An inverter power compensation method based on droop control

Abstract

The application provides an inverter power compensation method based on droop control, by acquiring real-time maximum power supply of a generator and real-time load power, when the real-time maximum power supply of the generator is less than the real-time load power, the active power control coefficient of the generator droop control is modified in real time, the active power control coefficient of the battery droop control is determined according to the active power control coefficient of the generator droop control, the adaptive characteristics of the inverter droop controller are utilized, the full use of the generator power is ensured, the battery discharge compensation power is reasonably distributed, the function of automatically compensating power according to the real-time load power demand under the condition of insufficient generator power is realized, the change demand of the load power is met in time, and therefore the sharp fluctuation of the bus voltage at the input end and the output end voltage of the inverter caused by the increase of the load power is effectively inhibited, the equipment is prevented from being damaged due to the overload of the generator power, and the stability of the operating voltage of the inverter is improved.

Description

Technical Field

[0001] This invention relates to the field of microgrid control technology, and in particular to an inverter power compensation method based on droop control. Background Technology

[0002] With the continuous advancement of various new energy power generation technologies, power generation methods have become extremely diverse, including photovoltaic power generation, wind power generation, and thermal power generation. However, the development of power generation technology has not solved the widespread problems of power supply imbalance and energy waste in power systems. Meanwhile, with the continuous development of electric vehicle technology, battery technology has made significant progress, with improvements in cost, charge / discharge performance, and safety. Benefiting from these advancements, how to apply the energy storage function of batteries to power systems and effectively integrate them to achieve energy balance and full utilization has become a research hotspot.

[0003] In the patent application CN 106099983 A, which describes an improved adaptive droop control method for inverters in a low-voltage microgrid, a virtual complex impedance is introduced to make the equivalent output impedance of the parallel inverters inductive. The voltage drop caused by this virtual complex impedance results in improved adaptive droop control, achieving load sharing in the parallel inverters. However, this method is not suitable for power supplementation by energy storage batteries or for energy storage in general. Furthermore, the load power sharing is detrimental to grid dispatching. Therefore, how to achieve automatic power supplementation and automatic energy storage operation using inverters is a problem that needs to be solved. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, this application aims to provide an inverter power compensation method based on droop control. This method can automatically switch the battery charge and discharge controller in the microgrid according to the real-time changes in load power. When the real-time maximum power of the generator can meet the load power demand, the excess power is used to charge the battery with constant current or constant voltage. When the real-time maximum power of the generator cannot meet the load power demand, the battery discharge is controlled by correcting the active power control coefficients of the generator droop control and the active power control coefficients of the battery droop control to achieve power compensation for the inverter, thereby meeting the load power demand. This method can effectively suppress the fluctuations in bus voltage caused by sudden changes in load power, improve the stability of the inverter, and make full use of the excess power of the generator to charge the battery, thereby improving the energy utilization rate.

[0005] This application provides an inverter power compensation method based on droop control, comprising the following steps:

[0006] S1: Obtain the generator's real-time maximum power supply and real-time load power;

[0007] S2: Compare the generator's real-time maximum power supply with the real-time load power.

[0008] When the generator's real-time maximum power supply is less than the real-time load power, the battery discharges, including the following steps:

[0009] S23: Calculate the active power control coefficient for battery droop control;

[0010] S24: Calculate the battery droop control output reference voltage under the load power using the battery droop control active power control coefficient;

[0011] S25: Input the battery droop control output reference voltage to the battery voltage integration point, combine it with the generator bus boost converter circuit voltage feedback value to obtain the first reference deviation, input the first reference deviation to the battery PI regulator, and output the battery boost converter circuit duty cycle one.

[0012] S26: Input the duty cycle 1 into the first PWM generation timer, and output the battery boost circuit PWM drive square wave 1;

[0013] S27: Input the driving square wave 1 into the battery boost circuit IGBT drive module, amplify the driving square wave 1, and feed the amplified driving square wave 1 back to the battery boost circuit IGBT drive module to obtain the battery output voltage.

[0014] S28: Calculate the real-time supplementary power output by the battery using the battery output voltage, and calculate the sum of the real-time maximum power output of the generator and the real-time supplementary power output by the battery to obtain the first power.

[0015] S29: Compare the first power with the real-time load power.

[0016] When the first power equals the real-time load power, the generator and battery continue to discharge.

[0017] When the first power is less than the real-time load power, return to step S25.

[0018] Specifically, because the generator's increase in active power output by increasing its speed has a relatively long time lag, when the load increases or sudden changes occur, if the generator's maximum real-time output power at its current speed cannot meet the real-time load power demand, the battery is directly controlled to discharge to compensate for the insufficient power from the generator. This prevents drastic fluctuations in the inverter input bus voltage or generator overload damage caused by increased load power. As the generator speed increases, the generator's real-time maximum output power also gradually increases. When the real-time maximum output power obtained in a certain calculation cycle meets the real-time load power demand, the battery stops discharging.

[0019] When a battery needs to discharge to replenish power, the Battery Management System (BMS) first prepares the battery for discharge. This includes the BMS switching the battery discharge state, checking if the relays are functioning properly, and then calculating the active power control coefficients for generator droop control and battery droop control. If the BMS detects that the battery preparation is complete, it begins executing the battery discharge program. This improves program stability, reduces computational load, ensures computational efficiency, and guarantees the safety of the charging process.

[0020] According to the technical solution provided in the embodiments of this application, calculating the active power control coefficient for battery droop control includes the following steps:

[0021] S241: Calculate the absolute value of the difference between the generator's real-time maximum power supply and the real-time load power, and set it as the first difference value;

[0022] S242: Determine the droop control active power control coefficient of the generator based on the first difference;

[0023] S243: Calculate the active power control coefficient for battery droop control using the active power control coefficient for generator droop control.

[0024] Specifically, the absolute value of the difference between the generator's real-time maximum power supply and the real-time load power reflects the deviation between the current load power and the generator's real-time maximum power supply. It serves as the basis for subsequently determining the amount of power the inverter needs to supplement and for correcting the calculation of the generator droop control active power control coefficient and the battery droop control active power control coefficient.

[0025] According to the technical solution provided in the embodiments of this application, the correspondence between the first difference and the active power control coefficient of the generator droop control is as follows.

[0026] K gent_m =m i P error ∈ (P i P i+1)

[0027] In the formula, K gent_m m is the active power control coefficient for generator droop control. i Let P be the specific value of the active power control coefficient for the generator's droop control, where i ≥ 1 and is a natural number; error P is the absolute value of the difference between the generator's real-time maximum power supply and the real-time load power. i P i+1 All are interval values.

[0028] Specifically, by segmenting and assigning values ​​to the active power control coefficient of the generator based on real-time load power changes, the program calculation process can be greatly simplified and the computational load reduced; the specific value m of the generator's active power control coefficient is as follows: i Obtained from experimental measurements.

[0029] According to the technical solution provided in the embodiments of this application, the formula for calculating the active power control coefficient for battery droop control is as follows.

[0030] K bat_m =P error *K gent_m / P gen

[0031] In the formula, K bat_m P is the active power control coefficient for battery droop control. gent This refers to the active power output of the generator in real time.

[0032] Specifically, the active power control coefficient for battery droop control is adaptively corrected based on the active power control coefficient for generator droop control, ensuring a reasonable and effective allocation of generator power and battery discharge power, ultimately achieving automatic power compensation of the inverter and timely meeting the changing power requirements of real-time load.

[0033] According to the technical solution provided in the embodiments of this application, the formula for calculating the battery droop control output reference voltage is as follows.

[0034] V bat_dc =u _dc -K bat_m *P bat

[0035] In the formula, V bat_dc The reference voltage for the battery droop control output; u _dc K represents the desired boost voltage at the inverter input bus. bat_m P is the active power control coefficient for battery droop control. bat Provides real-time power output to the battery.

[0036] Specifically, u_dc This is the desired voltage boost value for the inverter input bus. To meet inverter requirements, this value is usually set to 600V.

[0037] Considering the actual power loss of the inverter itself, the calculated power of the load, and the specific changes in the battery output power requirements, the active power P output by the generator in real time... gent The calculation formula is as follows:

[0038] P gent =P all -P bat =U dc *I dc -P bat

[0039] In the formula, P all U is the sum of the power of all current loads; dc I is the real-time voltage of the inverter output bus. dc P represents the real-time current of the inverter output bus. bat Provides real-time power output to the battery.

[0040] Battery output voltage U bat and battery output current I bat The real-time output power of the battery can be obtained through the battery management system (BMS), and the calculation formula is as follows:

[0041] P bat =3*U bat *I bat

[0042] In the formula, U bat I is the battery output voltage. bat This represents the battery output current.

[0043] According to the technical solution provided in the embodiments of this application, the following steps are included after step S25:

[0044] S251: Compare the battery droop control output reference voltage V bat_dc The inverter input bus boost voltage is 1.15 times the expected value u. _dc When V bat_dc ≥1.15*u _dc When, then V bat_dc =1.15*u _dc Otherwise V bat_dc This is the calculated value of the reference voltage for the battery droop control output.

[0045] Specifically, when the calculated value of the battery droop control output reference voltage is greater than 1.15 times the expected value of the inverter input bus voltage boost, the calculated value of the battery droop control output reference voltage is limited to 1.15 times the expected value of the inverter input bus voltage boost. This ensures that the output bus voltage after inverter rectification and boosting is within the safe range of the equipment, preventing severe overheating of the IGBT drive module and device damage caused by excessive voltage due to the excessively high output bus voltage after inverter rectification and boosting.

[0046] According to the technical solution provided in the embodiments of this application, step S2 further includes the following steps:

[0047] When the generator's real-time maximum power supply equals the real-time load power, the generator continues to supply power.

[0048] When the generator's real-time maximum power supply exceeds the real-time load power, the battery is charged, including the following steps:

[0049] S21: Obtain the real-time battery state of charge;

[0050] S22: Determine the magnitude of the battery's state of charge.

[0051] When the battery's state of charge is ≥90%, the battery is subjected to constant voltage charging, including the following steps:

[0052] S221: Obtain the allowable charging voltage of the battery corresponding to the battery state of charge;

[0053] S222: Charge the battery at a constant voltage using the battery's allowable charging voltage. When the battery's state of charge reaches 100%, stop charging the battery and maintain the generator's power supply operation.

[0054] When the battery's state of charge is <90%, the battery is charged with constant current, including the following steps:

[0055] S223: Obtain the constant current charging current of the battery corresponding to the battery state of charge;

[0056] S224: Charge the battery with the constant current charging current. When the battery state of charge is ≥90%, return to step S221.

[0057] Specifically, the battery state of charge (SOC) represents the percentage of remaining usable battery capacity. This SOC can be obtained in real-time through the battery management system (BMS). This application sets a 90% SOC as the threshold. When the SOC is ≥90%, the BMS obtains the allowable charging voltage corresponding to the SOC and uses this voltage for constant-voltage charging, placing the battery in a float charging state to ensure battery safety and extend its lifespan. When the SOC is <90%, constant-current charging is applied. The charging current is determined by comparing the maximum charging current provided by the generator's excess power with the maximum allowable charging current of the battery, selecting the smaller value as the charging current for constant-current charging until the SOC reaches 90%. Then, constant-voltage charging is switched, or the charging / discharging mode is re-evaluated and selected based on changes in real-time load power.

[0058] According to the technical solution provided in the embodiments of this application, in step S221, obtaining the allowable charging voltage of the battery corresponding to the battery state of charge includes the following steps:

[0059] S2211: Obtain the reference voltage for constant voltage charging;

[0060] S2212: Input the reference voltage of the constant voltage charging to the battery voltage integration point, and combine it with the real-time battery voltage feedback value to obtain the third reference deviation. Input the third reference deviation to the bus step-down chopper circuit voltage PI regulator and output the bus step-down chopper circuit duty cycle three.

[0061] S2213: Input the duty cycle three into the third PWM generation timer, and output the bus buck chopper circuit PWM drive square wave three;

[0062] S2214: The driving square wave three is input to the bus step-down chopper circuit IGBT driving module, the driving waveform of the driving square wave three is amplified, and the amplified driving square wave three is fed back to the bus step-down chopper circuit IGBT driving module to obtain the battery's allowable charging voltage.

[0063] According to the technical solution provided in the embodiments of this application, in step S223, obtaining the constant current charging current of the battery corresponding to the battery state of charge includes the following steps:

[0064] S2231: Calculate the maximum charging current that the generator's excess power can provide;

[0065] S2232: Obtain the maximum allowable charging current of the current battery;

[0066] S2233: Compare the maximum charging current that the generator's excess power can provide with the maximum charging current that the current battery allows, and retain the smaller of the two as the reference current for constant current charging.

[0067] S2234: Input the reference current of the constant current charging to the battery current integration point, combine it with the real-time current feedback value of the battery to obtain the fourth reference deviation, input the fourth reference deviation to the bus step-down chopper circuit current PI regulator, and output the bus step-down chopper circuit duty cycle four.

[0068] S2235: Input the duty cycle four into the third PWM generation timer, and output the bus buck chopper circuit PWM drive square wave four;

[0069] S2236: The driving square wave four is input to the bus step-down chopper circuit IGBT driving module, which amplifies the driving waveform of the driving square wave four, and feeds the amplified driving square wave four back to the bus step-down chopper circuit IGBT driving module to obtain the constant current charging current of the battery.

[0070] According to the technical solution provided in the embodiments of this application, the formula for calculating the interval value is as follows:

[0071] P1=0, P i+1 =P error_max *i / n

[0072] In the formula, P error_max This represents the maximum compensable power that the battery can currently provide; n represents the number of intervals, n≥3 and is an odd number; 1≤i≤n.

[0073] Specifically, the number of intervals and the values ​​of the intervals can be determined by further subdivision based on the control accuracy requirements. In order to meet the requirements of simplifying the processor's computing load while allocating the battery's output power, the maximum compensable power that the battery can currently provide is divided into odd-numbered intervals.

[0074] In summary, this application discloses an inverter power compensation method based on droop control. The beneficial effects of the above scheme are: obtaining the real-time maximum power supply of the generator and the real-time load power; when the real-time maximum power supply of the generator is less than the real-time load power, starting the battery discharge mode; modifying the generator droop control active power control coefficient in real time; and determining the battery droop control active power control coefficient based on the generator droop control active power control coefficient; fully utilizing the adaptive characteristics of the inverter droop controller; ensuring full utilization of generator power; rationally allocating battery discharge power compensation; fully guaranteeing the utilization rate of generator power and battery power; realizing the function of automatic power compensation according to load power demand when generator power is insufficient; timely meeting the changing load power demand; thereby effectively suppressing the drastic fluctuations in inverter input bus voltage and output voltage caused by the increase of load power; preventing generator power overload damage to equipment; and improving the stability of inverter operating voltage.

[0075] This application also has the following effects: when the real-time maximum power supply of the generator equals the real-time load power, the current generator power supply operation status is maintained; when the real-time maximum power supply of the generator exceeds the real-time load power, the battery charging mode is entered. Combining inverter droop control technology and battery management technology, it is realized that while the real-time maximum power supply of the generator meets the real-time load power requirements, the excess power of the generator is fully utilized to charge and store energy in the battery, making full use of energy. Moreover, when the battery state of charge is <90%, a constant current charging mode is adopted. By comparing the maximum charging current that the excess power of the generator can provide and the maximum charging current that the current battery can allow, the smaller value is taken to calculate the battery charging current and perform constant current charging on the battery. This ensures both the speed of battery charging and the full utilization of the excess power of the generator. When the battery state of charge is ≥90%, a constant voltage charging mode is adopted, and the battery is charged at a constant voltage using the battery's allowable charging voltage, which fully ensures the safety and stability of battery charging. Attached Figure Description

[0076] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0077] Figure 1 This is a flowchart of the inverter power compensation method based on droop control in this application.

[0078] Figure 2 This is a schematic diagram of the control system structure for using the excess power of the generator to charge the battery at constant voltage or constant current, as described in this application.

[0079] Figure 3 This is a schematic diagram of the inverter-battery power compensation droop control system structure of this application.

[0080] Figure 4 This is a diagram showing the voltage fluctuation at the output bus of the inverter after rectification and boosting during the battery discharge process in Embodiment 1 of this application. Detailed Implementation

[0081] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. The present application will now be described in detail with reference to the accompanying drawings and embodiments.

[0082] According to such Figure 1 The illustrated process, a power compensation method for inverters based on droop control, includes the following steps:

[0083] S1: Obtain the generator's real-time maximum power supply and real-time load power;

[0084] The power output range of a generator can be determined based on its model. The real-time maximum power output of the generator used in this application is approximately linearly related to the effective value of its terminal voltage, which in turn is approximately linearly related to the generator speed. Therefore, the effective value of the generator terminal voltage can be calculated based on the generator speed, and then the real-time maximum power output of the generator can be calculated based on the effective value of the generator terminal voltage. Thus, the formula for calculating the real-time maximum power output of the generator is as follows:

[0085] P gent_max =N*U gent =Y*N*n (1)

[0086] In the formula, P gent_max U represents the real-time maximum power supplied to the motor; N is the conversion factor between the effective value of the generator power and the effective value of the generator terminal voltage; U gent Y is the effective value of the generator terminal voltage; Y is the conversion coefficient between the effective value of the generator terminal voltage and the generator speed.

[0087] The conversion coefficient N between the effective value of generator power and the effective value of generator terminal voltage, and the conversion coefficient Y between the effective value of generator terminal voltage and the generator speed are given in Table 1.

[0088]

[0089] Based on the analysis of existing three-phase four-wire system operation, for a three-phase balanced load, its total load power is equal to three times the single-phase load power. Therefore, the formula for calculating the real-time load power is as follows:

[0090] P load =3*U load *Iload (2)

[0091] In the formula, P load For real-time load power; U load This refers to the real-time single-phase voltage value of a three-phase generator; I load This represents the real-time single-phase current value of a three-phase generator.

[0092] S2: Compare the generator's real-time maximum power supply with the real-time load power.

[0093] When the generator's real-time maximum power supply equals the real-time load power, the generator continues to supply power.

[0094] When the generator's real-time maximum power supply exceeds the real-time load power, the battery is charged, including the following steps:

[0095] S21: Obtain the real-time battery state of charge.

[0096] The battery state of charge (SBC) represents the percentage of the battery's remaining usable charge relative to its total capacity. The current real-time SBC can be obtained through the battery management system (BMS).

[0097] S22: Determine the magnitude of the battery's state of charge.

[0098] When the battery's state of charge is ≥90%, the battery is charged under constant voltage, such as... Figure 2 As shown, it includes the following steps:

[0099] S221: Obtain the allowable charging voltage of the battery corresponding to the battery's state of charge, including the following steps:

[0100] S2211: Obtain the reference voltage V_bat_ref for constant voltage charging;

[0101] Among them, the reference voltage V_bat_ref for constant voltage charging corresponding to the current state of battery charge can be obtained through the battery management system (BMS);

[0102] S2212: Input the reference voltage V_bat_ref of the constant voltage charging to the battery voltage integration point Q3, and combine it with the real-time battery voltage feedback value V_bat_fbk to obtain the third reference deviation. Input the third reference deviation to the bus step-down chopper circuit voltage PI regulator and output the bus step-down chopper circuit duty cycle three.

[0103] S2213: Input the duty cycle three into the third PWM generation timer, and output the bus buck chopper circuit PWM drive square wave three;

[0104] S2214: The driving square wave three is input to the bus step-down chopper circuit IGBT driving module, the driving waveform of the driving square wave three is amplified, and the amplified driving square wave three is fed back to the bus step-down chopper circuit IGBT driving module to obtain the battery's allowable charging voltage.

[0105] S222: Charge the battery at a constant voltage using the battery's allowable charging voltage and obtain the real-time battery state of charge. When the battery state of charge reaches 100%, the battery stops charging, and the generator continues to supply power.

[0106] By utilizing the excess power of the generator to charge the battery in a constant-voltage mode, the battery enters a float charging state, which can fully ensure the safety and stability of the battery and improve its service life. When the battery's state of charge reaches 100%, the battery management system (BMS) stops charging the battery to prevent the battery from being in a charging state for a long time and reducing its service life.

[0107] When the battery's state of charge is less than 90%, the battery is charged with a constant current, such as... Figure 2 As shown, it includes the following steps:

[0108] S223: Obtain the constant current charging current of the battery corresponding to the battery state of charge, including the following steps:

[0109] S2231: Calculate the maximum charging current that the generator's excess power can provide;

[0110] The specific formula for calculating the maximum charging current that the excess power of the generator can provide is as follows:

[0111] I bat_chg_gent =P error / U bat (3)

[0112] In the formula, I bat_chg_gent The maximum charging current that the generator can provide for excess power; P error U is the absolute value of the difference between the generator's real-time maximum power supply and the real-time load power. bat This refers to the battery output voltage.

[0113] The battery output voltage U bat This can be obtained through the battery management system (BMS);

[0114] The absolute value P of the difference between the generator's real-time maximum power supply and real-time load power error This reflects the deviation between the current load power and the real-time maximum power supply of the generator. It serves as the basis for subsequently determining the amount of additional power required by the inverter and for correcting the calculation of the generator droop control active power control coefficient and the battery droop control active power control coefficient.

[0115] S2232: Obtain the maximum allowable charging current I of the current battery bat_chg_need ;

[0116] The maximum allowable charging current I of the current battery can be obtained through the battery management system (BMS). bat_chg_need .

[0117] S2233: Compare the maximum charging current I that can be provided by the generator's excess power. bat_chg_gent and the current maximum allowable charging current I of the battery bat_chg_need The smaller of the two values ​​is retained as the reference current I_bat_ref for constant current charging;

[0118] S2234: Input the constant current charging reference current I_bat_ref to the battery current integration point Q4, and combine it with the real-time battery current feedback value I_bat_fbk to obtain the fourth reference deviation. Input the fourth reference deviation to the bus step-down chopper circuit current PI regulator and output the bus step-down chopper circuit duty cycle four.

[0119] S2235: Input the duty cycle four into the third PWM generation timer, and output the bus buck chopper circuit PWM drive square wave four;

[0120] S2236: The driving square wave four is input to the bus step-down chopper circuit IGBT driving module, which amplifies the driving waveform of the driving square wave four, and feeds the amplified driving square wave four back to the bus step-down chopper circuit IGBT driving module to obtain the constant current charging current of the battery.

[0121] S224: Charge the battery with the constant current charging current and obtain the real-time state of charge of the battery. When the state of charge of the battery is ≥90%, return to step S221.

[0122] The bus buck chopper circuit current PI regulator obtains the constant current charging reference current I_bat_ref in real time. By calculating the difference between the real-time battery current feedback value I_bat_fbk and the constant current charging reference current I_bat_ref, PI regulation is performed to adjust the output voltage of the bus buck chopper circuit in real time, thereby ensuring current stability.

[0123] Compared to constant voltage charging mode, constant current charging mode has a higher charging speed. Therefore, constant current charging mode is preferred when the battery's state of charge is low. However, as the battery is charged with constant current, its state of charge gradually increases. When the battery's state of charge reaches 90% or above in a certain calculation cycle, the battery management system (BMS) immediately obtains the current allowable charging voltage of the battery and outputs the allowable charging voltage of the battery through the bus step-down chopper circuit. The battery management system (BMS) then switches to constant voltage charging mode to fully ensure the battery's safety, stability, and lifespan.

[0124] When the generator's real-time maximum power supply is less than the real-time load power, the battery discharges, including the following steps:

[0125] When a battery needs to discharge to compensate for power, the battery management system (BMS) must first prepare the battery for discharge. This includes the BMS switching the battery discharge state and determining the relay's operating state. Then, the active power control coefficient for battery droop control is calculated. If the BMS detects that the battery preparation is complete, it starts executing the battery discharge program. This improves program stability, reduces computational load, ensures computational efficiency, and guarantees the safety of the charging process.

[0126] S23: Calculate the active power control coefficient for battery droop control, including the following steps:

[0127] S231: Calculate the absolute value of the difference between the generator's real-time maximum power supply and the real-time load power, and set it as the first difference value. The specific calculation formula is as follows:

[0128] P error =|P gent_max -P load | (4)

[0129] In the formula, P error P is the absolute value of the difference between the real-time active power output of the generator and the real-time load power; gent_max P represents the generator's real-time maximum power output. load Real-time load power;

[0130] Since the amount of computation involving signed numbers in CPU operation is much greater than that involving unsigned numbers, taking the absolute value of the generator's excess power can reduce the CPU's computational load in order to calculate the charging current that the generator's excess power can provide.

[0131] Additionally, taking the absolute value of the difference between the generator's real-time output active power and the real-time load power facilitates the later division of interval values.

[0132] S232: Based on the first difference, determine the droop control active power control coefficient of the generator.

[0133] The correspondence between the first difference and the active power control coefficient of the generator's droop control is as follows:

[0134] K gent_m =m i P error ∈ (P i P i+1 (5)

[0135] In the formula, K gent_m m is the active power control coefficient for generator droop control. i Let P be the specific value of the active power control coefficient for the generator's droop control, where i ≥ 1 and is a natural number; error P is the absolute value of the difference between the generator's real-time maximum power supply and the real-time load power. i P i+1 All are range values;

[0136] Among them, the specific value m of the active power control coefficient for generator droop control i The values ​​were obtained from experimental measurements under various specific load conditions. The determination of the interval values ​​can be further subdivided according to the control accuracy requirements. In order to meet the requirements of simplifying the processor's computational load while specifically allocating the battery output power, the maximum compensable power that the battery can currently provide is divided into odd-numbered intervals. The calculation formula for each interval value is as follows:

[0137] P1=0, P i+1 =P error_max *i / n (6)

[0138] In the formula, P error_max This represents the maximum compensable power that the battery can currently provide; n represents the number of intervals, n≥3 and is odd; P1, P i+1 This represents an interval value, where 1 ≤ i ≤ n.

[0139] Based on the real-time load power changes and the first difference, the active power control coefficient of the generator's droop control is set and valued in segments, which greatly simplifies the program calculation process and reduces the amount of calculation.

[0140] S233: Calculate the active power control coefficient for battery droop control using the generator droop control active power control coefficient. The specific calculation formula is as follows.

[0141] K bat_m =P error *K gent_m / P gent (7)

[0142] In the formula, K bat_m K is the active power control coefficient for battery droop control. gent_m P is the active power control coefficient for generator droop control. gent This refers to the active power output of the generator in real time.

[0143] The active power P output by the generator in real time gent The calculation formula is as follows:

[0144] P gent =P all -P bat =U dc *I dc -P bat (8)

[0145] In the formula, P all U is the sum of the power of all current loads; dc I is the real-time voltage of the inverter output bus. dc P represents the real-time current of the inverter output bus. bat Provides real-time power output for the battery;

[0146] Among them, the generator's real-time maximum power supply P gent_max The active power P output by the generator is determined by its current operating speed and status, and is independent of the connected load. gent Related to the connected load; the sum of the power of all current loads, P all This includes loads such as inverter losses, while the real-time load power P load This refers only to the load connected after the inverter output port.

[0147] Real-time active power output P of the generator gent The active power P of the generator is calculated by collecting the effective value of the generator terminal voltage and the real-time output current. The effective value of the generator terminal voltage and the real-time output current are obtained using corresponding sensors. When the load is too large and battery power compensation is required, the real-time active power P output by the generator is calculated. gent With the generator's real-time maximum power supply P gent_max Equal to the real-time active power P output by the generator when the load is small and battery power supplementation is not required. gent Less than the generator's real-time maximum power supply P gent_max .

[0148] like Figure 3The schematic diagram of the inverter-battery power compensation droop control system shown here places the calculation of the active power control coefficients of the generator droop control and the active power control coefficients of the battery droop control outside the closed loop of the droop controller. This can improve the stability of the calculation results of the droop control system and reduce the amount of computation in the program.

[0149] The active power control coefficient for battery droop control is calculated based on the active power control coefficient for generator droop control, ensuring a reasonable and effective allocation of generator power and battery discharge compensation power, fully guaranteeing the utilization rate of generator power and battery power, and thus improving the energy utilization rate of generator and battery.

[0150] S24: Calculate the generator droop control output reference voltage V under real-time load power using the generator droop control active power control coefficient. gent_dc This refers to the generator step-up reference voltage, and the specific calculation formula is as follows.

[0151] V gent_dc =u _dc -K gent_m *P gent (9)

[0152] In the formula, V gent_dc The generator droop control output reference voltage; u _dc The desired boost voltage at the inverter input bus;

[0153] The battery droop control output reference voltage V under real-time load power is calculated using the active power control coefficient of battery droop control. bat_dc This refers to the battery boost reference voltage, and the specific calculation formula is as follows.

[0154] V bat_dc =u _dc -K bat_m *P bat (10)

[0155] In the formula, V bat_dc The reference voltage for the battery droop control output; P bat Provides real-time power output for the battery;

[0156] In order to meet the requirements of the inverter, the expected value of the inverter input bus boost voltage u in this application is... _dc It is 600V;

[0157] Battery output voltage U bat and battery output current I bat The real-time output power of the battery can be obtained through the battery management system (BMS), and the calculation formula is as follows:

[0158] P bat=3*U bat *I bat (11)

[0159] In the formula, U bat I is the battery output voltage. bat This represents the battery output current.

[0160] S25: As Figure 3 As shown, the generator boost reference voltage Vgent_ref is input to the generator voltage synthesis point Q1, and combined with the generator bus boost converter voltage feedback value V_fbk, the second reference deviation is obtained. The second reference deviation is input to the generator PI regulator, and the generator boost converter duty cycle 2 is output.

[0161] The battery boost reference voltage Vbat_ref is input to the battery voltage integration point Q2. Combined with the voltage feedback value V_fbk of the generator bus boost converter circuit, the first reference deviation is obtained. The first reference deviation is input to the battery PI regulator, and the duty cycle of the battery boost converter circuit is output as one.

[0162] S26: Input the duty cycle 2 into the second PWM generation timer, and output the generator boost circuit PWM drive square wave 2;

[0163] Input the duty cycle 1 into the first PWM generation timer, and output the battery boost circuit PWM drive square wave 1.

[0164] S27: Input the second driving square wave into the IGBT drive module of the generator boost circuit to amplify the second driving square wave, and feed the amplified second driving square wave back to the IGBT drive module of the generator boost circuit to obtain the second voltage. The second voltage is the inverter output bus voltage after the battery discharges and compensates for the power. By observing the fluctuation of the inverter output bus voltage, it can be known whether the battery power compensation has been effective.

[0165] The driving square wave is input into the battery boost circuit IGBT driver module, the driving square wave is amplified, and the amplified driving square wave is fed back to the battery boost circuit IGBT driver module to obtain the first voltage, which is the battery output voltage.

[0166] S28: Calculate the real-time output power of the battery using the voltage at the battery output terminal, and calculate the sum of the real-time maximum power supply of the generator and the real-time output power of the battery to obtain the first power;

[0167] S29: Compare the first power with the real-time load power.

[0168] When the first power equals the real-time load power, the generator and battery continue to discharge.

[0169] When the first power is less than the real-time load power, return to step S25.

[0170] Because the generator's increase in active power output occurs over a relatively long period due to speed increases, exhibiting a lag, when the load increases or sudden changes occur, if the generator's current maximum active power output at its current speed cannot meet the real-time load power demand, the battery discharge program is directly executed to compensate for the insufficient power from the generator. This effectively suppresses or eliminates the potential for drastic fluctuations in the inverter's input bus voltage and output voltage caused by increased load power, preventing generator overload damage and improving the stability of the inverter's operating voltage. As the generator speed increases, the generator's real-time maximum power output also gradually increases. When the generator's real-time maximum discharge power obtained in a certain operating cycle meets the real-time load power demand, the battery stops discharging and enters a charging state.

[0171] Furthermore, such as Figure 3 As shown, the following steps are included after step S24:

[0172] S241: Compare the generator droop control output reference voltage V respectively. gent_dc The inverter input bus boost voltage is 1.15 times the expected value u. _dc The battery droop control output reference voltage V bat_dc The inverter input bus boost voltage is 1.15 times the expected value u. _dc ,

[0173] When V gent_dc ≥1.15*u _dc When, then V gent_dc =1.15*u _dc Otherwise V gent_dc This is the calculated value of the generator droop control output reference voltage, i.e., the generator boost reference voltage Vgent_ref.

[0174] When V bat_dc ≥1.15*u _dc When, then V bat_dc =1.15*u _dc Otherwise V bat_dc The calculated value of the battery droop control output reference voltage is the battery boost reference voltage Vbat_ref.

[0175] To prevent severe overheating of the IGBT drive module and device damage due to excessive bus voltage, when the calculated value of the generator droop control output reference voltage or the battery droop control output reference voltage exceeds 1.15 times the expected value of the inverter input bus voltage boost, the calculated value of the generator droop control output reference voltage or the battery droop control output reference voltage is limited to 1.15 times the expected value of the inverter input bus voltage boost. This ensures that the output bus voltage after inverter rectification and boosting is within the safe range of the equipment.

[0176] Example 1

[0177] In a preferred embodiment, a 30kW inverter was selected for verification. The inverter has two distributed generation ports, one energy storage charging and discharging port, and one inverter output port. The inverter output port is a three-phase four-wire port. Distributed generation port one is a three-phase universal power supply port that can be connected to a 100-500V common power frequency power supply. Distributed generation port two is a backup port that has the same structure and function as distributed generation port one.

[0178] The distributed generation port is connected to a three-phase power frequency generator with adjustable output voltage. The energy storage charging and discharging port is connected to an energy storage battery with a rated voltage of 535V. The inverter output port is connected to a three-wire or four-wire electronic load. The real-time load power change is achieved by adjusting the electronic load, thereby verifying the inverter power compensation method based on droop control in this application.

[0179] At time T1, generator DTC-308 has reached a stable operating state. After passing through the generator Boost circuit, the inverter input bus voltage reaches 600V, and the output voltage after inversion is a stable 220V power frequency. At this time, the generator speed is n=3000r / min. The electronic load is turned on, applying a load power of 3.5KW, and keeping the load power constant, according to... Figure 1 The flowchart shown illustrates that inverter power compensation based on droop control includes the following steps:

[0180] S1: Calculate the generator's real-time maximum power supply and real-time load power;

[0181] According to Table 1, when the generator speed is 3000 r / min, the conversion factor N between the effective value of the generator power and the effective value of the generator terminal voltage is 0.04, and the conversion factor Y between the effective value of the generator terminal voltage and the generator speed is 25. According to formula (1), the effective value of the generator terminal voltage can be calculated to be 120V, and the real-time maximum power supply P of the generator is... gent_max It is 3KW.

[0182] As can be seen from the electronic load, the real-time load power P loadIt has a power rating of 3.5KW.

[0183] S2: The real-time maximum power supply P of the generator gent_max <The real-time load power P load This indicates that the current real-time maximum power of the generator cannot meet the real-time load power requirements, necessitating battery power compensation. The Battery Management System (BMS) detects that the battery preparation is incomplete, and the inverter sends a command to the BMS to switch the battery discharge state and check the relay's operational status. Once preparation is complete, the BMS responds to the discharge request, and the battery enters the discharge procedure, which includes the following steps:

[0184] S23: Calculate the active power control coefficient for battery droop control, including the following steps:

[0185] S231: Calculate the absolute value P of the difference between the generator's real-time maximum power supply and the real-time load power according to formula (4). error The value is 0.5KW, which is the first difference P. error It is 0.5KW;

[0186] S232: Obtain the maximum compensable power P currently available from the battery through the battery management system. error_max The maximum compensable power that the battery can currently provide is 3KW. The maximum compensable power is divided into three intervals. According to formula (6), the values ​​of each interval are P1=0, P2=1KW, P3=2KW, and P4=3KW. According to formula (5) and experimental measurements, the active power control coefficient K for generator droop control is... gent_m The specific values ​​in each interval are:

[0187] K gent_m =0.001, P error_ ∈ (0, 1)

[0188] K gent_m =0.00075, P error_ ∈ (1, 2)

[0189] K gent_m =0.0005, P error_ ∈ (2, 3);

[0190] Because of the first difference P error Since it is 0.5KW, we know that K is at this time. gent_m =0.001.

[0191] S233: Active power control coefficient K based on generator droop control gent_m Calculate the active power control coefficient K for battery droop control. bat_m According to formula (7), the active power control coefficient K for battery droop control can be obtained.bat_m It is 0.00017.

[0192] S24: Expected boost voltage value u at the inverter input bus _dc For 600V, such as Figure 3 As shown, the generator droop control output reference voltage V under real-time load power is calculated using the generator droop control active power control coefficient. gent_dc According to formula (9) and the limiting process, the generator droop control output reference voltage V can be obtained. gent_dc The value is 597V, meaning the generator boost reference voltage Vgent_ref is 597V.

[0193] The real-time output power P of the battery is obtained through the battery management system. bat For a load of 500W, the battery droop control output reference voltage V is calculated using the battery droop control active power control coefficient under real-time load power. bat_dc According to formula (10), the battery droop control output reference voltage V can be obtained. bat_dc The value is 599.92V, meaning the battery boost reference voltage Vbat_ref is 599.92V.

[0194] S25: As Figure 3 As shown, the generator boost reference voltage Vgent_ref is input to the generator voltage synthesis point Q1, and combined with the generator bus boost converter voltage feedback value V_fbk, the second reference deviation is obtained. The second reference deviation is input to the generator PI regulator, and the generator boost converter duty cycle 2 is output.

[0195] The battery boost reference voltage Vbat_ref is input to the battery voltage synthesis point Q2. Combined with the voltage feedback value V_fbk of the generator bus boost converter circuit, the first reference deviation is obtained. The first reference deviation is input to the battery PI regulator, and the duty cycle of the battery boost circuit is output as 1.

[0196] S26: Input the duty cycle 2 into the second PWM generation timer, and output the generator boost circuit PWM drive square wave 2;

[0197] The duty cycle is input into the first PWM generation timer, and the output is the second PWM drive square wave of the battery boost circuit.

[0198] S27: Input the second driving square wave into the IGBT drive module of the generator boost circuit to amplify the second driving square wave. Feed the amplified second driving square wave back to the IGBT drive module of the generator boost circuit to obtain the second voltage. The second voltage is the inverter output bus voltage after battery discharge compensation. Figure 4 As shown, after the battery discharges to compensate for the power loss, the fluctuation of the inverter output bus voltage is very small, indicating that the battery discharge compensation is effective and ensures the normal operation of each device.

[0199] The driving square wave is input into the battery boost circuit IGBT driver module, the driving square wave is amplified, and the amplified driving square wave is fed back to the battery boost circuit IGBT driver module to obtain the first voltage, which is the battery output voltage.

[0200] S28: The battery output current is 1.08A, obtained from the sensor and battery management system. The real-time output power P of the battery is calculated using the battery output voltage. bat The power is 0.5KW (excluding the inverter's own power loss), and the sum of the generator's real-time maximum power supply and the battery's real-time output power is calculated to obtain the first power as 3.5KW;

[0201] S29: The first power of 3.5KW = real-time load power of 3.5KW, the generator and battery continue to operate.

[0202] This application describes how adjusting the droop control coefficients of both the generator and battery droop controls allows for the control of battery discharge to compensate for insufficient generator power. This enables a reasonable and effective allocation of generator power and battery discharge compensation power, ensuring the full utilization of both generator and battery power, thereby improving the energy efficiency of both. Simultaneously, by supplementing power through battery discharge, the stability of the inverter input bus voltage is ensured during operation. Figure 4 As shown, this protects the equipment.

[0203] Example 2

[0204] The operating conditions are the same as in Example 1, so they will not be repeated here. The difference is that...

[0205] At time T2, the generator speed n = 3300 r / min, according to... Figure 1 The flowchart shown includes the following steps:

[0206] S1: Calculate the generator's real-time maximum power supply and real-time load power;

[0207] According to Table 1, when the generator speed is 3300 r / min, the conversion factor N between the generator power RMS and the generator terminal voltage RMS is 0.045, and the conversion factor Y between the generator terminal voltage RMS and the generator speed is 40. Calculations show that the generator terminal voltage RMS is 150V, and the generator's real-time maximum power supply P... gent_max It has a power rating of 6.00KW.

[0208] As can be seen from the electronic load, the real-time load power P load It has a power rating of 2.7KW.

[0209] S2: The real-time maximum power supply P of the generator gent_max >The real-time load power P load This indicates that the current real-time maximum power of the generator can meet the real-time load power requirements, and there is a significant amount of surplus power that can be fully utilized to charge the battery. The battery then enters charging mode, which includes the following steps:

[0210] S21: The current real-time battery state of charge (SOC) obtained through the battery management system (BMS) is 60%, indicating that the current remaining usable battery capacity accounts for 60% of the total capacity;

[0211] S22: To fully ensure charging efficiency and charging safety, this application uses 90% battery state of charge as a boundary to distinguish between constant current charging and constant voltage charging modes. Since the current battery state of charge is <90%, it enters the battery constant current charging mode to charge the battery at a constant current, including the following steps:

[0212] S223: Obtain the constant current charging current of the battery corresponding to the battery state of charge, including the following steps:

[0213] S2231: According to formula (4), the absolute value P of the difference between the real-time output active power of the generator and the load power can be calculated. error The power output is 3.3kW, and the battery output voltage U is obtained through the battery management system. bat The voltage is 527V. According to formula (3), the maximum charging current I that the generator's excess power can provide can be calculated. bat_chg_gent =6.26A;

[0214] S2232: Obtain the maximum allowable charging current I of the current battery through the battery management system (BMS). bat_chg_need =9A;

[0215] S2233: Compare the maximum charging current I that can be provided by the generator's excess power. bat_chg_gent and the current maximum allowable charging current I of the battery bat_chg_need Select the generator with excess power to provide the maximum charging current I. bat_chg_gent =6.26A is used as the reference current I_bat_ref for constant current charging;

[0216] S2234: As Figure 2As shown, the reference current I_bat_ref=6.26A of constant current charging is input to the battery current integration point Q4. Combined with the real-time battery current feedback value I_bat_fbk, the fourth reference deviation is obtained. The fourth reference deviation is input to the bus step-down chopper circuit current PI regulator, and the bus step-down chopper circuit duty cycle four is output.

[0217] S2235: Input the duty cycle four into the third PWM generation timer, and output the bus buck chopper circuit PWM drive square wave four;

[0218] S2236: The driving square wave four is input to the bus step-down chopper circuit IGBT driving module, the driving waveform of the driving square wave four is amplified, and the amplified driving square wave four is fed back to the bus step-down chopper circuit IGBT driving module to obtain the constant current charging current of 5.9A of the battery after bus step-down chopper.

[0219] S224: The battery is charged at a constant current of 5.9A, and the battery capacity will gradually increase.

[0220] Furthermore, under the condition that the generator speed and load power remain unchanged, during the execution of step S224, as the battery charge increases, the maximum allowable charging current I of the battery increases. bat_chg_need As the current gradually decreases, the maximum allowable charging current I of the energy storage battery in this application is as follows: when SOC=80%. bat_chg_need Reduce to 4A, then select the maximum allowable charging current I of the current battery. bat_chg_need =4A is used as the reference current I_bat_ref for constant current charging. Return to execute steps S2234-S2236 again to obtain the constant current charging current of 3.95A for the battery after bus chopper voltage reduction. The battery is charged with constant current using 3.95A as the constant current charging current. When the battery state of charge is ≥90%, return to execute step S221 to enter constant voltage charging mode.

[0221] Example 3

[0222] The similarities with Example 2 will not be repeated here; the differences are as follows:

[0223] S21: The current real-time battery state of charge (SOC) obtained through the battery management system (BMS) is 91%, indicating that the current remaining usable battery capacity accounts for 91% of the total capacity;

[0224] S22: To fully ensure charging efficiency and charging safety, this application uses 90% battery state of charge as a boundary to distinguish between constant current charging and constant voltage charging modes. Since the current battery state of charge is >90%, it enters the battery constant voltage charging mode to charge the battery at a constant voltage, including the following steps:

[0225] S221: Obtain the allowable charging voltage of the battery corresponding to the battery's state of charge, including the following steps:

[0226] S2211: The reference voltage V_bat_ref for constant voltage charging corresponding to the current state of battery charge is obtained through the battery management system (BMS) and is 570V;

[0227] S2212: As Figure 2 As shown, the reference voltage V_bat_ref of constant voltage charging is input to the battery voltage integration point Q3. Combined with the real-time battery voltage feedback value V_bat_fbk, the third reference deviation is obtained. The third reference deviation is input to the bus step-down chopper circuit voltage PI regulator, and the bus step-down chopper circuit duty cycle three is output.

[0228] S2213: Input the duty cycle three into the third PWM generation timer, and output the bus buck chopper circuit PWM drive square wave three;

[0229] S2214: The driving square wave three is input to the bus step-down chopper circuit IGBT driving module, the driving waveform of the driving square wave three is amplified, and the amplified driving square wave three is fed back to the bus step-down chopper circuit IGBT driving module to obtain the allowable charging voltage of 570V for the battery after bus step-down chopper.

[0230] S222: The battery is charged at a constant voltage of 570V, which is the allowable charging voltage of the battery, and the real-time state of charge of the battery is obtained. When the state of charge of the battery reaches 100%, the battery charging stops and the generator continues to supply power.

[0231] As can be seen from the above embodiments, this application provides an inverter power compensation method based on droop control. By obtaining the real-time maximum power supply of the generator and the real-time load power, when the real-time maximum power supply of the generator is less than the real-time load power, the method enters the battery discharge mode. The method modifies the generator droop control active power control coefficient in real time and determines the battery droop control active power control coefficient based on the generator droop control active power control coefficient. Utilizing the adaptive characteristics of the inverter droop controller, the method ensures full utilization of the generator power and rationally allocates the battery discharge power compensation, thus fully guaranteeing the utilization rate of both generator and battery power. This achieves the function of automatic power compensation based on real-time load power demand when generator power is insufficient, promptly meeting the changing load power requirements. This effectively suppresses the drastic fluctuations in the inverter input bus voltage and output voltage caused by the increase in load power, preventing generator overload damage to the equipment and improving the stability of the inverter operating voltage. The system maintains its current generator operation when the generator's real-time maximum power supply equals the real-time load power. When the generator's real-time maximum power supply exceeds the real-time load power, it enters battery charging mode. Combining inverter droop control technology and battery management technology, it fully utilizes the generator's excess power to charge and store energy for the battery while meeting the real-time load power requirements, thus maximizing energy utilization. When the battery's state of charge is less than 90%, a constant current charging mode is used. By comparing the maximum charging current provided by the generator's excess power with the maximum allowable charging current of the current battery, the smaller value is used to calculate the battery's constant current charging current and charge the battery accordingly. This ensures both rapid battery charging and full utilization of the generator's excess power. When the battery's state of charge is ≥90%, a constant voltage charging mode is used, charging the battery at the battery's allowable charging voltage, thus ensuring the safety and stability of battery charging.

[0232] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. Any obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A power compensation method for inverters based on droop control, characterized in that, Includes the following steps: S1: Obtain the generator's real-time maximum power supply and real-time load power; S2: Compare the generator's real-time maximum power supply with the real-time load power. When the generator's real-time maximum power supply is less than the real-time load power, the battery discharges, including the following steps: S23: Calculate the active power control coefficient for battery droop control; S24: Calculate the battery droop control output reference voltage under real-time load power using the active power control coefficient of battery droop control; S25: Input the battery droop control output reference voltage to the battery voltage integration point, combine it with the generator bus boost converter circuit voltage feedback value to obtain the first reference deviation, input the first reference deviation to the battery PI regulator, and output the battery boost converter circuit duty cycle one. S26: Input the duty cycle 1 into the first PWM generation timer and output the battery boost circuit PWM drive square wave 1. S27: Input the driving square wave 1 into the battery boost circuit IGBT drive module, amplify the driving square wave 1, and feed the amplified driving square wave 1 back to the battery boost circuit IGBT drive module to obtain the battery output voltage. S28: Calculate the real-time output power of the battery using the battery output terminal voltage, and calculate the sum of the real-time maximum power supply of the generator and the real-time output power of the battery to obtain the first power; S29: Compare the first power with the real-time load power. When the first power equals the real-time load power, the generator and battery continue to discharge. When the first power is less than the real-time load power, return to step S25. Calculating the active power control coefficient for battery droop control includes the following steps: S231: Calculate the absolute value of the difference between the generator's real-time maximum power supply and the real-time load power, and set it as the first difference value; S232: Determine the droop control active power control coefficient of the generator based on the first difference; S233: Calculate the active power control coefficient for battery droop control using the active power control coefficient for generator droop control; The correspondence between the first difference and the active power control coefficient of the generator droop control is as follows. K gent_m =m i ,P error ∈(P i ,P i+1 ) In the formula, K gent_m m is the active power control coefficient for generator droop control. i Let P be the specific value of the active power control coefficient for the generator's droop control, where i ≥ 1 and is a natural number; error P is the first difference; i P i+1 All are interval values; The formula for calculating the active power control coefficient for battery droop control is as follows. K bat_m =P error *K gent_m / P gent In the formula, K bat_m P is the active power control coefficient for battery droop control. gent This refers to the active power output of the generator in real time.

2. The inverter power compensation method based on droop control according to claim 1, characterized in that, The formula for calculating the reference voltage for battery droop control output is as follows. V bat_dc =u _dc -K bat_m *P bat In the formula, V bat_dc The reference voltage for the battery droop control output; u _dc K represents the desired boost voltage at the inverter input bus. bat_m P is the active power control coefficient for battery droop control. bat Provides real-time power output to the battery.

3. The inverter power compensation method based on droop control according to claim 2, characterized in that, The following steps are included after step S24: S241: Compare the battery droop control output reference voltage V bat_dc The inverter input bus boost voltage is 1.15 times the expected value u. _dc When V bat_dc ≥1.15*u _dc When, then V bat_dc =1.15*u _dc Otherwise V bat_dc This is the calculated value of the reference voltage for the battery droop control output.

4. The inverter power compensation method based on droop control according to claim 1, characterized in that, Step S2 also includes the following steps: When the generator's real-time maximum power supply equals the real-time load power, the generator continues to supply power. When the generator's real-time maximum power supply exceeds the real-time load power, the battery is charged, including the following steps: S21: Obtain the real-time battery state of charge; S22: Determine the magnitude of the battery's state of charge. When the battery's state of charge is ≥90%, the battery is subjected to constant voltage charging, including the following steps: S221: Obtain the allowable charging voltage of the battery corresponding to the battery state of charge; S222: Charge the battery at a constant voltage using the battery's allowable charging voltage. When the battery's state of charge reaches 100%, stop charging the battery and maintain the generator's power supply operation. When the battery's state of charge is <90%, the battery is charged with constant current, including the following steps: S223: Obtain the constant current charging current of the battery corresponding to the battery state of charge; S224: Charge the battery with the constant current charging current. When the battery state of charge is ≥90%, return to step S221.

5. The inverter power compensation method based on droop control according to claim 4, characterized in that, In step S221, obtaining the allowable charging voltage of the battery corresponding to the battery's state of charge includes the following steps: S2211: Obtain the reference voltage for constant voltage charging; S2212: Input the reference voltage of the constant voltage charging to the battery voltage integration point, and combine it with the real-time battery voltage feedback value to obtain the third reference deviation. Input the third reference deviation to the bus step-down chopper circuit voltage PI regulator and output the bus step-down chopper circuit duty cycle three. S2213: Input the duty cycle three into the third PWM generation timer, and output the bus buck chopper circuit PWM drive square wave three; S2214: The driving square wave three is input to the bus step-down chopper circuit IGBT driving module, the driving waveform of the driving square wave three is amplified, and the amplified driving square wave three is fed back to the bus step-down chopper circuit IGBT driving module to obtain the battery's allowable charging voltage.

6. The inverter power compensation method based on droop control according to claim 4, characterized in that, In step S223, obtaining the constant current charging current of the battery corresponding to the battery state of charge includes the following steps: S2231: Calculate the maximum charging current that the generator's excess power can provide; S2232: Obtain the maximum allowable charging current of the current battery; S2233: Compare the maximum charging current that the generator's excess power can provide with the maximum charging current that the current battery allows, and retain the smaller of the two as the reference current for constant current charging; S2234: Input the reference current of the constant current charging to the battery current integration point, combine it with the real-time current feedback value of the battery to obtain the fourth reference deviation, input the fourth reference deviation to the bus step-down chopper circuit current PI regulator, and output the bus step-down chopper circuit duty cycle four. S2235: Input the duty cycle four into the third PWM generation timer, and output the bus buck chopper circuit PWM drive square wave four; S2236: The driving square wave four is input to the bus step-down chopper circuit IGBT driving module, which amplifies the driving waveform of the driving square wave four, and feeds the amplified driving square wave four back to the bus step-down chopper circuit IGBT driving module to obtain the constant current charging current of the battery.

7. The inverter power compensation method based on droop control according to claim 1, characterized in that, The formula for calculating interval values ​​is as follows: P1=0,P i+1 =P error_max *i / n In the formula, P error_max This represents the maximum compensable power that the battery can currently provide; n represents the number of intervals, n≥3 and is an odd number; 1≤i≤n.

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