MMC DC transmission line protection method based on voltage correlation

A DC transmission line, voltage correlation technology, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve the problem of effectively identifying high-resistance grounding faults, high-resistance grounding faults cannot be effectively identified, etc., and achieves good quickness. Effect

Active Publication Date: 2019-08-16
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Moreover, the existing protection methods for DC transmission lines also have many deficiencies. For example, high-resistance ground faults cannot be effective

Method used

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  • MMC DC transmission line protection method based on voltage correlation
  • MMC DC transmission line protection method based on voltage correlation
  • MMC DC transmission line protection method based on voltage correlation

Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0024] Example 1: Establish as attached figure 2 The MMC HVDC transmission system shown as a simulation model. The winding on the valve side of the connecting transformer adopts a delta connection without a neutral point. The AC side of the connecting transformer adopts a star connection, and the neutral point is directly grounded. The DC side is grounded through a clamping resistor, and the resistance of the clamping resistor is very large. The main function is to clamp the two-pole voltage and provide a potential reference point for the DC system during normal operation. The DC voltage is ±320kV, the transmission line is 400km, the transmission active power is 1169MW, and the metallic short-circuit fault occurs at 260km of the positive line.

[0025] (1) After the MMC DC transmission system fails, the positive and negative voltages measured at the protection installation (sampling window is 3ms) are measured, and the correlation coefficient between the two is calculated accord...

Example Embodiment

[0027] Example 2: Establish as attached figure 2 The MMC HVDC transmission system shown as a simulation model. The winding on the valve side of the connecting transformer adopts a delta connection without a neutral point. The AC side of the connecting transformer adopts a star connection, and the neutral point is directly grounded. The DC side is grounded through a clamping resistor, and the resistance of the clamping resistor is very large. The main function is to clamp the two-pole voltage and provide a potential reference point for the DC system during normal operation. The DC voltage is ±320kV, the transmission line is 400km, and the transmission active power is 1169MW. It is assumed that a two-pole short-circuit fault occurs at the line 320km, and the transition resistance is 300Ω.

[0028] (1) After the MMC DC transmission system fails, the positive and negative voltages measured at the protection installation (sampling window is 3ms) are measured, and the correlation coef...

Example Embodiment

[0033] Example 3: Establish as attached figure 2 The MMC HVDC transmission system shown as a simulation model. The winding on the valve side of the connecting transformer adopts a delta connection without a neutral point. The AC side of the connecting transformer adopts a star connection, and the neutral point is directly grounded. The DC side is grounded through a clamping resistor, and the resistance of the clamping resistor is very large. The main function is to clamp the two-pole voltage and provide a potential reference point for the DC system during normal operation. The DC voltage is ±320kV, the transmission line is 400km, the active power is 1169MW, and the AC system three-phase short-circuit fault occurs on the rectifier side.

[0034] (1) After the MMC DC transmission system fails, the positive and negative voltages measured at the protection installation (sampling window is 3ms) are measured, and the correlation coefficient between the two is calculated according to f...

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Abstract

The invention relates to an MMC (Modular Multilevel Converter) DC transmission line protection method based on voltage correlation, which belongs to the technical field of power system relay protection. When a fault occurs in a DC transmission line, the positive and negative voltages at both ends of the line are collected and a correlation coefficient is obtained. Then, whether the fault is a single-pole grounding fault is judged according to the correlation coefficient. If the fault is judged to be a non-single-pole grounding fault, the inter-pole voltage is calculated, and the change rate ofthe inter-pole voltage is obtained. Finally, whether there is a short circuit between the two poles is judged according to the change rate of the voltage. The method of the invention has strong transition resistance endurance, and the data window is only 3ms. The method is quick in operation, and has a strong application prospect.

Description

technical field [0001] The invention relates to a voltage correlation-based MMC DC transmission line protection method, which belongs to the technical field of electric power system relay protection. Background technique [0002] Compared with traditional DC, the flexible DC transmission technology based on MMC (modular multilevel converter) has many advantages, such as no reactive power compensation problem, no commutation failure problem, and power supply for passive systems, etc. It has become a research hotspot today. At present, there are few researches on MMC DC transmission line protection. Since the topology structure of the MMC basic unit and the working principle of the sub-modules are very different from those of the traditional DC transmission line, the protection method of the DC transmission line can refer to the protection method of the traditional DC transmission line, but not all of them are applicable to the protection of the traditional DC transmission li...

Claims

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Application Information

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IPC IPC(8): H02H7/26
CPCH02H7/268
Inventor 安娜束洪春
Owner KUNMING UNIV OF SCI & TECH
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