Transmission Limit Calculation Considering Power Uncontrollable Fluctuation

Facing the increasing demand in energy and the increasing deterioration of environmental pollution problems,wind power be the mainstream development trend in power system.Wind energy is rich in China,but there is a strong regional distribution.The concentration of wind power and the load center are geographically reverse,the phenomenon of abandoning wind are increasingly serious with the growth of installed capacity of wind power.In this trend,the combined consumption of wind power is an effective means to alleviate the problem.In the combined consumption of wind power,certain areas need send part of own wind power to other areas for combined consumption.Therefor,including the concept of traction ACE and wide-area accompanied wind power consumption model.In this mode,it is necessary to break the inter-regional barrier and fully release the power transmission limit of the area tie-line.However,only the safe transmission limit of tie-line can be obtain clearly,the power transmission plan of area tie-line can be arranged reasonably.Based on the analysis of the characteristics of tie-line transmission limit in the above mode,the controllable tie-line transmission limit calculation method is put forward with the area tie-line fluctuation,the regional control ability and the contact line fluctuation control effect as the core content.Based on the GSDF,a linear calculation model of area tie-line fluctuation is proposed,which realizes the transfer of wind power fluctuation from node to tie line.The concept of area control ability is proposed,which means the maximum control rate and control capacity that can be achieved in the area.In order to solve the area control rate,a calculation model based on linear programming is proposed.In order to solve the area control capacity,two calculation models respectively based on linear programming and area control rate are proposed.The area control ability realizes the transfer of control ability from nodes to the area tie-line.Two methods of calculating the control effect of area tie-line are proposed: direct tracing based on time domain simulation and decomposition method based on tracking performance index T₀.The concept of area tracking performance T₀ is defined which means the critical period of controllable fluctuate.Two kinds of T₀ calculation methods based on Fourier transform are proposed: equivalent sine wave method and slope distribution method.According to T₀,two methods of calculating the control effect of tie-line are proposed: superposition method and filter method,and a complete calculation step based on T₀ decomposition method is presented.Two methods of correcting the control effect of tie-line based on the area control capacity are put forward: single-step method and multi-step method,of which the advantages are analyzed in detail.Finally,the tie-line fluctuation is divided into controllable wave component and uncontrollable wave component.This paper analyzes the nature of the uncontrollable fluctuation on tie-line,and points out that the uncontrollable fluctuation should be reallocated to eliminate the impact of the equilibrium node.Redistribution scheme of the uncontrollable wave component on tie-line based on PTDF is proposed,and the modified uncontrollable wave component on tie-line is obtained.The physical limit of the tie line is calculated,and the transmission limit of the tie line with the uncontrollable power fluctuation is calculated.Finally,based on the physical limit of the tie line,the transmission limit of tie-line considering the uncontrollable wave is calculated.IEEE 9 nodes system and IEEE 39 nodes system respectively used to verify the rationality and feasibility of above methods.