Method for protecting electric impedance element regulation by load self-adapting line

A self-adaptive adjustment, impedance element technology, applied in the direction of electrical components, emergency protection circuit devices, etc., can solve the problem of reducing sensitivity, achieve high sensitivity and improve reliability

Inactive Publication Date: 2008-06-18
GUODIAN NANJING AUTOMATION
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Problems solved by technology

[0003] The existing distance protection generally adopts fixed load limit relays, which can only simply prevent the problem of protection malfunction caused by general overl

Method used

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  • Method for protecting electric impedance element regulation by load self-adapting line
  • Method for protecting electric impedance element regulation by load self-adapting line

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Embodiment Construction

[0018] The technical solution of the present invention will be described in detail according to the accompanying drawings. (The applicant is requested to briefly introduce the content in Figure 4, and describe the load adaptive impedance adjustment logic in Figure 3 in detail.)

[0019] 1. Sampling the current and voltage of the analog input of the transmission line at a constant sampling frequency;

[0020] 2. Use the full-cycle Fourier algorithm to calculate the above sampling results. When the three-phase current is greater than the load current threshold, calculate the steady-state impedance Z of the two sampling periods before the protection starts online.  , and with the resistance component parameter R of the distance protection offset impedance element ZD For comparison (see Figure 1), the larger value of the amplitudes of the two is used as the parameter for the adaptive adjustment of impedance, which needs to be selected according to the conditions in the implemen...

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Abstract

The invention relates to a load which monitors a line online, carries out a real-time calculation to the changes of the resistance of the load, combines with the fixed value range of all resistance sections with distance protection and phase selectors to distinguish a plurality of practical situations such as different malfunction types, system oscillation identification of oscillation detection elements, sending end or receiving end, etc., and adjusts the elements in resistance range: the protection can not only avoid a load state and but also can ensure the reaction capability to transition resistance. The method carries out the load resistance judgement and comparison by adopting the data windows of two frequency currents and is not affected by the transitional data window; therefore, the invention can fast judge the changes of the load, thus improving the performance of distance protection real-time monitoring load and ensuring no misoperation of distance protection in over load; furthermore, the invention can reliably start the distance protection when a high-resistance earth fault occurs in the area, thus leading the protection to have higher sensitivity.

Description

technical field [0001] The invention belongs to the technical field of electric power system automation, and relates to a method for adjusting impedance elements of line distance protection with load self-adaptation. Background technique [0002] Because the load in the transmission and distribution network is easily affected by many aspects such as economy, politics, climate, etc., there is great uncertainty. Especially during the parallel power supply period of double-circuit lines, when a circuit fails, the load sent by this line will be transferred to the adjacent line. The operation of the line under overload conditions may cause incorrect distance protection action. [0003] The existing distance protection generally adopts fixed load limit relays, which can only simply prevent the problem of protection malfunction caused by general overload conditions, and also bring about the problem of reducing the sensitivity of the protection, and cannot flexibly adapt to the ope...

Claims

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Application Information

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IPC IPC(8): H02H7/26
Inventor 钱国明姚亮陈福锋魏曜张勇刚戴静
Owner GUODIAN NANJING AUTOMATION
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