CN113138336B - Test method for measuring generator voltage and power direction in high-power transformer short-circuit test - Google Patents

Abstract

The invention discloses a test method for testing and measuring voltage and power direction of a generator by a shortened road in a high plant, which comprises the following steps: 1) Increasing the secondary current of the low-voltage side of the factory to a preset current value, and checking and recording the current amplitude, the phase and the differential protection differential current of a current loop; 2) Raising the short-circuit current of the high-voltage side to the rated current I₂Stopping magnetizing, checking and recording generator end current I₁And a terminal voltage U; 3) The power and the impedance direction of the generator protection cabinet are checked and recorded, the correctness of a PT loop of the generator is checked under the working condition of low voltage at the generator end, and the test of measuring the voltage and the power direction of the generator by the short-path test in a high-rise factory is completed.

Description

Test Method for Measuring Generator Voltage and Power Direction in Short-circuit Test of High Plant Substation

technical field

The invention relates to a test method, in particular to a test method for measuring generator voltage and power direction in a short-circuit test of a high-power transformer.

Background technique

Before the power plant is put into operation, it is necessary to conduct a complete set of electrical start-up tests to test whether the unit can meet the conditions for trial production. The generator-transformer short-circuit test refers to gradually increasing the excitation current to simulate the generator and transformer running under load when the generator-transformer three-phase is short-circuited at the rated speed. The purpose is to record the generator short-circuit characteristic curve and calculate the main parameters of the generator. Check the symmetry of the three-phase current of the generator, main transformer and high power transformer, and verify the correctness of the generator-transformer current circuit and protection vector; the purpose of the generator no-load test is to check the correctness of the generator PT circuit and the no-load characteristics of the generator It is a particularly important link in the whole set of start-up test process of the power plant.

The generator-transformer short-circuit test includes the generator short-circuit test, the main transformer high-voltage side short-circuit test, and the high-voltage plant transformer low-voltage side short-circuit test. First, install the short-circuit busbar at the generator outlet sealing mother, measure the short-circuit curve of the generator, remove the short-circuit busbar after the generator short-circuit test is completed; Knife switch), grounding knife switch has limited capacity, generally long-term operation does not exceed 150A, generator terminal voltage does not exceed 500V, it is not easy to determine the power direction and impedance phase angle on the protection device, and remove it after the short-circuit test on the high-voltage side of the main transformer is completed Ground wire and three-phase short-circuit connection; finally, short-circuit the low-voltage branch on the low-voltage side of the high-voltage substation with a short-circuit trolley, and pull out the short-circuit trolley after the short-circuit test on the low-voltage side of the high-power plant substation is completed. After the short-circuit test is completed, the no-load test of the generator is carried out. Generally, the no-load test first boosts the voltage to 10% of the rated voltage, checks the correctness of the PT circuit of the generator, and then slowly boosts the voltage to the rated voltage, and records the no-load characteristic curve. During the short-circuit test and no-load test of the generator-transformer group, the current and voltage phase angles of the relay protection device and the measuring instrument are not obvious, and the power and impedance direction of the generator are not easy to determine. The generator lacks directional protection such as power impedance, but the test time used to detect generator power and impedance protection in the conventional generator-transformer short-circuit test is too long.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art, and provide a test method for measuring the voltage and power direction of the generator in the short-circuit test of the high power transformer, which can realize the test of generator power and impedance protection, and the test time is relatively short .

In order to achieve the above object, the test method for measuring generator voltage and power direction in the short-circuit test of high power plant transformer according to the present invention comprises the following steps:

1) Increase the secondary current on the low-voltage side of the factory transformer to the preset current value, check and record the current amplitude, phase and differential protection differential current of the current loop;

2) Raise the short-circuit current of the low-voltage side of the high-voltage transformer to the rated current I ₂ , stop the magnetization, check and record the generator terminal current I ₁ and the generator terminal voltage U;

3) Check and record the power and impedance direction of the generator protection cabinet, check the correctness of the PT circuit of the generator under the condition of low voltage at the machine end, and complete the short-circuit test of the high-factory transformer to measure the generator voltage and power direction.

Before step 1), it also includes: confirming the nameplate parameters of the high-level factory transformer.

The nameplate parameters of the high factory transformer include the rated capacity S of the high factory transformer, the rated voltage of the high voltage side U _e and the short circuit impedance U _d %.

The preset current value is 0.1A.

Generator terminal voltage U≈U _d %×(U _e ² /S)×I ₁ , where U _d % is the short-circuit impedance of the high power transformer, U _e is the rated voltage of the generator, and S is the capacity of the high power transformer.

The present invention has the following beneficial effects:

The test method for measuring the voltage and power direction of the generator in the high-power transformer short-circuit test described in the present invention is to simplify the detection of generator power and impedance direction by raising the current on the low-voltage side of the high-power transformer short-circuit test to the rated value. At the same time, the low-voltage inspection of the PT circuit at the generator end is carried out in advance, laying the foundation for the next generator no-load test, avoiding the shortcoming of a long test time, improving test efficiency, ensuring the accuracy of protection inspection, and ensuring that the unit Safe and reliable operation, reducing the number of shutdowns during commissioning and saving operating costs.

Description of drawings

Fig. 1 is the schematic diagram of the present invention during the high-factory short-circuit test.

Detailed ways

The present invention is described in further detail below in conjunction with accompanying drawing:

With reference to Fig. 1, the test method of measuring generator voltage and power direction in high factory transformer short-circuit test of the present invention comprises the following steps:

1. Preparation before the test

Ensure that the short-circuit point K1 at the generator end is firmly installed and in good contact; the three-phase short-circuit point K2 on the high-voltage side of the main transformer is well-connected, and the ground wire is reliably grounded; , There is no flammable material around the short-circuit point, and isolation precautions should be taken.

2. Generator short circuit test (K1 short circuit point)

Confirm that the generator stator current, rotor current and rotor voltage have been connected to the generator characteristic tester, start the generator characteristic tester, and operate the local magnetization button on the excitation regulator cabinet to make the generator stator current rise slowly, and the generator When the secondary current rises to 0.1A, stop the magnetization, check and record the current amplitude, phase and differential protection differential current of the relevant current loop. button to reduce the generator stator current to the minimum value.

After checking that there is no abnormal phenomenon, obtain the short-circuit characteristic test of the generator (the maximum current rises to the rated current of the generator) by operating the local magnetization increase button and the local demagnetization button on the excitation regulator, and record the short-circuit characteristic data and short-circuit characteristics After the test, reduce the stator current of the generator to the minimum value, trip the demagnetization switch, disconnect the power circuit breaker on the high-voltage side of the excitation transformer, connect the ground wire, and then remove the short-circuit busbar of the generator.

3. Short-circuit test on the high-voltage side of the main transformer (K2 short-circuit point)

Short-circuit the three phases of the short-circuit point K2 on the high-voltage side of the main transformer. By operating the local magnetization button on the excitation regulator, the short-circuit current of the high-voltage side of the main transformer is 100A. Check and record the current amplitude, phase and Differential protection differential current, after checking that there is no abnormal phenomenon, reduce the stator current of the generator to the minimum value by operating the local demagnetization button on the excitation regulator, trip the demagnetization switch, and then disconnect the power circuit breaker on the high voltage side of the excitation transformer .

4. Short-circuit test on the low-voltage side of the high-factory substation (K3, K4 short-circuit points)

By operating the local magnetization button on the excitation regulator cabinet, the stator current of the generator rises slowly. When the secondary current of the high-voltage transformer low-voltage side rises to 0.1A, the magnetization is stopped, and the current amplitude of the relevant current loop is checked and recorded. , phase and differential protection differential current, then continue to increase the magnetization, raise the current of the high-voltage transformer low-voltage side to the rated value, stop the magnetization, check and record the generator terminal current I ₁ and the generator terminal voltage U, among which, the generator terminal Voltage U≈U _d ％×(U _e ² /S)×I ₁ , U _d ％ is the short-circuit impedance of the high-power transformer, U _e is the rated voltage of the generator, S is the capacity of the high-power transformer, I ₁ is the terminal current, check And record the power and impedance direction of the generator protection cabinet, check the correctness of the generator PT circuit under the condition of low voltage at the machine terminal, after the inspection is completed, through the local demagnetization button on the excitation regulator cabinet, the generator stator current Reduce to the minimum value, trip the demagnetization switch, and then disconnect the power circuit breaker on the high voltage side of the excitation transformer, and the short circuit test is over.

In summary, under the premise of ensuring the correctness of the test, the present invention can optimize the shortcomings of the long test time for detecting generator power and impedance protection in the short-circuit test of the conventional generator-transformer group, which can greatly reduce the test time and simplify the test. Process, improve efficiency and accuracy.

Claims (8)

1. A test method for testing and measuring voltage and power direction of a generator in a short route in a high plant is characterized by comprising the following steps:

1) Increasing the secondary current of the low-voltage side of the factory to a preset current value, and checking and recording the current amplitude, the phase and the differential protection differential current of a current loop;

2) The short-circuit current of the high-voltage side and the low-voltage side of the factory is increased to the rated current I₂Stopping increasing magnetism, checking and recording generator end current I₁And a terminal voltage U;

3) The power and the impedance direction of the generator protection cabinet are checked and recorded, the correctness of a PT loop of the generator under the working condition of low voltage at the generator end is checked, and the test of measuring the voltage and the power direction of the generator by short-circuit test in a high-rise plant is completed.

2. The test method for testing and measuring the voltage and the power direction of the generator in the short-circuiting test of the high-rise station according to claim 1, further comprising the following steps before step 1): and (5) confirming the name plate parameters of the high factory change.

3. The method as claimed in claim 2, wherein the parameter of the nameplate of the high-speed transformer includes a short-circuit impedance of the high-speed transformer as U_d％。

4. The test method for measuring the voltage and power direction of the generator by the high-rise short-circuit test according to claim 2, wherein the nameplate parameters of the high-rise transformer comprise the rated capacity S of the high-rise transformer.

5. The method as claimed in claim 2, wherein the nameplate parameters of the high-speed transformer include a rated voltage of the high-speed side of the high-speed transformer as U_e。

6. The method as claimed in claim 1, wherein the predetermined current value is 0.1A.

7. The method as claimed in claim 1, wherein the terminal voltage U ≈ U_d％×(U_e ²/S)×I₁，U_d% of high factory-to-short circuit impedance, U_eThe rated voltage of the generator and S is the high plant capacity.

8. The test method for measuring the voltage and power direction of a generator according to claim 1, wherein the magnetization and the demagnetization are performed by operating an on-site magnetization-increasing button and an on-site demagnetization-decreasing button on the excitation regulator.

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