Differential quick-break protection setting method and device for transformer
A technology of quick-break protection and transformers, which is applied in the field of relay protection of power systems, and can solve the risk of misoperation of differential quick-break protection, misoperation of differential quick-break protection zone of current transformer, and greater refusal or malfunction of differential quick-break protection And other issues
Active Publication Date: 2020-07-31
STATE GRID JIANGXI ELECTRIC POWER CO LTD RES INST +1
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Problems solved by technology
[0004] First, the fixed value of the differential quick-break protection is only set based on the experience of the adjuster, without considering some special circumstances, and the differential quick-break protection has a greater risk of refusal or misoperation
[0005] Second, during the operation of the actual power system, too many out-of-area faults have occurred, causing saturation of the current transformer, resulting in misoperation outside the differential quick-break protection area
In my country's power grid, there have been many accidents of differential quick-break protection misoperation due to unreasonable setting of differential quick-break protection.
Method used
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[0080] figure 1 A schematic flowchart of the setting method of the differential quick-break protection of the present invention in an example is shown in .
[0081] Such as figure 1 As shown, the parameter setting method of the differential quick-break protection in this embodiment includes steps:
[0082] S1. Establish the system equivalent model of each branch of the transformer (except the transformer) according to the system parameters of the power system in the maximum operating mode to ensure that the short-circuit current remains unchanged;
[0083] If this side contains a power supply, the effective value of the voltage is U, and the short-circuit current of this side is I in the maximum operating mode sc , then the equivalent internal resistance is The power supply whose voltage effective value is U.
[0084] If this side does not contain a power source, this side is equivalent to an impedance depending on the size of the load. If the rated voltage of this side ...
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The invention discloses a transformer differential quick-break protection setting method and device. The method comprises the following steps: establishing an equivalent power system transformer differential quick-break protection setting model according to system parameters, transformer parameters and current transformer parameters on each side of a power system in a maximum operation mode; whenthe magnetizing inrush current of a transformer is maximum, calculating a differential current; setting a three-phase short-circuit fault on the low-voltage side outside a protection area, and calculating the differential current of the transformer by considering the saturation of the current transformer; and under the normal operation mode of the power system, re-establishing an equivalent system, and calculating the differential current during the metallic two-phase short circuit at the protection installation position. According to the three current values, the preset threshold value and the differential quick-break protection setting range, the differential quick-break protection setting value of the transformer can be determined. The invention further provides a transformer differential quick-break protection setting device, wherein the constant value of the transformer differential current is determined through a computer program under the condition that regulations and specifications are met, so that the power supply reliability is improved.
Description
technical field [0001] The invention relates to a setting method and device for transformer differential quick-break protection, which belongs to the technical field of relay protection for power systems. Background technique [0002] At present, the main protection of transformers based on electrical quantities is generally differential protection, including differential quick-break protection and proportional differential protection. The principle of differential protection is Kirchhoff's current theorem, that is, when the transformer is faulty outside the transformer area, the current vector sum of each branch of the transformer is zero, and when the transformer is faulty inside the transformer area, the vector sum of each branch of the transformer is not zero. In order to prevent maloperation of proportional differential protection, the proportional differential protection has anti-maloperation measures such as braking coefficient, second harmonic blocking, and discontin...
Claims
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Login to View More IPC IPC(8): H02H7/045H02H3/00
CPCH02H7/045H02H3/006
Inventor 周仕豪桂小智王冠南谢国强潘本仁
Owner STATE GRID JIANGXI ELECTRIC POWER CO LTD RES INST