Method and system for solving voltage instability by cooperating with DC frequency modulation and low voltage load shedding

Abstract

The invention provides a method and system for solving voltage instability through direct-current frequency modulation and low-voltage load shedding coordination. The problems of voltage instability and 'low voltage and high circle' after a power grid at a small-direct-current and weak-system receiving end has a severe fault can be solved through the method by verifying through time-domain simulation analysis; the problem of leading in frequency stability can be avoided when the problem of the voltage stability can be solved by sufficiently realizing a rapid power adjusting function of a direct-current system; and voltage and a frequency signal of the system can be respectively detected by a voltage-voltage load shedding device and direct-current frequency modulation without coordination control, so that the high reliability and the simpler fixed value setting can be realized. The method and the system provided by the invention can be applied to planning and operation of a power system, and is beneficial to reasonably configuring a control measure of a third defense line of the power grid through system analysts, so that the stable operation level of the power grid at the small-direct-current and weak-system receiving end can be improved.

Description

technical field [0001] The invention belongs to the field of power systems, and in particular relates to a method and a system for solving voltage instability by coordinating DC frequency modulation and low-voltage load shedding. Background technique [0002] HVDC technology has the advantages of flexible power adjustment and no constraints on synchronous operation of the two-terminal system. On the one hand, it is widely used in long-distance and large-capacity power transmission occasions, and plays an important role in the national power grid interconnection; on the other hand, in It is also widely used in power transmission to small systems with weak AC grids. [0003] According to actual operating experience, when the weak receiving end grid receives power through a large proportion of DC, voltage stability problems are prone to occur. The failure of the AC system at the receiving end often causes commutation failure in the DC system, and the absorbed reactive power fu...

AI Technical Summary

Problems solved by technology

But for the weak receiving end power grid of small systems, after the low-voltage load shedding device operates to cut off the load, the system has a surplus of active power, which solves the problem of voltage stability and introduces the problem of frequency stability at the same time. The low-voltage-high-cycle-low-cycle problems are coupled together , the controllability of the system is relatively poor; if the system frequency increases greatly, it may cause the system to cut off the machine at high frequency, resulting in a large oscillation or even loss of stability of the power grid

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