Analysis method for researching alternating-current/direct-current interactive influence mechanism

Abstract

The invention relates to an analysis method for researching an alternating-current / direct-current interactive influence mechanism. The analysis method includes the steps of: (1) via researching a practical record of power grid direct-current commutation failure and simulating a digital simulation system and electromagnetic transients, summarizing generating conditions and dynamic characteristics of the direct-current commutation failure caused by an alternating-current power grid fault; (2) analyzing influencing range of the alternating-current power grid fault onto direct-current operation via scanning a three-phase or single-phase short-circuit fault of a trunk power grid to summarize bus voltage drop levels of direct-current inverter stations in the entire power grid during a fault period, analyzing areas and direct-current power drop degrees of the direct-current commutation failure caused by the fault; (3) analyzing system stability characters of receiving ends during the period of the alternating-current fault; and (4) analyzing the system stability characters during direct current blocking. The analysis method is capable of analyzing the alternating-current / direct-current interactive influence mechanism and generated rules influencing the alternating-current / direct-current large power grid system stability characters, applicable to simulation of a large-scale alternating-current / direct-current hybrid system, and can improve reliability of analog simulation.

Description

technical field [0001] The invention relates to an analysis method for studying the mutual influence mechanism of AC and DC power grids, and belongs to the technical field of power system safety and stability analysis. Background technique [0002] The unbalanced distribution of energy resources and economic development determines that China Southern Power Grid needs to carry out west-to-east power transmission and cross-regional resource optimization for a long period of time. Prospects As the large-scale direct current of the Southern Power Grid is fed into the receiving end power grid, the problem of AC and DC interaction becomes more prominent, and the risk of power grid operation and the difficulty of operation control may increase. [0003] Due to the centralized feed-in of large-scale DC, the AC fault at the receiving end will cause multiple DC commutation failures. Multiple DC commutation failures lead to a large amount of power loss in the load center of the receiv...

AI Technical Summary

Problems solved by technology

Multiple DC commutation failures lead to a large amount of power loss in the load center of the receiving end grid, which may cause voltage stability problems; during the period from commutation failure to DC power recovery, a large amount of DC power is transferred to the AC channel, which may cause power angle stability problems; and multiple DC power Absorption of a large amount of reactive power during the recovery period may cause voltage stability problems at the receiving end

In addition, large-scale DC is fed into the power grid in a concentrated manner. After the networked DC is blocked or multiple DCs are blocked at the same time, large-scale DC power transfer will cause the power transmission capacity of the AC channel to decrease, and the power of the sending end system will be surplus, while the power of the receiving end system will be insufficient. The power angle of the end system is pulled apart, which may eventually lead to power angle instability

However, after the large-capacity island DC is blocked, the power loss of the receiving system will cause the system frequency to drop, which may cause frequency stability problems

It can be seen that the grid characteristics of AC-DC parallel operation and multi-circuit DC centralized feed-in make the problem of reactive power voltage, power angle stability and frequency stability of the receiving end system closely related and intertwined, and the stability characteristics are very complicated.

Images