A device for measuring the short circuit withstand capability of a power transformer

Abstract

The present application relates to a kind of electric power transformer short circuit bearing capacity measuring device, belong to high voltage electrical apparatus test technical field.The measuring device includes power supply and control system, and measuring system, measuring system includes controller and sensor module.When the primary side three-phase winding of the short circuit transformer test product is triangle connection, controller is used to in the process of carrying out short circuit bearing capacity test, according to the line current of each phase of three current sensors acquisition, and combining the vector relationship between the line current and transformer test product phase current, to obtain the phase current of each phase of short circuit transformer test product, and according to the phase current of each phase of short circuit transformer test product, the short circuit bearing capacity of short circuit transformer test product is evaluated.The whole process does not switch other measuring system, reduces test cost, and can meet the requirement of the transformer short circuit bearing capacity test of quickly obtaining test result.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of electric power transformer short circuit bearing capacity measuring device, belong to high voltage electrical apparatus test field. BACKGROUND

[0002] Electric power transformer in use, overcurrent caused by external sudden short circuit not only causes damage to electric power transformer, since its in the wide range of application of electric power system, surrounding environment is complex, even when failure secondary disaster will be caused, therefore, electric power transformer short circuit bearing capacity is more and more concerned.

[0003] When carrying out transformer short circuit bearing capacity test in laboratory, test loop, measuring element and device need to be arranged, and measuring element and device are composed of current sensor, voltage sensor and transient recorder etc..For the transformer with star connection winding, phase current is its line current, but for the transformer with delta connection winding, because there is no angle calculation in the measurement system, so phase current cannot be directly measured, and the prior art is to connect the secondary windings of three current transformers for measuring line current with each other, and use oscilloscope to record phase current, which has the advantage of directly measuring by hardware, but for test station, it needs to purchase expensive instrument equipment and modify test loop, and in addition, for different test products with star or delta connection, it needs to frequently switch the measurement system in test loop to obtain required data, which is very unfavorable condition for large capacity test, and also causes low test efficiency, and the requirement of quickly obtaining test result of transformer short circuit bearing capacity test will inevitably be affected. SUMMARY

[0004] The purpose of the present application is to provide a kind of electric power transformer short circuit bearing capacity measuring device, to solve the problem of high cost and low efficiency of electric power transformer short circuit bearing capacity measurement.

[0005] To solve the above technical problems, the present application provides a kind of electric power transformer short circuit bearing capacity measuring device, including power supply and control system, and measurement system;The power supply and control system includes short circuit test three-phase transformer, and the measurement system includes controller and sensor module;The primary three-phase winding of the short circuit test three-phase transformer is used to connect power supply, and the secondary three-phase winding is used to connect the primary three-phase winding of short circuit transformer test product through sensor module in measurement system, and the secondary three-phase winding of the short circuit transformer test product is short-circuited;The sensor module includes three current sensors, respectively for collecting line current of each phase;The controller samples connects the three current sensors;

[0006] When the primary three-phase winding of the short-circuit transformer sample is connected in a delta connection, the controller is configured to, during the short-circuit withstand capability test, obtain the phase current of each phase of the short-circuit transformer sample according to the line current of each phase collected by the three current sensors, and according to the vector relationship between the collected line current and the phase current of the transformer sample, and evaluate the short-circuit withstand capability of the short-circuit transformer sample according to the phase current of each phase of the short-circuit transformer sample.

[0007]

[0008] wherein, are the phase currents of the three phases of the short-circuit transformer sample, are the collected line currents of the three phases.

[0009] The power transformer short-circuit withstand capability measuring device has the following advantages: the measuring system in the measuring device mainly includes a sensor module and a controller in hardware. When the primary three-phase winding of the short-circuit transformer sample is connected in a delta connection, the phase current of each phase of the short-circuit transformer sample can be calculated by performing corresponding vector calculation according to the pre-stored vector relationship between the line current and the phase current and the line current of each phase collected by the sensor module, and the short-circuit withstand capability of the short-circuit transformer sample can be evaluated directly by using the value. The whole process does not need to switch other measuring systems, which reduces the test cost and meets the requirement of the transformer short-circuit withstand capability test for quickly obtaining the test result.

[0010] Further, the sensor module further includes three voltage sensors configured to collect the phase voltage of each phase, and the controller is connected to the three voltage sensors. When the primary three-phase winding of the short-circuit transformer sample is connected in a delta connection, the controller is further configured to, during the short-circuit withstand capability test, obtain the phase voltage of each phase of the short-circuit transformer sample according to the phase voltage of each phase collected by the three voltage sensors, and according to the vector relationship between the collected phase voltage and the phase voltage of the transformer sample, and evaluate the short-circuit withstand capability of the short-circuit transformer sample according to the phase voltage of each phase of the short-circuit transformer sample. The vector relationship between the collected phase voltage and the phase voltage of the transformer sample is:

[0011]

[0012] wherein, are the phase voltages of the three phases of the short-circuit transformer sample, are the collected phase voltages of the three phases.

[0013] The beneficial effect is that when the primary three-phase winding of the short-circuit transformer test sample is connected in a delta connection, the phase voltage of each phase of the short-circuit transformer test sample can be calculated by corresponding vector calculation according to the pre-stored vector relationship between the line voltage and the phase voltage and the phase voltage of each phase collected by the sensor module, and the short-circuit withstand capability of the short-circuit transformer test sample can be evaluated directly by using the value. The whole process does not need to switch other measurement systems, reduces the test cost, and can meet the requirements of the transformer short-circuit withstand capability test for quickly obtaining the test results.

[0014] Further, when the primary three-phase winding of the short-circuit transformer test sample is connected in a star connection, the controller is further configured to, during the short-circuit withstand capability test, take the line current of each phase collected by the three current sensors as the phase current of each phase of the short-circuit transformer test sample, and evaluate the short-circuit withstand capability of the short-circuit transformer test sample according to the phase current of each phase of the short-circuit transformer test sample.

[0015] Further, when the primary three-phase winding of the short-circuit transformer test sample is connected in a star connection, the controller is further configured to, during the short-circuit withstand capability test, take the line current of each phase collected by the three current sensors as the phase current of each phase of the short-circuit transformer test sample, and evaluate the short-circuit withstand capability of the short-circuit transformer test sample according to the phase current of each phase of the short-circuit transformer test sample.

[0016] Further, the power supply and control system further comprises an isolating switch and a primary side protection circuit breaker, the isolating switch and the primary side protection circuit breaker are connected in series along the line between the power supply and the primary three-phase winding of the short-circuit test three-phase transformer from upstream to downstream, and the controller controls the connection of the isolating switch and the primary side protection circuit breaker.

[0017] Further, the power supply and control system further comprises a secondary side protection circuit breaker, a closing switch and an operating circuit breaker, the secondary side protection circuit breaker, the closing switch and the operating circuit breaker are connected in series along the line between the secondary three-phase winding of the short-circuit test three-phase transformer and the sensor module in the measurement system from upstream to downstream, and the controller controls the connection of the secondary side protection circuit breaker, the closing switch and the operating circuit breaker.

[0018] Further, the power supply and control system further comprises an adjusting reactor, which is connected in series on the line between the secondary side protection circuit breaker and the closing switch.

[0019] Further, during the short circuit withstand capability test, the controller controls the operation sequence of the disconnecting switch, the primary side protection circuit breaker, the secondary side protection circuit breaker, the closing switch and the operating circuit breaker as follows: firstly, the disconnecting switch and the primary side protection circuit breaker are closed, and the secondary side protection circuit breaker, the closing switch and the operating circuit breaker are controlled to be in the open state, so as to excite the short circuit test three-phase transformer; then, the secondary side protection circuit breaker is closed, and the operating circuit breaker is closed, the closing switch is closed and the operating circuit breaker is opened in sequence according to the set time sequence. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic diagram of the power transformer short circuit withstand capability measuring device of the present application;

[0021] Figure 2 is a schematic diagram of the vector relationship between the line current and the phase current when the primary side three-phase winding of the short circuit transformer test sample is connected in a delta connection. DETAILED DESCRIPTION

[0022] The present application starts from the circuit principle, analyzes the vector relationship between the line (phase) current and the line (phase) voltage after the winding star or delta connection test sample is connected to the test circuit, uses the available development function of the existing measuring system, writes the vector relationship between the line (phase) current and the line (phase) voltage of the winding star or delta connection into the measuring system, and when the transformer short circuit withstand capability test is performed, the different connection modes can be conveniently called to analyze the measurement data and output the test oscillogram meeting the standard requirements. The existing current, voltage sensor and transient recorder and other measuring elements and test circuit do not need to be changed.

[0023] The present application will be further described in detail below in combination with the drawings and embodiments.

[0024] Device embodiment:

[0025] The power transformer short circuit withstand capability measuring device of the present application has the structure as shown in Figure 1 The power transformer short circuit withstand capability measuring device of the present application has the structure as shown in

[0026] The power supply and control system includes a disconnecting switch DS, a primary side protection circuit breaker PB1, a short circuit test three-phase transformer T, a secondary side protection circuit breaker PB2, a regulating reactor L, a closing switch MS and an operating circuit breaker OB. The 220kV power grid is connected to the primary side three-phase winding of the short circuit test three-phase transformer T through the disconnecting switch DS and the primary side protection circuit breaker PB1 in sequence, the secondary side three-phase winding of the short circuit test three-phase transformer T is connected to the primary side three-phase winding of the short circuit transformer test sample TO through the protection circuit breaker PB2, the regulating reactor L, the closing switch MS, the operating circuit breaker OB and the sensor module in the measuring system in sequence.

[0027] The measuring system comprises a sensor module, a measurement front end QD, a voltage and current signal conversion cabinet XH, a transient recorder host JL and a terminal computer CM. The sensor module comprises a first voltage sensor U1, a first current sensor I1, a second voltage sensor U2, a second current sensor I2, a third voltage sensor U3 and a third current sensor I3, which are used to measure the phase voltage of phase A, the line current of phase A, the phase voltage of phase B, the line current of phase B, the phase voltage of phase C and the line current of phase C respectively. The measurement front end QD is connected with each voltage sensor and current sensor, the voltage and current signal conversion cabinet XH is connected with the measurement front end QD and each voltage sensor and current sensor, the transient recorder host JL is connected with the voltage and current signal conversion cabinet XH to obtain voltage and current signals, and the terminal computer CM is connected with the transient recorder host JL to calculate the voltage and current signals.

[0028] Moreover, the terminal computer CM is also connected with the disconnector DS, the primary side protection circuit breaker PB1, the secondary side protection circuit breaker PB2, the regulating reactor L, the closing switch MS and the operating circuit breaker OB through a hard wire to control the opening or closing of these switches.

[0029] When the secondary side three-phase winding of the short-circuit transformer test object TO is short-circuited and the primary side three-phase winding is connected in a delta connection, the connection diagram of the entire measuring device is shown in FIG. 1. Figure 1 When the primary side three-phase winding of the short-circuit transformer test object TO is connected in a star connection, the external wiring of the measuring device is the same as that of the power transformer connected in a delta connection, which is not shown in another figure.

[0030] The entire test process is described below.

[0031] When the power transformer short-circuit withstand capability test is performed on the short-circuit transformer test object TO, first, the disconnector DS and the primary side protection circuit breaker PB1 are controlled to be closed, the secondary side protection circuit breaker PB2, the closing switch MS and the operating circuit breaker OB are controlled to be open, and the short-circuit test three-phase transformer T is excited. Then, the secondary side protection circuit breaker PB2 is controlled to be closed, and the operating circuit breaker OB is controlled to be closed, the closing switch MS is controlled to be closed, and the operating circuit breaker OB is controlled to be open in a certain time sequence. When the closing switch MS is closed, the power transformer withstand capability is measured, the data of the first voltage sensor U1, the second voltage sensor U2, the third voltage sensor U3, the first current sensor I1, the second current sensor I2 and the third current sensor I3 are recorded, and the data of each sensor obtained is automatically calculated on the terminal computer CM of the measuring system according to the star / delta connection of the primary side three-phase winding of the short-circuit transformer test object TO, and the oscillogram of the standard required power transformer short-circuit withstand capability is displayed and output.

[0032] When the primary three-phase windings of the short-circuit transformer test specimen TO are delta connected, according to Figure 1 The direction of the current shown can be obtained according to Kirchhoff's current law and the vector representation of sinusoidal alternating current: in, These are the line currents of the three phases, acquired by the first current sensor I1, the second current sensor I2, and the third current sensor I3, respectively. These are the phase currents of the three phases TO of the short-circuit transformer test sample, respectively. Based on the above formula, we can further draw... Figure 2 , Figure 2 From the vector diagram of line current and phase current of a power transformer with its primary three-phase windings connected in a delta configuration for a short-circuit transformer test specimen TO, we can deduce: That is, for phase A winding, its phase current I ab Instantaneous value and phase A line current I a Phase B line current I b The vector differences have the same phase and an amplitude of I. a and I b vector difference For phase B winding, its phase current I is [times] times; bc Instantaneous value and phase B line current I b C-phase line current I c The vector differences have the same phase and an amplitude of I. b and I c vector difference For the C-phase winding, the phase current I is [times] times; ca Instantaneous value and phase A line current I a C-phase line current I c The vector differences have the same phase and an amplitude of I. a and I c vector difference Times. According to Figure 2 The vector relationships in the diagram show that the line currents of phases A, B, and C lag behind the phase currents of phases A, B, and C by 30°.

[0033] For the three-phase phase voltage U ab U bc and U ca ,available: in, The three phase voltages are collected by the first voltage sensor U1, the second voltage sensor U2, and the third voltage sensor U3, respectively. These are the phase voltages of the three phases TO of the short-circuit transformer test sample. That is, for phase A winding, its phase voltage U is... abThe phase and amplitude of the vector difference of the voltage instantaneous values collected by the first voltage sensor U1 and the second voltage sensor U2 are the same, and the phase voltages of the B phase and the C phase also have the same corresponding relationship.

[0034] When the primary three-phase winding of the short-circuit transformer test sample TO is star-connected, the current values collected by the first current sensor I1, the second current sensor I2 and the third current sensor I3 are the standard required currents (i.e. the phase currents of the transformer test sample TO), and the voltage values collected by the first voltage sensor U1, the second voltage sensor U2 and the third voltage sensor U3 are the standard required voltages (i.e. the phase voltages of the transformer test sample TO).

[0035] The short-circuit withstand capability of the short-circuit transformer test sample TO is evaluated by using the standard required voltages and currents. The collected voltage and current waveforms are normal, which are standard sine waves without distortion. This is the most critical criterion and is also the basis for the evaluation of the reactance change rate and subsequent routine test evaluation.

[0036] The above analysis of the vector relationship of the winding delta or star connected test sample line (phase) current and line (phase) voltage is carried out in combination with the available functions of the existing measurement system, is realized by vector operation of the measurement channel of the measurement system, is input into the measurement system at the initial test, forms the measurement parameter setting file of the power transformer short-circuit withstand capability, and can be directly called in the later test.

Claims

1. A short circuit withstand capability measuring device of power transformer, comprising a power supply and control system and a measuring system; the power supply and control system comprises a short circuit test three-phase transformer, and the measuring system comprises a controller and a sensor module; a primary three-phase winding of the short circuit test three-phase transformer is used for connecting a power supply, a secondary three-phase winding is used for connecting a primary three-phase winding of a short circuit transformer test sample through a sensor module in the measuring system, and a secondary three-phase winding of the short circuit transformer test sample is short-circuited; the sensor module comprises three current sensors respectively used for collecting a line current of each phase; the controller is connected with the three current sensors; characterized in that the controller is used for, during a short circuit withstand capability test: when the primary three-phase winding of the short circuit transformer test sample is connected in a delta connection, obtaining a phase current of each phase of the short circuit transformer test sample according to the line current of each phase collected by the three current sensors and a pre-stored vector relationship between the collected line current and a transformer test sample phase current; when the primary three-phase winding of the short circuit transformer test sample is connected in a star connection, taking the line current of each phase collected by the three current sensors as the phase current of each phase of the short circuit transformer test sample; and then evaluating the short circuit withstand capability of the short circuit transformer test sample according to the phase current of each phase of the short circuit transformer test sample; the vector relationship between the collected line current and the transformer test sample phase current is: wherein are the phase currents of the three phases of the short-circuit transformer test specimen, respectively, are the line currents of the three phases collected, respectively.

2. The power transformer short circuit withstand capability measuring device according to claim 1, characterized in that, the sensor module further comprises three voltage sensors respectively used for collecting a phase voltage of each phase; the controller is connected with the three voltage sensors; when the primary three-phase winding of the short circuit transformer test sample is connected in a delta connection, the controller is further used for, during a short circuit withstand capability test, obtaining a phase voltage of each phase of the short circuit transformer test sample according to the phase voltage of each phase collected by the three voltage sensors and a vector relationship between the collected phase voltage and a transformer test sample phase voltage, and evaluating the short circuit withstand capability of the short circuit transformer test sample according to the phase voltage of each phase of the short circuit transformer test sample; the vector relationship between the collected phase voltage and the transformer test sample phase voltage is: wherein are the phase voltages of the three phases of the short-circuit transformer test object, respectively, are the phase voltages of the three phases of the short-circuit transformer test object, respectively, 3. The power transformer short circuit withstand capability measuring device according to claim 1, characterized in that, when the primary three-phase winding of the short circuit transformer test sample is connected in a star connection, the controller is further used for, during a short circuit withstand capability test, taking the phase voltage of each phase collected by the three voltage sensors as the phase voltage of each phase of the short circuit transformer test sample, and evaluating the short circuit withstand capability of the short circuit transformer test sample according to the phase voltage of each phase of the short circuit transformer test sample.

4. The power transformer short circuit withstand capability measuring device according to any one of claims 1 to 3, characterized in that the power supply and control system further comprises an isolating switch and a primary side protection circuit breaker, the isolating switch and the primary side protection circuit breaker are connected in series along a line between the power supply and the primary three-phase winding of the short circuit test three-phase transformer from upstream to downstream, and the controller is connected with the isolating switch and the primary side protection circuit breaker.

5. The power transformer short circuit withstand capability measuring device according to claim 4, characterized in that, the power supply and control system further comprises a secondary side protection circuit breaker, a closing switch and an operating circuit breaker, the secondary side protection circuit breaker, the closing switch and the operating circuit breaker are connected in series along a line between the secondary three-phase winding of the short circuit test three-phase transformer and the sensor module in the measuring system from upstream to downstream, and the controller is connected with the secondary side protection circuit breaker, the closing switch and the operating circuit breaker.

6. The power transformer short circuit withstand capability measuring device according to claim 5, characterized in that, The power supply and control system further comprises a regulating reactor, which is connected in series on the line between the secondary-side protection circuit breaker and the closing switch.

7. The power transformer short circuit withstand capability measuring device according to claim 5, characterized in that, During the short circuit withstand capability test, the controller controls the operation sequence of the disconnecting switch, the primary-side protection circuit breaker, the secondary-side protection circuit breaker, the closing switch and the operating circuit breaker as follows: firstly, the disconnecting switch and the primary-side protection circuit breaker are controlled to be closed, and the secondary-side protection circuit breaker, the closing switch and the operating circuit breaker are controlled to be open, so as to excite the three-phase transformer for short circuit test; then, the secondary-side protection circuit breaker is controlled to be closed, and the operating circuit breaker is controlled to be closed, the closing switch is controlled to be closed, and the operating circuit breaker is controlled to be open in sequence according to the set time sequence.

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