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Positive Damping Reconstruction Impedance Stability Control Method for HVDC Transmission System

A transmission system, impedance stabilization technology, applied in the field of positive damping reconstruction impedance stabilization control of high-voltage direct current transmission system, can solve problems affecting system stability, deterioration, etc., to improve system stability, suppress oscillation, and suppress DC side oscillation Effect

Active Publication Date: 2020-10-13
HUNAN UNIV +3
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Problems solved by technology

When the working switching frequency of the rectifier station is high, the virtual resistance can effectively suppress the resonance peak of the system, such as Figure 5 As shown in (a); however, when the working switching frequency of the rectifier station is low, the phase-frequency characteristics of the output impedance of the DC side of the rectifier are as follows: Figure 8 It can be seen that the lower the switching frequency, the narrower the control loop bandwidth of the rectifier, and its phase may sink below -90 degrees outside the control loop bandwidth. If the resonant frequency of the system exceeds the control loop cut-off frequency, the output impedance of the DC side will deteriorate to Negative resistance, when the length of the transmission line changes, the system may have a resonance peak, such as Image 6 As shown in (a), it seriously affects the stability of the system

Method used

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  • Positive Damping Reconstruction Impedance Stability Control Method for HVDC Transmission System
  • Positive Damping Reconstruction Impedance Stability Control Method for HVDC Transmission System
  • Positive Damping Reconstruction Impedance Stability Control Method for HVDC Transmission System

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Embodiment Construction

[0029] figure 1 It is a structural diagram of the high-voltage direct current transmission system mentioned in the present invention, including the AC power grid, the single-inductance filter on the grid side, the rectifier station, the capacitor on the DC side, the π-type equivalent model of the DC cable, the inverter station, and the LC filter on the inverter side and the distribution network as a load. The rectifier station is responsible for stabilizing the DC side voltage, and the inverter station works in the AC voltage control mode, which can be regarded as a constant power load. Among them, v g is the grid side AC line voltage, i g Input AC current for the grid side, L and r constitute the grid side filter of the rectifier station, C dcr is the DC side energy storage capacitor, u dcr is the voltage of the DC side capacitor, i dcr Input current for the DC side of the inverter station, C cab is the equivalent capacitance of the DC cable, L cab is the equivalent i...

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Abstract

The invention discloses a method for stable control of positive damping reconstruction impedance of a high-voltage direct-current power transmission system. When switching frequency of a rectificationstation is relatively high, through introduction of a virtual resistor, system damping within control bandwidth is enhanced, and direct current side oscillation is suppressed. When switching frequency of the rectification station is relatively low, and direct current side oscillation frequency is beyond the control bandwidth, the virtual resistor turns to show negative resistance property, and system stability is deteriorated. Phase correction is performed on negative resistance beyond bandwidth, and amplitude of the virtual resistor is not changed, thereby effectively improving a damping characteristic of the high-voltage direct-current power transmission system, suppressing oscillation of the system direct current side, and improving system stability.

Description

technical field [0001] The invention relates to the field of high-voltage direct current transmission systems, in particular to a positive damping reconstruction impedance stabilization control method for high-voltage direct current transmission systems. Background technique [0002] The HVDC transmission system is a cascade system composed of rectifier stations and inverter stations through DC transmission cables. It has the characteristics of high voltage level, large power level, and small controller bandwidth. It can be used as an effective long-distance power transmission system for new energy power stations. Way. In order to increase the damping of the system and suppress the oscillation of the DC side, the traditional control method adopted by the rectifier station of the HVDC transmission system is to introduce a virtual resistance link into the control loop. When the working switching frequency of the rectifier station is high, the virtual resistance can effectivel...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/36
CPCH02J3/36H02J2003/365Y02E60/60
Inventor 罗安姜捷周乐明陈燕东刘傲洋郭健周小平伍文华杨苓
Owner HUNAN UNIV
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