Device and method for measuring source side impedance of power supply system

Abstract

The invention provides a measuring device and a measuring method for source-side impedance of a power supply system, relates to the technical field of power supply system design, and aims to improve the measuring accuracy of the source-side impedance of the power supply system. The measuring device comprises a main working circuit, a sampling circuit and a disturbance generating device, wherein the main working circuit comprises source equipment and load equipment; the source equipment is connected with the load equipment, and the impedance of the source equipment is lower than that of the load equipment; the disturbance generation device is arranged between the source equipment and the load equipment, and the disturbance generation device is used for setting harmonic injection parameters and injecting voltage disturbance signals with different frequencies into the main working circuit according to the harmonic injection parameters; and the sampling circuit is arranged between the load equipment and the disturbance generation device and is used for acquiring voltage and current between the load equipment and the disturbance generation device within a preset time of injecting the voltage disturbance signal and transmitting the acquired voltage and current to the disturbance generation device.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply system design, and in particular to a device and method for measuring source side impedance of a power supply system. Background Art

[0002] With the development and application of more electric and all-electric aircraft, more and more power electronic devices are used in aircraft power systems. Due to the highly nonlinear time-varying characteristics of power electronic devices, it is very easy to cause stability problems for the power system. The impedance-based stability analysis method is commonly used for power system stability analysis. The system stability can be determined by measuring the output impedance of the power supply side and the input impedance of the load side.

[0003] At present, the commonly used method for measuring device impedance is series injection, which directly connects the disturbance signal to the circuit to be measured, samples the port voltage and current of the object to be measured, and then calculates its impedance value at different frequencies. Due to series injection, most of the disturbance signal sent flows to the load part with larger impedance. Therefore, for source devices such as generators with very small impedance, when connected in series with loads with larger impedance, the disturbance voltage signal generated is very small. When using series disturbance signals for direct measurement, it is usually difficult to collect the corresponding response signal, and a large measurement error will occur. Summary of the invention

[0004] The embodiments of the present application provide a device and a method for measuring the source-side impedance of a power supply system, which are used to improve the measurement accuracy of the source-side impedance of the power supply system.

[0005] An embodiment of the present invention provides a device for measuring source-side impedance of a power supply system, the device comprising: a main working circuit, a sampling circuit, and a disturbance generating device, the main working circuit comprising a source device and a load device;

[0006] The source device is connected to the load device, and the impedance of the source device is lower than the impedance of the load device;

[0007] The disturbance generating device is arranged between the source device and the load device, and is used to set harmonic injection parameters, and inject voltage disturbance signals of different frequencies into the main working circuit according to the harmonic injection parameters;

[0008] The sampling circuit is arranged between the load device and the disturbance generating device, and is used to collect the voltage and current between the load device and the disturbance generating device within a predetermined time of injecting the voltage disturbance signal, and transmit the collected voltage and current to the disturbance generating device.

[0009] In an optional embodiment, the disturbance generating device comprises: a host computer, a frequency response analyzer, an excitation small signal generating module, a linear amplifier unit, and an isolation transformer connected in sequence;

[0010] The isolation transformer is arranged between the source device and the load device. The host computer is used to set harmonic injection parameters and inject voltage disturbance signals of different frequencies into the main working circuit through the isolation transformer according to the harmonic injection parameters.

[0011] In an optional embodiment, the sampling circuit is connected to the frequency response analyzer, and is used to transmit the collected voltage and current between the load device and the disturbance generating device to the frequency response analyzer.

[0012] In an optional embodiment, the source device is a three-phase motor circuit, and the load device is composed of three resistors connected in parallel.

[0013] In an optional embodiment, each circuit in the three-phase motor circuit is connected in series with a resistor in the load device.

[0014] In an optional embodiment, the sampling circuit is used to collect the current I in the three-phase motor circuit. a Item b: Current I b ; and collecting the voltage Δu between phases ab in the three-phase motor circuit ab The voltage between phases b and c is Δu bc .

[0015] In an optional embodiment, the host computer is further used to calculate the impedance of the source device according to the collected voltage and current.

[0016] An embodiment of the present invention provides a method for measuring the source side impedance of a power supply system. The method is applied to a disturbance generating device in a measurement circuit of the source side impedance of the power supply system. The method includes:

[0017] In response to the operation of the measuring device of the source side impedance of the power supply system, voltage disturbance signals of different frequencies are injected into the main working circuit according to the harmonic injection parameters; the main working circuit includes a source device and a load device;

[0018] Within a predetermined time of injecting the voltage disturbance signal, collecting the voltage and current between the load device and the disturbance generating device;

[0019] The impedance of the source device is calculated based on the collected current and voltage.

[0020] In an optional embodiment, before injecting voltage disturbance signals of different frequencies into the main working circuit according to the harmonic injection parameters, the method further includes:

[0021] The harmonic injection parameters are determined according to the rated working state of the source device, and the harmonic injection parameters include: a frequency range, a step size, and a harmonic amplitude of harmonic injection.

[0022] In an optional embodiment, the source device is a three-phase motor circuit, and the collecting of the voltage and current between the source device and the fundamental frequency blocking device includes:

[0023] Collect the current i in the three-phase motor circuit a 、B item current i b ; and collecting the voltage u between phases ab in the three-phase motor circuit ab The voltage between phases b and c is u bc .

[0024] In an optional embodiment, calculating the impedance of the source device according to the collected current and voltage includes:

[0025] The system impedance Z of the three-phase circuit is calculated by the following formula S (s):

[0026]

[0027] The impedance Z of the load device is calculated by the following formula l (s):

[0028]

[0029] The source device impedance Z is calculated by the following formula g (s):

[0030]

[0031] Among them, Δu p It is the voltage of the isolation transformer in the disturbance generating device.

[0032] The present invention provides a device and method for measuring the source side impedance of a power supply system. The device comprises: a main working circuit, a sampling circuit, and a disturbance generating device. The main working circuit comprises a source device and a load device. The source device and the load device are connected, and the impedance of the source device is lower than the impedance of the load device. The disturbance generating device is arranged between the source device and the load device, and the disturbance generating device is used to set harmonic injection parameters, and inject voltage disturbance signals of different frequencies into the main working circuit according to the harmonic injection parameters. The sampling circuit is arranged between the load device and the disturbance generating device, and is used to collect the voltage and current between the load device and the disturbance generating device within a predetermined time of injecting the voltage disturbance signal, and transmit the collected voltage and current to the disturbance generating device. In this embodiment, the disturbance generating device controls the output of harmonic injection parameters of different frequencies, and then the disturbance signal corresponding to the harmonic injection parameter is injected into the main working circuit. The injected disturbance signal will generate a disturbance response in the main working circuit that is consistent with the frequency of the injected disturbance signal. The source side impedance of the power supply system can be calculated by the voltage and current collected in the sampling circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A diagram of a device for measuring source-side impedance of a power supply system provided in the present application;

[0034] Figure 2 A wiring diagram of a line measurement device for source side impedance of a power supply system provided in this application;

[0035] Figure 3 A flow chart for measuring source side impedance of a power supply system provided in this application;

[0036] Figure 4 Another flow chart for measuring source side impedance of a power supply system provided by the present application;

[0037] Figure 5 A schematic diagram of indirect measurement of source device impedance provided in this application;

[0038] Figure 6 A three-stage generator simulation model diagram provided for this application;

[0039] Figure 7 The system impedance simulation verification result diagram provided for this application;

[0040] Figure 8 The load impedance simulation verification result diagram provided for this application;

[0041] Fig. 9 This is a diagram of the simulation verification results of the output impedance of the three-stage generator provided in this application. DETAILED DESCRIPTION

[0042] In order to better understand the above-mentioned technical scheme, the technical scheme of the embodiments of the present application is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical scheme of the embodiments of the present application, rather than limitations on the technical scheme of the present application. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments may be combined with each other.

[0043] See also Figure 1 , a device for measuring the source side impedance of a power supply system provided in an embodiment of the present invention, the measuring device includes: a main working circuit 1, a sampling circuit 2, and a disturbance generating device 3.

[0044] Specific as Figure 1 As shown, the main working circuit 1 in this embodiment includes a source device and a load device, the source device and the load device are connected, and the impedance of the source device is lower than the impedance of the load device; the main working circuit 1 is the working circuit of the source device to be tested, and when an example of the source device is a generator, the main working circuit 1 is a generator driving a resistive load.

[0045] The disturbance generating device 3 is arranged between the source device and the load device, and the disturbance generating device 3 is used to set harmonic injection parameters, and inject voltage disturbance signals of different frequencies into the main working circuit 1 according to the harmonic injection parameters; the sampling circuit 2 is arranged between the load device and the disturbance generating device 3, and is used to collect the voltage and current between the load device and the disturbance generating device 3 within a predetermined time of injecting the voltage disturbance signal, and transmit the collected voltage and current to the disturbance generating device 3.

[0046] In this embodiment, since the response signal of the small impedance port of the source device is small and direct measurement has a large error, the impedance of the entire system and the impedance of the load can be calculated respectively by measuring the disturbance source port signal and the load port signal, and the impedance of the source device can be calculated using the difference between the two.

[0047] In an optional embodiment, the disturbance generating device 3 includes: a host computer 31, a frequency response analyzer 32, an excitation small signal generating module 33, a linear amplifier unit 34, and an isolation transformer 35 connected in sequence; the isolation transformer 35 is arranged between the source device and the load device, and the host computer 41 is used to set harmonic injection parameters, and inject voltage disturbance signals of different frequencies into the main working circuit 1 through the isolation transformer 35 according to the harmonic injection parameters.

[0048] In an optional embodiment, the sampling circuit 2 is connected to the frequency response analyzer 32 for transmitting the collected voltage and current between the load device and the disturbance generating device 3 to the frequency response analyzer 32 .

[0049] like Figure 2 As shown, in an optional embodiment, the source device is a three-phase motor circuit, and the load device is composed of three parallel resistors. Each circuit in the three-phase motor circuit is connected in series with the resistor in the load device.

[0050] According to the working circuit of the source device under test, determine the voltage and current sampling port. The sampling is realized by voltage and current probes. Take the ABC three-phase system as an example. Since it is a three-phase circuit, at least two-phase voltage and current need to be sampled. Taking the sampling terminal voltage ab and bc of the frequency response analyzer and the phase current a and b as an example, the measurement wiring is shown as follows Figure 2 As shown, the sampling circuit 2 is used to collect the current I in the three-phase motor circuit. a Item b: Current I b ; and collecting the voltage Δu between phases ab in the three-phase motor circuit ab The voltage between phases b and c is Δu bc .

[0051] The host computer 31 is also used to calculate the impedance of the source device according to the collected voltage and current. Specifically, the host computer 31 analyzes the sampled data, obtains the sequence voltage and sequence current components through coordinate transformation, calculates the measured system impedance and load impedance, and then, according to the indirect measurement principle, subtracts the load impedance from the system impedance to obtain the source device impedance.

[0052] The present embodiment provides a device for measuring the source side impedance of a power supply system, the device comprising: a main working circuit, a sampling circuit, and a disturbance generating device, wherein the main working circuit comprises a source device and a load device. The source device and the load device are connected, and the impedance of the source device is lower than the impedance of the load device; the disturbance generating device is arranged between the source device and the load device, and the disturbance generating device is used to set harmonic injection parameters, and inject voltage disturbance signals of different frequencies into the main working circuit according to the harmonic injection parameters; the sampling circuit is arranged between the load device and the disturbance generating device, and is used to collect the voltage and current between the load device and the disturbance generating device within a predetermined time of injecting the voltage disturbance signal, and transmit the collected voltage and current to the disturbance generating device. The disturbance generating device of the present embodiment controls the output of harmonic injection parameters of different frequencies, and then the disturbance signal corresponding to the harmonic injection parameter is injected into the main working circuit, and the injected disturbance signal will generate a disturbance response in the main working circuit that is consistent with the frequency of the injected disturbance signal, and the source side impedance of the power supply system can be calculated by the voltage and current collected in the sampling circuit.

[0053] like Figure 3 and Figure 4 As shown, an embodiment of the present invention provides a method for measuring the source side impedance of a power supply system, the method is applied to a disturbance generating device 1 in the measurement circuit of the source side impedance of the power supply system, and the method includes:

[0054] S101, in response to the operation of the device for measuring the source side impedance of the power supply system, injecting voltage disturbance signals of different frequencies into the main working circuit according to harmonic injection parameters.

[0055] Wherein, the main working circuit includes a source device and a load device; in an optional embodiment, before injecting voltage disturbance signals of different frequencies into the main working circuit according to harmonic injection parameters, the method also includes: determining the harmonic injection parameters according to the rated working state of the source device, and the harmonic injection parameters include: frequency range, step size and harmonic amplitude of harmonic injection.

[0056] S102: within a predetermined time of injecting the voltage disturbance signal, collecting the voltage and current between the load device and the disturbance generating device.

[0057] In an optional embodiment, the source device is a three-phase motor circuit, and the collecting of the voltage and current between the source device and the base frequency blocking device includes: collecting a current i in the three-phase motor circuit a 、B item current i b ; and collecting the voltage u between phases ab in the three-phase motor circuit ab The voltage between phases b and c is ubc .

[0058] S103, calculating the impedance of the source device according to the collected current and voltage.

[0059] In this embodiment, the frequency range, step size and harmonic amplitude of harmonic injection are set according to the measurement requirements. The frequency range, step size and harmonic amplitude of harmonic injection are set in the frequency response analyzer through the disturbance generating device, and the setting is based on the power of the generator to be measured, the rated frequency and the accuracy of the generator impedance to be obtained. After the setting is completed, the source device is made to work and output, and after working in the state to be measured, the harmonic injection of the corresponding frequency is performed through the instruction of the disturbance generating device, and the voltage and current values ​​of the corresponding sampling port when each set frequency harmonic is injected are collected, and then the impedance of the source device is calculated according to the collected voltage and current values.

[0060] Specifically, this embodiment indirectly collects the injected disturbance voltage of the corresponding frequency, the system current and the response voltage at the load end to obtain the system impedance and the load impedance that is more convenient to measure, and then subtracts the load impedance from the system impedance to calculate the impedance of the source device. Therefore, the impedance measurement of the source device is realized through this embodiment.

[0061] like Figure 5 As shown, it is a schematic diagram of the measurement method provided by this embodiment taking a single-port system as an example, and the impedance to be measured is the power port impedance Z g , the sampling data is the current ΔI flowing through the system a , the injected disturbance voltage ΔV p , and the response voltage Δu at the load end l . By ΔV p / ΔI can get the impedance Z of the whole system s , by Δu l / ΔI a The load impedance Z can be obtained l , then the source impedance is Z g =Z s -Z l =ΔV p / ΔI a -Δu l / ΔI a .

[0062] like Figure 2 As shown, if the source device is a three-phase motor circuit, first, determine the voltage and current sampling port according to the working circuit of the source device under test, and the sampling is realized through the voltage and current probes. Take the ABC three-phase system as an example. Since it is a three-phase circuit, at least two-phase voltage and current need to be sampled. The sampled voltage is the voltage u between the ab phases at the generator output end. ab The voltage between phases b and c is u bcThe current sampled and measured is the current i in the three-phase motor circuit. a 、B item current i b After that, the collected voltage and current values ​​are input into the four channels of CH.1, CH.2, CH.3, and CH.4 in the frequency response analyzer until the harmonic injection of the set frequency range is completed and the source device output is stopped.

[0063] Set the frequency range, step size and harmonic amplitude of harmonic injection according to the measurement requirements. After the settings are completed, the source device is made to work and output. After working in the test state, the corresponding frequency disturbance injection is performed through the host computer command, and the voltage and current values ​​of the corresponding sampling port are collected when each set frequency harmonic is injected. After the harmonic injection of the set frequency range is completed, the source device stops working and outputting.

[0064] Finally, the host computer is used to analyze the sampled data, and the sequence voltage and sequence current components are obtained through coordinate transformation. The impedance of the measured system and the load impedance are calculated. Then, according to the indirect measurement principle, the source device impedance is obtained by subtracting the load impedance from the system impedance. The specific calculation process is as follows:

[0065] The system impedance Z of the three-phase circuit is calculated by the following formula S (s):

[0066]

[0067] The impedance Z of the load device is calculated by the following formula l (s):

[0068]

[0069] The source device impedance Z is calculated by the following formula g (s):

[0070]

[0071] Among them, Δu p is the voltage of the isolation transformer in the disturbance generating device. p (s) is the positive sequence impedance of the source device, Z n (s) is the negative-sequence impedance of the source device. The s in the brackets represents the frequency domain representation of the impedance of the positive-sequence impedance and the negative-sequence impedance.

[0072] This embodiment provides a method for measuring the source side impedance of a power system. When a disturbance signal is injected, the response signal of the small impedance port on the source side is small, and direct measurement has a large error. This embodiment can measure the disturbance source port signal and the load port signal to calculate the impedance of the entire system and the impedance of the load respectively, and then use the difference between the two to calculate the impedance of the source device. In actual measurement, by indirectly measuring the load-side disturbance response signal with obvious response, measurement errors can be effectively avoided, measurement accuracy can be improved, and more accurate source impedance measurement can be achieved.

[0073] In this embodiment, a three-stage generator, a common low impedance source device in an aviation power supply system, is used as an example. Figure 6 An implementation example of measuring the output impedance of a three-stage generator is shown. Figure 6 As shown, the output impedance measurement of the three-stage generator in this embodiment includes a main working circuit of the main three-stage generator driving a resistive load and a disturbance signal injection and measurement device. The disturbance signal is injected into one phase of the main circuit, and the system impedance and load impedance are obtained by measuring the port response voltage and current, and then the impedance of the source device to be measured is calculated.

[0074] Optionally, the three-stage generator adopts proportional integral closed-loop control to control the output voltage of the three-stage generator to be 230V / 400Hz, the load adopts a pure resistance circuit, and the output power of Example 1 is 50kw. The measurement simulation in this embodiment is performed based on the MATLAB simulation platform, and the source device impedance is calculated by injecting a disturbance signal and sampling the voltage and current response signals of the port. The sampling circuit is implemented by a voltage and current measurement module, and the sampled data is subjected to FFT analysis to obtain the impedance of each frequency, thereby obtaining the impedance model of the required frequency band.

[0075] Figure 7 , 8 9 are impedance sweep measurement results in the simulation model of this embodiment, including the measurement and calculation results of the system impedance Zs, the load impedance Zl and the calculated impedance Zg of the source device three-stage generator. At the same time, the results of the indirect measurement method proposed in this embodiment and the three-stage generator output impedance obtained by directly sampling the voltage and current at the output port of the three-stage generator are compared. It can be seen that the results of the two measurement methods are basically consistent, which verifies the theoretical effectiveness of the method.

[0076] Depend on Figure 7 , 8 , 9, it can be seen that the power system source side impedance measurement device and method proposed in this embodiment can effectively measure the smaller output impedance of the three-stage generator on the power side. In actual measurement, since the load-side disturbance response signal with obvious response is measured indirectly, the measurement error can be effectively avoided, the measurement accuracy can be improved, and a more accurate source impedance measurement can be achieved.

[0077] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing related hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct RAMbus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.

[0078] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0079] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A device for measuring source side impedance of a power supply system, characterized in that: The measuring device comprises: a main working circuit, a sampling circuit, and a disturbance generating device, wherein the main working circuit comprises a source device and a load device; The source device is connected to the load device, and the impedance of the source device is lower than the impedance of the load device; The disturbance generating device is arranged between the source device and the load device, and is used to set harmonic injection parameters, and inject voltage disturbance signals of different frequencies into the main working circuit according to the harmonic injection parameters; The sampling circuit is arranged between the load device and the disturbance generating device, and is used to collect the voltage and current between the load device and the disturbance generating device within a predetermined time of injecting the voltage disturbance signal, and transmit the collected voltage and current to the disturbance generating device.

2. The measuring device according to claim 1, characterized in that The disturbance generating device comprises: a host computer, a frequency response analyzer, an excitation small signal generating module, a linear amplifier unit, and an isolation transformer connected in sequence; The isolation transformer is arranged between the source device and the load device. The host computer is used to set harmonic injection parameters and inject voltage disturbance signals of different frequencies into the main working circuit through the isolation transformer according to the harmonic injection parameters.

3. The measuring device according to claim 2, characterized in that The sampling circuit is connected to the frequency response analyzer and is used to transmit the collected voltage and current between the load device and the disturbance generating device to the frequency response analyzer.

4. The measuring device according to claim 3, characterized in that The source device is a three-phase motor circuit, and the load device is composed of three resistors connected in parallel.

5. The measuring device according to claim 4, characterized in that Each circuit in the three-phase motor circuit is connected in series with a resistor in the load device.

6. The measuring device according to claim 5, characterized in that The sampling circuit is used to collect the current I in the three-phase motor circuit. a Item b: Current I b ; and collecting the voltage Δu between phases ab in the three-phase motor circuit ab The voltage between phases b and c is Δu bc .

7. The measuring device according to claim 2, characterized in that The host computer is also used to calculate the impedance of the source device according to the collected voltage and current.

8. A method for measuring source side impedance of a power supply system, characterized in that: The method is applied to a disturbance generating device in a device for measuring source side impedance of a power supply system according to any one of claims 1 to 7, and the method comprises: In response to the operation of the measuring device of the source side impedance of the power supply system, voltage disturbance signals of different frequencies are injected into the main working circuit according to the harmonic injection parameters; the main working circuit includes a source device and a load device; Within a predetermined time of injecting the voltage disturbance signal, collecting the voltage and current between the load device and the disturbance generating device; The impedance of the source device is calculated based on the collected current and voltage.

9. The method according to claim 8, characterized in that Before injecting voltage disturbance signals of different frequencies into the main working circuit according to the harmonic injection parameters, the method further includes: The harmonic injection parameters are determined according to the rated working state of the source device, and the harmonic injection parameters include: a frequency range, a step size, and a harmonic amplitude of harmonic injection.

10. The method according to claim 8, characterized in that The source device is a three-phase motor circuit, and the collecting of the voltage and current between the source device and the fundamental frequency blocking device includes: Collect the current i in the three-phase motor circuit a 、B item current i b ; and collecting the voltage u between phases ab in the three-phase motor circuit ab The voltage between phases b and c is u bc .

11. The method according to claim 10, characterized in that The calculating the impedance of the source device according to the collected current and voltage includes: The system impedance Z of the three-phase circuit is calculated by the following formula S (s): The impedance Z of the load device is calculated by the following formula l (s): The source device impedance Z is calculated by the following formula g (s): Among them, Δu p It is the voltage of the isolation transformer in the disturbance generating device.

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