A test system and method for a static frequency converter and an excitation device

Abstract

The present invention discloses a testing system and method for a static frequency converter and an excitation device. The testing system includes a tested frequency converter, a tested excitation device, a synchronous motor, a companion motor, a companion frequency converter, an excitation transformer, a first isolation transformer, a second isolation transformer, a measurement and control cabinet, a control console, an electrical signal acquisition component, an input switch, a grid-connected switch, and an isolation switch. The testing method includes a speed regulation and load test of a static frequency converter, a soft start test of a static frequency converter, and an excitation test. The present invention can not only realize the speed regulation, load test, and soft start test of a static frequency converter, but also complete the no-load and grid-connected dynamic characteristic test of static excitation, thereby providing a more complete and sufficient test for the static frequency converter and the excitation device.

Description

Technical Field

[0001] The invention relates to the technical field of static frequency converter and static excitation testing, and in particular to a testing system and method for a static frequency converter and an excitation device. Background Art

[0002] Static frequency converter (SFC) is a frequency conversion device used for starting large synchronous motors. It is widely used in the starting of heavy-duty gas turbine units, pumped storage units and phase-shifting units, and requires long-term stable operation. However, the factory test items of static frequency converters are usually limited to insulation withstand voltage test, sampling and protection test, short circuit test, and there is no motor starting speed regulation and load test, which makes it impossible to fully test the functions of static frequency converters, resulting in various unpredictable situations during on-site startup. Therefore, it is necessary to make more complete and sufficient test items for static frequency converters.

[0003] Motor dragging is the most commonly used inverter testing method. Usually, the inverter under test and the accompanying inverter are both voltage source inverters. Their DC sides are connected in parallel through the busbar, and the energy feedback point is at the DC busbar, which can save a set of rectifier bridges. However, the static inverter is a current source inverter, the rectifier element is a thyristor, and the DC link uses inductive energy storage. It cannot share the rectifier bridge and DC busbar with the voltage source inverter, so the method of sharing the DC busbar is not suitable for testing static inverters.

[0004] The patent document with publication number CN105790672A discloses a frequency converter test system, including a tested frequency converter BP1 and a high-voltage frequency conversion test motor driven by the tested frequency converter BP1 to operate as a motor, and also including a medium-voltage frequency conversion test motor coaxially connected to the high-voltage frequency conversion test motor and driven by the high-voltage frequency conversion test motor to operate as a generator, and the medium-voltage frequency conversion test motor is connected to the test converter and the test transformer in sequence. The test converter drives the medium-voltage frequency conversion test motor and feeds back the energy output by the tested frequency converter BP1 to the power grid; the test system uses the medium-voltage frequency converter to drive the test motor to realize the back-to-back active feedback of the test unit. However, it is found through analysis that the motor in this technology is an asynchronous motor and has no excitation device, so it can only test ordinary frequency converters, but is not suitable for testing static frequency converters.

[0005] In addition, the existing inverter test platform has a single function, which only has the inverter test function, but cannot test the excitation function at the same time. Therefore, it is necessary to develop a new technology that has the functions of testing static inverters and excitation at the same time. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned technical problems existing in the prior art, and to provide a testing system and method for a static frequency converter and an excitation device. The present invention can not only realize the speed regulation and load test and soft start test of the static frequency converter, but also complete the no-load and grid-connected dynamic characteristic test of the static excitation, thereby providing a more complete and sufficient test for the static frequency converter and the excitation device.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A test system for a static frequency converter and an excitation device, comprising a tested frequency converter, a tested excitation device, a synchronous motor, a companion motor, a companion frequency converter, an excitation transformer, a first isolation transformer, a second isolation transformer, a measurement and control cabinet, a control console, an electrical signal acquisition component, an input switch, a grid-connected switch and an isolation switch, wherein the excitation transformer, the first isolation transformer and the second isolation transformer are respectively connected to the grid through the input switch, the tested excitation device is respectively connected to the excitation transformer and the synchronous motor, the tested frequency converter is respectively connected to the first isolation transformer and the synchronous motor, and the companion frequency converter is respectively connected to the second isolation transformer. The transformer is connected to the test motor, the synchronous motor is connected to the test motor through a coupling, the isolating switch is connected in series to the output end of the tested inverter, and the grid-connected switch is connected in parallel to one side of the tested inverter; the electrical signal acquisition component is used to respectively acquire electrical signals from the excitation transformer, the first isolating transformer, the tested inverter and the synchronous motor; the measurement and control cabinet is used to control the synchronous motor to be connected to the grid through the grid-connected switch according to the acquired electrical signals; the control console is used to test the logic control of the system, the start and stop control of the tested inverter, the frequency and load adjustment of the tested inverter, the start and stop control of the tested excitation device, and the recording and display of electrical signals.

[0009] The measurement and control cabinet is equipped with a transmitter and a synchronization device connected to the electrical signal acquisition component. The transmitter is used to obtain electrical signals and send them to the control console; the synchronization device is used to adjust the excitation current and the frequency of the accompanying frequency converter according to the electrical signals, thereby adjusting the voltage and frequency of the synchronous motor, and controlling the grid-connected switch to close when the voltage amplitude, frequency difference and phase angle difference of the synchronous motor reach a preset range, so that the synchronous motor is connected to the power grid.

[0010] The first isolation transformer is a three-winding transformer, with one winding on the high-voltage side and two windings on the low-voltage side. The line voltage amplitudes of the two windings are the same, the phase difference is 30°, and the rated voltage on the low-voltage side is equal to the rated voltage of the synchronous motor; the tested inverter is connected to the two windings on the low-voltage side through the first input branch and the second input branch respectively, one end of the grid-connected switch is connected to the first input branch, and the other end is connected between the isolation switch and the synchronous motor.

[0011] The electrical signal acquisition components are respectively arranged between the excitation transformer and the input switch, between the first isolation transformer and the input switch, between the isolation switch and the synchronous motor, and on the first input branch.

[0012] The electrical signal acquisition component includes a current transformer and a voltage transformer, and the current transformer and the voltage transformer are used to respectively acquire current signals and voltage signals.

[0013] The excitation transformer and the second isolation transformer are both rectifier-step-down transformers with one winding on the high-voltage side and one winding on the low-voltage side.

[0014] The synchronous motor is a three-phase reversible electrically excited synchronous motor, and the accompanying motor is a three-phase variable frequency asynchronous motor. The synchronous motor and the asynchronous motor are coaxially connected and fixed on the motor skid-mounted platform.

[0015] The accompanying test inverter is a four-quadrant inverter using an IGBT module as a rectifier.

[0016] The input switch, grid-connected switch and isolating switch are all installed in the switch cabinet.

[0017] A test method for a static frequency converter and an excitation device includes a static frequency converter speed regulation and load test, a static frequency converter soft start test and an excitation test, wherein:

[0018] The method for speed regulation and load testing of the static frequency converter is as follows:

[0019] A1. The console selects the static inverter speed regulation and load test and enters the test control mode;

[0020] A2. The console controls the input switch and the isolating switch to close;

[0021] A3. The control console manually starts the inverter and excitation device under test, and the inverter under test controls the synchronous motor to increase its speed to the set value;

[0022] A4. Operate the console to start the test inverter and adjust the output power of the test inverter gradually to the rated value of the tested inverter;

[0023] A5. Operate the console to stop the test inverter and gradually reduce the output power to zero, then exit the operation;

[0024] A6. Operate the console to stop the inverter and excitation device under test, and disconnect the input switch and isolation switch to complete the speed regulation and load test of the static inverter;

[0025] The method for the soft start test of the static frequency converter is:

[0026] B1. The console selects the static inverter soft start function test and enters the test control mode;

[0027] B2, the control console controls the input switch between the excitation transformer and the power grid, the input switch between the first isolation transformer and the power grid, and the isolation switch to close;

[0028] B3. Operate the console to start the inverter and excitation device under test, and the inverter under test controls the synchronous motor to increase its speed to the set value;

[0029] B4. The control console controls the tested inverter to stop running and disconnect the isolating switch. The synchronous motor idles freely, and the excitation device enters the synchronous soft start mode. The voltage of the synchronous motor rises to the rated voltage. The synchronization device is started to adjust the excitation current to adjust the voltage of the synchronous motor. When the voltage amplitude, frequency difference and phase angle difference of the synchronous motor reach the preset range, the grid-connected switch is controlled to close, so that the synchronous motor is connected to the grid;

[0030] B5. Start the test inverter and gradually increase the output power to the rated power of the synchronous motor;

[0031] B6. Operate the console to gradually reduce the power of the accompanying inverter and the excitation current of the synchronous motor to the set minimum value, then disconnect the grid-connected switch;

[0032] B7. The control console stops the excitation device and disconnects the input switch to complete the soft start test of the static inverter;

[0033] The method of the excitation test is:

[0034] C1. The console selects the excitation test and enters the test control mode;

[0035] C2, console controls the input switch to close;

[0036] C3. Start the test inverter manually on the console to increase the test motor to the rated speed of the synchronous generator;

[0037] C4. The control console starts the excitation device under test, and the excitation device under test injects no-load excitation current into the rotor winding of the synchronous motor, so that the voltage of the synchronous motor rises rapidly to the rated voltage;

[0038] C5. The control console starts the synchronization device, which adjusts the excitation current and the output frequency of the accompanying inverter to adjust the voltage and frequency of the synchronous motor, so that the voltage amplitude, frequency difference and phase angle difference of the synchronous motor reach the preset range. The synchronization device controls the grid-connected switch to close so that the synchronous motor is connected to the grid;

[0039] C6. Operate the console to gradually increase the power of the accompanying inverter to the rated power of the synchronous motor;

[0040] C7. Operate the console to gradually reduce the power of the accompanying test inverter to zero, stop the accompanying test inverter and disconnect the grid-connected switch;

[0041] C8. Operate the console to stop the excitation device under test and disconnect the input switch to complete the excitation test.

[0042] The advantages of adopting the present invention are:

[0043] 1. The present invention can realize the speed regulation, load test and soft start test of the static frequency converter, and can also complete the no-load and grid-connected dynamic characteristic test of the static excitation. The same system can be used to complete the test of two different devices, and has the advantages of wide applicability, high utilization rate and high test efficiency.

[0044] 2. When testing the static frequency converter, the static frequency converter drives the synchronous motor, and the energy is fed back to the power grid through the accompanying test frequency converter; when testing the excitation device, the accompanying test frequency converter drives the accompanying test motor to drag the synchronous generator to the rated speed, and the synchronous motor generates electricity to feed back energy to the power grid. In the steady-state working mode, the power consumed by the power grid side is only the sum of the losses of the transformer, frequency converter, motor and excitation device in the test system. After selecting the test mode through the console, the system automatically enters the selected test mode, and the measurement and control cabinet measures the operating data and automatically uploads it to the console, which has the advantages of facilitating analysis and improving test efficiency.

[0045] 3. The present invention can obtain sufficient electrical measurement points, and has a control console to monitor and record these measurement data, which can provide data support for analyzing and studying frequency converters and excitation devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is the system principle diagram of the present invention;

[0047] Figure 2 A test system diagram of a static frequency converter in the present invention;

[0048] Figure 3 It is a test system diagram of the excitation device in the present invention;

[0049] Figure 4 It is a control flow chart of the present invention.

[0050] The following are marked in the figure: 1. The inverter under test, 2. The excitation device under test, 3. The synchronous motor, 4. The accompanying motor under test, 5. The accompanying inverter under test, 6. The excitation transformer, 7. The first isolation transformer, 8. The second isolation transformer, 9. The measurement and control cabinet, and 10. The control console. DETAILED DESCRIPTION

[0051] The present invention provides a test system for a static frequency converter and an excitation device, the test system having two test functions: a static frequency converter (SFC) and an excitation device. Figure 1As shown, it includes a tested inverter 1 (a tested static inverter SFC), a tested excitation device 2, a synchronous motor 3, a test companion motor 4, a test companion inverter 5, an excitation transformer 6, a first isolation transformer 7, a second isolation transformer 8, a measurement and control cabinet 9, a control console 10, an electrical signal acquisition component, an input switch, a grid-connected switch and an isolation switch. Among them, the excitation transformer 6, the first isolation transformer 7 and the second isolation transformer 8 are respectively connected to the power grid through the input switch, the tested excitation device 2 is respectively connected to the excitation transformer 6 and the rotor winding of the synchronous motor 3, the tested inverter 1 is respectively connected to the first isolation transformer 7 and the stator winding of the synchronous motor 3, the test companion inverter 5 is respectively connected to the second isolation transformer 8 and the stator winding of the test companion motor 4, and the test companion motor 4 is connected to the synchronous motor 3 through a coupling. The isolating switch is connected in series to the output end of the tested inverter 1, and the grid-connected switch is connected in parallel to one side of the tested inverter 1; the electrical signal acquisition component is used to respectively acquire electrical signals of the excitation transformer 6, the first isolating transformer 7, the tested inverter 1 and the synchronous motor 3, the measurement and control cabinet 9 is used to control the synchronous motor 3 to be connected to the grid through the grid-connected switch according to the acquired electrical signals, and the control console 10 is used to test the logic control of the system, the start and stop control of the tested inverter 1, the adjustment of the frequency and load of the tested inverter 1, the start and stop control of the tested excitation device 2, the control of the measurement and control cabinet 9, the recording and display of electrical signals, etc.

[0052] The measurement and control cabinet 9 in the present invention is equipped with a transmitter and a synchronization device connected to the electrical signal acquisition component. The transmitter is used to obtain the electrical signal and send it to the control console 10; the synchronization device is used to adjust the excitation current and the frequency of the accompanying frequency converter 5 according to the electrical signal, thereby adjusting the voltage and frequency of the synchronous motor 3, and controlling the grid-connected switch to close when the voltage amplitude, frequency difference and phase angle difference of the synchronous motor 3 reach a preset range, so that the synchronous motor 3 is connected to the power grid.

[0053] The excitation transformer 6 and the second isolation transformer 8 in the present invention are both rectifier-step-down transformers with one winding on the high-voltage side and one winding on the low-voltage side. The first isolation transformer 7 is a rectifier-step-down transformer with three windings. The high-voltage sides of the excitation transformer 6, the first isolation transformer 7, and the second isolation transformer 8 are all connected to the same busbar of the power grid. Among them, the excitation transformer 6 and the second isolation transformer 8 adopt the Dy11 wiring form to eliminate the third harmonic. The first isolation transformer 7 has one winding on the high-voltage side and two windings on the low-voltage side. The line voltage amplitudes of the two windings on the low-voltage side are the same, the phase difference is 30°, and the rated voltage on the low-voltage side is equal to the rated voltage of the synchronous motor 3, which can meet the two SFC tests of the rectifier bridge with 6 pulses and 12 pulses. The transformers are equipped with a microcomputer-type transformer protection device, which can realize differential, over-current and fast-break protection.

[0054] The tested inverter 1 in the present invention is connected to two windings on the low voltage side through the first input branch and the second input branch respectively. One end of the grid-connected switch is connected to the first input branch, and the other end is connected between the isolating switch and the synchronous motor 3.

[0055] Combine the following Figure 1 The present invention is described in further detail.

[0056] The input switch, grid-connected switch and isolating switch in the present invention are all installed in the switch cabinet, which not only facilitates the unified control of the test system, but also effectively disconnects the system power supply from the input of the tested inverter 1, and the output of the tested inverter 1 from the motor platform. In addition, when the equipment fails, the connection between the components can be quickly disconnected, which can protect the tested inverter 1 and the motor from damage.

[0057] Specifically, the input switches are set to be CB1, CB2 and CB3, the isolating switch is CB4, and the grid-connected switch is CB5. Then: the excitation transformer 6 is connected to the grid through the input switch CB1, the first isolating transformer 7 is connected to the grid through the input switch CB2, the second isolating transformer 8 is connected to the grid through the input switch CB3, the isolating switch CB4 is connected in series to the output end of the measured inverter 1, the grid-connected switch CB5 is connected in parallel to one side of the measured inverter 1, and one end of the grid-connected switch CB5 is connected to the first input branch of the measured inverter 1, and the other end is connected between the isolating switch CB4 and the synchronous motor 3.

[0058] The electrical signal acquisition components in the present invention are respectively arranged between the excitation transformer 6 and the input switch, between the first isolation transformer 7 and the input switch, between the isolation switch and the synchronous motor 3, and on the first input branch. The electrical signal acquisition components include a current transformer and a voltage transformer, which are used to respectively collect current signals and voltage signals of the excitation transformer 6, the first isolation transformer 7, the measured inverter 1, and the synchronous motor 3.

[0059] Specifically, the current transformers are set to be CT1, CT2, CT3, CT4 and CT5, and the voltage transformers are set to be PT1, PT2, PT3 and PT4, then: the current transformer CT1 and the voltage transformer PT1 are both arranged between the excitation transformer 6 and the input switch CB1, the current transformer CT5 is arranged between the excitation transformer 6 and the excitation device 2 under test and is used to collect the current on the low-voltage side (excitation device 2 under test) of the excitation transformer 6, the current transformer CT2 and the voltage transformer PT2 are both arranged between the first isolation transformer 7 and the input switch CB2 and are used to collect the current and voltage signals of the first isolation transformer 7, the current transformer CT3 and the voltage transformer PT3 are both arranged between the first isolation transformer 7 and the frequency converter 1 under test and are used to collect the input current and voltage signals of the frequency converter 1 under test, and the current transformer CT4 and the voltage transformer PT4 are both arranged between the isolation switch CB4 and the synchronous motor 3 and are used to collect the current signal and voltage signal of the synchronous motor 3.

[0060] The accompanying motor 4 in the present invention is a three-phase variable frequency asynchronous motor, whose power matches that of the synchronous motor 3, and can be used as both a load motor and a prime mover. When testing a static frequency converter, it is a load motor that provides an adjustable load torque for the static frequency converter, and when testing an excitation device, it is a prime mover that drags the synchronous motor 3 to the rated speed.

[0061] The synchronous motor 3 in the present invention is a three-phase reversible electrically excited synchronous motor, which is coaxially connected to the asynchronous motor and fixed on the motor skid-mounted platform. The synchronous motor 3 can be used as both a motor and a synchronous generator, and an additional excitation current needs to be applied to the rotor winding during operation. When used as a motor, it is driven by a static frequency converter and can run at any point in the rated speed range of 0~105% (except for the critical speed of the motor); when used as a synchronous generator, the accompanying frequency converter 5 drives the asynchronous motor to drag the synchronous generator to the rated speed, and then the excitation device injects excitation current into it, and the generator is boosted to the rated voltage.

[0062] The transmitter in the present invention is used to obtain electrical signals through the electrical signal acquisition component, and convert the electrical signals into 4~20mA signals and send them to the control console 10, and at the same time has the ability to communicate with the control console 10.

[0063] During the period of synchronous motor grid connection, the synchronization device in the present invention adjusts the excitation current output by the excitation device and the output frequency of the accompanying test inverter 5 to adjust the voltage and frequency of the synchronous motor 3, and sends a closing command to the grid-connected switch CB5 to connect the synchronous motor 3 to the grid when the voltage amplitude, frequency difference and phase angle difference of the synchronous motor 3 enter the preset range. The test system converts the mechanical energy of the accompanying test motor 4 into electrical energy and injects it into the grid to complete the energy feedback. The synchronization device is a microcomputer automatic synchronization device that can automatically adjust the voltage and frequency of the synchronous motor 3. Once the voltage amplitude, frequency difference and phase angle difference of the synchronous voltage enter the preset range, the automatic synchronization device sends a closing command to connect the synchronous motor 3 to the grid system to prevent the asynchronous grid connection of the synchronous motor 3.

[0064] The accompanying test inverter 5 in the present invention adopts an IGBT module as a four-quadrant inverter of the rectifier device, has four-quadrant operation capability, can realize two-way flow of energy, can feed back load energy to the power grid, and achieve energy-saving operation effect.

[0065] The control console 10 in the present invention is a set of PLC control system, which has a human-machine interface, a CPU, an analog input module, a digital input and output module and a communication module. It is mainly used for the logic control of the test system, the start and stop control of the tested inverter 1, the adjustment of the frequency and load of the tested inverter 1, the start and stop control of the excitation device, the control of the measurement and control cabinet 9, the real-time recording and display of electrical signals, the real-time recording and display of the excitation device and the motor operation data, etc. In addition, the control console 10 is provided with an emergency stop button. No matter what kind of test is being carried out at this time, as long as the emergency stop button is pressed, all switches will be disconnected immediately, and the electrical connection will be quickly cut off to ensure the safety of the equipment.

[0066] The present invention also provides a test method for a static frequency converter and an excitation device, which includes a static frequency converter speed regulation and load test, a static frequency converter soft start test and an excitation test, which are described in detail below in conjunction with the accompanying drawings.

[0067] like Figure 2 , 4 As shown, the method of speed regulation and load testing of the static frequency converter is:

[0068] A1. The control console 10 selects the static inverter speed regulation and load test and enters the test control mode.

[0069] A2. The control console 10 controls the input switches CB1, CB2, CB3 and the isolating switch CB4 to close (all switches are in the open state in the default state).

[0070] A3. The control console 10 manually starts the inverter 1 and the excitation device under test. The inverter 1 under test controls the speed of the synchronous motor 3 to increase to the set value (any value between 0 and 1.05 times the rated speed).

[0071] A4. The control console 10 starts the accompanying test inverter 5 and adjusts the output power of the accompanying test inverter 5 gradually to the rated value of the tested inverter 1.

[0072] A5. The control console 10 operates to stop the test inverter 5 and gradually reduce the output power to zero, and then exits the operation.

[0073] A6. Operation of the control console 10 stops the operation of the inverter 1 and the excitation device under test, and disconnects the input switches CB1, CB2, CB3 and the isolating switch CB4 to complete the speed regulation and load test of the static inverter.

[0074] like Figure 2 , 4 As shown, the method for soft starting test of the static inverter is:

[0075] B1. The control console 10 selects the static inverter soft start function test and enters the test control mode.

[0076] B2. The control console 10 controls the input switches CB1, CB2 and the isolating switch CB4 to close (all switches are in the open state in the default state).

[0077] B3. The control console 10 operates to start the inverter 1 under test and the excitation device. The inverter 1 under test controls the speed of the synchronous motor 3 to increase to the set value (1.05 times the rated speed).

[0078] B4. The control console 10 controls the tested inverter 1 to stop running and disconnects the isolating switch CB4. The synchronous motor 3 idles freely, and the excitation device enters the synchronous soft start mode. The voltage of the synchronous motor 3 rises to the rated voltage. The synchronization device is started to adjust the excitation current and thus the voltage of the synchronous motor 3. When the voltage amplitude, frequency difference and phase angle difference of the synchronous motor 3 reach the preset range, the grid-connected switch CB5 is controlled to close, so that the synchronous motor 3 is connected to the power grid.

[0079] B5. Start the test inverter 5 and gradually increase the output power to the rated power of the synchronous motor 3.

[0080] B6. The control console 10 is operated to gradually reduce the power of the accompanying frequency converter 5 and the exciting current of the synchronous motor 3 to the set minimum value, and then disconnect the grid-connected switch CB5.

[0081] B7. Control console 10 stops the excitation device, disconnects input switches CB1, CB2 and CB3, and completes the soft start test of the static inverter.

[0082] like Figure 3 , 4 As shown, the method of the excitation test is:

[0083] C1, console 10 selects excitation test and enters test control mode;

[0084] C2, console 10 controls input switches CB1, CB2, and CB3 to close (all switches are in the open state by default);

[0085] C3, the control console 10 manually starts the accompanying test inverter 5, so that the accompanying test motor 4 increases to the rated speed of the synchronous generator;

[0086] C4, the control console 10 operates to start the excitation device 2 under test, and the excitation device 2 under test injects a no-load excitation current into the rotor winding of the synchronous motor 3, so that the voltage of the synchronous motor 3 rises rapidly to the rated voltage;

[0087] C5, the control console 10 starts the synchronization device, which adjusts the excitation current and the output frequency of the accompanying frequency converter 5 to adjust the voltage and frequency of the synchronous motor 3, so that the voltage amplitude, frequency difference and phase angle difference of the synchronous motor 3 reach the preset range, and the synchronization device controls the grid-connected switch CB5 to close so that the synchronous motor 3 is connected to the grid;

[0088] C6. The control console 10 is operated to gradually increase the power of the accompanying test inverter 5 to the rated power of the synchronous motor 3;

[0089] C7, the control console 10 is operated to gradually reduce the power of the accompanying test inverter 5 to zero, and after stopping the accompanying test inverter 5, the grid-connected switch CB5 is disconnected;

[0090] C8. The control console 10 operates to stop the excitation device 2 under test, and disconnects the input switches CB1, CB2, and CB3 to complete the excitation test.

[0091] It should be noted that since the above-mentioned static inverter speed regulation and load test and static inverter soft start test are all tests on the static inverter, but not on the excitation device, the excitation device under test is used as a normal excitation device during the above-mentioned test of the static inverter.

[0092] The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other alternative features that are equivalent or have similar purposes; all the disclosed features, or all the steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A test method for a static frequency converter and an excitation device, characterized in that: It includes static inverter speed regulation and load test, static inverter soft start test and excitation test, among which: The method for speed regulation and load testing of the static frequency converter is as follows: A1. The control console (10) selects the static inverter speed regulation and load test and enters the test control mode; A2, control console (10) controls the input switch and the isolating switch to close; A3, the control console (10) manually starts the inverter (1) and the excitation device under test, and the inverter (1) under test controls the speed of the synchronous motor (3) to increase to a set value; A4, the control console (10) starts the accompanying test inverter (5) and adjusts the output power of the accompanying test inverter (5) gradually to the rated value of the tested inverter (1); A5. The control console (10) operates to stop the test inverter (5) and gradually reduce the output power to zero, and then exits operation; A6. The control console (10) stops the inverter (1) and the excitation device under test, and disconnects the input switch and the isolation switch to complete the speed regulation and load test of the static inverter; The method for the soft start test of the static frequency converter is: B1. On the control console (10), select the static inverter soft start function test and enter the test control mode; B2, the control console (10) controls the input switch between the excitation transformer (6) and the power grid, the input switch between the first isolation transformer (7) and the power grid, and the isolation switch to close; B3, the control console (10) operates to start the inverter (1) and the excitation device under test, and the inverter (1) under test controls the speed of the synchronous motor (3) to increase to a set value; B4, the control console (10) controls the inverter (1) under test to stop running and disconnect the isolating switch, the synchronous motor (3) is allowed to idle freely, the excitation device enters the synchronous soft start mode, the voltage of the synchronous motor (3) rises to the rated voltage, the synchronization device is started to adjust the excitation current and thus the voltage of the synchronous motor (3), and when the voltage amplitude, frequency difference and phase angle difference of the synchronous motor (3) reach a preset range, the grid-connected switch is controlled to close, so that the synchronous motor (3) is connected to the grid; B5. Start the test inverter (5) and gradually increase the output power to the rated power of the synchronous motor (3); B6, the control console (10) operates to gradually reduce the power of the accompanying test inverter (5) and the excitation current of the synchronous motor (3) to the set minimum value and then disconnect the grid-connected switch; B7, control console (10) stops the excitation device and disconnects the input switch to complete the soft start test of the static inverter; The method of the excitation test is: C1. The console (10) selects the excitation test and enters the test control mode; C2, control console (10) controls the input switch to close; C3, the control console (10) manually starts the accompanying test inverter (5), so that the accompanying test motor (4) increases to the rated speed of the synchronous generator; C4, the control console (10) operates to start the excitation device (2) under test, and the excitation device (2) under test injects a no-load excitation current into the rotor winding of the synchronous motor (3), so that the voltage of the synchronous motor (3) rises rapidly to the rated voltage; C5, the control console (10) starts the synchronization device, the synchronization device adjusts the excitation current and the output frequency of the accompanying measurement inverter (5) to adjust the voltage and frequency of the synchronous motor (3), so that the voltage amplitude, frequency difference and phase angle difference of the synchronous motor (3) reach a preset range, and the synchronization device controls the grid-connected switch to close so that the synchronous motor (3) is connected to the grid; C6. The control console (10) is operated to gradually increase the power of the test inverter (5) to the rated power of the synchronous motor (3); C7, the control console (10) is operated to gradually reduce the power of the accompanying test inverter (5) to zero, and the accompanying test inverter (5) is stopped and then the grid-connected switch is disconnected; C8. The control console (10) operates to stop the excitation device (2) under test and disconnects the input switch to complete the excitation test.

2. The method for testing a static frequency converter and an excitation device according to claim 1, characterized in that: The excitation transformer (6) and the first isolation transformer (7) are respectively connected to the power grid via an input switch; the excitation device (2) under test is respectively connected to the excitation transformer (6) and the synchronous motor (3); the frequency converter (1) under test is respectively connected to the first isolation transformer (7) and the synchronous motor (3); one end of the accompanying frequency converter (5) under test is connected to the power grid via a second isolation transformer (8) and the input switch, and the other end is connected to the accompanying motor (4); the synchronous motor (3) and the accompanying motor (4) are connected via a coupling; the isolation switch is connected in series to the output end of the frequency converter (1) under test; and the grid-connected switch is connected in parallel to one side of the frequency converter (1) under test; the excitation transformer (6) The first isolation transformer (7), the measured frequency converter (1) and the synchronous motor (3) are all connected to the measurement and control cabinet (9) through an electrical signal acquisition component. The electrical signal acquisition component is used to respectively acquire electrical signals from the excitation transformer (6), the first isolation transformer (7), the measured frequency converter (1) and the synchronous motor (3). The measurement and control cabinet (9) is used to control the synchronous motor (3) to be connected to the grid through a grid-connected switch according to the acquired electrical signals. The control console (10) is used to control the logic control of the test system, the start and stop control of the measured frequency converter (1), the frequency and load adjustment of the measured frequency converter (1), the start and stop control of the measured excitation device (2), and the recording and display of electrical signals.

3. The method for testing a static frequency converter and an excitation device according to claim 2, characterized in that: The measurement and control cabinet (9) is provided with a transmitter and a synchronization device connected to the electrical signal acquisition component. The transmitter is used to obtain the electrical signal and send it to the control console (10); the synchronization device is used to adjust the excitation current and the frequency of the accompanying measurement frequency converter (5) according to the electrical signal, thereby adjusting the voltage and frequency of the synchronous motor (3), and controlling the grid-connected switch to close when the voltage amplitude, frequency difference and phase angle difference of the synchronous motor (3) reach a preset range, so that the synchronous motor (3) is connected to the power grid.

4. A method for testing a static frequency converter and an excitation device according to claim 2 or 3, characterized in that: The first isolation transformer (7) is a three-winding transformer, with one winding on the high-voltage side and two windings on the low-voltage side. The line voltage amplitudes of the two windings are the same, the phase difference is 30°, and the rated voltage of the low-voltage side is equal to the rated voltage of the synchronous motor (3). The measured frequency converter (1) is connected to the two windings on the low-voltage side through a first input branch and a second input branch respectively, one end of the grid-connected switch is connected to the first input branch, and the other end is connected between the isolation switch and the synchronous motor (3).

5. The method for testing a static frequency converter and an excitation device according to claim 2, characterized in that: The electrical signal acquisition components are respectively arranged between the excitation transformer (6) and the input switch, between the first isolation transformer (7) and the input switch, between the isolation switch and the synchronous motor (3), and on the first input branch.

6. The method for testing a static frequency converter and an excitation device according to claim 2, characterized in that: The electrical signal acquisition component includes a current transformer and a voltage transformer, and the current transformer and the voltage transformer are used to respectively acquire current signals and voltage signals.

7. The method for testing a static frequency converter and an excitation device according to claim 2, characterized in that: The excitation transformer (6) and the second isolation transformer (8) are both rectifier-step-down transformers with one winding on the high-voltage side and one winding on the low-voltage side.

8. The method for testing a static frequency converter and an excitation device according to claim 2, characterized in that: The synchronous motor (3) is a three-phase reversible electrically excited synchronous motor, the accompanying measurement motor (4) is a three-phase variable frequency asynchronous motor, and the synchronous motor (3) and the asynchronous motor are coaxially connected and fixed on the motor skid-mounted platform.

9. The method for testing a static frequency converter and an excitation device according to claim 2, characterized in that: The accompanying test inverter (5) is a four-quadrant inverter using an IGBT module as a rectifier.

10. The method for testing a static frequency converter and an excitation device according to claim 2, characterized in that: The input switch, grid-connected switch and isolating switch are all installed in the switch cabinet.

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