Establishment And Evaluation Decision Of Beijing Power Grid Partition Scheme Based On Short-circuit Current Limit

With the continuous increase of load and the gradual improvement of grid structure,the electrical connection of the receiving-end power grid becomes increasingly close,and the problem of short-circuit current exceeding the standard is more obvious.As the most important receiving-end power grid in North China,Beijing Power Grid has the characteristics of complex power supply structure,high load density and varied types.With the commissioning of Zhangbei flexible DC engineering,the formation of Beijing-Tianjin-Hebei 500 k V large ring network,Beijing-Tianjin-Tangshan 500 k V double ring network and the reinforcement of 220 k V power grid,the grid density is getting higher and higher,and the phenomenon of short-circuit current exceeding the standard obviously exists,so it is urgent to limit the short-circuit current of the grid.It is an inevitable trend of the development of the receiving-end power grid that the power grid operation in different regions can limit the short-circuit current by optimizing the power grid structure,and at the same time create conditions for opening the electromagnetic ring network,which is convenient for power flow control and accident isolation.Under the new power grid operation mode,the zoning scheme formulation method,which is dominated by professional experience and verified by simulation calculation,is limited by the range of experience cognition and exhaustive combination explosion,which shows great limitations.Based on this,this paper studies from the following aspects:Firstly,the common problems faced by the receiving-end power grid under the new development situation are expounded,and the actual operation characteristics of Beijing power grid are analyzed.According to the construction situation of Beijing power grid,three zoning measures are put forward,namely,simultaneous operation of high and low voltage buses,separate operation of low voltage buses and disconnection of low voltage level routing,and the short-circuit current limiting effects of different zoning measures are comparatively studied.Then,based on the two-station hand-in-hand partition model and the three-station chain partition model suitable for Beijing power grid,the analysis method of the partition scale of the receiving power grid is studied from the perspective of short-circuit current and capacity-load ratio.In this paper,the complex network characteristics of power system are introduced.According to the basic concept of complex network theory,the short-circuit current weighted edge dielectric is defined.Based on the short-circuit current weighted edge dielectric,the node set GN splitting algorithm is improved,and a selection method for disconnecting low-voltage lines is formed.Combined with the two constraints of ring network structure and reasonable partition scale,a "search-type" partition method for Beijing power grid partition scheme is proposed.After that,the quantitative evaluation index system of the regional operation of the receiving-end power grid is constructed from five aspects: network topology,system security and stability,power supply reliability,economy and development adaptability Aiming at the deficiency of constant weight comprehensive decision-making,the incentive variable weight function is introduced on the basis of constant weight,and the incentive variable weight comprehensive decision-making model is constructed A decision-making method of receiving-end power grid zoning scheme is proposed.Finally,the reasonable partition scale of Beijing power grid is determined according to the partition scale analysis method of the receiving power grid,and then the proposed partition scheme formulation and decision-making method is applied to the southwest power grid of Beijing,which proves the effectiveness and applicability of the partition method.The accuracy of the proposed partition scheme decision-making method of the receiving power grid is verified by using different weighting methods to evaluate the current partition scheme and the new partition scheme.