Method and device for suppressing specific grid-connected current harmonic waves of energy storage converter

Abstract

The invention discloses a specific grid-connected current harmonic suppression method and device for an energy storage converter, and belongs to the technical field of power systems, and the method comprises the steps: obtaining a given current value of a fundamental current loop, and carrying out the dq / abc conversion to obtain a three-phase current reference value; acquiring a three-phase current value of a power grid side, and subtracting the three-phase current value from the three-phase current reference value to obtain a harmonic current value; converting the harmonic current value to a target subharmonic synchronous rotating coordinate system to obtain a target subharmonic current value; extracting the target sub-harmonic current value in a direct current form through a low-pass filter, and sending the target sub-harmonic current value to a PI regulator for regulation to obtain a harmonic voltage compensation amount; and injecting the harmonic voltage compensation amount into a modulation wave to realize suppression of the target subharmonic current. According to the invention, the grid-connected side current harmonic of the energy storage converter can be effectively suppressed, and the grid-side current quality is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power systems, and particularly relates to a specific order grid-connected current harmonic suppression method and device for energy storage converters. BACKGROUND

[0002] Harmonic currents in the power grid will produce harmonic voltage drops on the impedance of the transmission line, increasing the power loss in the transmission and distribution process. At the same time, the total harmonic distortion of the transmission voltage will also increase, and the harmonics in the transmission voltage will accelerate the aging of power equipment and increase the loss of transformer equipment, and in severe cases, it may also cause safety accidents. In addition, harmonic currents will also produce electromagnetic interference, affecting the stable operation of precision instruments and communication equipment connected to the grid, and in severe cases, it may also interfere with the relay protection equipment of the power grid, causing serious accidents.

[0003] At present, full-controlled PWM conversion circuits are widely used in energy storage converters, especially single-phase conversion circuits and three-phase conversion circuits, due to their low voltage and current harmonic content, bidirectional energy flow, high power factor and high efficiency.

[0004] In order to avoid the problem of bridge arm shoot-through in three-phase bridge circuits and damage to components, a dead time is usually added to the switching tube drive signal in the same bridge arm. Although only a few microseconds, the output voltage of each bridge arm will deviate from the expected state due to the short delay caused by the dead time, which is the dead-time effect, which greatly increases the odd harmonic current component in the grid-connected current of the energy storage converter. In addition, there is always some distortion in the actual grid voltage, and when the harmonic content of the grid voltage is high, it will inevitably lead to an increase in the harmonic of the grid-connected current of the energy storage converter. Although the three-phase circuit of the energy storage converter has the same hardware parameters in theory, in actual application, due to the differences in manufacturing process and device performance as well as the influence of external environment (temperature, air humidity, electromagnetic interference), the hardware parameters of the three-phase circuit will be slightly different, which will also cause three-phase imbalance and further produce current harmonics. Therefore, although the energy storage converter has improved the output current harmonics compared to traditional uncontrolled and half-controlled converters, it is still limited by switching devices and affected by grid voltage harmonics and three-phase imbalance, so the current harmonics of the energy storage converter still need to be addressed. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art, and provides a specific order grid-connected current harmonic suppression method and device for energy storage converters, which solves the technical problem of how to suppress the grid-connected current harmonics of the energy storage converter.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a method for suppressing specific harmonic grid currents of energy storage converters, comprising:

[0008] obtaining a given current value of a fundamental current loop and performing dq / abc transformation to obtain a three-phase current reference value;

[0009] obtaining a three-phase current value of a grid side and subtracting the three-phase current reference value to obtain a harmonic current value;

[0010] converting the harmonic current value to a target harmonic synchronous rotating coordinate system to obtain a target harmonic current value;

[0011] extracting the target harmonic current value in the form of a direct current through a low-pass filter and sending it to a PI regulator for regulation to obtain a harmonic voltage compensation amount;

[0012] injecting the harmonic voltage compensation amount into a modulation wave to achieve suppression of the target harmonic current.

[0013] Optionally, the conversion of the harmonic current value to the target harmonic synchronous rotating coordinate system comprises:

[0014]

[0015] wherein, is a harmonic current value in a harmonic synchronous rotating coordinate system, a three-phase current value of a grid side, a three-phase current reference value; a conversion matrix, a three-phase stationary coordinate system, a synchronous rotating coordinate system;

[0016] when:

[0017]

[0018] when:

[0019]

[0020] wherein, is a positive integer, is a fundamental angular frequency, is a time.

[0021] Optionally, the low-pass filter adopts a Chebyshev low-pass IIR filter.

[0022] Optionally, the mathematical model of the energy storage converter in the target harmonic synchronous rotating coordinate system is:

[0023]

[0024] wherein, is the dq-axis voltage of the energy storage converter AC side in the sub-synchronous rotating coordinate system, is the dq-axis voltage of the capacitor in the LCL filter of the energy storage converter AC side in the sub-synchronous rotating coordinate system, is the dq-axis current of the inductor in the LCL filter of the energy storage converter AC side in the sub-synchronous rotating coordinate system, is the inductance value of the inductor in the LCL filter of the energy storage converter AC side, is the dq-axis voltage of the grid side in the sub-synchronous rotating coordinate system, is the dq-axis current of the grid side in the sub-synchronous rotating coordinate system, or , is a positive integer, is the time, is the rated angular frequency of the grid voltage;

[0025] Based on the mathematical model of the energy storage converter in the target sub-synchronous rotating coordinate system, the direct current value of the target sub-harmonic current is extracted, the reference value of the harmonic current loop is set to 0, and the harmonic voltage compensation amount is obtained by using the zero static error tracking characteristic of the PI regulator.

[0026] Optionally, the injecting the harmonic voltage compensation amount into the modulation wave further includes:

[0027] converting the harmonic voltage compensation amount from the target sub-synchronous rotating coordinate system to the fundamental synchronous rotating coordinate system:

[0028]

[0029] wherein, is the harmonic voltage compensation amount in the fundamental synchronous rotating coordinate system, is the harmonic voltage compensation amount in the sub-synchronous rotating coordinate system, is the conversion matrix;

[0030] when:

[0031]

[0032] when:

[0033]

[0034] wherein, is a positive integer, is the fundamental angular frequency, is the time;

[0035] The harmonic voltage compensation quantity is superimposed on the compensation quantity of the fundamental current loop, and is converted into the three-phase stationary coordinate system through dq / abc conversion and is sent to the modulation module to realize sinusoidal pulse width modulation.

[0036] In a second aspect, the present application provides a specific harmonic current suppression device for energy storage converter, comprising:

[0037] A reference current module configured to obtain the current value given by the fundamental current loop and perform dq / abc conversion to obtain three-phase current reference values;

[0038] A harmonic current module configured to obtain three-phase current values on the grid side and subtract the three-phase current reference values to obtain harmonic current values;

[0039] A harmonic conversion module configured to convert the harmonic current values to target harmonic synchronous rotating coordinate system to obtain target harmonic current values;

[0040] A compensation calculation module configured to extract the target harmonic current values in the form of direct current through a low-pass filter and send them to a PI regulator for adjustment to obtain harmonic voltage compensation quantities;

[0041] A compensation modulation module configured to inject the harmonic voltage compensation quantities into the modulation wave to achieve the suppression of the target harmonic current.

[0042] Optionally, the conversion of the harmonic current values to the target harmonic synchronous rotating coordinate system comprises:

[0043]

[0044] wherein, is harmonic current values in the harmonic synchronous rotating coordinate system, is three-phase current values on the grid side, is three-phase current reference values; is a conversion matrix, is a three-phase stationary coordinate system, is a synchronous rotating coordinate system;

[0045] Time:

[0046]

[0047] Time:

[0048]

[0049] wherein, is a positive integer, is a fundamental angular frequency, is a time instant.

[0050] In a third aspect, the present application provides an electronic device, comprising a processor and a storage medium;

[0051] The storage medium is configured to store instructions;

[0052] The processor is configured to operate according to the instructions to perform the steps of the above method.

[0053] In a fourth aspect, the present application provides a computer-readable storage medium having stored thereon a computer program, which, when executed by a processor, implements the steps of the above method.

[0054] In a fifth aspect, the present application provides a computer program product comprising a computer program / instructions, which, when executed by a processor, implements the steps of the above method.

[0055] Compared with the prior art, the present application has the following beneficial effects:

[0056] The present application provides a specific harmonic current suppression method and device for energy storage converter grid-connected current, based on a harmonic current extraction method of multiple synchronous rotating coordinate systems, and introduces a specific harmonic current suppression algorithm based on a PI controller into the harmonic current loop of the energy storage converter to obtain a corresponding harmonic voltage compensation amount; then the harmonic voltage compensation amount and the compensation amount of the fundamental current loop are superimposed, converted to a three-phase stationary coordinate system through dq / abc conversion, and sent to a modulation module to realize sinusoidal pulse width modulation, thereby realizing suppression of the target harmonic current and improving the quality of grid-side current. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 is a flowchart of the specific harmonic current suppression method for energy storage converter grid-connected current provided by the present application;

[0058] Figure 2 is a schematic diagram of the principle of the specific harmonic current suppression for energy storage converter grid-connected current provided by the present application;

[0059] Figure 3 is a proportional resonant controller Bode diagram provided by the present application;

[0060] Figure 4 is a proportional resonant controller Bode diagram provided by the present application;

[0061] Figure 5 This is the Bode plot of the proportional resonant controller during Kp transformation provided in this embodiment of the invention;

[0062] Figure 6 This is the grid-side current waveform provided in this embodiment of the invention when the harmonic suppression algorithm is not used;

[0063] Figure 7 This is the grid-side current spectrum provided in this embodiment of the invention when the harmonic suppression algorithm is not used;

[0064] Figure 8 This is the grid-side current waveform provided in this embodiment of the invention when using a harmonic suppression algorithm;

[0065] Figure 9 This is the grid-side current spectrum when using the harmonic suppression algorithm provided in the embodiments of the present invention. Detailed Implementation

[0066] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0067] Example 1

[0068] like Figure 1 As shown, this embodiment of the invention provides a method for suppressing specific grid-connected current harmonics in an energy storage converter, comprising the following steps:

[0069] Step S1: Obtain the current value given by the fundamental current loop and perform dq / abc transformation to obtain the three-phase current reference value.

[0070] Step S2: Obtain the three-phase current value on the grid side and subtract it from the three-phase current reference value to obtain the harmonic current value.

[0071] Step S3: Convert the harmonic current value to the target subharmonic synchronous rotating coordinate system to obtain the target subharmonic current value.

[0072] Step S4: Extract the target subharmonic current value in DC form through a low-pass filter and send it to a PI regulator for adjustment to obtain the harmonic voltage compensation amount.

[0073] Step S5: Inject the harmonic voltage compensation amount into the modulation wave to suppress the target subharmonic current.

[0074] by Figure 2For example, the main circuit is a three-phase three-level energy storage converter, adopts a three-level topology with diode clamping, Q1-Q12 are 12 insulated gate bipolar transistors (IGBT) with anti-parallel diodes; D1-D6 are 6 clamping diodes. Lc, Rc are the filter inductance on the converter side and its internal resistance respectively; Lg, Rg are the filter inductance on the grid side and its internal resistance respectively; Cf is the AC side filter capacitor; Rd is the damping resistance.v ga 、v gb 、v gc are three-phase grid phase voltages, the values are sampled by using a voltage sensor;v ga 、i gb 、i gc are three-phase grid currents, the values are sampled by using a current sensor;v a 、e b 、e c are the fundamental waves of the output voltages at the three-phase bridge arm midpoints;v ca 、v cb 、v cc are the AC voltages of the three-phase filter capacitors;v dc is a DC voltage source voltage or an energy storage battery voltage, the value is sampled by using a voltage sensor; C1, C2 are upper and lower split capacitors on the DC side.

[0075] The control system is composed of a fundamental current loop and a group of specific harmonic current loops, and the specific harmonic current loop adopts the specific harmonic current suppression method provided in the embodiment to realize the suppression of the target harmonic current:

[0076] Step S1, obtaining the current value given by the fundamental current loop , and performing dq / abc conversion to obtain the three-phase current reference value.

[0077] Step S2, obtaining the three-phase current value on the grid side, and subtracting the three-phase current reference value to obtain the harmonic current value .

[0078] Step S3, converting the harmonic current value to the target harmonic synchronous rotating coordinate system to obtain the target harmonic current value , the expression is:

[0079]

[0080] In the formula, is the harmonic current value in the harmonic synchronous rotating coordinate system, is the three-phase current value on the grid side, is the three-phase current reference value; is a transformation matrix, is a three-phase stationary coordinate system, is a synchronous rotating coordinate system.

[0081]

[0082]

[0083]

[0084]

[0085] wherein, is a positive integer, is a fundamental angular frequency, is a time instant.

[0086] Step S4, the target harmonic current value is extracted in the form of direct current through a low-pass filter, and is sent into a PI regulator for regulation to obtain a harmonic voltage compensation amount.

[0087] In digital signal filtering, there are mainly two types of digital filters, namely Infinite Impulse Response (IIR) and Finite Impulse Response (FIR).

[0088] The IIR filter has characteristics such as phase nonlinearity, input and output feedback. Compared with the FIR filter, it can meet the index requirements with fewer orders, but the phase response of the IIR filter is nonlinear. The IIR design has a simple and effective approximation algorithm and accurate design formula, so the parameter design process is relatively simple and convenient to use. This time, a digital low-pass filter for filtering out the alternating current through the direct current is needed. The IIR filter has good dynamic and static performance and the highest precision. The commonly used IIR filters at present include Butterworth, Chebyshev, elliptical filter, etc. The specific harmonic current extraction method proposed this time uses a Chebyshev low-pass IIR filter.

[0089] The mathematical model of the energy storage converter in the target harmonic synchronous rotating coordinate system is:

[0090]

[0091] wherein, is is the dq-axis voltage of the energy storage converter on the alternating current side in the harmonic synchronous rotating coordinate system, is is the dq-axis voltage of the capacitor in the LCL filter of the energy storage converter on the alternating current side in the harmonic synchronous rotating coordinate system,​​ is dq-axis current of the inductor in the LCL filter on the AC side of the energy storage converter in the sub-harmonic synchronous rotating coordinate system, is the inductance value of the inductor in the LCL filter on the AC side of the energy storage converter, is dq-axis voltage of the grid side in the sub-harmonic synchronous rotating coordinate system, is dq-axis current of the grid side in the sub-harmonic synchronous rotating coordinate system, or , is a positive integer, is the time, is the rated angular frequency of the grid voltage;

[0092] Based on the mathematical model of the energy storage converter in the target sub-harmonic synchronous rotating coordinate system, the direct current of the target sub-harmonic current value is extracted, the reference value of the harmonic current loop is set to 0, i.e. , the harmonic voltage compensation amount is obtained by using the zero-error tracking characteristic of the PI regulator.

[0093] Taking the specified sub-harmonic as the n=5th harmonic as an example, in the 5th harmonic synchronous rotating coordinate system, the expression of the PI regulator is:

[0094]

[0095] In the formula, is the proportional parameter and the integral parameter of the PI controller, is the Laplace operator; is the PI regulator output,

[0096] The conversion of the PI regulator to the fundamental dq coordinate system is:

[0097]

[0098] is the converted , is the imaginary unit, is the fundamental frequency.

[0099] According to the above formula, it can be seen that the 5th harmonic current loop PI controller in the fundamental synchronous rotating coordinate system is a proportional resonant controller. The Bode diagram of the transfer function of the above formula is drawn, the proportional parameter is set to 1, and the integral parameter is set to 10, Figure 3 as shown.

[0100] From Figure 3It can be seen that the PI controller in n times dq coordinate system has a great gain at 6ω frequency when transformed into fundamental dq coordinate system, and has no phase shift and gain at other frequency points. Therefore, from the above analysis, it can be known that the PI controller in harmonic synchronous rotating coordinate system is equivalent to a harmonic resonance control of n times harmonic in fundamental synchronous rotating coordinate system.

[0101] It can be seen that the PI controller in n times dq coordinate system has a great gain at 6ω frequency when transformed into fundamental dq coordinate system, and has no phase shift and gain at other frequency points. Therefore, from the above analysis, it can be known that the PI controller in harmonic synchronous rotating coordinate system is equivalent to a harmonic resonance control of n times harmonic in fundamental synchronous rotating coordinate system. Figure 4 Figure 4 It can be seen that the PI controller in n times dq coordinate system has a great gain at 6ω frequency when transformed into fundamental dq coordinate system, and has no phase shift and gain at other frequency points. Therefore, from the above analysis, it can be known that the PI controller in harmonic synchronous rotating coordinate system is equivalent to a harmonic resonance control of n times harmonic in fundamental synchronous rotating coordinate system. Figure 5 Figure 5 It can be seen that the PI controller in n times dq coordinate system has a great gain at 6ω frequency when transformed into fundamental dq coordinate system, and has no phase shift and gain at other frequency points. Therefore, from the above analysis, it can be known that the PI controller in harmonic synchronous rotating coordinate system is equivalent to a harmonic resonance control of n times harmonic in fundamental synchronous rotating coordinate system.

[0102] Step S5, injecting the harmonic voltage compensation quantity into the modulation wave to realize suppression of the target harmonic current.

[0103] Injecting the harmonic voltage compensation quantity into the modulation wave further includes:

[0104] Converting the harmonic voltage compensation quantity from the target harmonic synchronous rotating coordinate system to the fundamental synchronous rotating coordinate system:

[0105]

[0106] In the formula, is the harmonic voltage compensation quantity in the fundamental synchronous rotating coordinate system, is the harmonic voltage compensation quantity in the n times harmonic synchronous rotating coordinate system, is the conversion matrix;

[0107] When:

[0108]

[0109] When:

[0110]

[0111] In the formula, is a positive integer, is the fundamental angular frequency, is the time;

[0112] Injecting the harmonic voltage compensation quantity into the modulation wave​​​ The compensation amount of the superimposed fundamental current loop is converted into the three-phase static coordinate system through dq / abc conversion, and is sent to a modulation module to realize sinusoidal pulse width modulation.

[0113] To verify the effectiveness of the specific harmonic current suppression method proposed in the application, a corresponding energy storage converter system simulation model is established. The parameters used in the simulation are shown in Table 1.

[0114] Table 1: Parameter information of the simulation model

[0115]

[0116] The three-phase grid-side current without using the harmonic suppression algorithm is shown in FIG. 15, and the total harmonic distortion rate is 8.42% at the 15kW power level. The FFT analysis of the grid-connected current is shown in FIG. 16, and it can be seen from the waveform spectrum that the harmonics are mainly distributed on 6k±1. Figure 6 Figure 7 The three-phase current after using the specific harmonic suppression algorithm to suppress 5, 7, 11, 13, 17 and 19 harmonics is shown in FIG. 17, and the total harmonic distortion rate is 4.37% at this time. The FFT analysis of the grid-connected current is shown in FIG. 18, and it can be seen from the waveform spectrum that the 5, 7, 11, 13, 17 and 19 harmonics are effectively suppressed.

[0117] The three-phase current after using the specific harmonic suppression algorithm to suppress 5, 7, 11, 13, 17 and 19 harmonics is shown in FIG. 17, and the total harmonic distortion rate is 4.37% at this time. The FFT analysis of the grid-connected current is shown in FIG. 18, and it can be seen from the waveform spectrum that the 5, 7, 11, 13, 17 and 19 harmonics are effectively suppressed. Figure 8 Figure 9 The three-phase current after using the specific harmonic suppression algorithm to suppress 5, 7, 11, 13, 17 and 19 harmonics is shown in FIG. 17, and the total harmonic distortion rate is 4.37% at this time. The FFT analysis of the grid-connected current is shown in FIG. 18, and it can be seen from the waveform spectrum that the 5, 7, 11, 13, 17 and 19 harmonics are effectively suppressed.

[0118] The embodiment aims at the poor power quality of the grid-side current under the grid-connected operation condition of the energy storage converter, and proposes a specific harmonic suppression method. The harmonic current extraction method based on the multi-synchronous rotating coordinate system is used, and the specific harmonic current suppression algorithm based on the PI controller is introduced into the control loop of the energy storage converter to suppress the harmonic of the grid-connected current. Finally, the simulation verification of the specific harmonic suppression is performed, and the results show that the harmonic suppression method proposed in the application can effectively suppress the harmonic of the grid-connected current of the energy storage converter and improve the quality of the grid-side current.

[0119] Embodiment two

[0120] The embodiment of the application provides a specific harmonic suppression device for grid-connected current of an energy storage converter, which comprises:

[0121] The reference current module is configured to obtain the current value given by the fundamental current loop and perform dq / abc conversion to obtain a three-phase current reference value;

[0122] The harmonic current module is configured to obtain the three-phase current value of the grid side and subtract the three-phase current reference value to obtain a harmonic current value;

[0123] ​​The harmonic conversion module is configured to convert the harmonic current value to a target sub-harmonic synchronous rotating coordinate system to obtain a target sub-harmonic current value.

[0124] The compensation calculation module is configured to extract the target sub-harmonic current value in the form of a direct current through a low-pass filter and send it into a PI regulator for adjustment to obtain a harmonic voltage compensation amount.

[0125] The compensation modulation module is configured to inject the harmonic voltage compensation amount into a modulation wave to achieve suppression of the target sub-harmonic current.

[0126] Specifically, converting the harmonic current value to the target sub-harmonic synchronous rotating coordinate system comprises:

[0127]

[0128] In the formula, is the harmonic current value in the sub-harmonic synchronous rotating coordinate system, is a three-phase current value on the grid side, is a three-phase current reference value; is a conversion matrix, is a three-phase stationary coordinate system, is a synchronous rotating coordinate system;

[0129] When:

[0130]

[0131] When:

[0132]

[0133] In the formula, is a positive integer, is a fundamental angular frequency, is a time.

[0134] Embodiment Three

[0135] Based on the energy storage converter specific sub-grid current harmonic suppression method provided in Embodiment One, the electronic device provided in the embodiment comprises a processor and a storage medium.

[0136] The storage medium is used to store instructions.

[0137] The processor is used to operate according to the instructions to execute the steps according to the above method.

[0138] Embodiment Four

[0139] Based on the energy storage converter specific harmonic suppression method provided in embodiment one, the embodiment of the present application provides a computer readable storage medium, which stores a computer program, and the program is executed by a processor to realize the steps of the above method.

[0140] Embodiment five

[0141] Based on the energy storage converter specific harmonic suppression method provided in embodiment one, the embodiment of the present application provides a computer program product, which includes computer program / instructions, and the computer program / instructions are executed by a processor to realize the steps of the above method.

[0142] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) containing computer-usable program code.

[0143] The present application is described with reference to flowcharts and / or block diagrams of the method, device (system), and computer program product according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that performs the functions specified in one or more flows and / or blocks.

[0144] These computer program instructions can also be stored in a computer-readable memory that can direct the computer or other programmable data processing apparatus to work in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including instruction apparatus, which implements the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that performs the functions specified in one or more flows and / or blocks.

[0145] These computer program instructions can also be loaded into a computer or other programmable data processing apparatus, so that a series of operation steps are performed on the computer or other programmable data processing apparatus to produce a computer-implemented process, so that the instructions executed on the computer or other programmable data processing apparatus provide a process for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1steps of the functions specified in the flowchart or flowcharts and / or block diagram. Figure 1

[0146] The above description is merely that of the preferred embodiments of the present application, and it is to be understood that numerous improvements and modifications will occur to those skilled in the art, and it is intended that the following claims cover all such improvements and modifications as fall within the scope of the present application.​

Claims

1. A method for energy storage converter specific order grid-connection current harmonic suppression, characterized in that, The method comprises the following steps: obtaining the current value given by the fundamental current loop and performing dq / abc conversion to obtain three-phase current reference value; obtaining the three-phase current value of the power grid side and subtracting the three-phase current reference value to obtain the harmonic current value; converting the harmonic current value to the target sub-harmonic synchronous rotating coordinate system to obtain the target sub-harmonic current value; extracting the target sub-harmonic current value in the form of direct current through a low-pass filter and sending it into a PI regulator for regulation to obtain the harmonic voltage compensation amount; injecting the harmonic voltage compensation amount into the modulation wave to achieve the suppression of the target sub-harmonic current.

2. The energy storage inverter specific low order grid current harmonic rejection method of claim 1, wherein, The conversion of the harmonic current value to the target sub-harmonic synchronous rotating coordinate system comprises: ； In the formula, is harmonic current value in the sub-harmonic synchronous rotating coordinate system, is a three-phase current value of the power grid side, is a three-phase current reference value; is a conversion matrix, is a three-phase stationary coordinate system, is a synchronous rotating coordinate system; Time: ； Time: ； wherein is a positive integer, is the fundamental angular frequency, is the time instant.

3. The energy storage inverter specific low order grid current harmonic mitigation method of claim 1, wherein, The low-pass filter adopts a Chebyshev low-pass IIR filter.

4. The energy storage inverter specific low order grid current harmonic mitigation method of claim 1, wherein, The mathematical model of the energy storage converter in the target sub-harmonic synchronous rotating coordinate system is: ； wherein is dq-axis voltage of the capacitor in the LCL filter at the AC side of the energy storage converter in the sub-harmonic synchronous rotating coordinate system, is dq-axis voltage of the capacitor in the LCL filter at the AC side of the energy storage converter in the sub-harmonic synchronous rotating coordinate system, is dq-axis current of the inductor in the LCL filter at the AC side of the energy storage converter in the sub-harmonic synchronous rotating coordinate system, is the inductance value of the inductor in the LCL filter at the AC side of the energy storage converter, is dq-axis voltage of the grid at the AC side of the energy storage converter in the sub-harmonic synchronous rotating coordinate system, is dq-axis current of the grid at the AC side of the energy storage converter in the sub-harmonic synchronous rotating coordinate system, or , is a positive integer, is the time instant, is the rated angular frequency of the grid voltage; Based on the mathematical model of the energy storage converter in the target sub-harmonic synchronous rotating coordinate system, the direct current amount of the target sub-harmonic current value is extracted, the reference value of the harmonic current loop is set to 0, and the harmonic voltage compensation amount is obtained by using the zero static error tracking characteristic of the PI regulator.

5. The energy storage inverter specific low order grid current harmonic rejection method of claim 1, wherein, The injection of the harmonic voltage compensation amount into the modulation wave further comprises: converting the harmonic voltage compensation amount from the target sub-harmonic synchronous rotating coordinate system to the fundamental synchronous rotating coordinate system: ； In the formula, is the harmonic voltage compensation quantity in the fundamental synchronous rotating coordinate system, is is the harmonic voltage compensation quantity in the sub-synchronous rotating coordinate system, is the conversion matrix; Time: ； Time: ； wherein is a positive integer, is the fundamental angular frequency, is the time instant; Compensation of harmonic voltage The compensation quantity of the superimposed fundamental current loop is converted into the three-phase stationary coordinate system through dq / abc conversion and is sent into a modulation module to realize sinusoidal pulse width modulation.

6. A device for suppressing specific order grid-connection current harmonics of an energy storage converter, characterized in that The method comprises the following steps: a reference current module configured to obtain the current value given by the fundamental current loop and perform dq / abc conversion to obtain three-phase current reference value; a harmonic current module configured to obtain the three-phase current value of the power grid side and subtract the three-phase current reference value to obtain the harmonic current value; a harmonic conversion module configured to convert the harmonic current value to the target sub-harmonic synchronous rotating coordinate system to obtain the target sub-harmonic current value; a compensation calculation module configured to extract the target sub-harmonic current value in the form of direct current through a low-pass filter and send it into a PI regulator for regulation to obtain the harmonic voltage compensation amount; a compensation modulation module configured to inject the harmonic voltage compensation amount into the modulation wave to achieve the suppression of the target sub-harmonic current.

7. The energy storage inverter specific low order grid current harmonic rejection apparatus of claim 6, wherein, The conversion of the harmonic current value to the target sub-harmonic synchronous rotating coordinate system comprises: ； wherein is a harmonic current value in a sub-harmonic synchronous rotating coordinate system, is a three-phase current value at the grid side, is a three-phase current reference value; is a conversion matrix, is a three-phase stationary coordinate system, is a synchronous rotating coordinate system; Time: ； Time: ； wherein is a positive integer, is the fundamental angular frequency, is the time instant.

8. An electronic device, comprising: The method comprises the following steps: a processor and a storage medium; the storage medium is used to store instructions; 9. A computer-readable storage medium having stored thereon a computer program, characterized in that, the processor is used to operate according to the instructions to perform the steps of the method according to any one of claims 1-5.

10. A computer program product comprising computer programs / instructions, characterized in that, The program is executed by the processor to realize the steps of the method according to any one of claims 1-5. The computer program / instructions are executed by the processor to realize the steps of the method according to any one of claims 1-5.

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