Method and system for lowering measuring error of current transformer
A technology for current transformers and measurement errors, applied to measuring devices, measuring electrical variables, instruments, etc., can solve problems such as complex design, inability to be guaranteed, and difficult implementation, so as to reduce measurement errors, improve measurement accuracy, and achieve high measurement accuracy. The effect of precision
Active Publication Date: 2014-10-29
STATE GRID CORP OF CHINA +2
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Problems solved by technology
[0005] The technical problem to be solved by the present invention is that existing methods for reducing measurement errors of current transformers by using parallel transformers or reducing load impedance to reduce measurement errors have problems such as complex design, difficult implementation or unsatisfactory effects, and the current transformer The measurement calibration is still done manually, and the measurement accuracy cannot be guaranteed
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[0026] Such as figure 1 As shown, a method for reducing the measurement error of a current transformer provided by the present invention includes the following steps:
[0027] Step 1, read the load impedance voltage value collected from the secondary side of the current transformer in real time, and enter step 2 after the reading is completed;
[0028] Step 2. Calculate the secondary side loop current of the current transformer according to the collected load impedance voltage value, and then use the saturation criterion of the current transformer to judge whether the current transformer is in a saturated state. The saturation state of the current transformer is judged by using the derivative method The saturation criterion for :
[0029] |ΔI(t)-ΔI(t-Δt)|>K (1)
[0030] Among them, |ΔI(t)-ΔI(t-Δt)| is the second derivative of the secondary side current of the current transformer, Δt is the sampling interval, K is a constant, and the corresponding value can be set according t...
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The invention discloses a method and a system for lowering a measuring error of a current transformer. The method includes steps that reading a load impedance voltage value in real time, judging whether arriving at a saturated state, calculating a compensation capacitance value, controlling a thyristor switched capacitance device, and feeding back a measuring error after the capacitance compensation. The system comprises a voltage value reading module, a saturation judging module, a capacitance calculating and controlling module and a feedback module. The method and the system for lowering the measuring error of the current transformer effectively improve the measuring precision of the current transformer through lowering the measuring error due to the saturation of the current transformer.
Description
technical field [0001] The invention relates to a method and a system for reducing the measurement error of a current transformer, in particular to a method and a system for reducing the measurement error of a current transformer by dynamically compensating the excitation current of an excitation branch circuit by using a controllable capacitance compensation technology. Background technique [0002] The error characteristic curve of the current transformer is the basis for checking whether the output result of the current transformer is accurate or not, and it is directly related to whether the secondary equipment such as the relay protection device and the measurement and control device can operate normally. In actual work, the operation mode of the power grid is changing every year. The dispatching department issues the short-circuit capacity of the busbars in each substation at the beginning of each year according to the actual operation of the power grid in the year. The...
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Inventor 陈恒祥邓星李振兴沈逸文赵珏斐陈驰张玥
Owner STATE GRID CORP OF CHINA