Method for evaluating maximum power supply load of unstable power generation urban agglomeration power grid

Abstract

The invention provides a probability evaluation model which takes maximization of the maximum power supply load of an urban agglomeration power grid as a target and can consider various non-deterministic factors of intermittent unstable power generation; a probability model is established for wind power plant output, photovoltaic power station output, electric vehicle charging and discharging output and other non-deterministic factors, and a solving method combining a probability matrix simulation method, a multi-scene simulation method and a nonlinear optimization algorithm based on a primal-dual interior point method is provided for the established probability optimization model. The provided model and method are corrected by adopting a modified node test system comprising a plurality of intermittent unstable power generation sources, and analysis is carried out according to four different simulation conditions; the result shows that the output uncertainty of the intermittent unstable power supply and the uncertainty of the line operation state have important bad influences on the maximum power supply load index of the system, and the operation safety and reliability of the urban power distribution system are improved to the maximum extent.

Description

technical field [0001] The present application relates to a method for evaluating the power supply load of an intermittent power generation grid, in particular to a method for evaluating the maximum power supply load of a power grid of an unstable power generation urban agglomeration, belonging to the technical field of distributed power grid power distribution. Background technique [0002] Urban agglomeration power grid refers to a regional power system that covers an urban agglomeration and its surrounding suburbs and undertakes power supply and distribution functions. It includes high, medium and low power distribution systems of various voltage levels. With the continuous growth of urban scale and load demand, the power supply mode of high-voltage power reception and step-down power distribution is gradually formed. As a bridge connecting the power generation and transmission system and the terminal load, its safe and stable operation is an important guarantee for the ...

AI Technical Summary

Problems solved by technology

[0007] (1) The evaluation and calculation of the power supply load of the existing urban distribution network can be roughly divided into manual analysis and calculation methods, traditional methods (such as capacity-load ratio method, trial method, network maximum flow method) and new modeling methods, capacity-load ratio method The substation capacity is idealized as the power supply load of the power grid without considering the influence of the distribution network and load on the power supply load, and the calculation results are relatively optimistic. At the same time, this method neglects the consideration of node power, node voltage and branch power flow constraints Therefore, the weak link that limits the power supply load of the power grid cannot be found in time; the accuracy of the evaluation results of the trial method depends on the rationality of the load distribution factor, and the calculation process is cumbersome; the maximum load multiple method also has many problems, which is the starting point in the line The initial charge cannot be completely excluded, the existence of these charges will make the calculated value low, and the proportional increase of the load will also affect this method, which is insufficient for accurately locating the bottleneck of the power supply load of the load unit; the network maximum flow method is only suitable for a larger range The solution to the power distribution scheme in a small area, in the face of a large-scale situation like a city, its evaluation ability will be greatly reduced; most of the calculations of the power supply load in the existing technology focus on the improvement of system safety and reliability, There are relatively few studies on the influence of uncertain factors in the system on the power supply load.

[0008] (2) The evaluation of power supply load in an uncertain environment needs to carefully determine many influencing factors. The existing technology cannot comprehensively consider many influencing factors in an uncertain environment, resulting in insufficient factors to be considered, and it is impossible to obtain the actual distribution network. The results are as close as possible to the operating conditions, such results used to guide the production and operation of the distribution network may produce invalid or even wrong results and lose practical significance

However, urban agglomeration power grids with intermittent and unstable distributed power sources obviously cannot meet the above calculation conditions, and the deterministic evaluation calculation methods of existing technologies cannot take these uncertain factors into consideration.

The problems faced in evaluating the power supply load of urban agglomeration grids with intermittent unsteady power generation include: First, from the perspective of distributed power grid connection, existing technologies focus on reliability impact issues, distribution network planning issues, preventive protection or Second, from the perspective of maximum power supply load evaluation, most of the existing technologies only simply extend the traditional calculation methods such as the capacity-load ratio method and the maximum load multiple method based on the requirements in the urban power network planning and design guidelines and improvement, the lack of assessment of the impact of distributed power generation combined with intermittent instability and the maximum power supply load of the urban distribution network

[0010] (4) The existing technology lacks a probabilistic evaluation model that aims to maximize the maximum power supply load of the urban agglomeration power grid and can take into account various uncertain factors of intermittent unsteady power generation; The probabilistic model of vehicle charging and discharging output and other non-deterministic factors cannot be proposed for the model by combining the probability matrix simulation method, multi-scenario simulation method, and nonlinear optimization algorithm based on the primal-dual interior point method. Several intermittent unsteady power generation power sources, the modified IEEE30 node test system to correct the proposed model and method, lack of considering the influence of intermittent unsteady power output output uncertainty and line state operation uncertainty, only intermittent The simulation analysis of the four different conditions of the non-deterministic output of the unsteady power supply, the non-determinism of the line operation status only, and the consideration of two kinds of non-deterministic factors at the same time cannot determine the relationship between the output non-determinism of the intermittent unsteady power supply and the line operation status. The impact of uncertainty on the maximum power supply load index of the system is not conducive to improving the safety and reliability of urban power distribution system operation

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