MINLP),the linear AC power flow technology(Line Flow Based,LFB)is used to linearly convert the DPFC grid-connected AC power flow to the MILP model,and GAMS/ CPLEX solves. |
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