A Data Synchronization Algorithm for Relay Protection Based on Mutation
A data synchronization and relay protection technology, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve the problems of loss of synchronization, errors, and refusal between data
Active Publication Date: 2019-04-30
CHINA THREE GORGES UNIV
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[0002] When a fault occurs in the power system, each substation measures the data of various electrical quantities before and after the fault, and transmits the data to the protection device for calculation and processing. Some protection devices need to collect the sampling value data of electrical quantities of multiple substations in order to realize relay protection and power grid Stability control and other functions; during data transmission, there will be a delay in the communication data link, and due to different communication data links, routing changes, and link congestion, the link delay of the data will vary. Therefore, when the sampling value data of different measurement points arrive at the protection device, there will be a time difference between the data and the synchronization will be lost. For the power system, the time difference between the data is equal to the existence of a phase difference, and the protection device will calculate the fault data accordingly. And a large error is generated, which leads to the malfunction and refusal of the protection device.
[0003] Common data synchronization methods include Beidou or GPS satellite time signal synchronization method, channel clock correction method, etc. These methods all assume that the link of channel data is fixed and the delay is constant, and then determine the fixed time difference between each data to achieve synchronization. If the data link changes or loses synchronization, the synchronization operation must be performed again, and if the system fails at this time, the protection device will not be able to correctly calculate the fault due to the loss of data synchronization, which will inevitably lead to protection refusal or malfunction
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[0022] Calculation method of sudden change in electrical quantity:
[0023] Δf k =|f k -f k-N |-|f k-N -f k-2N | (1)
[0024] Among them, Δf k , f k , f k-N , f k-2N They are the mutation amount of the voltage and current sampling value sequence, the sampling value at time k, the sampling value at time k-N, and the sampling value at time k-2N.
[0025] Multi-terminal longitudinal differential protection calculates the differential current I of each branch in the protection area d with braking current I r for:
[0026]
[0027] Among them, i j is the branch j current.
[0028] In the normal operation of the system and faults outside the zone, the differential current value under ideal conditions is 0, and the actual value is the unbalanced current caused by factors such as measurement errors, while the braking current is relatively large; when the fault occurs in the system, The differential current value is the sum of the fault currents provided by each branch...
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Disclosed is a mutation variable-based relay protection data synchronization algorithm. The relay protection data synchronization algorithm comprises the following steps of 1, collecting sampling data of each data point in short-circuit fault by a protection apparatus; 2, calculating the mutation variable moments of each data mutation variable; 3, compensating transmission time error between the sampling values according to the mutation variable moments of the data to realize fault data sequence synchronization; and 4, calculating a differential current and a braking current after fault by adopting the re-synchronized sampling values. The invention provides the mutation variable-based relay protection data synchronization algorithm; and by calculating the mutation variable moment of each end current sequence, the time difference caused by transmission chain time delay can be compensated, the additional phase error of each end current sequence can be eliminated, and synchronization of each end current sequence can be realized again, so that the protection apparatus can correctly calculate the differential current after fault, judge a fault region, and avoid the misoperation of the protection apparatus caused by the data transmission chain time-delay fault.
Description
technical field [0001] The invention relates to the field of relay protection, in particular to a data synchronization algorithm for relay protection based on sudden change. Background technique [0002] When a fault occurs in the power system, each substation measures the data of various electrical quantities before and after the fault, and transmits the data to the protection device for calculation and processing. Some protection devices need to collect the sampling value data of electrical quantities of multiple substations in order to realize relay protection and power grid Stability control and other functions; during data transmission, there will be a delay in the communication data link, and due to different communication data links, routing changes, and link congestion, the link delay of the data will vary. Therefore, when the sampling value data of different measurement points arrive at the protection device, there will be a time difference between the data and the ...
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IPC IPC(8): H02H7/26
CPCH02H7/263
Inventor 黄景光赵娇娇罗亭然申涛叶元翁汉琍
Owner CHINA THREE GORGES UNIV