Damping control method and system for suppressing low-frequency oscillation and subsynchronous oscillation

Abstract

The invention discloses a damping control method and system for suppressing low-frequency oscillation and subsynchronous oscillation. According to the damping control method and system provided by thetechnical schemes of the invention, the per-unit value of the speed deviation value of the rotor of a high-pressure cylinder, the per-unit value of the power deviation quantity of the rotor of the high-pressure cylinder and the per-unit value of the deviation quantity of the rotating speed of a generator are obtained through calculation according to the operation parameters of a unit; subsynchronous oscillation suppression processing is performed on the per-unit value of the speed deviation quantity of the rotor of the high-pressure cylinder and the per-unit value of the rotating speed deviation quantity of the generator, so that subsynchronous oscillation control signals are obtained; low-frequency oscillation suppression processing is performed on the per-unit value of the speed deviation quantity of the rotor of the high-pressure cylinder and the per-unit value of the power deviation quantity of the rotor of the high-pressure cylinder, so that low-frequency oscillation control signals are obtained; and the subsynchronous oscillation suppression signals and the low-frequency oscillation suppression signals are inputted into an excitation control system, and low-frequency oscillation and subsynchronous oscillation are comprehensively suppressed. According to the prior art, the implementation of the suppression of low-frequency oscillation and sub-synchronous oscillation or the independent design of a controller usually depends on different control devices, and as a result, the problem of the lack of coordination between different controls is brought about, and however, with the damping control method and system adopted, the problem can be solved, an ultra-low-frequency oscillation mode is considered, and an action range is comprehensive.

Description

technical field [0001] The invention belongs to the technical field of power system operation control, and in particular relates to a damping control method and system for suppressing low-frequency oscillation and subsynchronous oscillation. Background technique [0002] Power system low-frequency oscillation generally refers to the phenomenon of active power fluctuations with a frequency between 0.2 and 2.5 Hz. According to the difference of oscillation mechanism and oscillation frequency, the low-frequency oscillation is divided into inter-area oscillation and intra-area oscillation, among which the oscillation between 0.2 and 0.7Hz is called inter-area oscillation, which refers to the swing between the unit groups in different areas ; Oscillation between 0.7 and 2.5Hz is called intra-area oscillation, also known as local / local oscillation, which refers to the swing between different units in the area. With the continuous expansion of the national power grid interconnecti...

AI Technical Summary

Problems solved by technology

The first type of form originates from the torsional vibration of the shafting of the rotating electrical machine, where the rotating electrical machine includes large steam turbines, water turbines, 1-3 type wind turbines and large electric motors; series capacitors, high-speed control equipment / devices (including SVC, LCC-HVDC, VSC-HVDC, PSS / electro-hydraulic speed control) and switches for switching operations respond to mechanical torsional vibrations, which may cause the damping torque of the unit in the corresponding torsional vibration mode to weaken or even become negative, resulting in Oscillation persistence and even amplification

The second type of form originates from the electrical oscillation formed by inductance (L)-capacitance (C) in the power grid. There are circuit components that constitute L-C oscillation in the AC series compensation power grid, various filter circuits, and parallel compensation. Only from the perspective of the power grid, due to Network elements have positive resistance characteristics, which will not cause the continuation or divergence of this L-C oscillation, but rotating electrical machines (including synchronous / asynchronous generators / motors) or power electronic converters may present an "induction" to this oscillation mode under certain operating conditions. Generator / negative resistance” effect, when the negative resistance exceeds the total positive resistance of the grid, it may cause L-C oscillation to diverge; of course, the motor or converter will also change the equivalent inductance / capacitance parameters, thereby changing the oscillation frequency to a certain extent

The suppression / controller for low-frequency oscillation and subsynchronous oscillation is often designed independently and implemented by different control devices. There are problems such as large investment costs and lack of coordination between different controls.

[0005] There are two main problems in the research on simultaneous suppression of low-frequency oscillation and subsynchronous oscillation: (1) the comprehensive suppression of ultra-low-frequency oscillation mode (<0.2Hz) is not considered; (2) the integrated controller of low-frequency oscillation and subsynchronous oscillation relies on high voltage DC transmission system and STATCOM (SVG), high-voltage DC transmission system requires high operational reliability, and the application of additional modulation function to suppress oscillation is generally less considered in actual operation; STATCOM (SVG) has limited capacity and high cost, which limits The exertion and popularization and application of its ability to suppress oscillation

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