A high-power synchronous motor testing system
By using coaxial connection and vector injection control, the cost and grid impact of large synchronous motor testing systems are reduced, and the high cost and harmonic distortion problems of existing systems are solved, making it suitable for the field of new energy wind power.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA MACHINERY INT ENG DESIGN & RES INST
- Filing Date
- 2024-05-28
- Publication Date
- 2026-05-12
AI Technical Summary
Existing large-scale synchronous motor testing systems are costly and prone to causing harmonic distortion in the power grid, especially due to the high power requirements of rectifiers and frequency converters and the impact on the power grid.
The test motor and the auxiliary test motor are connected coaxially. The auxiliary test motor provides no-load rotation. The voltage vector is adjusted by a three-phase transformer and a vector injection control module. The synchronous rotation and loading of the motor are achieved by using a low-capacity frequency converter, which reduces the dependence on the power grid and power electronic equipment.
It reduces system costs and grid impact, decreases the demand for power electronic equipment, expands the application scope, and is particularly suitable for the new energy wind power field.
Smart Images
Figure CN118641943B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of synchronous motor testing, in particular, to a high-power synchronous motor testing system. BACKGROUND
[0002] Motor testing needs to make it run normally, which requires power supply. Power supply can use ordinary power grid or variable frequency power supply with control algorithm. Using power grid full voltage to start motor can produce a great impact at the moment of starting, and the impact on the power grid is acceptable if the power of the tested motor is hundreds of kilowatts or below. If a direct start of a megawatt motor will bring a great impact on the power grid and the test system (incoming line switch, ferromagnetic components, etc.), therefore, in most cases, the test of large synchronous motor needs to use variable frequency power supply to drive the motor for testing. The early common AC incoming line motor and gearbox test system is shown in Figure 1 and Figure 2 The tested motor M1 and M2 are coaxial and are driven by variable frequency power supply 1 and variable frequency power supply 2. One power supply operates in speed mode to control the speed of the corresponding motor; one power supply operates in torque mode to control the torque of the corresponding motor. The rectifier provides the DC bus required by the variable frequency power supply. The tested and accompanying test two test branches are merged in the AC incoming line, in which the tested motor is mainly used to feed back the power generated by the tested motor to the power grid to form an energy loop. The energy transfer process is power grid -> rectifier x -> variable frequency power supply x -> tested motor -> coupling -> accompanying test motor -> variable frequency power supply x -> rectifier x -> power grid, which forms a convergence in the power grid. This test topology has the following shortcomings:
[0003] a) The rectifier needs to provide the same level of power as the tested motor or the accompanying test motor, which requires the use of full-power rectification. For example, if the tested motor is 10 MW, the accompanying test motor needs to be greater than 10 MW, and the rectifier also needs to be 10 MW power level, which is expensive and high in cost.
[0004] b) The operation of two full-power rectifiers in the system will cause harmonic distortion of the power grid. SUMMARY
[0005] The present application provides a high-power synchronous motor testing system to solve the technical problems of high cost and easy harmonic distortion of the power grid in the existing motor testing topology.
[0006] The technical solution adopted by the present application is as follows:
[0007] A high-power synchronous motor testing system, comprising a tested motor M1, an accompanying test motor M2, an auxiliary test motor M3, a three-phase transformer, a first variable frequency power supply, a second variable frequency power supply, and a voltage sensor, wherein:
[0008] The tested motor M1 and the accompanying motor M2 are coaxially connected, and the auxiliary test motor M3 is coaxially connected to the tested motor M1. The first frequency converter is connected to the auxiliary test motor M3 circuit to provide energy for the unloaded rotation of the tested motor M1 and the accompanying motor M2, so that the auxiliary test motor M3 drives the tested motor M1 and the accompanying motor M2 to rotate synchronously. The output terminal of the second frequency converter is connected to the primary circuit of the three-phase transformer. The AC terminal of the tested motor M1 is connected to one end of the three open windings of the secondary side of the three-phase transformer, and the other end of the three open windings of the secondary side of the three-phase transformer is connected to the AC terminal of the accompanying motor M2. The second frequency converter obtains the three-phase voltage signal of the AC terminal of the tested motor M1 through the voltage sensor.
[0009] The second frequency converter injects a voltage vector into the primary side of the three-phase transformer. The voltage vector on the secondary side of the three-phase transformer is superimposed with the AC output voltage of the tested motor M1 to form a new output voltage vector. The amplitude and phase of the new output voltage vector are adjusted within the allowable capacity range of the second frequency converter and the three-phase transformer. The AC output voltage of the tested motor M1 is superimposed with the output voltage of the three-phase transformer and converges with the AC output voltage of the auxiliary motor M2. The loading of the tested motor M1 and the auxiliary motor M2 is achieved by adjusting the output of the second frequency converter.
[0010] Furthermore, the maximum capacity of the three-phase transformer is less than or equal to 25% of the capacity of the tested motor M1.
[0011] Furthermore, the capacity of the first frequency converter is 25% to 30% of the capacity of the tested motor M1.
[0012] Furthermore, the second frequency converter is used to provide a superimposed vector of the AC terminal voltage of the test motor M1, and its capacity is 25% to 35% of the capacity of the test motor M1.
[0013] Furthermore, the tested motor M1 and the accompanying tested motor M2 are synchronous motors connected to their respective excitation devices.
[0014] Furthermore, the tested motor M1 and the auxiliary tested motor M2 are permanent magnet synchronous motors.
[0015] Furthermore, the second frequency converter includes a vector injection control module, the vector injection control module comprising:
[0016] The system includes an active power closed-loop module, a reactive power closed-loop module, a power calculation module, a terminal voltage PLL module, and an SPWM modulation module, among which:
[0017] The power calculation module is used to process the current i collected by the voltage sensor. abc Voltage u abc Calculate the feedback reactive power Q of the synchronous motor output. backand feedback active power P back ;
[0018] The terminal voltage PLL module is used to detect and lock the amplitude u and phase angle θ of the output voltage of the tested motor M1;
[0019] The active power closed-loop module is given an active power P. ref and feedback active power P back The correction angle Δθ is calculated and output. The correction angle Δθ is limited to obtain Δθ'. This is added to the phase angle θ output by the terminal voltage PLL module to obtain the modulation angle θ'.
[0020] The reactive power closed-loop module is provided with a reference reactive power Q. ref and feedback reactive power Q back The output correction voltage Δu is calculated, and the correction voltage Δu is limited to obtain Δu'. The amplitude of the voltage u output by the terminal voltage PLL module is added to obtain the modulation voltage amplitude u'.
[0021] The SPWM modulation module uses the modulation angle θ' and modulation voltage amplitude u' to generate a three-phase voltage injection into the primary side of the three-phase transformer, providing a superimposed vector of AC terminal voltages of the deflected motor M1.
[0022] Furthermore, a first gearbox GBX1 and a second gearbox GBX2 are provided between the test motor M1 and the auxiliary test motor M2. The input end of the first gearbox GBX1 is connected to the output end of the test motor M1, the output end of the first gearbox GBX1 is connected to the input point of the second gearbox GBX2, and the output end of the second gearbox GBX2 is connected to the input point of the auxiliary test motor M2, for the purpose of forming a test of the gearbox.
[0023] This application has the following beneficial effects:
[0024] 1. This application does not rely on a full-power loading device. The first frequency converter only needs to drive the motor to rotate under no-load, and does not need to be fully loaded. The required capacity is small. The second frequency converter only needs to be used to change the output voltage vector of the tested motor M1. Its voltage level requirement is very low, and only current capability is required. Therefore, it can save a lot of costs for testing large motors.
[0025] 2. This application does not require a large incoming line capacity, only the capacity to support the motor's no-load rotation and the drag loss. Therefore, for large motor testing, it can save a considerable amount of incoming line costs.
[0026] 3. This application reduces the use of ferromagnetic components. For testing high-voltage synchronous motors, this application does not require a transformer to convert low voltage to high voltage. The regulating transformer only needs to have a certain insulation capacity.
[0027] 4. Compared with the current mainstream feedback testing system, this application significantly reduces the requirements for power electronic equipment, and can be applied to the field of new energy wind power, thus expanding the scope of application;
[0028] 5. Power electronic equipment does not need to be connected in series in the original system, which can also reduce the impact of voltage harmonics on motor testing.
[0029] In addition to the purposes, features, and advantages described above, this application has other purposes, features, and advantages. A further detailed description of this application will be provided below with reference to the figures. Attached Figure Description
[0030] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:
[0031] Figure 1 This is a schematic diagram of the existing AC synchronous motor test topology.
[0032] Figure 2 This is a schematic diagram of the existing AC synchronous motor and gearbox test topology.
[0033] Figure 3 The preferred embodiment of this application is a high-power synchronous motor testing system.
[0034] Figure 4 The preferred embodiment of this application is a high-power synchronous motor testing system (with a gearbox).
[0035] Figure 5 A schematic diagram of the vector injection control module of a preferred embodiment of this application. Detailed Implementation
[0036] The embodiments of this application are described in detail below with reference to the accompanying drawings; however, this application may be implemented in a variety of different ways as defined and covered below.
[0037] like Figure 3 As shown, a preferred embodiment of this application provides a high-power synchronous motor testing system, including a test motor M1, a companion test motor M2, an auxiliary test motor M3, a three-phase transformer, a first frequency converter, a second frequency converter, and a voltage sensor, wherein:
[0038] The tested motor M1 and the accompanying motor M2 are coaxially connected, and the auxiliary test motor M3 is coaxially connected to the tested motor M1. The first frequency converter is connected to the auxiliary test motor M3 circuit to provide energy for the unloaded rotation of the tested motor M1 and the accompanying motor M2, so that the auxiliary test motor M3 drives the tested motor M1 and the accompanying motor M2 to rotate synchronously. The output terminal of the second frequency converter is connected to the primary circuit of the three-phase transformer. The AC terminal of the tested motor M1 is connected to one end of the three open windings of the secondary side of the three-phase transformer, and the other end of the three open windings of the secondary side of the three-phase transformer is connected to the AC terminal of the accompanying motor M2. The second frequency converter obtains the three-phase voltage signal of the AC terminal of the tested motor M1 through the voltage sensor.
[0039] The second frequency converter injects a voltage vector into the primary side of the three-phase transformer. The voltage vector on the secondary side of the three-phase transformer is superimposed with the AC output voltage of the tested motor M1 to form a new output voltage vector. The amplitude and phase of the new output voltage vector are adjusted within the allowable capacity range of the second frequency converter and the three-phase transformer. The AC output voltage of the tested motor M1 is superimposed with the output voltage of the three-phase transformer and converges with the AC output voltage of the auxiliary motor M2. The loading of the tested motor M1 and the auxiliary motor M2 is achieved by adjusting the output of the second frequency converter.
[0040] Compared with the prior art, this embodiment has the following beneficial effects:
[0041] 1. This embodiment does not rely on a full-power loading device. The first frequency converter only needs to drive the motor to rotate under no-load conditions and does not need to be fully loaded. The required capacity is small. The second frequency converter only needs to be used to change the output voltage vector of the tested motor M1. Its voltage level requirement is very low and only current capability is required. Therefore, it can save a lot of costs for testing large motors.
[0042] 2. This embodiment does not require a large incoming line capacity; it only needs to support the motor's no-load rotation and the drag loss. Therefore, it can save a considerable amount of incoming line costs for testing large motors.
[0043] 3. This embodiment reduces the use of ferromagnetic components. For testing high-voltage synchronous motors, this application does not require a transformer to convert low voltage to high voltage. The regulating transformer only needs to have a certain insulation capacity.
[0044] 4. Compared with the current mainstream feedback testing system, this embodiment significantly reduces the requirements for power electronic equipment, and can be applied to the field of new energy wind power, thus expanding the scope of application.
[0045] 5. Power electronic equipment does not need to be connected in series in the original system, which can also reduce the impact of voltage harmonics on motor testing.
[0046] In a preferred embodiment of this application, the maximum capacity of the three-phase transformer is less than or equal to 25% of the capacity of the tested motor M1.
[0047] In a preferred embodiment of this application, the capacity of the first frequency converter is 25% to 30% of the capacity of the tested motor M1.
[0048] Preferably, the second frequency converter is used to provide a superimposed vector of the AC terminal voltage of the test motor M1, and its capacity is 25% to 35% of the capacity of the test motor M1.
[0049] In a preferred embodiment of this application, the test motor M1 and the auxiliary test motor M2 are synchronous motors connected to their respective excitation devices.
[0050] In a preferred embodiment of this application, the tested motor M1 and the co-test motor M2 are permanent magnet synchronous motors.
[0051] like Figure 5 As shown, in a preferred embodiment of this application, the second frequency converter includes a vector injection control module, the vector injection control module comprising:
[0052] The system includes an active power closed-loop module, a reactive power closed-loop module, a power calculation module, a terminal voltage PLL module, and an SPWM modulation module, among which:
[0053] The power calculation module is used to process the current i collected by the voltage sensor. abc Voltage u abc Calculate the feedback reactive power Q of the synchronous motor output. back and feedback active power P back ;
[0054] The terminal voltage PLL module is used to detect and lock the amplitude u and phase angle θ of the output voltage of the tested motor M1;
[0055] The active power closed-loop module is given an active power P. ref and feedback active power P back The correction angle Δθ is calculated and output. The correction angle Δθ is limited to obtain Δθ'. This is added to the phase angle θ output by the terminal voltage PLL module to obtain the modulation angle θ'.
[0056] The reactive power closed-loop module is provided with a reference reactive power Q. ref and feedback reactive power Q back The output correction voltage Δu is calculated, and the correction voltage Δu is limited to obtain Δu'. The amplitude of the voltage u output by the terminal voltage PLL module is added to obtain the modulation voltage amplitude u'.
[0057] The SPWM modulation module uses the modulation angle θ' and modulation voltage amplitude u' to generate a three-phase voltage injection into the primary side of the three-phase transformer, providing a superimposed vector of AC terminal voltages of the deflected motor M1.
[0058] like Figure 4 As shown in the preferred embodiment of this application, a first gearbox GBX1 and a second gearbox GBX2 are further provided between the test motor M1 and the auxiliary test motor M2. The input end of the first gearbox GBX1 is connected to the output end of the test motor M1, the output end of the first gearbox GBX1 is connected to the input point of the second gearbox GBX2, and the output end of the second gearbox GBX2 is connected to the input point of the auxiliary test motor M2, for forming a test of the gearbox.
[0059] In summary, to reduce the testing costs of high-power synchronous motors and gearboxes, this application provides an improved AC test system. This system uses a three-phase transformer and connects the secondary side open in series with the existing AC output terminal. It is the simplest approach to superimpose another vector on the AC voltage vector, which can reduce the requirements of the frequency converter, eliminate the need for power electronic equipment to be connected in series in the original system, and reduce the impact of voltage harmonics on motor testing.
[0060] The specific testing process for this application is as follows:
[0061] The first frequency converter drives M1 and M2 to rotate via M3. The excitation systems of M1 and M2 are respectively given excitation, and the AC terminals of synchronous motors M1 and M2 generate AC voltages of the same voltage, frequency, and phase (M1 and M2 are identical motors, generating output voltages at the terminals under the same excitation and speed). The second frequency converter acquires the three-phase voltage signal at the terminals of M1 through a voltage sensor. The voltage sensor can be a closed-loop Hall effect type or a magnetic balance type; a conventional sensor with 1% accuracy and a bandwidth of 50kHz is sufficient for control. Of course, those skilled in the art can choose other types of voltage sensors as needed, which is not limited here. Based on the measurement data from the voltage sensor, frequency converter 2 obtains the output voltage u and phase θ of motor M1 through conversion and a phase-locked loop. The three-phase transformer is customized according to actual test requirements, and its maximum capacity does not exceed 25% of the tested motor. Frequency converter 2 injects a vector into the primary side of the transformer; the vector on the secondary side of the transformer, together with the terminal voltage of the tested motor M1, forms a new output vector. The magnitude and phase of the newly output voltage vector can be adjusted within the allowable capacity range of the frequency converter 2 and the transformer. The secondary voltage of the transformer is much smaller than the rated terminal voltage of the tested motor M1. The output voltage of the tested motor M1 and the output voltage of the transformer are superimposed and converged with the terminal output voltage of the auxiliary motor M2. Adjusting the output of the second frequency converter can achieve loading of M1 and M2.
[0062] The loading process is as follows: Figure 5As shown, where Q represents reactive power, P represents active power, and u abc It is the voltage output by the tested motor M1, i abc This is the output current of the tested motor M1. Two identical motors, when coaxial, have the same speed and, under the same excitation, also have the same output voltage. abc The value is essentially zero. When the output voltage of the tested motor M1 is changed (through the second frequency converter and the three-phase transformer), active power is generated when the phase changes, and reactive power is generated when the amplitude changes. By controlling the angle of the transformer output vector, the loading conditions can be adjusted, stabilizing reactive and active power, which is equivalent to stabilizing the motor's operating conditions. The above process can easily achieve the testing of synchronous motors.
[0063] Specifically, a sampling circuit for the output voltage / current of the synchronous machine is added to the second frequency converter, and the current i is used to sample the output voltage / current of the synchronous machine. abc Voltage u abc Calculate the reactive power Q output by the synchronous motor. back and active power P back The PLL module detects and locks the amplitude u and phase θ of the output voltage of M1. The active power closed-loop module, given the active power P... ref and active power feedback P back The output correction angle Δθ is calculated, and after being limited (Δθ'), it is added to the output angle θ of the phase-locked loop to obtain the modulation angle θ'. The reactive power closed loop is connected to a given reference reactive power Q. ref and reactive power feedback Q back The output correction voltage Δu is calculated. The correction voltage Δu is then limited (Δu') and added to the output voltage u of the phase-locked loop to obtain the modulation voltage amplitude u'. The modulation module uses θ' and u' to generate the three-phase voltage injection power part.
[0064] The losses of M1 and M2 during the test can be compensated by either the first or second frequency converter. The first frequency converter replenishes the system by stabilizing the speed of M1 and M2, while the second frequency converter can directly inject energy into the main energy cycle through a transformer. The first frequency converter provides the energy for the no-load rotation of M1 and M2, and its capacity is only 25% to 30% of that of M1. Similarly, the second frequency converter provides the superimposed vector to deflect the terminal voltage of M1, and its capacity is also only about 30% of that of M1. For a 10MW dual-drive test system, this is equivalent to replacing two 10MW full-power frequency converters, one rectifier, and the corresponding transformer with two 2MW to 3MW frequency converters, one 3MW drive motor, and one 3MVA transformer, significantly reducing system costs.
[0065] All aspects not detailed in this application are well-known to those skilled in the art. Finally, it should be noted that the above embodiments are merely illustrative of the technical solutions of this invention and not intended to limit it. Although the invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this invention without departing from the spirit and scope of the invention, and all such modifications and substitutions should be covered within the scope of the claims of this invention.
Claims
1. A high-power synchronous motor testing system, characterized in that, This includes the tested motor M1, the accompanying tested motor M2, the auxiliary tested motor M3, a three-phase transformer, a first frequency converter, a second frequency converter, and voltage and current sampling circuits, wherein: The tested motor M1 and the coaxial test motor M2 are connected together. The auxiliary test motor M3 is also connected together with the tested motor M1. The first frequency converter is connected to the auxiliary test motor M3 to provide energy for the unloaded rotation of the tested motor M1 and the coaxial test motor M2, enabling the auxiliary test motor M3 to drive the tested motor M1 and the coaxial test motor M2 to rotate synchronously. The output terminal of the second frequency converter is connected to the primary circuit of the three-phase transformer. The AC terminal of the tested motor M1 is connected to one end of each of the three open windings on the secondary side of the three-phase transformer, and the other end of each of the three open windings on the secondary side of the three-phase transformer is connected to the AC terminal of the coaxial test motor M2. The second frequency converter obtains the three-phase voltage signal of the AC terminal of the tested motor M1 through the voltage and current sampling circuit. The second frequency converter injects a voltage vector into the primary side of the three-phase transformer. The voltage vector on the secondary side of the three-phase transformer is superimposed with the AC output voltage of the tested motor M1 to form a new output voltage vector. The amplitude and phase of the new output voltage vector are adjusted within the allowable capacity range of the second frequency converter and the three-phase transformer. The AC output voltage of the tested motor M1 is superimposed with the output voltage of the three-phase transformer and converges with the AC output voltage of the auxiliary motor M2. The loading of the tested motor M1 and the auxiliary motor M2 is achieved by adjusting the output of the second frequency converter.
2. The high-power synchronous motor testing system according to claim 1, characterized in that, The maximum capacity of the three-phase transformer is less than or equal to 25% of the capacity of the tested motor M1.
3. The high-power synchronous motor testing system according to claim 1, characterized in that, The capacity of the first frequency converter is 25% to 30% of the capacity of the tested motor M1.
4. The high-power synchronous motor testing system according to claim 1, characterized in that, The second frequency converter is used to provide a superimposed vector of AC terminal voltage of the test motor M1, and its capacity is 25% to 35% of the capacity of the test motor M1.
5. The high-power synchronous motor testing system according to claim 1, characterized in that, The tested motor M1 and the co-tested motor M2 are synchronous motors connected to their respective excitation devices.
6. The high-power synchronous motor testing system according to claim 1, characterized in that, The tested motor M1 and the accompanying tested motor M2 are permanent magnet synchronous motors.
7. The high-power synchronous motor testing system according to claim 1, characterized in that, The second frequency converter includes a vector injection control module, which includes: The system includes an active power closed-loop module, a reactive power closed-loop module, a power calculation module, a terminal voltage PLL module, and an SPWM modulation module, among which: The power calculation module is used to collect the current i from the voltage and current sampling circuit. abc Voltage u abc Calculate the feedback reactive power Q of the synchronous motor output. back and feedback active power P back ; The terminal voltage PLL module is used to detect and lock the amplitude u and phase angle θ of the output voltage of the tested motor M1; The active power closed-loop module is given an active power P. ref and feedback active power P back The correction angle Δθ is calculated and output. The correction angle Δθ is limited to obtain Δθ'. This is added to the phase angle θ output by the terminal voltage PLL module to obtain the modulation angle θ'. The reactive power closed-loop module is given a reference reactive power Q. ref and feedback reactive power Q back The output correction voltage Δu is calculated, and the correction voltage Δu is limited to obtain Δu'. This Δu' is then added to the amplitude u of the voltage output by the terminal voltage PLL module to obtain the modulation voltage amplitude u'. The SPWM modulation module uses the modulation angle θ' and modulation voltage amplitude u' to generate a three-phase voltage injection into the primary side of the three-phase transformer, providing a superimposed vector of AC terminal voltages of the deflected motor M1.
8. The high-power synchronous motor testing system according to any one of claims 1 to 7, characterized in that, A first gearbox GBX1 and a second gearbox GBX2 are also provided between the test motor M1 and the auxiliary test motor M2. The input end of the first gearbox GBX1 is connected to the output end of the test motor M1, the output end of the first gearbox GBX1 is connected to the input point of the second gearbox GBX2, and the output end of the second gearbox GBX2 is connected to the input point of the auxiliary test motor M2, which is used to form a test of the gearbox.