Harmonic compensation method, computer readable storage medium, and energy storage converter

Abstract

The present application relates to the field of power electronics, and particularly relates to a harmonic compensation method, a computer readable storage medium and an energy storage converter, the method comprising: obtaining an operating voltage range of a battery module, determining a DC bus voltage operating range of the energy storage converter according to the operating voltage range; obtaining a lower limit voltage and an upper limit voltage corresponding to the DC bus voltage operating range, and a first compensation capacity of the lower limit voltage and a second compensation capacity of the upper limit voltage; obtaining a current DC bus voltage of the energy storage converter based on a current battery residual capacity of the battery module, and determining a harmonic compensation capacity based on the lower limit voltage, the first compensation capacity, the upper limit voltage, the second compensation capacity and the current DC bus voltage, wherein the current DC bus voltage is greater than or equal to the lower limit voltage, and the current DC bus voltage is less than or equal to the upper limit voltage; and compensating for harmonics of a power grid according to the harmonic compensation capacity. The present application improves the adaptive capability of harmonic compensation.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a harmonic compensation method, a computer-readable storage medium, and an energy storage converter. Background Technology

[0002] In recent years, despite the rapid development of power electronics technology, how to eliminate harmonic pollution remains a pressing technical problem that needs to be solved. In other words, eliminating harmonic pollution has become an important aspect of today's electricity utilization.

[0003] Currently, poor power grid harmonics can lead to power quality problems such as overheating of electrical equipment, electromagnetic interference, and increased equipment failure rates. Existing power quality management primarily utilizes active power filters (APS filters). Based on AC wiring configuration, APS filters can be categorized into three-phase three-wire (3P3L) and three-phase four-wire (3P4L) types. APS filters only have bus capacitors on the DC side and typically employ a dual closed-loop voltage and current loop for harmonic compensation. The DC bus voltage loop stabilizes the DC bus voltage, while the inner current loop compensates for harmonics. However, since the bus capacitor selection is fixed, the DC bus voltage will stabilize at a certain value, and the harmonic compensation capacity will remain essentially unchanged. This approach using APS filters has significant limitations; the harmonic compensation capacity obtained using APS filters cannot flexibly compensate for harmonics generated by the power grid.

[0004] In summary, the use of existing active power filters for harmonic compensation suffers from the technical problem of poor harmonic compensation adaptability. Summary of the Invention

[0005] The main objective of this invention is to provide a harmonic compensation method, a computer-readable storage medium, and an energy storage converter, aiming to improve the adaptability of harmonic compensation.

[0006] To achieve the above objectives, the present invention provides a harmonic compensation method, which is applied to an energy storage converter, wherein the energy storage converter is connected to a battery module and to the power grid.

[0007] The harmonic compensation method includes:

[0008] Obtain the operating voltage range of the battery module, and determine the DC bus voltage operating range of the energy storage converter based on the operating voltage range;

[0009] Obtain the lower limit voltage and upper limit voltage corresponding to the DC bus voltage operating range, as well as the first compensation capacity of the lower limit voltage and the second compensation capacity of the upper limit voltage;

[0010] The current DC bus voltage of the energy storage converter is obtained based on the current remaining battery capacity of the battery module, and the harmonic compensation capacity is determined based on the lower limit voltage, the first compensation capacity, the upper limit voltage, the second compensation capacity, and the current DC bus voltage, wherein the current DC bus voltage is greater than or equal to the lower limit voltage, and the current DC bus voltage is less than or equal to the upper limit voltage.

[0011] The harmonics of the power grid are compensated according to the harmonic compensation capacity.

[0012] Optionally, the step of determining the harmonic compensation capacity based on the lower limit voltage, the first compensation capacity, the upper limit voltage, the second compensation capacity, and the current DC bus voltage includes:

[0013] Obtain the voltage difference between the lower limit voltage and the upper limit voltage, and obtain the compensation capacity difference between the first compensation capacity and the second compensation capacity;

[0014] Obtain the voltage compensation difference between the product of the lower limit voltage and the second compensation capacity and the product of the upper limit voltage and the first compensation capacity;

[0015] The harmonic compensation capacity is determined based on the current DC bus voltage, the voltage difference, the compensation capacity difference, and the voltage compensation difference.

[0016] Optionally, the step of determining the harmonic compensation capacity based on the current DC bus voltage, the voltage difference, the compensation capacity difference, and the voltage compensation difference includes:

[0017] The harmonic compensation capacity is adjusted in real time based on the current DC bus voltage, wherein the harmonic compensation capacity is obtained by summing the product of the reciprocal of the voltage difference, the current DC bus voltage and the compensation capacity difference, and the product of the reciprocal of the voltage difference and the voltage compensation difference.

[0018] Optionally, the step of compensating for harmonics in the power grid according to the harmonic compensation capacity includes:

[0019] Obtain the AC three-phase load current of the power grid;

[0020] The harmonics of the AC three-phase load current are extracted using a preset harmonic extraction algorithm to obtain the target order load harmonic current, and the effective value corresponding to the target order load harmonic current is obtained.

[0021] The inner loop setpoint of the target order current is obtained based on the effective value, the target order load harmonic current, and the harmonic compensation capacity.

[0022] The AC three-phase inductor current of the energy storage converter is obtained, and the current loop inductor current feedback value is determined based on the AC three-phase inductor current. The AC three-phase inductor current is obtained by current sampling on the inductor module of the energy storage converter.

[0023] The current inner loop control output value is obtained based on the target number current inner loop setpoint and the current loop inductor current feedback value.

[0024] The output value of the inner current control loop is superimposed on the output of the energy storage converter to compensate for the harmonics of the power grid.

[0025] Optionally, the target-order load harmonic current includes: a first-phase load harmonic current of the target order, a second-phase load harmonic current of the target order, and a third-phase load harmonic current of the target order. The step of obtaining the effective value corresponding to the target-order load harmonic current includes:

[0026] The first phase load harmonic current, the second phase load harmonic current, and the third phase load harmonic current are transformed from the three-phase stationary coordinate system to the synchronous rotating coordinate system through the preset Clark transformation and the preset Park transformation, so as to obtain the direct axis target order load harmonic current and the quadrature axis target order load harmonic current.

[0027] Obtain the first effective value of the direct-axis target order load harmonic current and the second effective value of the quadrature-axis target order load harmonic current, and use the first effective value and the second effective value as the effective value.

[0028] Optionally, the step of obtaining the inner loop setpoint of the target order current based on the effective value, the target order load harmonic current, and the harmonic compensation capacity includes:

[0029] Determine the product data between the harmonic compensation capacity and the reciprocal of the effective value;

[0030] The inner loop setpoint of the target order current is obtained by multiplying the product data with the target order load harmonic current.

[0031] Optionally, the step of obtaining the inner current loop control output value based on the target number of current inner loop setpoints and the current loop inductor current feedback value includes:

[0032] Obtain the difference data between the target number of times current inner loop setpoint and the current loop inductor current feedback value;

[0033] The current inner loop control output value is determined based on the difference data and the preset transfer function.

[0034] Optionally, the step of obtaining the current DC bus voltage of the energy storage converter based on the current remaining battery capacity of the battery module includes:

[0035] Obtain the battery voltage corresponding to the current remaining battery capacity of the battery module;

[0036] The battery voltage is used as the current DC bus voltage of the energy storage converter.

[0037] Furthermore, to achieve the above objectives, the present invention also provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores a harmonic compensation program, which, when executed by a processor, implements the steps of any of the harmonic compensation methods described above.

[0038] In addition, to achieve the above objectives, the present invention also provides an energy storage converter, characterized in that the energy storage converter is connected to a battery module and a power grid respectively, and the energy storage converter includes the aforementioned computer-readable storage medium.

[0039] In this invention, the DC bus voltage operating range of the energy storage converter is determined based on the operating voltage range of the battery module. Then, the lower limit voltage and upper limit voltage corresponding to the DC bus voltage operating range, as well as the first compensation capacity of the lower limit voltage and the second compensation capacity of the upper limit voltage, are obtained. Next, the current DC bus voltage of the energy storage converter is obtained based on the current remaining battery capacity of the battery module. The harmonic compensation capacity is determined based on the lower limit voltage, the first compensation capacity of the lower limit voltage, the upper limit voltage, the second compensation capacity of the upper limit voltage, and the current DC bus voltage, wherein the current DC bus voltage is greater than or equal to the lower limit voltage and less than or equal to the upper limit voltage. Then, the harmonics of the power grid are compensated according to the harmonic compensation capacity.

[0040] Unlike traditional active power filter methods, this invention determines the DC bus voltage operating range of the energy storage converter based on the operating voltage range of the battery modules. In other words, the operating range of the DC-side battery voltage of the energy storage converter is equivalent to the operating range of the DC bus voltage. Then, the current DC bus voltage of the energy storage converter is determined based on the battery modules, meaning the DC bus voltage is variable. In other words, the harmonic compensation capacity is automatically adjusted according to different DC bus voltages, which to a certain extent increases the harmonic compensation capability and flexibility, and improves the adaptive capability to compensate for harmonics in the power grid. Attached Figure Description

[0041] Figure 1 This is a flowchart illustrating the first embodiment of the harmonic compensation method of the present invention;

[0042] Figure 2 This is a schematic diagram of the hardware topology for harmonic mitigation in an energy storage converter.

[0043] Figure 3 This is a block diagram of the inner current loop control according to an embodiment of the harmonic compensation method of the present invention;

[0044] Figure 4 This is a block diagram of the inner current loop control according to another embodiment of the harmonic compensation method of the present invention;

[0045] Figure 5 This is a schematic diagram of the energy storage converter involved in the embodiment of the present invention;

[0046] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0047] This invention provides a harmonic compensation method, referring to... Figure 1 As shown, Figure 1 This is a flowchart illustrating the first embodiment of the harmonic compensation method of the present invention.

[0048] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0049] The harmonic compensation method of this application is applied to energy storage converters, with reference to... Figure 2 , Figure 2 This is a schematic diagram of the hardware topology for harmonic mitigation in an energy storage converter. The energy storage converter 10 is connected to the battery module 20. The energy storage converter 10 is also connected to the load 30 and the power grid 40. The power grid 40 is connected to the load 30. In other words, the connection between the load 30 and the power grid 40 is connected to the energy storage converter 10.

[0050] In this embodiment, it should be noted that the energy storage converter 10 is used to control the charging and discharging process of the battery, and can also perform AC-DC conversion, and can directly supply power to AC loads in the absence of a power grid.

[0051] Battery module 10 can be understood as an energy storage battery, also known as a accumulator.

[0052] Load 30 can be understood as load equipment, including but not limited to rectifier loads, frequency converter loads, medium frequency furnaces, commercial electric furnaces, electric arc furnaces, and resistance furnaces.

[0053] In this embodiment, the power grid contains a high level of harmonics due to uninterruptible power supplies, DC power supplies, rectifiers, chargers, variable frequency drives, energy-saving lamps, computers, and peripheral devices (i.e., load devices). This application can flexibly compensate for the harmonic content of the power grid based on the lower limit voltage, the first compensation capacity of the lower limit voltage, the upper limit voltage, the second compensation capacity of the upper limit voltage, and the current DC bus voltage, thereby improving the adaptive capability of the power grid harmonic compensation.

[0054] In this embodiment, the harmonic compensation method of the present invention is applied to a terminal device that compensates for harmonics in the power grid, and is specifically executed by the control center of the terminal device.

[0055] The harmonic compensation method of the present invention includes:

[0056] Step S10: Obtain the operating voltage range of the battery module 20, and determine the DC bus voltage operating range of the energy storage converter 10 based on the operating voltage range;

[0057] In this embodiment, the control center determines the operating voltage range of the battery module 20 based on the SOC (State of Charge) capacity range of the battery module 20, and then converts the operating voltage range of the battery module 20 into the DC bus voltage operating range of the energy storage converter 10. In other words, when the operating voltage range of the battery module 20 is determined, the DC bus voltage operating range of the energy storage converter 10 can be obtained.

[0058] Step S20: Obtain the lower limit voltage and upper limit voltage corresponding to the DC bus voltage operating range, as well as the first compensation capacity of the lower limit voltage and the second compensation capacity of the upper limit voltage;

[0059] In this embodiment, the control center can acquire the DC bus lower limit voltage V1 and DC bus upper limit voltage V2 corresponding to the DC bus voltage operating range. In addition, when it is determined that the DC bus voltage of the energy storage converter 10 is operating at the lower limit voltage V1, the first compensation capacity σ1 corresponding to the lower limit voltage V1 can be determined. In addition, when it is determined that the DC bus voltage of the energy storage converter 10 is operating at the upper limit voltage V2, the second compensation capacity σ2 corresponding to the upper limit voltage V2 can be determined.

[0060] Step S30: Obtain the current DC bus voltage of the energy storage converter 10 based on the current remaining battery capacity of the battery module 20, and determine the harmonic compensation capacity according to the lower limit voltage, the first compensation capacity, the upper limit voltage, the second compensation capacity and the current DC bus voltage, wherein the current DC bus voltage is greater than or equal to the lower limit voltage and the current DC bus voltage is less than or equal to the upper limit voltage;

[0061] In this embodiment, the control center first obtains the battery voltage corresponding to the current remaining battery capacity of the battery module 20, and then uses the battery voltage as the current DC bus voltage V of the energy storage converter 10. dc Based on the lower limit voltage V1, the first compensation capacity σ1, the upper limit voltage V2, the second compensation capacity σ2, and the current DC bus voltage V... dc The harmonic compensation capacity σ can be determined, where the current DC bus voltage V dc The current DC bus voltage V is greater than or equal to the lower limit voltage V1. dc Less than or equal to the upper limit voltage V2.

[0062] It should be noted that the current DC bus voltage V dc It changes with the current remaining battery capacity of battery module 20.

[0063] Additionally, it should be noted that the lower limit voltage V1, the first compensation capacity σ1, the upper limit voltage V2, the second compensation capacity σ2, and the current DC bus voltage V are all included. dc Substituting into formula (1), we can obtain the value of harmonic compensation capacity σ.

[0064]

[0065] Among them, based on the current DC bus voltage V dc The adaptive harmonic compensation capacity σ, in other words, is the current DC bus voltage V. dc The higher the value, the greater the harmonic compensation capacity σ.

[0066] Step S40: Compensate the harmonics of the power grid according to the harmonic compensation capacity.

[0067] In this embodiment, the control center can obtain the AC three-phase load current of the power grid, such as... Figure 2 As shown, i la i lb i lc These are the three-phase AC load currents. The harmonics of these three-phase AC load currents are then extracted using a preset harmonic extraction algorithm to obtain the target order load harmonic current i. lh and obtained

[0068] Take the load harmonic current i of the target order lh The corresponding effective value i lh_RMS Then, the target number of current inner loop given value i can be obtained by calculating using the following formula (2). h_ref The relationship in formula (2) is as follows:

[0069] i h_ref =(σ / i lh_RMS )*ilh (2)

[0070] Then obtain the AC three-phase inductor current of the energy storage converter, such as Figure 2 As shown, i a i b i c These are the AC three-phase inductor currents of the energy storage converter, and the feedback value of the current loop inductor current is determined based on the AC three-phase inductor currents; finally, the inner current loop setpoint i is determined based on the target number. h_ref and current loop inductor current feedback value i fdb Obtain the current inner loop control output value i h_out .

[0071] It should be noted that the AC three-phase inductor current of the energy storage converter can be understood as being obtained by a current sampling ear based on the Hall effect sensor connected to the inductor module.

[0072] Additionally, it should be noted that the target number is represented by h in the formulas of this application, where h is greater than or equal to 2.

[0073] Target number of load harmonic current i lh Including the target order of each phase load harmonic current i lkh (k = a, b, c); Transform the three-phase abc stationary coordinate system containing the load harmonic currents of phase a (first phase), phase b (second phase), and phase c (third phase) to a synchronous rotating coordinate system, i.e., the target order load harmonic current i. lh This can include the target order load harmonic current i along the d-axis. ld ( h+1 ) and q-axis target order load harmonic current i lq(h+1) ; Effective value i lh_RMS It can include the d-axis i ld(h+1)_RMS and q-axis i lq(h+1)_RMS Current inner loop control output value i h_out Including the d-axis current inner loop control output value i d_out and q-axis current inner loop control output value i q_out .

[0074] Additionally, it should be noted that the current inner loop control output value i h_out This can be understood as an intermediate variable. When the current loop inductor feedback value of the energy storage converter 10 completely tracks the target current inner loop given value, in other words, when the current loop inductor feedback value is the same as the data of the current loop inductor feedback value, it can play a role in suppressing the harmonics of the power grid, that is, compensating for the harmonics of the power grid.

[0075] In this invention, the DC bus voltage operating range of the energy storage converter 10 is determined based on the operating voltage range of the battery module 20. Then, the lower limit voltage and upper limit voltage corresponding to the DC bus voltage operating range are obtained. Next, the current DC bus voltage of the energy storage converter 10 is determined based on the battery module 20. The harmonic compensation capacity is determined based on the lower limit voltage, the first compensation capacity of the lower limit voltage, the upper limit voltage, the second compensation capacity of the upper limit voltage, and the current DC bus voltage. The current DC bus voltage is greater than or equal to the lower limit voltage, and the current DC bus voltage is less than or equal to the upper limit voltage. Then, the harmonics of the power grid are compensated according to the harmonic compensation capacity.

[0076] Unlike traditional active power filter methods, this invention determines the DC bus voltage operating range of the energy storage converter 10 based on the operating voltage range of the battery module 20. In other words, the operating range of the DC side battery voltage of the energy storage converter 10 is equivalent to the operating range of the DC bus voltage. Then, the current DC bus voltage of the energy storage converter is determined based on the battery module, meaning the DC bus voltage is variable. In other words, the harmonic compensation capacity is automatically adjusted according to different DC bus voltages, which to a certain extent increases the harmonic compensation capability and flexibility, and improves the adaptive capability of harmonic compensation.

[0077] Furthermore, based on the first embodiment of harmonic compensation of the present invention, a second embodiment of harmonic compensation of the present invention is proposed.

[0078] In this embodiment, step S30, which involves obtaining the current DC bus voltage of the energy storage converter 10 based on the current remaining battery capacity of the battery module 20, may further include the following implementation steps.

[0079] Step S301: Obtain the battery voltage corresponding to the current remaining battery capacity of the battery module 20;

[0080] In this embodiment, the control center can be connected to the battery module 20 via the energy storage converter 10 to obtain the battery voltage corresponding to the current remaining battery capacity of the battery module 20.

[0081] It should be noted that the battery voltage of battery module 20 will change according to the current remaining battery capacity.

[0082] Step S302: Use the battery voltage as the current DC bus voltage of the energy storage converter.

[0083] In this embodiment, the control center uses the battery voltage of the battery module 20 as the current DC bus voltage of the energy storage converter.

[0084] Furthermore, in some other feasible embodiments, the above step S30: determining the harmonic compensation capacity based on the lower limit voltage, the first compensation capacity, the upper limit voltage, the second compensation capacity, and the current DC bus voltage may also include the following implementation steps.

[0085] Step S303: Obtain the voltage difference between the lower limit voltage and the upper limit voltage, and obtain the compensation capacity difference between the first compensation capacity and the second compensation capacity;

[0086] In this embodiment, referring to formula (1), the control center first obtains the voltage difference (V1-V2) between the lower limit voltage V1 and the upper limit voltage V2, and can also determine the compensation capacity difference (σ1-σ2) between the first compensation capacity σ1 and the second compensation capacity σ2.

[0087] Step S304: Obtain the voltage compensation difference between the product of the lower limit voltage and the second compensation capacity and the product of the upper limit voltage and the first compensation capacity;

[0088] In this embodiment, referring to formula (1), the control center first determines the product of the lower limit voltage V1 and the second compensation capacity σ2, σ2V1, then determines the product of the upper limit voltage V2 and the first compensation capacity σ1, σ1V2, and then obtains the voltage compensation difference (σ2V1-σ1V2) based on the difference between the product σ2V1 and the product σ1V2.

[0089] Step S305: Determine the harmonic compensation capacity based on the current DC bus voltage, the voltage difference, the compensation capacity difference, and the voltage compensation difference.

[0090] In this embodiment, referring to formula (1), since the voltage difference (V1-V2), the compensation capacity difference σ1-σ2, and the voltage compensation difference (σ2V1-σ1V2) are all constant values, the current DC bus voltage V dc It is a changing value, depending on the current DC bus voltage V. dc As the harmonic compensation capacity σ changes, it also increases.

[0091] Furthermore, in some feasible embodiments, step S305 above, which determines the harmonic compensation capacity based on the current DC bus voltage, the voltage difference, the compensation capacity difference, and the voltage compensation difference, may also include the following implementation steps.

[0092] Step S3051: Adjust the harmonic compensation capacity in real time based on the current DC bus voltage, wherein the harmonic compensation capacity is obtained by summing the product of the reciprocal of the voltage difference, the current DC bus voltage and the compensation capacity difference, and the product of the reciprocal of the voltage difference and the voltage compensation difference.

[0093] In this embodiment, the control center can adjust the current DC bus voltage V. dc The harmonic compensation capacity σ is adjusted in real time, wherein the reciprocal of the voltage difference is used. With the current voltage V of the DC bus dc The product of the compensation capacity difference (σ1-σ2) and the reciprocal of the voltage difference. The product of the voltage compensation difference (σ2V1-σ1V2) and the voltage compensation difference is summed to obtain the harmonic compensation capacity σ.

[0094] Furthermore, in some other feasible embodiments, step S40 above, which involves compensating for the harmonics of the power grid according to the harmonic compensation capacity, may also include the following implementation steps.

[0095] Step S401: Obtain the AC three-phase load current of the power grid;

[0096] In this embodiment, refer to Figure 2 The control center is connected to the energy storage converter 10 through the connection terminal between the load 30 and the power grid 40, and can obtain the AC three-phase load current of the power grid 40, where i la i lb i lc These are the three-phase AC load currents.

[0097] Step S402: Extract the harmonics of the AC three-phase load current using a preset harmonic extraction algorithm to obtain the target order load harmonic current, and obtain the effective value corresponding to the target order load harmonic current.

[0098] In this embodiment, the control center extracts the harmonics of the three-phase AC load current using a preset harmonic extraction algorithm to obtain the target order load harmonic current i. lh And obtain the effective value i corresponding to the target order load harmonic current. lh_RMS .

[0099] Step S403: Based on the effective value, the target order load harmonic current, and the harmonic compensation capacity, obtain the inner loop setpoint value of the target order current;

[0100] In this embodiment, the control center determines the effective value i. lh_RMS Target number of load harmonic current i lh Harmonic compensation capacity σ yields the target order current inner loop setpoint i h_ref .

[0101] It should be noted that the target order load harmonic current i is calculated according to the preset root mean square algorithm. lhCalculations are performed to obtain the effective value i of the target harmonic current. lh_RMS .

[0102] Step S404: Obtain the AC three-phase inductor current of the energy storage converter 10, and determine the current loop inductor current feedback value based on the AC three-phase inductor current, wherein the AC three-phase inductor current is obtained by current sampling on the inductor module of the energy storage converter;

[0103] In this embodiment, the hardware topology for harmonic mitigation of the energy storage converter is as follows: Figure 2 As shown, inductor module L is an AC filter inductor, and C is an AC filter capacitor. The control center determines the AC three-phase inductor current based on inductor module L of the energy storage converter 10, where i a i b i c These are the AC three-phase inductor currents of the energy storage converter 10, and then the current loop inductor current feedback value i is determined based on the AC three-phase inductor currents. fab .

[0104] It should be noted that the current feedback value i of the current loop inductor fdb This can include the d-axis inductor current feedback value i d and q-axis inductor current feedback value i q .

[0105] Step S405: Obtain the current inner loop control output value based on the target number of current inner loop given value and the current loop inductor current feedback value.

[0106] In this embodiment, refer to Figure 3 , Figure 3 This is a block diagram of the inner current loop control according to an embodiment of the harmonic compensation method of the present invention. The control center first determines the target order current inner loop setpoint i. h_ref and i fdb The difference data between the two is then transmitted to the PR (proportional resonant regulator), where it is processed according to the transfer function to obtain the current loop output value i. h_out .

[0107] In yet another embodiment, reference is made to... Figure 4 , Figure 4 This is a block diagram of the inner current loop control according to another embodiment of the harmonic compensation method of the present invention. The control center sets the d-axis current loop setpoint i. dlh_ref and d-axis inductor current feedback value i d The difference data is transmitted to the PR (proportional resonant regulator) and processed using the transfer function in the proportional resonant regulator to obtain the d-axis current loop output i. d_out The control center sets the q-axis current loop setpoint i.qlh_ref and q-axis inductor current feedback value i q The difference data is transmitted to the PR (proportional resonant regulator) and processed using the transfer function in the proportional resonant regulator to obtain the q-axis current loop output i. q_out .

[0108] Step S406: The output value of the inner current control loop is superimposed on the output of the energy storage converter to compensate for the harmonics of the power grid.

[0109] In this embodiment, the control center superimposes the output value of the inner current loop control onto the output of the energy storage converter to compensate for the harmonics of the power grid.

[0110] Furthermore, in some other feasible embodiments, step S402 above: obtaining the effective value corresponding to the target number of load harmonic current may also include the following implementation steps.

[0111] Step S4021: Transform the first phase load harmonic current, the second phase load harmonic current and the third phase load harmonic current from the three-phase stationary coordinate system to the synchronous rotating coordinate system through the preset Clark transformation and the preset Park transformation, so as to obtain the direct axis target order load harmonic current and the quadrature axis target order load harmonic current.

[0112] In this embodiment, the control center transforms the first phase load harmonic current, the second phase load harmonic current, and the third phase load harmonic current of the target order from the three-phase stationary coordinate system to the synchronous rotating coordinate system through preset Clark transformation and preset Park transformation, so as to obtain the direct axis target order load harmonic current and the quadrature axis target order load harmonic current.

[0113] For example, in a three-phase abc stationary coordinate system, the target order load harmonic current Includes: the load harmonic current i of each phase at the target order. lkh (k = a, b, c), where the first phase load harmonic current of the target order can be represented by i lah This is also called the a-phase load harmonic current; the target order second-phase load harmonic current can be represented by i. lbh This is also called the b-phase load harmonic current; the target order third-phase load harmonic current can be represented by i. lch The term "c-phase load harmonic current" is also referred to as the c-phase load harmonic current. The control center can transform the three-phase abc stationary coordinate system containing the a-phase load harmonic current, b-phase load harmonic current, and c-phase load harmonic current into the synchronous rotating coordinate system by successively performing the Clark transformation and Park transformation as shown in equations (3) and (4).

[0114] The Clark transform can be expressed as follows:

[0115]

[0116] Assuming the current rotates with an angular velocity ω, and setting the initial phase angle to 0, then at any time t, we have the following equation:

[0117]

[0118] The transformation from the three-phase abc stationary coordinate system to the synchronously rotating dq coordinate system can be obtained from formulas (3) and (4), as shown in formula (5):

[0119]

[0120] In other words, after the control center transforms the three-phase abc stationary coordinate system containing the a-phase load harmonic current, b-phase load harmonic current, and c-phase load harmonic current to the synchronous rotating coordinate system, it can obtain the direct-axis target order load harmonic current (i.e., the d-axis target order load harmonic current i). ld(h+1) ) and the target order load harmonic current (i.e., the target order load harmonic current i) on the quadrature axis. lq(h+1) That is, in the synchronous rotating coordinate system, the target order load harmonic current i lh Includes: d-axis target order load harmonic current i ld(h+1) and q-axis target order load harmonic current i lq(h+1) .

[0121] It should be noted that the d-axis in the dq coordinate system is also called the direct axis, and the q-axis is also called the intersection axis.

[0122] In another embodiment, after transforming from the three-phase abc stationary coordinate system to the synchronous rotating coordinate system, i a i b i c Substituting into formula (5), the harmonic current i of the direct-axis load can be obtained similarly. d and cross-axis load harmonic current i q As shown in formula (6):

[0123]

[0124] Step S4022: Obtain the first effective value of the direct-axis target order load harmonic current and the second effective value of the quadrature-axis target order load harmonic current, and use the first effective value and the second effective value as the effective value.

[0125] In this embodiment, after determining the load harmonic current i to the target order on the d-axis ld(h+1) and q-axis target order load harmonic current i lq(h+1) Then, through effective value calculation (using the preset root mean square algorithm), i can be obtained respectively.ld(h+1) and i lq(h+1) The effective value is i ld(h+1)_RMS and i lq(h+1)_RMS .

[0126] Furthermore, in some feasible embodiments, the above step S403: obtaining the inner loop given value of the target order current based on the effective value, the target order load harmonic current, and the harmonic compensation capacity may also include the following implementation steps.

[0127] Step S4031: Determine the product data between the harmonic compensation capacity and the reciprocal of the effective value;

[0128] In this embodiment, the control center first determines the harmonic compensation capacity σ and the reciprocal i of the effective value. lh_RMS The product data between (σ / i) lh_RMS ).

[0129] Step S4032: Obtain the inner loop setpoint of the target order current based on the product of the product data and the target order load harmonic current.

[0130] In this embodiment, the control center uses the product data (σ / i) lh_RMS ) and target order load harmonic current i lh The product of the two yields the target number of current inner loop given value i. h_ref .

[0131] It should be noted that the target number of times the inner loop current is given by i. h_ref Including the inner current loop setpoint i for d-axis target order harmonic compensation ldh_ref The inner loop current setpoint i for q-axis target order harmonic compensation lqh_ref .

[0132] In another embodiment, the control center will use the target order load harmonic current i on the d-axis calculated by the above formula (5) and the preset root mean square value. ld(h+1) q-axis target order load harmonic current i lq(h+1) d-axis effective value i ld(h+1)_RMS and the effective value of the q-axis i lq(h+1)_RMS Substituting these values ​​into formula (7), we can obtain the inner loop current setpoint i for d-axis target harmonic compensation. ldh_ref The inner loop current setpoint i for q-axis target order harmonic compensation lqh_ref Formula (7) is shown below:

[0133]

[0134] Furthermore, in some other feasible embodiments, the above step S405: obtaining the current inner loop control output value based on the target number of current inner loop given value and the current loop inductor current feedback value may also include the following implementation steps.

[0135] Step S4051: Obtain the difference data between the target number of current inner loop given value and the current loop inductor current feedback value;

[0136] In this embodiment, the control center first determines the target number of times the inner loop current setpoint i. h_ref and i fdb The difference data between them.

[0137] Step S4052: Determine the current inner loop control output value based on the difference data and the preset transfer function.

[0138] In this embodiment, the control center transmits the difference data to the PR (proportional resonant regulator), and processes the difference data according to the transfer function in the proportional resonant regulator to obtain the current loop output value i. h_out .

[0139] It should be noted that the preset transfer function can be understood as the transfer function in the proportional resonant regulator, and its expression is shown in formula (8):

[0140]

[0141] Where K p K is the proportionality coefficient. r ω is the resonance coefficient. c ω is the cutoff frequency of the quasi-resonant modulator. h The frequency of the h-th harmonic is angular frequency.

[0142] Additionally, it should be noted that, due to the proportional resonant regulator at a fixed frequency f h Since the gain is infinite at the resonant frequency, zero steady-state error control of a sinusoidal signal can be achieved. Therefore, by designing a reasonable K... p K r and ω c With the given parameters, harmonic compensation can be achieved through current inner loop control.

[0143] In summary, the harmonic compensation of this application can increase the harmonic compensation capacity when the DC bus voltage is high, and can still ensure that the harmonic compensation capacity is within a certain range when the DC bus voltage is low, thereby improving the adaptive capability of the DC bus voltage adaptive harmonic compensation capacity.

[0144] Furthermore, the present invention also provides a terminal device. Please refer to... Figure 5 , Figure 5This is a schematic diagram of the energy storage converter involved in an embodiment of the present invention. Specifically, the terminal device in this embodiment of the present invention may be a device for locally operating harmonic compensation.

[0145] like Figure 5 As shown, the energy storage converter in this embodiment of the invention may further include: a processor 1001, such as a CPU; a communication bus 1002; a user interface 1003; a network interface 1004; a memory 1005; and a sensing unit 1006. The communication bus 1002 is used to enable communication between these components. The user interface 1003 may include a display screen and an input unit such as a keyboard; optionally, the user interface 1003 may also include a standard wired interface or a wireless interface. The network interface 1004 may optionally include a standard wired interface or a wireless interface (such as a Wi-Fi interface).

[0146] The memory 1005 is disposed on the main body of the terminal device. The memory 1005 stores a program that performs corresponding operations when executed by the processor 1001. The memory 1005 is also used to store parameters for use by the terminal device. The memory 1005 can be a high-speed RAM or a stable, non-volatile memory, such as a disk drive. Optionally, the memory 1005 can also be a storage device independent of the aforementioned processor 1001.

[0147] Those skilled in the art will understand that Figure 5 The terminal device structure shown does not constitute a limitation on the terminal device and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0148] like Figure 5 As shown, the memory 1005, which serves as a storage medium, may include an operating system, a network communication module, a user interface module, and a harmonic compensation program for a terminal device.

[0149] exist Figure 5 In the terminal device shown, the processor 1001 can be used to call the harmonic compensation program of the terminal device stored in the memory 1005 to implement the steps of the above-described harmonic compensation method.

[0150] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0151] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0152] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a computer-readable storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0153] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A harmonic compensation method, characterized in that, The harmonic compensation method is applied to an energy storage converter, which is connected to a battery module and to the power grid. The harmonic compensation method includes: Obtain the operating voltage range of the battery module, and determine the DC bus voltage operating range of the energy storage converter based on the operating voltage range; Obtain the lower limit voltage and upper limit voltage corresponding to the DC bus voltage operating range, as well as the first compensation capacity of the lower limit voltage and the second compensation capacity of the upper limit voltage; The current DC bus voltage of the energy storage converter is obtained based on the current remaining battery capacity of the battery module, and the harmonic compensation capacity is determined based on the lower limit voltage, the first compensation capacity, the upper limit voltage, the second compensation capacity, and the current DC bus voltage, wherein the current DC bus voltage is greater than or equal to the lower limit voltage, and the current DC bus voltage is less than or equal to the upper limit voltage. The harmonics of the power grid are compensated according to the aforementioned harmonic compensation capacity; wherein, The step of determining the harmonic compensation capacity based on the lower limit voltage, the first compensation capacity, the upper limit voltage, the second compensation capacity, and the current DC bus voltage includes: Obtain the voltage difference between the lower limit voltage and the upper limit voltage, and obtain the compensation capacity difference between the first compensation capacity and the second compensation capacity; Obtain the voltage compensation difference between the product of the lower limit voltage and the second compensation capacity and the product of the upper limit voltage and the first compensation capacity; The harmonic compensation capacity is adjusted in real time based on the current DC bus voltage, wherein the harmonic compensation capacity is obtained by summing the product of the reciprocal of the voltage difference, the current DC bus voltage and the compensation capacity difference, and the product of the reciprocal of the voltage difference and the voltage compensation difference.

2. The harmonic compensation method as described in claim 1, characterized in that, The step of compensating for harmonics in the power grid according to the harmonic compensation capacity includes: Obtain the AC three-phase load current of the power grid; The harmonics of the AC three-phase load current are extracted using a preset harmonic extraction algorithm to obtain the target order load harmonic current, and the effective value corresponding to the target order load harmonic current is obtained. The inner loop setpoint of the target order current is obtained based on the effective value, the target order load harmonic current, and the harmonic compensation capacity. The AC three-phase inductor current of the energy storage converter is obtained, and the current loop inductor current feedback value is determined based on the AC three-phase inductor current. The AC three-phase inductor current is obtained by current sampling on the inductor module of the energy storage converter. The current inner loop control output value is obtained based on the target number current inner loop setpoint and the current loop inductor current feedback value. The output value of the inner current control loop is superimposed on the output of the energy storage converter to compensate for the harmonics of the power grid.

3. The harmonic compensation method as described in claim 2, characterized in that, The target-order load harmonic current includes: a first-phase load harmonic current of the target order, a second-phase load harmonic current of the target order, and a third-phase load harmonic current of the target order. The step of obtaining the effective value corresponding to the target-order load harmonic current includes: The first phase load harmonic current, the second phase load harmonic current, and the third phase load harmonic current are transformed from the three-phase stationary coordinate system to the synchronous rotating coordinate system through the preset Clark transformation and the preset Park transformation, so as to obtain the direct axis target order load harmonic current and the quadrature axis target order load harmonic current. Obtain the first effective value of the direct-axis target order load harmonic current and the second effective value of the quadrature-axis target order load harmonic current, and use the first effective value and the second effective value as the effective value.

4. The harmonic compensation method as described in claim 2, characterized in that, The step of obtaining the inner loop setpoint of the target order current based on the effective value, the target order load harmonic current, and the harmonic compensation capacity includes: Determine the product data between the harmonic compensation capacity and the reciprocal of the effective value; The inner loop setpoint of the target order current is obtained by multiplying the product data with the target order load harmonic current.

5. The harmonic compensation method as described in claim 2, characterized in that, The step of obtaining the current inner loop control output value based on the target number of current inner loop setpoints and the current loop inductor current feedback value includes: Obtain the difference data between the target number of times current inner loop given value and the current loop inductor current feedback value; The current inner loop control output value is determined based on the difference data and the preset transfer function.

6. The harmonic compensation method as described in claim 1, characterized in that, The step of obtaining the current DC bus voltage of the energy storage converter based on the current remaining battery capacity of the battery module includes: Obtain the battery voltage corresponding to the current remaining battery capacity of the battery module; The battery voltage is used as the current DC bus voltage of the energy storage converter.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a harmonic compensation program, which, when executed by a processor, implements the steps of the harmonic compensation method as described in any one of claims 1 to 6.

8. An energy storage converter, characterized in that, The energy storage converter is connected to the battery module and the power grid respectively, and the energy storage converter includes the computer-readable storage medium as described in claim 7.

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