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An AC circuit and electrical secondary technology, applied in the direction of electrical components, emergency protection circuit devices, fault locations, etc., can solve the problems of not being intuitive enough, and the error detection of the transformation ratio cannot be detected, so as to save time and fuel, and solve the problem of bus difference Protect and avoid the effect of CT open circuit
Active Publication Date: 2008-08-27
ELECTRIC POWER RESEARCH INSTITUTE OF STATE GRID SHANDONG ELECTRIC POWER COMPANY +1
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Problems solved by technology
It is not intuitive enough to look at the problem from the height of the system, and it is impossible to detect the error of the transformation ratio
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Embodiment 1
[0024] Embodiment 1: This technical solution is suitable for the AC circuit detection of substations and power plants, combined below image 3 Simply compare the advantages and disadvantages of the foreign and domestic original schemes and the technical scheme adopted in the present invention for the electrical total start-up test of the power plant unit. Among them, the power plant generator-transformer system includes generators, main transformers, plant transformers, excitation transformers, booster stations, and corresponding switches, knife switches, and CTs. There are about 170 CT circuits and more than 600 nodes.
[0025] The original Chinese plan: After the steam turbine stabilizes at 3000 rpm, use the short-circuit point K1 to start the short-circuit test of the generator-transformer group. Manually increase the magnetization, and after the current rises to 1400A (secondary 0.1A), check that there is no open circuit in each CT circuit. Continue to increase the magnet...
Embodiment 2
[0045] Example 2: In order to better understand this test plan, we simplify the system below, remove generators, high-speed transformers, excitation transformers, step-up stations and other equipment, and only use an ideal transformer energization test as an example to illustrate its principle. The test wiring is shown in Figure 4.
[0046] Transformer parameters are as follows, capacity 6000kVA, transformation ratio 20000 / 1000V, short-circuit impedance 10%, high-voltage side CT ratio 300 / 1A, low-voltage side transformation ratio 5000 / 1A, wiring method Y, d-11.
[0047] Before the test, first reliably short-circuit the three phases on the low-voltage side of the transformer, connect a cable with sufficient cross-section to the 380V power supply panel on the high-voltage side of the transformer, and then check the connecting pieces of each CT terminal to ensure that the CT secondary circuit is not open. After checking, turn on the 380V power switch. At this time, 380V voltage i...
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Abstract
The invention relates to an electric secondary AC circuit detection method which comprises the following steps: before a power plant machine set is started, a low-voltage short-circuit point or a short-circuit bogie is input; three-phase 380 V voltage is added at the high-voltage side of a booster station to form a circuit by means of the impedance of a transformer and a generator; current amplitude and phase are measured through a current detecting apparatus to check polarity and transformation ratio in advance; all current protective directions such as generator differential motion are measured. When a neutral point is not connected, a short-circuit point is made at a high plant transformer low-voltage side, and the three-phase 380 V voltage is added at the neutral point of the generator, thereby realizing overall checkup of a generator AC circuit; then, the three-phase 380 V voltage is converted into one-phase voltage or two-phase voltage to carry out overall checkup of a zero sequence circuit. The detection method can check all CT and PT circuits of a generation-transformer group before power transmission; moreover, all protection directions of the generation-transformer group are checked in advance, thereby saving time and fuel oil along with economical efficiency, environmental protection and safety. The electric secondary AC circuit detection method can check secondary circuits such as the transformer and the bus differential protection of a transformer substation.
Description
Technical field: [0001] The invention relates to a power system relay protection and its related secondary system, in particular to a detection method for an electrical secondary AC circuit. Background technique: [0002] In recent years, power plants and substations have undergone many transformations, and a large number of new substations have been newly built. Defects in the secondary circuit of equipment have become an important threat to the safe power supply of the power grid. Especially with the rapid increase of social power consumption, power outages of substation equipment are difficult, and the problem of relay protection direction verification of new lines and light-load lines has become a prominent contradiction. big test. In the past AC circuit debugging process of substations, due to the lack of ideal AC circuit detection technology, the secondary circuit debugging work can only rely on the staff to manually detect each cable and each connection, which is not...
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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/08H02H7/26H02H7/045H02H7/06
Inventor 周大洲张国辉李磊刘延华王大鹏王涛王鑫牟旭涛张大海
Owner ELECTRIC POWER RESEARCH INSTITUTE OF STATE GRID SHANDONG ELECTRIC POWER COMPANY
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