Method and system for judging large disturbance stability of grid-connected voltage source type converter

Abstract

The invention discloses a method and system for judging the large disturbance stability of a grid-connected voltage source type converter. The method comprises the following steps of: establishing a mathematical model that a VSC (Voltage Source Converter) containing a PLL (Phase Locked Loop) is connected into an infinite system through a power transmission line; obtaining a steady-state equation of the system, and solving a balance point of the system according to a control target; simplifying the mathematical model of the system; deducing a simplified model for researching the large disturbance stability of the system when the VSC control reaches an amplitude limiting value; and finally, deducing a criterion of large disturbance stability of the grid-connected VSC according to an equal-area rule. According to the method, the relationship between the grid-connected VSC large disturbance stability and the system state quantity delta and the relationship between the stability or instability range of the delta and the VSC controller parameters, the line parameters and the system operation mode are clearly represented. The method and system can be used for qualitatively analyzing key factors influencing system stability and revealing a system instability mechanism, and can also be used for guiding VSC controller parameter design and system operation mode formulation.

Description

technical field [0001] The invention belongs to the field of electric power technology, and in particular relates to a method and system for judging the large-disturbance stability of a grid-connected voltage source converter. Background technique [0002] The increasing number of grid-connected voltage source converters (voltage source converters, VSCs) has profoundly changed the dynamic behavior of today's power systems. Unlike synchronous generators (SGs), the normal operation of voltage source converters (VSCs) largely depends on their control strategies. A large number of studies have shown that under certain working conditions or unreasonable control parameters, voltage source converters may cause system resonance to stabilize. In addition, under fault conditions, phase-locked loops (PLL) may cause system out-of-step, serious Threat to the stability of the high proportion of new energy power system. [0003] Existing research generally adopts numerical simulation, ph...

AI Technical Summary

Problems solved by technology

Studies have shown that long electrical distances, improper PLL parameters, and system overloads can all degrade system stability

On the other hand, in actual operation, there are certain current-limiting measures in the grid-side converter, and the passing current is not allowed to increase infinitely, which increases the complexity of its dynamic characteristics. However, almost none of the existing studies consider the Influence of Power Electronic Equipment Limiting Link on System Stability

Images