CN103823183A - Method for measuring stator open circuit transient time-constant of synchronous generator - Google Patents

Abstract

In order to solve the problems in the existing excitation system modeling process, the traditional method of measuring the open circuit transient time constant of the generator stator generally needs to change the wiring of the primary circuit, so that the measurement safety requirements are high and the test workload is relatively large. A method for measuring the transient time constant of the stator open circuit of a synchronous generator, the measurement method is based on the matlab/simulink platform to build a generator no-load simulation system, with the measured synchronous generator excitation voltage as input, the simulation obtains the generator output voltage curve, Comparing the measured curve and the simulation curve of the output voltage of the generator, the transient time constant of the stator open circuit is obtained by fitting. The test method combined with test and simulation fitting proposed by the invention effectively solves the problems of complicated wiring and low accuracy of results in the traditional test method, and has high economical and practical value.

Description

A Measuring Method of Stator Open Transient Transient Time Constant of Synchronous Generator

technical field

The present invention relates to the technical field related to power system operation and measurement, and furthermore, relates to a method for measuring the stator open-circuit transient time constant of a synchronous generator, especially a synchronous generator stator open-circuit transient time constant using a self-shunt excitation system In order to solve the measurement problem of generator stator open-circuit transient time constant in the process of excitation system modeling.

the

Background technique

With the development of the economy, the scale of power grid interconnection continues to grow, and the speed of power supply construction is also accelerated simultaneously. The safety and stability of large-capacity generating units in grid-connected operation is related to the safety and stability of the entire power grid, and the excitation system of these units plays a vital role in the stable operation of the units. Therefore, whether the adjustment performance of the excitation system can meet the requirements of the grid-connected safe and stable operation of the unit when the new large-capacity unit is put into operation has become the focus of attention of the power system.

The excitation system modeling is based on providing technical support and on-site supervision services for the commissioning test of the excitation system of the generator set, establishing an excitation system model that can truly reflect the adjustment characteristics of the unit, and combining various commissioning test waveforms to analyze the excitation system. Whether the regulation performance meets the grid connection requirements. Among them, during the modeling process of the excitation system, the transient time constant of the generator stator open circuit has a great influence on the simulation results. The traditional measurement method needs to change the wiring of the primary circuit, which has high safety requirements and a large test workload.

Contents of the invention

In order to solve the problems in the existing excitation system modeling process, the traditional method of measuring the open circuit transient time constant of the generator stator generally needs to change the wiring of the primary circuit, so that the measurement safety requirements are high and the test workload is relatively large. A method for measuring the transient time constant of the stator open circuit of a synchronous generator.

Technical scheme of the present invention is as follows:

A method for measuring the transient time constant of the stator open circuit of a synchronous generator, characterized in that it comprises the following steps:

1. Let the synchronous generator under test run under no-load conditions, adjust the output voltage of the synchronous generator to be lower than the rated output voltage of the synchronous generator, and make the excitation regulator run in the automatic channel;

2. Carry out a voltage step test on the synchronous generator under test, and record the output voltage curve and excitation voltage curve of the synchronous generator under test during the step test;

3. Use matlab/simulink to build the no-load simulation system of the tested synchronous generator, draw up the stator open-circuit transient time constant in the no-load simulation system, and use the measured synchronous generator excitation voltage curve recorded in step 2 as the no-load simulation The simulation curve of the input and output synchronous generator output voltage of the system;

4. When the deviation of the rise time, overshoot and steady-state value of the simulation curve and the output voltage curve of the measured synchronous generator all meet the preset deviation range, the stator open-circuit transient time constant proposed in step 3 As the stator open-circuit transient time constant of the tested synchronous generator, otherwise adjust the stator open-circuit transient time constant proposed in step 3 until the rise time, overshoot and steady-state value of the simulation curve all meet the preset deviation range, and get Stator open circuit transient time constant of the synchronous generator under test.

In the present invention, in step 1, the output voltage of the synchronous generator is adjusted to be 50% to 70% of the rated output voltage of the synchronous generator.

In the present invention, the voltage step test in step 2 is a 3% to 5% voltage step test of the synchronous generator under test.

In the present invention, in the step 2, the output voltage and the excitation voltage of the synchronous generator under test are converted per unit to obtain the output voltage per unit curve and the excitation voltage per unit curve of the measured synchronous generator after the unit, The per unit value of the output voltage of the synchronous generator Ut=Ut_sc/Un, the per unit value of the excitation voltage Uf=(Ut_w/Uf_w/Un)*Uf_sc, wherein, Ut_sc is the output voltage value of the measured synchronous generator, Un is the measured Measure the rated output voltage value of the synchronous generator, Uf_w is the steady-state excitation voltage value of the measured synchronous generator voltage step test, and Ut_w is the measured steady-state output voltage value of the synchronous generator.

After the steady-state voltage step test of the tested synchronous generator is adopted, the average value of the excitation voltage values at multiple time points on the excitation voltage curve is used as the steady-state excitation voltage value of the measured synchronous generator voltage step test. The average value of the output voltage values of the synchronous generators at the same time for the excitation voltage values at each time point is taken as the steady-state output voltage value of the measured synchronous generator.

In the step 3, the excitation voltage per unit curve is used as the input of the no-load simulation system, and the no-load simulation system outputs the simulation curve of the output voltage per unit curve of the synchronous generator.

In the step 4, when the deviation of the simulation curve of the output voltage per unit curve, the rise time, the overshoot and the steady state value and the output voltage per unit curve of the synchronous generator under test are all in the preset deviation range, The stator open-circuit transient time constant proposed in step 3 is used as the stator open-circuit transient time constant of the synchronous generator under test.

In the present invention, when the overshoot of the simulation curve is relatively large, the stator open-circuit transient time constant proposed in step 3 is increased, and vice versa, the stator open-circuit transient time constant proposed in step 3 is reduced.

The adjustment step of the proposed stator open-circuit transient time constant is 0.01s to 0.05s.

In the present invention, the preset deviation range of the rise time is ±0.005s, the preset deviation range of the overshoot is ±1%, and the preset deviation range of the steady-state value is not more than the step amount ±1%.

The method for measuring the transient time constant of the stator open circuit of the synchronous generator of the present invention proposes a test method combining test and simulation fitting. The present invention has the excellent characteristics of no need to change the wiring of the primary circuit and the test process is simple. The present invention is especially suitable for The measurement of the generator stator open-circuit transient time constant of the self-shunt excitation system effectively solves the problems of complex wiring and low accuracy of the traditional test method, and has high economic and practical value.

Description of drawings

Fig. 1 is a flowchart of the present invention.

Figure 2 is a schematic diagram of the comparison between the output voltage per unit curve of the synchronous generator and the simulation per unit curve of the no-load simulation system in the voltage step test, the first case.

Figure 3 is a schematic diagram of the comparison between the output voltage per unit curve of the synchronous generator and the simulation per unit curve of the no-load simulation system in the voltage step test, the second case.

Figure 4 is a schematic diagram of the comparison between the output voltage per unit curve of the synchronous generator and the simulation per unit curve of the no-load simulation system in the voltage step test, and the third case.

the

Detailed ways

First of all, it needs to be explained that for synchronous generators, especially the self-shunt excitation system, the excitation voltage of the generator is output by the excitation regulator, which is input to the rotor circuit of the generator for excitation, and the output voltage of the generator is output by the stator .

Referring to Fig. 1, the measuring method of synchronous generator stator open-circuit transient time constant of the present invention comprises the steps:

First, let the synchronous generator under test run under no-load conditions, adjust the output voltage of the synchronous generator to be less than the rated output voltage of the synchronous generator, and make the excitation regulator run in the automatic channel. In order to obtain better measurement results, the output voltage of the synchronous generator is preferably 50% to 70% of the rated output voltage of the synchronous generator. This is because, when the voltage of the synchronous generator is lower than 70%, the power generated The generator is in an unsaturated state, and its model is a first-order inertia link. When it is greater than 70%, the generator is running in the saturation region. The model needs to consider the saturation characteristics, and the model is relatively complicated; the voltage of the self-shunt excitation system is too low to establish a voltage , so the output voltage of the synchronous generator cannot be lower than 50% of the rated output voltage, and the excitation system is stable at this time.

Then, carry out the voltage step test on the synchronous generator under test. The voltage step test is better to use the 3% to 5% voltage step test of the synchronous generator under test. In the limiting area of the regulator, the step amount is too small and the process is not clear enough. During the step test process, the output voltage curve and excitation voltage curve of the synchronous generator under test are recorded. The recording process can be carried out by using a power record analyzer. The curve is formed by the recorded wave data of the power record analyzer.

Then, use matlab/simulink to build the no-load simulation system of the synchronous generator under test, draw up the stator open-circuit transient time constant in the no-load simulation system, and use the excitation voltage curve of the synchronous generator under test recorded in the previous step as the no-load simulation The input of the system, here, the wave recording data of the excitation voltage by the power recorder analyzer is converted into an excel file and imported into matlab, which is well known to those skilled in the art, and will not be repeated here. Finally, the no-load simulation The simulation curve of the output voltage of the synchronous generator output by the system;

Finally, compare the simulation curve of the output voltage of the synchronous generator output by the no-load simulation system with the output voltage curve of the measured synchronous generator. When the deviation of the output voltage curve meets the preset deviation range, the stator open-circuit transient time constant proposed in the no-load simulation system is used as the stator open-circuit transient time constant of the synchronous generator under test; otherwise, the stator open-circuit time constant proposed in the no-load simulation system is adjusted. Transient time constant until the rise time, overshoot and steady-state value of the simulation curve all meet the preset deviation range, and the stator open-circuit transient time constant of the synchronous generator under test is obtained. Here, for the preset deviation range of rise time, overshoot and steady-state value, it is better that the preset deviation range of rise time is ±0.005s, that is, the simulated curve is compared with the output voltage curve of the measured synchronous generator The deviation of the rise time is within ±0.005s; the preset deviation range of the overshoot is ±1%, that is, the deviation of the overshoot between the simulation curve and the output voltage curve of the measured synchronous generator does not exceed ±1%; The preset deviation range of the steady-state value is not more than ±1% of the step value, that is, the deviation of the steady-state value between the simulation curve and the output voltage curve of the synchronous generator under test is not more than ±1%.

Referring to Fig. 2 to Fig. 4, the present invention takes a certain synchronous generator as an example, adopts the method of the present invention to measure the open circuit transient time constant of the generator stator, and combines the data provided in the manual of the synchronous generator and the actual situation on site to verify the Effectiveness of the method of invention. The specific implementation process is as follows:

When the synchronous generator under test is running without load, adjust the output voltage of the generator under test to 50% of the rated output voltage, and conduct a 5% voltage step test on the synchronous generator under test. The recorded wave data of the analyzer forms the output voltage curve and excitation voltage curve of the synchronous generator under test.

In order to avoid the impact of the ambient temperature of the measured synchronous generator on the output voltage curve and the excitation voltage curve of the measured synchronous generator, and cause an impact on the measurement result of the final synchronous generator stator open circuit transient time constant, in this embodiment, the measured The output voltage and excitation voltage of the measured synchronous generator are transformed into per unit, and the output voltage per unit curve and excitation voltage per unit curve of the measured synchronous generator are obtained after per unit. The specific method is as follows:

Suppose the per unit value of the output voltage of the synchronous generator at any time is Ut, the per unit value of the excitation voltage at any time is Uf, the output voltage value of the measured synchronous generator at any time is Ut_sc, and the rated output voltage of the measured synchronous generator is Un, the steady-state excitation voltage value of the measured synchronous generator voltage step test is Uf_w, and the measured steady-state output voltage value of the synchronous generator is Ut_w, the following formula exists:

Same generator output voltage per unit value Ut=Ut_sc/Un （1）

Per unit value of excitation voltage Uf=(Ut_w/Uf_w/Un)*Uf_sc （2）

Then, through the output voltage curve and excitation voltage curve of the synchronous generator under test obtained before, the output voltage and excitation voltage of the synchronous generator under test can be converted into per unit, and the output voltage of the synchronous generator under test after per unit can be obtained. Output voltage per unit curve and excitation voltage per unit curve.

Since the steady-state excitation voltage value Uf_w of the measured synchronous generator voltage step test is read through the excitation voltage curve, in order to eliminate the influence of inaccurate values, it is possible to select more points in the steady state for calculation and then take the average After the voltage step test of the synchronous generator under test is stable, several reading points are selected at different time points on the excitation voltage curve, and the average value of the excitation voltage of the above several reading points is used as the value of the synchronous generator under test. The steady-state excitation voltage value of the motor voltage step test, and then read the output voltage value of the synchronous generator at each time point (reading point) before, and use the average output voltage value of the synchronous generator at the above several time points (reading point) The value is taken as the steady-state output voltage value of the synchronous generator under test.

In this way, when the stator open-circuit transient time constant is drawn up in the no-load simulation system, and the voltage step test is performed, the per unit curve of the excitation voltage will be used as the input of the voltage step test of the no-load simulation system, and the output of the no-load simulation system will be synchronous Simulation curve of generator output voltage per unit curve. Further, when judging whether the stator open-circuit transient time constant proposed in the no-load simulation system can be used as the stator open-circuit transient time constant of the synchronous generator under test, the rise time and overshoot of the simulation curve of the output voltage per unit curve will be used Whether the deviation between the output voltage and the steady-state value of the measured synchronous generator per unit curve is within the preset deviation range. The preset deviation range is the same when using the standard unit curve and comparing with the actual voltage value curve, so it will not be repeated here.

很不合理，并且励磁电压标幺值未采用本发明的方法计算，仿真曲线（即空载仿真系统输出的同步发电机输出电压标幺曲线的仿真曲线，图3和图4亦同）与实测曲线（即被测同步发电机输出电压标幺曲线，图3和图4亦同）无论是上升时间、超调量，还是稳态值的偏差都很大。 See Figure 2 again, the proposed stator open circuit transient time constant in the no-load simulation system

It is very unreasonable, and the per unit value of excitation voltage is not calculated by the method of the present invention, and the simulation curve (that is, the simulation curve of the output voltage per unit curve of the synchronous generator output by the no-load simulation system, the same as Fig. 3 and Fig. 4) and the measured The curve (that is, the output voltage per unit curve of the measured synchronous generator, the same as in Figure 3 and Figure 4) has a large deviation in terms of rise time, overshoot, and steady-state value.

时，较好的是首先选取同步发电机说明书提供的定子开路瞬变时间常数作为空载仿真系统中拟定的定子开路瞬变时间常数，本实施例中，同步发电机说明书中的定子开路瞬变时间常数

为8.6s。经过再次仿真，仿真曲线和实测曲线的稳态值一致，但仿真曲线的超调量超出了预设偏差范围，那么，需要修改空载仿真系统中拟定的定子开路瞬变时间常数

。 Referring again to Figure 3, in order to complete the stator open transient time constant as quickly as possible The test, the stator open circuit transient time constant proposed in the no-load simulation system

, it is better to first select the stator open circuit transient time constant provided by the synchronous generator manual as the stator open circuit transient time constant proposed in the no-load simulation system , in this embodiment, the stator open-circuit transient time constant in the specification of the synchronous generator

It is 8.6s. After re-simulation, the steady-state values of the simulated curve and the measured curve are consistent, but the overshoot of the simulated curve exceeds the preset deviation range, then the stator open-circuit transient time constant proposed in the no-load simulation system needs to be modified

.

，反之，应当调小空载仿真系统中拟定的定子开路瞬变时间常数，拟定的定子开路瞬变时间常数的调节步长为较好的是采用0.01s至0.05s。 When the overshoot of the simulation curve is too large, the stator open-circuit transient time constant proposed in the no-load simulation system should be increased

, on the contrary, the stator open-circuit transient time constant proposed in the no-load simulation system should be reduced , the proposed stator open circuit transient time constant The adjustment step size is preferably 0.01s to 0.05s.

并仿真得出仿真曲线，经过几次调节，当拟定的定子开路瞬变时间常数=8.85s时，仿真曲线与实测曲线吻合的很好，仿真曲线的上升时间、超调量和稳态值均满足预设偏差范围，最终，得到被测同步发电机的定子开路瞬变时间常数

=8.85s。 Referring to Fig. 4 again, in this embodiment, the proposed stator open-circuit transient time constant is increased in steps of 0.05s

And the simulation curve is obtained by simulation. After several adjustments, when the proposed stator open-circuit transient time constant =8.85s, the simulation curve is in good agreement with the measured curve, and the rise time, overshoot and steady-state value of the simulation curve all meet the preset deviation range. Finally, the stator open-circuit transient time constant of the measured synchronous generator is obtained

=8.85s.

Claims (10)

1. a method for measuring a synchronous generator stator open-circuit transient time constant, is characterized in that, comprises the steps: 1) Let the synchronous generator under test run under no-load conditions, adjust the output voltage of the synchronous generator to be less than the rated output voltage of the synchronous generator, and make the excitation regulator run in the automatic channel; 2) Carry out a voltage step test on the synchronous generator under test, and record the output voltage curve and excitation voltage curve of the synchronous generator under test during the step test; 3) Use matlab/simulink to build the no-load simulation system of the synchronous generator under test, draw up the stator open-circuit transient time constant in the no-load simulation system, and use the excitation voltage curve of the synchronous generator under test recorded in step 2) as the no-load The input of the simulation system outputs the simulation curve of the output voltage of the synchronous generator; 4) When the deviations between the rise time, overshoot and steady-state value of the simulation curve and the output voltage curve of the measured synchronous generator all meet the preset deviation range, the stator open circuit transient time proposed in step 3) The constant is used as the stator open-circuit transient time constant of the tested synchronous generator, otherwise adjust the stator open-circuit transient time constant proposed in step 3) until the rise time, overshoot and steady-state value of the simulation curve all meet the preset deviation range , to obtain the stator open circuit transient time constant of the synchronous generator under test. 2. A method for measuring the transient time constant of a synchronous generator stator open circuit according to claim 1, characterized in that: in the step 1), the output voltage of the synchronous generator is adjusted to be the rated output voltage of the synchronous generator 50% to 70% of that. 3. The measuring method of a kind of synchronous generator stator open circuit transient time constant according to claim 1, it is characterized in that: the voltage step test in the described step 2 is 3% to 5% voltage of the synchronous generator under test step test. 4. A method for measuring the transient time constant of a synchronous generator stator open circuit according to claim 1, characterized in that: in the step 2), the measured output voltage and excitation voltage of the synchronous generator are measured to obtain the output voltage per unit curve and the excitation voltage per unit curve of the measured synchronous generator after the per unit, the per unit value of the synchronous generator output voltage Ut=Ut_sc/Un, the per unit value of the excitation voltage Uf=(Ut_w /Uf_w/Un)*Uf_sc, where Ut_sc is the output voltage value of the tested synchronous generator, Un is the rated output voltage value of the tested synchronous generator, Uf_w is the steady-state excitation voltage of the tested synchronous generator after the voltage step test value, Ut_w measured synchronous generator steady-state output voltage value. 5. The measuring method of a kind of synchronous generator stator open-circuit transient time constant according to claim 4, it is characterized in that: after adopting the measured synchronous generator voltage step test steady state, multiple time points on the excitation voltage curve The average value of the excitation voltage value is taken as the steady-state excitation voltage value of the measured synchronous generator voltage step test, and the average value of the synchronous generator voltage stator value at the same time of the excitation voltage values at the previous multiple time points is used as the measured value. Measure the steady-state output voltage value of the synchronous generator. 6. A method for measuring the transient time constant of a synchronous generator stator open circuit according to claim 4 or 5, characterized in that: in the step 3), the per unit curve of the excitation voltage is used as the input of the no-load simulation system , the no-load simulation system outputs the simulation curve of the output voltage per unit curve of the synchronous generator. 7. A method for measuring the transient time constant of a synchronous generator stator open circuit according to claim 6, characterized in that: in the step 4), when the rise time of the simulation curve of the per unit curve of the output voltage, When the deviation between the overshoot and steady-state value and the per-unit curve of the output voltage of the synchronous generator under test is within the preset deviation range, the stator open-circuit transient time constant proposed in step 3) is used as the stator of the synchronous generator under test. Open circuit transient time constant. 8. The method for measuring the open-circuit transient time constant of a synchronous generator stator according to claim 1, characterized in that: when the overshoot of the simulation curve is too large, adjust the stator value drawn up in step 3). Open-circuit transient time constant, otherwise, reduce the stator open-circuit transient time constant prepared in step 3). 9. A method for measuring the stator open-circuit transient time constant of a synchronous generator according to claim 8, wherein the adjustment step of the proposed stator open-circuit transient time constant is 0.01s to 0.05s. 10. The method for measuring the transient time constant of a stator open circuit of a synchronous generator according to claim 1, wherein the preset deviation range of the rise time is ±0.005s, and the preset value of the overshoot is ±0.005s. The deviation range is ±1%, and the preset deviation range of the steady-state value is no more than ±1% of the step value.

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