Equipment control method, energy storage equipment and storage medium

Abstract

The invention provides an equipment control method, energy storage equipment and a storage medium, and the method comprises the steps: determining a first active droop coefficient and a first reactive droop coefficient according to the rated power of a power converter; determining a direct current bus voltage and a preset voltage value of the direct current bus corresponding to the power converter, and determining a second active droop coefficient according to the direct current bus voltage and the preset voltage value; determining a third active droop coefficient according to the first active droop coefficient and the second active droop coefficient; and controlling the power converter according to the third active droop coefficient and the first reactive droop coefficient. According to the invention, the output power can be balanced, and the ring current suppression effect can be improved.

Description

Technical Field

[0001] The present application belongs to the field of energy storage technology, and in particular, relates to a device control method, an energy storage device, and a storage medium. Background Art

[0002] With the rapid development of photovoltaic energy storage technology, the parallel application of power converters is increasing, among which droop control is a common parallel control method.

[0003] In the related art, droop control mostly adopts a fixed droop coefficient, which easily affects the output power balance and the suppression effect of circulating current. Summary of the invention

[0004] The embodiments of the present application provide a device control method, an energy storage device and a storage medium, which can solve the problem that the use of a fixed droop coefficient in a parallel system of multiple power converters easily affects the output power balance and the suppression effect of circulating current.

[0005] In a first aspect, an embodiment of the present application provides a device control method, which is applied to an energy storage device, wherein the energy storage device includes a power converter and a DC bus, and the power converter is connected to the DC bus. The method includes: determining a first active droop coefficient and a first reactive droop coefficient based on the rated power of the power converter; determining a DC bus voltage and a preset voltage value of the power converter corresponding to the DC bus, and determining a second active droop coefficient based on the DC bus voltage and the preset voltage value; determining a third active droop coefficient based on the first active droop coefficient and the second active droop coefficient; and controlling the power converter based on the third active droop coefficient and the first reactive droop coefficient.

[0006] In a possible embodiment, determining a first active droop coefficient and a first reactive droop coefficient based on the rated power of the power converter includes: determining a frequency change threshold and a voltage change threshold corresponding to the power converter; determining the first active droop coefficient based on the rated power and the frequency change threshold; determining the first reactive droop coefficient based on the rated power and the voltage change threshold.

[0007] In a possible embodiment, determining the second active power droop coefficient based on the DC bus voltage and the preset voltage value includes: determining a target voltage based on the DC bus voltage and the preset voltage value; determining a voltage droop coefficient corresponding to the DC bus; and determining the second active power droop coefficient based on the target voltage and the voltage droop coefficient.

[0008] In a possible embodiment, after determining the second active power droop coefficient based on the DC bus voltage and the preset voltage value, the method further includes: if the second active power droop coefficient is less than or equal to a preset coefficient threshold, keeping the second active power droop coefficient unchanged; if the second active power droop coefficient is greater than the preset coefficient threshold, updating the second active power droop coefficient to the preset coefficient threshold.

[0009] In a possible embodiment, controlling the power converter based on the third active power droop coefficient and the first reactive power droop coefficient includes: determining the active power and reactive power corresponding to the power converter; determining the reference frequency and reference voltage corresponding to the power converter; determining the reference frequency based on the active power, the reference frequency and the third active power droop coefficient, and determining the reference voltage based on the reactive power, the reference voltage and the first reactive power droop coefficient; and controlling the power converter based on the reference frequency and the reference voltage.

[0010] In a possible embodiment, determining the reference frequency based on the active power, the reference frequency and the third active droop coefficient includes: determining the frequency change value corresponding to the power converter based on the third active droop coefficient and the active power; determining the reference frequency based on the reference frequency and the frequency change value.

[0011] In a possible embodiment, determining the reference voltage based on the reactive power, the reference voltage and the first reactive droop coefficient includes: determining the voltage change value corresponding to the power converter based on the first reactive droop coefficient and the reactive power; determining the reference voltage based on the reference voltage and the voltage change value.

[0012] In a possible embodiment, controlling the power converter according to the reference frequency and the reference voltage includes: determining an angular frequency according to the reference frequency; and controlling an output voltage corresponding to the output of the power converter according to the angular frequency and the reference voltage.

[0013] In a second aspect, an embodiment of the present application further provides an energy storage device, the energy storage device further comprising a processor and a memory, the processor being configured to implement any one of the above-described device control methods when executing a computer program stored in the memory.

[0014] In a third aspect, an embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor in an energy storage device, any of the above-mentioned device control methods is implemented.

[0015] In the device control method provided in the embodiment of the present application, the first active droop coefficient and the first reactive droop coefficient are determined according to the rated power of the power converter, so that when power converters of different models are connected in parallel, each power converter can operate in a corresponding proportion to achieve power balance between different models; and the present application adjusts the active droop coefficient in real time based on the DC bus voltage, which can effectively avoid the problem of overvoltage on the DC bus during parallel operation and ensure the stability of the parallel system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings.

[0017] Figure 1 It is a schematic diagram of the droop characteristics provided in an embodiment of the present application.

[0018] Figure 2 It is an application scenario diagram of the device control method provided in the embodiment of the present application.

[0019] Figure 3 It is a flow chart of the device control method provided in the embodiment of the present application.

[0020] Figure 4 It is a schematic diagram of the process of determining the droop coefficient provided in the embodiment of the present application.

[0021] Figure 5 It is a schematic diagram of the determination process of the second droop coefficient provided in an embodiment of the present application.

[0022] Figure 6 It is a schematic diagram of the control flow of the power converter provided in an embodiment of the present application.

[0023] Figure 7 It is a flow chart of a method for determining an output voltage provided in an embodiment of the present application.

[0024] Figure 8 It is a flow chart of the device control method provided in the embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. The embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0028] With the rapid development of photovoltaic energy storage technology, the parallel application of power converters is increasing. In order to achieve automatic coordination between multiple power converters, ensure the stable operation of the parallel system and load balance distribution, a parallel control strategy can be adopted. Among them, droop control is a common parallel control strategy. Droop control controls the power distribution of parallel power converters by simulating the droop characteristics of synchronous generators in traditional power systems. Among them, the droop characteristics can include the linear relationship between the active power output of the power converter and the voltage frequency, and the linear relationship between the reactive power and the voltage amplitude. When the active power and reactive power output by the power converter change, the frequency and amplitude of the corresponding voltage of the power converter change linearly according to the droop characteristic curve. Among them, active power can represent the energy conversion rate at which the power converter actually completes the work in unit time, represented by P; reactive power can represent the energy conversion rate at which part of the electric energy oscillates back and forth between the power source and the load without doing actual work in the AC circuit due to the presence of reactance (for example, capacitors and inductors), represented by Q.

[0029] Combination Figure 1 The following is a schematic diagram illustrating the droop characteristics provided by the embodiment of the present application. Figure 1 As shown, the horizontal axis represents the active power P output by the power converter, and the vertical axis represents the frequency w of the voltage corresponding to the power converter, P max Indicates the maximum active power of the power converter, P min Indicates the minimum active power of the power converter. When the active power output of the power converter increases, the active power output of the power converter will decrease by reducing the frequency of the corresponding voltage of the power converter; when the active power output of the power converter decreases, the active power output of the power converter will increase by increasing the frequency of the corresponding voltage of the power converter. Finally, the power converters in the parallel system will reach power balance at a new output frequency point (for example, Figure 1 Medium set ).

[0030] In droop control, a droop coefficient is usually set, which can be used to describe the relationship between the output power of the power converter and the frequency (or voltage). The droop coefficient is a key parameter in the parallel control strategy, affecting the stability and reliability of the entire parallel system. The droop control coefficient can include an active droop coefficient and a reactive droop coefficient, wherein the active droop coefficient can be used to describe the relationship between the active power output of the power converter and the frequency, and the reactive droop coefficient can be used to describe the relationship between the reactive power output of the power converter and the voltage.

[0031] In the related art, droop control mostly adopts a fixed droop coefficient, for example, the following formula 1 and formula 2 are used to perform droop control:

[0032] Formula 1: w = w0-K p *P.

[0033] Formula 2: V = V0 - K q *Q.

[0034] Wherein, w represents the frequency output by the power converter, V represents the voltage output by the power converter, w0 represents the reference frequency of the power converter, V0 represents the reference voltage of the power converter, P represents the active power of the power converter, Q represents the reactive power of the power converter, and K p represents the fixed active power droop coefficient of the power converter, K q Represents the fixed reactive droop factor of the power converter.

[0035] However, if the hardware parameters of the power converters running in parallel are different, or the line impedance does not match, the use of a fixed droop coefficient may not ensure that the load is evenly distributed among the power converters, resulting in some power converters being overloaded and others being underloaded, affecting the balance of the power converter output power. In addition, when there is a difference in voltage phase or amplitude between the parallel power converters, a circulating current may be generated, causing part of the energy to circulate between the power converters without outputting power to the outside, resulting in overvoltage of the DC bus connected to the power converter, and the stability of the parallel system cannot be guaranteed.

[0036] In view of this, it is necessary to provide a device control method that can achieve power balance between different models and effectively avoid the problem of overvoltage on the DC bus during parallel operation to ensure the stability of the parallel system.

[0037] Figure 2: is an application scenario diagram of the device control method provided in the embodiment of the present application. The device control method is applied to the energy storage device 1, the energy storage device 1 is connected to the load device 2, and the energy storage device 1 provides power to the load device 2, so that the load device 2 can operate normally. Among them, the energy storage device 1 can be an electronic device with energy storage function, and the load device 2 can include but is not limited to household appliances (for example, refrigerators, lighting equipment, air conditioners, etc.), industrial equipment (for example, conveyor belts, robotic arms, etc.), power grids, etc. In some embodiments, the energy storage device 1 may include a battery pack 11, a power converter 12 and a DC bus 13, wherein the battery pack 11 can be used to provide direct current, and the power converter 12 can be used to convert direct current into alternating current, so that the power of the battery pack 11 is converted into the alternating current required by the load device 2, for example, the power converter 12 is an inverter. In some embodiments, the number of battery packs 11 can be 1 or more. The embodiment of the present application takes the number of battery packs 12 as 1 as an example, and the number of power converters 12 can be more than one, for example, power converter 1, power converter 2, ..., power converter n. The battery pack 11 and the multiple power converters 12 may be connected via a DC bus 13 to achieve parallel configuration of the multiple power converters 12 .

[0038] In some embodiments, in the scenario where multiple power converters 12 are connected in parallel, droop control is used to ensure stable operation of the parallel system and balanced load distribution. In droop control, the embodiment of the present application achieves power balancing between different models by adaptively adjusting the droop coefficient of the power converter 12, effectively avoiding the problem of overvoltage on the DC bus 13 during parallel operation, and ensuring the stability of the parallel system.

[0039] Figure 3 is a flow chart of a device control method provided in an embodiment of the present application, and the device control method is applied to an energy storage device (for example, Figure 2 Energy storage device in 1). Figure 3 The method comprises the following steps:

[0040] S11, determining a first active power droop coefficient and a first reactive power droop coefficient according to the rated power of the power converter.

[0041] In at least one embodiment of the present application, the rated power of the power converter may represent the maximum power that the power converter can continuously and stably output under specified working conditions. Different types of power converters all have corresponding rated powers. In some embodiments, the correspondence between different types of power converters and rated powers may be pre-set, and by querying the correspondence, the rated power corresponding to the power converter may be determined.

[0042] In some embodiments, a preset value can be determined based on the parallel effect of multiple power converters, and then a first active droop coefficient and a first reactive droop coefficient are determined respectively based on the preset value and the rated power of the power converter. The preset value is used to describe the value that enables the power converter to operate within a preset range of the rated output frequency or the rated output voltage, wherein the preset range can be set according to actual needs and is not limited here. The rated output frequency can represent the standard frequency of the AC voltage output by the power converter under normal conditions, and the rated output voltage can represent the voltage that the power converter can continuously and stably output under specified input and load conditions.

[0043] In some embodiments, the preset value can be set according to the type of power output of the power converter. For example, the type of power output of the power converter can include active power and reactive power. Accordingly, the number of preset values ​​can be 2, namely, a first preset value and a second preset value. The first preset value corresponds to the active power, and the first preset value is used to describe the value that makes the power converter work within the preset range of the rated output frequency; the second preset value corresponds to the reactive power, and the second preset value is used to describe the value that makes the power converter work within the preset range of the rated output voltage. In some embodiments, according to the rated power of the power converter and the first preset value, the first active droop coefficient of the power converter can be determined; according to the rated power of the power converter and the second preset value, the first reactive droop coefficient of the power converter can be determined.

[0044] S12, determining a DC bus voltage of the power converter corresponding to the DC bus and a preset voltage value, and determining a second active power droop coefficient according to the DC bus voltage and the preset voltage value.

[0045] In at least one embodiment of the present application, the DC bus voltage may represent the voltage of the DC bus connected to the power converter, and a voltage sensor may be installed in the DC bus to monitor and output the DC bus voltage in real time according to the voltage sensor. The preset voltage value may represent the regulated voltage after the DC bus voltage exceeds a threshold value, and by setting the preset voltage value, a protection operation may be automatically performed to reduce the DC bus voltage after the DC bus voltage exceeds the threshold value, thereby ensuring the safe operation of the parallel system. The preset voltage value and the threshold value may be set according to actual needs, and are not limited here.

[0046] In some embodiments, a second active droop coefficient can be determined according to the DC bus voltage and the preset voltage value, the second active droop coefficient can change in real time according to the DC bus voltage, and the second active droop coefficient is used to compensate for the first active droop coefficient. By setting the second active droop coefficient, the problem of overvoltage of the DC bus when multiple power converters are connected in parallel can be effectively avoided, thereby ensuring the stability of the parallel system.

[0047] S13: Determine a third active power droop coefficient according to the first active power droop coefficient and the second active power droop coefficient.

[0048] In at least one embodiment of the present application, the second active power droop coefficient is superimposed on the first active power droop coefficient to obtain a third active power droop coefficient.

[0049] S14, controlling the power converter according to the third active power droop coefficient and the first reactive power droop coefficient.

[0050] In at least one embodiment of the present application, the frequency of the power converter output is controlled according to the third active power droop coefficient, and the active power output by the power converter is controlled by adjusting the frequency. The voltage of the power converter output is controlled according to the first reactive power droop coefficient, and the reactive power output by the power converter is controlled by adjusting the voltage.

[0051] Exemplarily, when the active power output by the power converter increases, the frequency of the power converter output can be reduced according to the third active power droop coefficient, and the active power output by the power converter will decrease accordingly; when the active power output by the power converter decreases, the frequency of the power converter output can be increased according to the third active power droop coefficient, and the active power output by the power converter will increase accordingly. Ultimately, the power converters in the parallel system will reach power balance at a new output frequency point.

[0052] As another example, when the reactive power output by the power converter increases, the voltage output by the power converter can be reduced according to the first reactive droop coefficient, and the reactive power output by the power converter will decrease accordingly; when the reactive power output by the power converter decreases, the voltage output by the power converter can be increased according to the first reactive droop coefficient, and the reactive power output by the power converter will increase accordingly, and ultimately the power converters in the parallel system will reach power balance at a new output voltage point.

[0053] In the device control method provided in the embodiment of the present application, the first active droop coefficient and the first reactive droop coefficient are determined according to the rated power of the power converter, so that when power converters of different models are connected in parallel, each power converter can operate in a corresponding proportion to achieve power balance between different models; and the present application adjusts the active droop coefficient in real time based on the DC bus voltage, which can effectively avoid the problem of overvoltage on the DC bus during parallel operation and ensure the stability of the parallel system.

[0054] In at least one embodiment of the present application, a preset value can be determined based on the parallel effect of multiple power converters, and then the first active droop coefficient and the first reactive droop coefficient are determined respectively based on the preset value and the rated power of the power converter. Among them, the preset value may include a first preset value and a second preset value, and the first preset value is used to describe the value that makes the power converter work within the preset range of the rated output frequency. For example, the first preset value can be a frequency change threshold, that is, the maximum frequency change, and the frequency change threshold can be 0.942 radians / second. The second preset value is used to describe the value that makes the power converter work within the preset range of the rated output voltage. For example, the second preset value can be a voltage change threshold, that is, the maximum voltage change, and the power change threshold can be the rated output voltage*5%.

[0055] Figure 4 is a schematic diagram of the determination process of the droop coefficient provided in the embodiment of the present application. Figure 4 As shown, the frequency change threshold and the voltage change threshold corresponding to the power converter are determined. According to the rated power and the frequency change threshold, the first active power droop coefficient is determined. According to the rated power and the voltage change threshold, the first reactive power droop coefficient is determined.

[0056] In some embodiments, the first active power droop coefficient may be determined according to the rated power and the frequency change threshold using the following formula 3:

[0057] Formula 3: K p0 =Δw max / Prate.

[0058] Among them, K p0 Indicates the first active power droop coefficient, Δw max Indicates the frequency change threshold, and Prate indicates the rated power.

[0059] In some embodiments, the first reactive power droop coefficient may be determined according to the rated power and the voltage change threshold using the following formula 4:

[0060] Formula 4: K q0 =ΔV max / Prate.

[0061] Among them, K q0 Represents the first reactive droop coefficient, ΔV max It indicates the voltage change threshold, and Prate indicates the rated power.

[0062] In the device control method provided in the embodiment of the present application, the first active droop coefficient and the first reactive droop coefficient are determined according to the rated power of the power converter, so that when power converters of different models are connected in parallel, each power converter can operate in a corresponding proportion to achieve power balance between different models.

[0063] In at least one embodiment of the present application, the second active droop coefficient can be determined according to the DC bus voltage of the DC bus connected to the power converter, and then the first active droop coefficient is compensated by the second active droop coefficient. In some embodiments, the voltage droop coefficient corresponding to the DC bus can be determined, and then the second active droop coefficient is determined according to the voltage droop coefficient, the DC bus voltage and the preset voltage value. Among them, the voltage droop coefficient can be set according to actual needs, for example, the voltage droop coefficient can be 0.0000942.

[0064] Figure 5 is a schematic diagram of the determination process of the second droop coefficient provided in the embodiment of the present application. Figure 5 As shown, the target voltage is determined based on the DC bus voltage and the preset voltage value; the voltage droop coefficient corresponding to the DC bus is determined; and the second active power droop coefficient is determined based on the target voltage and the voltage droop coefficient.

[0065] In some embodiments, the target voltage is determined according to the DC bus voltage and the preset voltage value using Formula 5:

[0066] Formula 5: V = V bus –V bus_overref .

[0067] Where V represents the target voltage, V bus Indicates the DC bus voltage, V bus_overref Indicates the preset voltage value.

[0068] In some embodiments, the second active power droop coefficient is determined according to the target voltage and the voltage droop coefficient using Formula 6:

[0069] Formula 6: K p_bus =V*K bus .

[0070] Among them, K p_bus represents the second active power droop coefficient, V represents the target voltage, K bus Indicates the voltage droop coefficient.

[0071] In the device control method provided in the embodiment of the present application, the second active droop coefficient is determined based on the DC bus voltage. When the DC bus voltage exceeds the preset voltage value, the second active droop coefficient is used to compensate for the first active droop coefficient. By setting the second active droop coefficient, the problem of overvoltage in the DC bus when multiple power converters are connected in parallel can be effectively avoided, and the stability of the parallel system can be ensured. For example, when the DC bus voltage increases, the active droop coefficient will increase accordingly, so that the frequency of the power converter decreases, and the active power output by the power converter increases, so that the DC bus voltage can drop quickly, effectively avoiding the problem of overvoltage in the DC bus when connecting in parallel, and ensuring the stability of the parallel system.

[0072] In at least one embodiment of the present application, after determining the second active droop coefficient according to the DC bus voltage and the preset voltage value, the second active droop coefficient can also be limited to avoid the second active droop coefficient being too large, thereby improving the accuracy of power converter control. In some embodiments, the method further includes: if the second active droop coefficient is less than or equal to the preset coefficient threshold, the second active droop coefficient is kept unchanged; if the second active droop coefficient is greater than the preset coefficient threshold, the second active droop coefficient is updated to the preset coefficient threshold. Among them, the preset coefficient threshold can be set according to actual needs, for example, the preset coefficient threshold can be 0.002512. By setting the preset coefficient threshold, the value of the second active droop coefficient is within the valid range, for example, the value range of the second active droop coefficient is 0-0.002512.

[0073] In at least one embodiment of the present application, the frequency output by the power converter is controlled according to the third active power droop coefficient (referred to as reference frequency in this application for ease of description), and the active power output by the power converter is controlled according to the reference frequency. The voltage output by the power converter is controlled according to the first reactive power droop coefficient (referred to as reference voltage in this application for ease of description), and the reactive power output by the power converter is controlled according to the reference voltage.

[0074] Figure 6 Schematic diagram of the control flow of the power converter provided in the embodiment of the present application. Figure 6 As shown, the active power and reactive power corresponding to the power converter are determined; the reference frequency and reference voltage corresponding to the power converter are determined; the reference frequency is determined based on the active power, the reference frequency and the third active power droop coefficient, and the reference voltage is determined based on the reactive power, the reference voltage and the first reactive power droop coefficient; the power converter is controlled based on the reference frequency and the reference voltage.

[0075] In some embodiments, in a parallel system of multiple power converters, the electric quantity of a three-phase AC system (phases a, b, and c) is converted into a quantity on a rotating two-phase orthogonal coordinate system (i.e., the D-axis and the Q-axis) by direct-quadrature (DQ) transformation. The D-axis corresponds to the direction of the rotor magnetic flux, and the Q-axis is perpendicular to the D-axis. In some embodiments, the instantaneous active power and reactive power can be determined based on the voltage component on the D-axis (denoted as Ud) and the voltage component on the Q-axis (denoted as Uq) after the AC voltage is transformed by DQ, and the current component on the D-axis (denoted as Id) and the current component on the Q-axis (denoted as Iq) after the AC current is transformed by DQ. For example, the value of Ud*Id+Uq*Iq is used as the active power, and the value of Ud*Id-Uq*Iq is used as the reactive power.

[0076] In some embodiments, the reference frequency of the power converter may be a preset reference value for adjusting and controlling the frequency of the power converter output voltage, and the reference voltage may be a preset reference value for adjusting and controlling the amplitude of the power converter output voltage. In some embodiments, the corresponding relationship between the power converter and the reference frequency and the reference voltage may be preset, and by querying the corresponding relationship, the reference frequency and the reference voltage corresponding to the power converter may be determined.

[0077] In some embodiments, determining the reference frequency according to the active power, the reference frequency and the third active droop coefficient may include: determining a frequency change value corresponding to the power converter according to the third active droop coefficient and the active power; and determining the reference frequency according to the reference frequency and the frequency change value. For example, refer to the following formula 7 and formula 8:

[0078] Formula 7: Δw=(Ud*Id+Uq*Iq)*K p .

[0079] Formula 8: w ref =w0–Δw.

[0080] Among them, Δw represents the frequency change value, Ud represents the voltage component of the AC voltage on the D axis after the DQ transformation, Id represents the current component of the AC current on the D axis after the DQ transformation, Uq represents the voltage component of the AC voltage on the Q axis after the DQ transformation, Iq represents the current component of the AC current on the Q axis after the DQ transformation, Ud*Id+Uq*Iq represents the instantaneous active power, K p represents the third active power droop coefficient, w ref represents the reference frequency, and w0 represents the base frequency.

[0081] In some embodiments, determining the reference voltage according to the reactive power, the reference voltage and the first reactive droop coefficient may include: determining a voltage change value corresponding to the power converter according to the first reactive droop coefficient and the reactive power; and determining the reference voltage according to the reference voltage and the voltage change value. For example, referring to the following formula 9 and formula 10:

[0082] Formula 9: ΔV=(Uq*Id-Ud*Iq)*K q0 .

[0083] Formula 10: V ref =V0–ΔV.

[0084] Among them, ΔV represents the voltage change value, Ud represents the voltage component of the AC voltage on the D axis after the DQ transformation, Id represents the current component of the AC current on the D axis after the DQ transformation, Uq represents the voltage component of the AC voltage on the Q axis after the DQ transformation, Iq represents the current component of the AC current on the Q axis after the DQ transformation, Ud*Id-Uq*Iq represents the instantaneous reactive power, K q0 Represents the first reactive droop coefficient, V ref represents the reference voltage, and V0 represents the base voltage.

[0085] In the device control method provided in the embodiment of the present application, the reference frequency of the power converter is determined according to the third active power droop coefficient, and the active power output by the power converter is controlled according to the reference frequency; the reference voltage of the power converter is controlled according to the first reactive power droop coefficient, and the reactive power output by the power converter is controlled according to the reference voltage, so that the power converters in the parallel system can achieve power balance, and can effectively avoid the problem of overvoltage on the DC bus during parallel operation, thereby ensuring the stability of the parallel system.

[0086] In at least one embodiment of the present application, the reference voltage is a DC voltage, and the reference voltage needs to be converted to obtain an AC voltage, so as to control the power converter to output a corresponding AC voltage (for ease of description, referred to as "output voltage" in this application). Figure 7 1 is a flow chart of a method for determining an output voltage provided in an embodiment of the present application, and the method for determining an output voltage is applied to an energy storage device. Figure 7 As shown, the following steps are included:

[0087] S21, determining an angular frequency according to the reference frequency.

[0088] In at least one embodiment of the present application, the reference frequency is used to adjust and control the effective value and phase difference of the output voltage corresponding to the power converter to achieve power balance between multiple power converters and stable operation of the parallel system. The angular frequency is a parameter used in calculating the output voltage, which is used to calculate the phase angle of the output voltage waveform. The relationship between the angular frequency and the reference frequency can be referred to in Formula 11:

[0089] Formula 11: W=2πw ref .

[0090] Where W represents the angular frequency, w ref Indicates the reference frequency.

[0091] S22, controlling the power converter to output a corresponding output voltage according to the angular frequency and the reference voltage.

[0092] In at least one embodiment of the present application, the output voltage may be a three-phase AC voltage. For example, the output voltage may include three phase voltages, and the phase difference between the three phase voltages is 120°. The output voltage is denoted as V abc_ref , the three phase voltages are denoted as V a_ref 、V b_ref With V c_ref The three phase voltages can be determined according to the following formulas 12, 13 and 14:

[0093] Formula 12: V a_ref =V ref *SinWt;

[0094] Formula 13: V b_ref =V ref *Sin(Wt–2*π / 3);

[0095] Formula 14: V c_ref =V ref *Sin(Wt+2*π / 3).

[0096] Combination Figure 8 The device control method provided in the embodiment of the present application is described as follows: Figure 8 As shown, the active power P and reactive power Q corresponding to the power converter are determined according to the third active droop coefficient (K p0 +K p_bus ) and the active power P, the frequency change value Δω corresponding to the power converter can be obtained, and according to the first reactive droop coefficient (K q0 ) and reactive power Q, the voltage change value ΔV corresponding to the power converter can be obtained. Determine the reference frequency w0 and reference voltage V0 of the power converter, and the reference frequency w0 can be determined according to the frequency change value Δw and the reference frequency w0 ref, and the reference voltage V can be determined based on the voltage change value ΔV and the reference voltage V0 ref . According to the reference frequency w ref , the DC reference voltage V ref Converted to AC output voltage V abc_ref .in, Figure 8 Here, v represents a preset voltage amplitude, and θ represents a preset phase angle. v and θ are important parameters for converting a reference voltage in a DC form into an output voltage in an AC form.

[0097] then Figure 2 In the description of the energy storage device 1, in some embodiments, the energy storage device 1 further includes a processor, a memory, and at least one communication bus, wherein the at least one communication bus is configured to realize connection and communication between the memory and the processor. The memory stores a computer program; the processor is configured to implement the device control method when executing the computer program stored in the memory.

[0098] In some embodiments, a computer program is stored in the memory, and when the computer program is executed by at least one processor, all or part of the steps in the above-mentioned device control method are implemented. The memory includes a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), a one-time programmable read-only memory (OTPROM), an electronically erasable rewritable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, magnetic disk storage, magnetic tape storage, or any other computer-readable medium that can be used to carry or store data.

[0099] In some embodiments, the computer-readable storage medium may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function, etc.; the data storage area may store data created according to the use of the energy storage device 1, etc.

[0100] In some embodiments, at least one processor is the control core (Control Unit) of the energy storage device 1, and uses various interfaces and lines to connect the various components of the entire energy storage device 1, and executes various functions and processes data of the energy storage device 1 by running or executing programs or modules stored in the memory, and calling data stored in the memory. For example, when at least one processor executes a computer program stored in the memory, all or part of the steps of the device control method in the embodiment of the present application are implemented. At least one processor can be composed of an integrated circuit, for example, it can be composed of a single packaged integrated circuit, or it can be composed of multiple integrated circuits with the same function or different functions, including one or more central processing units (CPU), microprocessors, digital processing chips, graphics processors, and a combination of various control chips.

[0101] The above integrated unit implemented in the form of software function modules can be stored in a computer-readable storage medium. The above software function modules are stored in a storage medium and include several instructions for enabling an energy storage device 1 or a processor to execute parts of the methods of various embodiments of the present application.

[0102] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of modules is only a logical function division, and there may be other division methods in actual implementation.

[0103] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical units, and may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0104] In addition, each functional module in each embodiment of the present application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of hardware plus software functional modules.

[0105] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or basic features of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present application is limited by the attached claims rather than the above description, so it is intended to include all changes that fall within the meaning and scope of the equivalent elements of the claims in the present application. Any figure mark in the claims should not be regarded as limiting the claims involved. In addition, it is obvious that the word "including" does not exclude other units or, and the singular does not exclude the plural. Multiple units or devices stated in the specification can also be implemented by one unit or device through software or hardware. The words first, second, etc. are used to indicate names, and do not indicate any particular order.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the preferred embodiments, a person of ordinary skill in the art should understand that the technical solution of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present application.

Claims

1. A device control method, applied to energy storage equipment, characterized in that: The energy storage device includes a power converter and a DC bus, the power converter is connected to the DC bus, and the method includes: Determining a first active power droop coefficient and a first reactive power droop coefficient according to the rated power of the power converter; Determine a DC bus voltage of the power converter corresponding to the DC bus and a preset voltage value, and determine a second active droop coefficient according to the DC bus voltage and the preset voltage value; determining a third active power droop coefficient according to the first active power droop coefficient and the second active power droop coefficient; The power converter is controlled according to the third active power droop coefficient and the first reactive power droop coefficient.

2. The method according to claim 1, characterized in that The step of determining a first active power droop coefficient and a first reactive power droop coefficient according to the rated power of the power converter comprises: Determining a frequency change threshold and a voltage change threshold corresponding to the power converter; Determining the first active power droop coefficient according to the rated power and the frequency change threshold; The first reactive power droop coefficient is determined according to the rated power and the voltage change threshold.

3. The method according to claim 1, characterized in that The determining of the second active droop coefficient according to the DC bus voltage and the preset voltage value includes: Determining a target voltage according to the DC bus voltage and the preset voltage value; Determining a voltage droop coefficient corresponding to the DC bus; The second active power droop coefficient is determined according to the target voltage and the voltage droop coefficient.

4. The method according to claim 1, characterized in that After determining the second active droop coefficient according to the DC bus voltage and the preset voltage value, the method further includes: If the second active power droop coefficient is less than or equal to a preset coefficient threshold, keeping the second active power droop coefficient unchanged; If the second active power droop coefficient is greater than the preset coefficient threshold, the second active power droop coefficient is updated to the preset coefficient threshold.

5. The method according to claim 1, characterized in that The controlling the power converter according to the third active power droop coefficient and the first reactive power droop coefficient comprises: Determining active power and reactive power corresponding to the power converter; Determining a reference frequency and a reference voltage corresponding to the power converter; Determine a reference frequency according to the active power, the reference frequency and the third active power droop coefficient, and determine a reference voltage according to the reactive power, the reference voltage and the first reactive power droop coefficient; The power converter is controlled according to the reference frequency and the reference voltage.

6. The method according to claim 5, characterized in that The determining of the reference frequency according to the active power, the reference frequency and the third active droop coefficient comprises: Determining a frequency change value corresponding to the power converter according to the third active droop coefficient and the active power; The reference frequency is determined according to the base frequency and the frequency change value.

7. The method according to claim 5, characterized in that The step of determining a reference voltage according to the reactive power, the reference voltage and the first reactive droop coefficient comprises: Determining a voltage change value corresponding to the power converter according to the first reactive droop coefficient and the reactive power; The reference voltage is determined according to the base voltage and the voltage change value.

8. The method according to claim 5, characterized in that The controlling the power converter according to the reference frequency and the reference voltage comprises: determining an angular frequency according to the reference frequency; The power converter is controlled to output a corresponding output voltage according to the angular frequency and the reference voltage.

9. An energy storage device, characterized in that: The energy storage device further includes a processor and a memory, and the processor is configured to implement the device control method according to any one of claims 1 to 8 when executing a computer program stored in the memory.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, which, when executed by a processor in an energy storage device, implements the device control method according to any one of claims 1 to 8.

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