A method for busbar protection to prevent power frequency magnetic field interference
A technology of power frequency magnetic field and busbar protection, applied in emergency protection circuit devices, electrical components, etc., can solve problems such as differential protection misoperation, and achieve the effects of eliminating interference, increasing reliability, and preventing misoperation
Active Publication Date: 2021-08-10
GUODIAN NANJING AUTOMATION
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Problems solved by technology
Due to the principle of electromagnetic induction, the load current or fault current of the primary equipment may induce an interference current with the power frequency on the secondary circuit, which is called power frequency magnetic field interference. Due to the large number of busbar protection branches, the power frequency magnetic field interference current is accumulated and formed Large differential current may cause misoperation of differential protection
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[0033] In order to make the technical means, creative features, goals and effects achieved by the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.
[0034] Such as Figure 1-Figure 3 As shown, a method for busbar protection to prevent power frequency magnetic field interference is disclosed, including the following steps:
[0035] 1) Carry out data collection and collect the current of each branch on the bus Among them, n=1,2,3...is the serial number of the branch, for the difference;
[0036] 2) Identify the standby interval, judge the sampling value of each interval in turn, if the previous cycle of the interval is in a no-flow state, then it is determined that the interval is a spare interval;
[0037] 3) Perform power frequency magnetic field interference identification on the spare interval in step 2), if the interval satisfies the three-phase current increment condition and the thre...
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The invention discloses a method for busbar protection to prevent power frequency magnetic field interference. The method comprises the following steps: collecting current data values of each branch of the busbar; identifying power frequency magnetic field interference for spare intervals; recording the power frequency magnetic field interference The serial number of the spare interval and the current value of each phase of the spare interval, and calculate the average interference current value of each phase; calculate the total interference value of the power frequency magnetic field through the average interference current value of each phase; calculate the current data value of each branch of the bus collected and get the original differential current, and use the original differential current to subtract the total interference value of the power frequency magnetic field to obtain the actual differential current value, which is used for protection logic calculation; the interference of load current and fault current is eliminated, and the final difference Compensate the total interference value during flow calculation, accurately eliminate the influence of power frequency magnetic field interference on differential flow, prevent differential protection misoperation due to accumulated power frequency magnetic field interference, and increase the reliability of busbar protection.
Description
technical field [0001] The invention relates to a method for preventing power frequency magnetic field interference by busbar protection, and belongs to the technical field of busbar protection in power systems. Background technique [0002] Due to its high reliability and rapidity, busbar differential protection is widely used as the main protection in busbar protection. The busbar protection collects the current information of each branch through the current transformer, and then calculates the differential current of the busbar. When the differential current is greater than the fixed value and the braking coefficient is satisfied, the busbar differential protection will operate. Due to the principle of electromagnetic induction, the load current or fault current of the primary equipment may induce an interference current with the power frequency on the secondary circuit, which is called power frequency magnetic field interference. Due to the large number of busbar protect...
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IPC IPC(8): H02H7/22
CPCH02H7/22
Inventor 陈琦王永旭唐治国李玉平吴路明陈宏岩
Owner GUODIAN NANJING AUTOMATION