A Criterion Method for Multi-Frequency Oscillation Composite Out-of-Sequence Decoupling of AC System Based on Wide-area Measurement Information

Abstract

The invention relates to an alternating current system multi-frequency oscillation composite out-of-step separation criterion method based on wide area measurement information. The method is characterized in that the method comprises the steps that: a phasor measurement unit is utilized to measure voltages, phase angles and frequencies of buses at two sides of a separation section of the circuit, and the voltages, phase angles and frequencies a circuit are used as original data; a calculation center calculates a phase angle difference of the voltages of the buses at two sides of the circuit, and whether [delta][theta] is larger than 130 degrees is used as a starting criterion; the system out-of-step separation criterion is actuated; whether two coherent generator groups cross zero is calculated; a circuit set L is determined through a path searching algorithm; the phasor measurement unit is utilized to collect voltage frequencies at two sides of each circuit in the circuit set L at the zero-crossing moment; whether the derivative d[omega] / dt of bus frequencies at two sides of the circuit to time is smaller than zero is calculated; and the calculation center sends a separation instruction to control the separation of a separation device at an optimal section. The alternating current system multi-frequency oscillation composite out-of-step separation criterion method is scientific and reasonable, high in application, high in reliability and good in effect.

Description

Technical field [0001] The invention belongs to the technical field of power system transient safety and stability and control, and in particular relates to a multi-frequency oscillation composite out-of-synchronization criterion method of an AC system based on wide area measurement information (Wide Area Measurement System, WAMS). Background technique [0002] From the large power outages that have occurred at home and abroad in recent years, we can know that although a series of measures have been taken to improve the stability of the system in the operation and design of the power system, it is still possible to encounter sudden failures to make the system lose stability. Therefore, it is necessary to understand the phenomenon after the system loses stability and take corresponding measures to reduce the damage caused by the stability damage, and quickly restore the system to stable operation. As my country’s major regional power grids become more and more closely connected, a...

AI Technical Summary

Problems solved by technology

At present, there are many different types of out-of-synchronization solution criteria, Criteria are widely used. According to the characteristics of reactive power flowing into the oscillation center on both sides of the oscillation center, the criterion can determine the position of the oscillation center by looking for the lowest point of voltage. However, in practical applications, it can only determine the moment when the oscillation center appears. The position of the oscillation center is often misjudged; the phase angle criterion is based on the characteristics of the phase angle when the two fleets are out of sync to find the orientation of the oscillation center, and the specific position cannot be determined; the impedance angle criterion and the apparent impedance trajectory criterion are based on the active power The principle of reciprocating oscillation zero crossing, judges whether the functional relationship between voltage and current enters the setting area, but the active power of adjacent lines may also have the same characteristics; the reactive power integration criterion judges the out-of-step center by reactive power integration , the out-of-synchronization center can be determined by measuring the electrical quantity on both sides of the line, but it needs to go through an oscillation cycle to determine, and it is not practical

The current research on the out-of-synchronization separation criterion is difficult to adapt to the multi-frequency oscillation in the actual system, because the result of the superposition of multiple clusters may lead to two oscillation centers on one line, resulting in the detection of the separation device on the other line. To the oscillation center without action; the traditional out-of-synchronization decoupling work is that the out-of-synchronization device judges whether the position of the sagittal step center is on the line according to the on-site measurement information and the set out-of-synchronization decoupling criterion, and then determines whether to decoupling system, ignoring the mutual cooperation between decoupling devices on the contact section between out-of-synchronization clusters; the line where the oscillation center is located may not be the optimal choice for decoupling systems, and consideration should be given to the sum of unbalanced power of each island after decoupling In actual situations, the optimal choice to meet the minimum unbalanced power may not be a line, but a section composed of several lines. When a complex system is in normal operation, there may be multiple operating modes to meet the minimum unbalanced power. The optimal section changes and cannot be determined by off-line calculation

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