Household energy storage inverter control strategy based on direct current bus control and terminal

Abstract

The invention relates to a household energy storage inverter control strategy and terminal based on direct-current bus control, and the strategy comprises the steps: sampling the port voltage and inductive current of each converter, calculating the basic parameters of each converter in a household energy storage inverter, setting the direct-current bus voltage reference instruction priority of each converter, and calculating the direct-current bus voltage reference instruction priority of each converter. Based on the internal sampling voltage of the DC bus and the basic parameters of each converter, proportional-integral operation is carried out on the outer ring of each converter to obtain the current reference instruction value of the current inner ring of each converter, then the difference between the current reference instruction value of the current inner ring and the current value of each converter is obtained to obtain a difference value, and proportional-integral or proportional resonance operation is carried out on the difference value to obtain the current reference instruction value of the current inner ring of each converter. The control pulse duty ratio of each converter is obtained, driving control is carried out on each converter, and energy balance on the direct-current bus is achieved.

Description

Technical Field

[0001] This invention relates to the field of microgrid residential energy storage technology, and in particular to a residential energy storage inverter control strategy and terminal based on DC bus control. Background Technology

[0002] Residential energy storage systems, such as Figure 1 As shown, it includes three converters, each with a corresponding control loop: a photovoltaic (PVDC) converter, a battery converter (BATDC), and an AC / DC inverter (DCAC). The PV terminal of the PVDC converter is used to connect to the photovoltaic input, and the first DC terminal is connected to the DC bus of the residential energy storage system. The BAT terminal of the BATDC converter is used to connect to the battery, and the second DC terminal is connected to the DC bus of the residential energy storage system. The third DC terminal of the AC / DC inverter (DCAC) is connected to the DC bus of the residential energy storage system, and the AC terminal is used to connect to the mains power or the load.

[0003] In photovoltaic DC converters, the maximum power point tracking (MPPT) algorithm is used to calculate the power of photovoltaic panels. In battery converters, the charging and discharging control of energy storage batteries is realized. AC / DC inverters are used to convert DC to AC for grid-connected or independent off-grid operation.

[0004] In grid-connected operation mode, the grid serves as the main power source, and the DC bus voltage of the DC / AC stabilized energy storage inverter acts as a constant voltage source. The BATDC and PVDC controls act as current sources, and the charging and discharging power of the BATDC and the MPPT tracking power of the PVDC are adjusted by detecting the grid-connected power.

[0005] In off-grid operation mode, BATDC stabilizes the DC bus voltage, DC / AC operates in off-grid VF mode, and PVDC adjusts MPPT tracking power according to the rechargeable power of the energy storage battery and the load power of DC / AC.

[0006] When a residential energy storage system is connected to the grid, it generally operates in three modes: self-consumption, battery backup (or battery priority), and peak shaving and valley filling. These three modes have different energy management strategies, i.e., different power control methods. In self-consumption, PV and battery energy are prioritized for power supply to the load; excess energy is fed to the grid, and only when there is a shortage is grid energy used. In battery priority mode, battery power is prioritized for charging; PV power is used to charge the battery first, and excess power is used to supply the load. When PV power is insufficient, grid power is used to charge the battery and supply the load. In peak shaving and valley filling mode, priority is given to meeting the power dispatching needs of the grid.

[0007] Because the energy management strategies differ among the three modes, the aforementioned control method in grid-connected mode involves control strategy switching under different operating modes. Achieving these three operating modes requires complex conversion logic. In various actual application conditions, the matching between the three control loops of the three converters is crucial. For example, in peak shaving and valley filling mode, the DC / AC converter acts as a current source, operating in PQ mode, while the BATDC converter acts as a constant voltage source to stabilize the DC bus voltage of the energy storage inverter. During grid-connected / off-grid switching, the BATDC converter also experiences control strategy switching, which may cause DC bus fluctuations and prolong the switching time. Therefore, how to achieve energy balance on the DC bus to ensure DC bus stability is a problem that urgently needs to be solved. Summary of the Invention

[0008] The purpose of this invention is to provide a control strategy and terminal for a residential energy storage inverter based on DC bus control. According to the circuit topology of the residential energy storage inverter, a photovoltaic MPPT algorithm is implemented using a PVDC converter, battery charging and discharging functions are implemented using a BATDC converter, and the AC / DC inverter tracks the grid and provides independent power supply. A converter control block diagram is established. An outer loop of DC bus voltage is added to the three power electronic converters, each implementing its own inner-loop algorithm. All three converters can achieve stable DC bus operation. The respective DC bus voltage outer loops function as power dispatching loops. Power dispatching commands are then used to control the operation of the three converters via the inner-loop algorithm, achieving stable operation of the residential energy storage system.

[0009] Firstly, the above-mentioned objective of this invention is achieved through the following technical solution: A control strategy for a residential energy storage inverter based on DC bus control is disclosed. The residential energy storage inverter includes a photovoltaic converter, a battery converter, and an AC / DC inverter. The strategy includes sampling the port voltage and inductor current of each converter, calculating the basic parameters of each converter in the residential energy storage inverter, setting the priority of the DC bus voltage reference command for each converter, performing proportional-integral calculations within each converter based on the internal sampled voltage of the DC bus and the basic parameters of each converter to obtain the current inner loop reference command value of each converter, subtracting the current inner loop reference command value from the current value of each converter to obtain the difference, calculating the control pulse duty cycle of each converter based on the difference, and driving control of each converter.

[0010] The present invention is further configured such that: when the battery is discharging, the DC bus voltage reference first command of the photovoltaic converter has the highest priority, the DC bus voltage reference second command of the battery converter has the second highest priority, and the DC bus voltage reference third command of the AC / DC inverter has the lowest priority; when the battery is charging, the DC bus voltage reference first command of the photovoltaic converter has the highest priority, the DC bus voltage reference third command of the AC / DC inverter has the second highest priority, and the DC bus voltage reference second command of the battery converter has the lowest priority.

[0011] The present invention is further configured as follows: the first input voltage and the first inductor current of the photovoltaic converter are collected; the DC bus current reference first command is obtained through the outer loop calculation of the first PI regulator of the photovoltaic converter voltage; based on the first PI regulator of the photovoltaic converter DC bus voltage reference first command and the internal sampling voltage of the DC bus, the photovoltaic current limit reference command is obtained through the outer loop calculation of the second PI regulator of the photovoltaic converter voltage; based on the first PI regulator of the DC bus current reference first command and the photovoltaic current limit reference command, the inner loop current reference command value of the photovoltaic converter inductor current is obtained; combined with the photovoltaic inductor current, the photovoltaic PWM pulse drive duty cycle is obtained through the inner loop calculation of the third PI regulator of the current.

[0012] The present invention is further configured as follows: a control strategy for a photovoltaic converter, comprising the following steps: B1. Based on the first input voltage and the first inductor current, the photovoltaic voltage reference setpoint is calculated using the photovoltaic maximum power point tracking algorithm; B2. Compare the photovoltaic voltage reference setpoint with the first input voltage ν pv Calculate the difference to obtain the first difference; B3. Perform the first proportional integral operation on the first difference to obtain the first reference command for the DC bus current; B4. Set the photovoltaic DC bus voltage to reference the first instruction u. pv_ref With DC bus voltage u bus Take the difference to obtain the second difference; B5. Perform the outer loop second proportional integral operation on the second difference to obtain the photovoltaic current limit reference instruction; B6. Calculate the minimum value between the DC bus current reference first command and the photovoltaic current limit reference command, and use it as the inner loop current reference command value of the photovoltaic converter inductor current. B7. Calculate the difference between the inner loop current reference command value of the photovoltaic converter inductor current and the first inductor current in the converter to obtain the third difference value. B8. Perform a third proportional-integral inner loop operation on the third difference to obtain the PWM pulse drive duty cycle of the photovoltaic converter.

[0013] The present invention is further configured such that: in the battery converter, the lower limit of battery discharge voltage and the upper limit of battery charging voltage are obtained according to the battery access port voltage and inductor current; during discharge, the lower limit of discharge voltage is used as the outer loop setpoint of battery voltage, and during charging, the upper limit of charging voltage is used as the outer loop setpoint of battery voltage.

[0014] The invention is further configured as follows: A battery protection current limit is obtained based on the outer loop setpoint of the battery voltage and the battery access port voltage; a battery current reference command limit for the battery converter is calculated based on the grid power, load power, and the operating mode of the residential energy storage inverter; an output battery current inner loop reference command is calculated based on the DC bus voltage and the battery DC bus voltage reference second command; the battery protection current limit, battery current reference command limit, and output battery current inner loop reference command are logically minimized to obtain the battery inductor current inner loop current reference command value; the difference between the battery inductor current inner loop current reference command value and the battery inductor current is calculated, and then a proportional-integral inner loop operation is performed on the difference to obtain the PWM pulse drive duty cycle of the battery converter.

[0015] The present invention is further configured such that: the operating modes of the residential energy storage inverter include self-consumption mode, battery priority mode, and peak shaving and valley filling mode; under different operating modes, the reference command limit of the battery current of the battery converter is calculated based on the grid power and load power, including the following steps: D1. In self-consumption mode, the battery current reference command limit I bat_ref_aclimit The calculation method is as follows: erro1[k]=P set -P gridsum (15); erro1[k-1]=erro1[k] (17); In the formula, P set P represents the expected total mains power output issued by the host computer or dispatcher. gridsum This indicates the total power of the three-phase mains electricity; k bat_p k represents the proportional coefficient of the incremental first PI regulator in the battery converter. bat_i is the integral coefficient of the incremental first PI controller; k represents the current time, and k-1 represents the previous time. D2. Battery current reference command limit I during battery priority mode or peak shaving and valley filling charging. bat_ref_aclimit The calculation method is as follows: I bat_ref_aclimit =I bat_charge (18); I bat_charge Indicates the charging current; D3. During peak shaving and valley filling discharge, the battery current reference command limit I bat_ref_aclimit The calculation method is as follows: I bat_ref_aclimit =I bat_Discharge (19); I bat_Discharge This represents the discharge current.

[0016] The present invention is further configured as follows: a control strategy for the battery converter, comprising the following steps: C1. Calculate the difference between the outer loop setpoint of the battery voltage and the voltage at the battery input port to obtain the fourth difference value. Then, perform the fourth difference value through the outer loop calculation of the fourth PI regulator of the battery voltage protection to obtain the battery protection current limit value. C2. Based on the grid power and load power, calculate the battery current reference command limit I for the battery converter in different operating modes. bat_ref_aclimit : C3. Calculate the difference between the DC bus voltage and the battery DC bus voltage referenced by the second instruction to obtain the sixth difference value; perform the fifth proportional-integral operation on the sixth difference value to obtain the inner loop reference instruction for the output battery current; C4. Perform a logical minimum operation on the battery protection current limit, battery current reference command limit, and output battery current inner loop reference command to obtain the minimum value, which is used as the battery inductor current inner loop current reference command value. C5. The difference between the inner loop current reference command value of the battery inductor current and the battery inductor current is obtained to get the seventh difference value. The seventh difference value is then processed by the sixth proportional-integral operation to obtain the PWM pulse drive duty cycle of the battery converter.

[0017] The present invention is further configured as follows: In the AC / DC inverter, the inverter current inner loop reference command limit is calculated according to the grid power and load power of each phase, under different operating modes; the inverter current limit reference command is obtained by proportional-integral operation based on the AC / DC inverter bus voltage outer loop reference command and DC bus voltage; the inverter current inner loop reference command limit and the inverter current limit reference command are logically minimized to obtain the minimum value, which is used as the inverter current inner loop reference command value of the AC / DC inverter; the PWM control signal of the AC / DC inverter is calculated based on the inverter current inner loop reference command value and the inverter output inductor current.

[0018] The present invention is further configured such that the control strategy includes the following steps: E1. Calculate the inverter current inner loop reference command limit for different operating modes based on the grid power and load power of each phase. E2. The difference between the outer loop reference command of the AC / DC inverter bus voltage and the DC bus voltage is used to obtain the eighth difference value. The eighth difference value is then used for the seventh proportional-integral operation to obtain the inverter current limit reference command. E3. Logically take the minimum value of the inverter current inner loop reference command limit and the inverter current limit reference command, and use the minimum value as the inverter current inner loop current reference command value. E4. The inner loop current reference command value of the inverter is compared with the output inductor current of each phase of the inverter to obtain the ninth difference value of each phase. The ninth difference value of each phase is processed by proportional resonance control to obtain the PWM control signal of each phase of the AC / DC inverter.

[0019] The present invention further specifies that the calculation method for the inverter current inner loop reference command limit under different operating modes is as follows: F1. In self-consumption mode, the inverter current inner loop reference command limit I inv_ref_limit The calculation method is as follows: erro2[k]=P setx -P gridx (25); erro2[k-1]=erro2[k] (27); In equation (25), x represents any one of the three phases A / B / C, and P setx This represents the power per phase issued by the host computer or dispatcher. When the residential inverter is protected against reverse current, P... setx equals 0; k inv_p k is the proportional coefficient of the AC / DC inverter incremental seventh PI controller. inv_i represents the integral coefficient of the AC / DC inverter incremental PI regulator; k represents the current time, and k-1 represents the previous time. F2, during battery priority mode or peak shaving and valley filling charging, the inverter current inner loop reference command limit I inv_ref_limit The calculation method is as follows: I inv_ref_limit =I grid_charge (28); I grid_charge Indicates the charging current; F3. The operating mode of the residential energy storage inverter is during peak shaving and valley filling discharge, with the inverter current inner loop reference command limit I. inv_ref_limit The calculation method is as follows: I inv_ref_limit =I grid_Discharge (29); I grid_Discharge This represents the discharge current.

[0020] Secondly, the above-mentioned objective of this invention is achieved through the following technical solution: A residential energy storage inverter control terminal based on DC bus control includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the method described in this application.

[0021] Compared with the prior art, the beneficial technical effects of this application are as follows: 1. This application achieves energy balance on the DC bus by sampling and calculating in three converters respectively, and calculating the duty cycle of the control pulse signal of each converter based on the DC bus voltage; 2. Furthermore, this application performs calculations for each converter separately. In the photovoltaic converter, based on the photovoltaic parameters and the DC bus voltage, the photovoltaic pulse drive duty cycle is obtained through multiple proportional-integral operations. The DC bus voltage is then introduced into the control to achieve energy balance of the photovoltaic converter on the DC bus. 3. Furthermore, in this application, based on battery parameters and DC bus voltage, and combined with the operating mode, the battery pulse drive duty cycle is obtained through multiple proportional-integral calculations in the battery converter, and the DC bus voltage is introduced into the control to achieve energy balance of the battery converter on the DC bus. 4. Furthermore, in the AC / DC inverter, based on the power of each AC / DC phase, the load power, and the operating mode, the present application obtains the control signals of each phase of the AC / DC inverter through proportional-integral and proportional-resonant control calculations, thereby realizing the energy balance of the battery converter on the DC bus. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a residential energy storage inverter in the existing technology; Figure 2 This is a schematic diagram of the internal structure of a residential energy storage inverter according to a specific embodiment of this application; Figure 3 This is a schematic diagram of the sampling location of a residential energy storage inverter according to a specific embodiment of this application; Figure 4 This is a schematic diagram of photovoltaic converter control operation according to a specific embodiment of this application; Figure 5 This is a schematic diagram of the battery converter control operation according to a specific embodiment of this application; Figure 6 This is a schematic diagram of AC / DC inverter control operation according to a specific embodiment of this application. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the accompanying drawings.

[0024] This application discloses a control strategy and terminal for a residential energy storage inverter based on DC bus control, based on, for example... Figure 2 , 3The topology shown samples the port voltage and inductor current of each converter, calculates the parameters in each converter circuit, obtains the outer loop voltage setpoint of each converter, calculates the current protection limit of each converter through the PI regulator of each converter, sets the DC bus voltage reference command priority of each converter, and calculates the PWM pulse drive duty cycle of each converter based on the internal sampled voltage of the DC bus and the parameters of each converter to realize the control of each converter.

[0025] In one specific embodiment of this application, the internal sampling voltage of the DC bus is set to u. bus As the feedback quantity of the bus voltage loop, the difference and proportional-integral calculations are performed in the outer loop of each converter to obtain the reference current command value of the inner loop of each converter. In the inner loop, the difference and proportional-integral or proportional-resonance calculations are performed on the reference current command value of the inner loop and the corresponding current value to obtain the control pulse duty cycle of each converter, and the converter is controlled.

[0026] Step S1: Calculate the basic parameters of each converter circuit, including: A1. Photovoltaic DC Converter: Photovoltaic input voltage is ν pv The voltage is marked as the first voltage, and the current in the first inductor L1 is i. lpv The current, marked as the first current, is calculated by the outer loop of the first PI regulator of the photovoltaic converter voltage to obtain the DC bus current reference first command I. pv_ref This serves as the initial reference command for the first current in the inner loop of the first inductor current of the photovoltaic converter.

[0027] A2, Battery Converter (BATDC): The battery input port voltage is V bat This is marked as the second voltage, serving as the feedback value for the outer loop of the battery voltage with battery protection function; the current in the inductor (L3 / L4) is i. lbat This is marked as the second current, serving as the inner loop feedback quantity of the inductor current during battery charging and discharging. Based on the second voltage and the second current, the lower limit of the battery discharge voltage is obtained as v. bat_dn The upper limit of battery charging voltage is V. bat_up During discharge, the lower limit of the discharge voltage v is used. bat_dn As the outer loop given value of the battery voltage During charging, the upper limit of the charging voltage v is used. bat_up As the outer loop given value of the battery voltage

[0028] Based on the given value, the battery current protection limit I of the battery converter is obtained through calculation by the outer loop of the second PI regulator of the battery converter voltage. bat_protect_limit .

[0029] A3. AC / DC Inverter: A31. The output of the AC / DC inverter includes three-phase power. The current of the third inductor in phase A is calculated by sampling each phase separately. la Marked as the third current, output voltage u inva This is marked as the third voltage; the fourth inductor current of phase B is i. lb Marked as the fourth current, output voltage u invb This is marked as the fourth voltage; the fifth inductor current of phase C is i. lc Marked as the fifth current, the output voltage is u. invc It is marked as the fifth voltage.

[0030] A32. For the power grid, the voltage of phase A is u. grida Marked as the sixth voltage, the grid current is i Grida Marked as the sixth current, based on voltage and current, the power of the grid in phase A is calculated to be P. grida Marked as the first power; the voltage of the B-phase power grid is u. gridb Marked as the seventh voltage, the grid current is i Gridb Marked as the seventh current, based on the voltage and current of phase B, the power of the grid in phase B is calculated as P. gridb Marked as the second power; the voltage of the C-phase power grid is u. gridc Marked as the eighth voltage, the grid current is i Gridc Marked as the eighth current, based on the voltage and current of phase C, the power of the C-phase grid is calculated to be P. gridc , marked as the third power.

[0031] Based on the grid voltage, the frequency ω and phase angle θ of the grid are calculated using the generalized second-order integral DSOGI software phase-locked loop.

[0032] A33. For the load, the load current of phase A is i Loada Marked as the ninth current, the load current of phase B is i Loadb Marked as the tenth current, the C-phase load current is i Loadc It is marked as the eleventh current.

[0033] Based on the grid voltage and load current, or the output voltage and load current, calculate the load power, as follows: Phase A load is labeled P. Loada The fourth power is marked as the B-phase load, and the B-phase load is marked as P. Loadb The fifth power is marked as the C-phase load, and the C-phase load is marked as P. Loadc It is marked as the sixth power.

[0034] Step S2: Set the priority of the DC bus voltage reference command for the three converters: Let u be the reference first command for the DC bus voltage of the photovoltaic converter (PVDC). pv_ref The DC bus voltage reference of the battery converter (BATDC) is u. bat_ref The DC bus voltage of the AC / DC inverter (DCAC) references the third instruction as u. inv_ref .

[0035] When the battery is discharging, the priority of the three commands is as follows: u pv_ref >u bat_ref >u inv_ref (1); When the battery is charging, the priority of the three commands is as follows: u pv_ref >u inv_ref >u bat_ref (2); set up u pv_ref =U dc +ΔU pv (3); In the formula, ΔU pv This indicates the voltage loop error of the photovoltaic converter.

[0036] When the battery discharges, u bat_ref =U dc +ΔU bat (4); ΔU bat This indicates the voltage loop error of the battery converter.

[0037] When the battery is charging, u bat_ref =U dc -ΔU bat (5). The following analysis covers the control of photovoltaic converters, battery converters, and AC / DC inverters. Step S3 discusses the control methods in the photovoltaic converter (PVDC), such as... Figure 4 As shown, it includes the following steps: B1. Calculate the photovoltaic voltage reference setpoint and the DC bus current reference first instruction: The photovoltaic voltage reference setpoint is calculated using the conductance-perturbation photovoltaic maximum power point tracking (MPPT) algorithm. The photovoltaic voltage reference setpoint is compared with the first input voltage ν. pv The difference is calculated to obtain the first difference value. This first difference value is then processed by the outer loop of the first PI regulator of the photovoltaic voltage for proportional-integral calculation to obtain the DC bus current reference first command I. pv_ref The calculation method is as follows: I pv_ref =(kpv_p +k pv_i ∫)Δv pv (7); In the formula, k pv_p k represents the proportional gain of the PI regulator in a photovoltaic converter. pv_i This represents the integral coefficient of the PI regulator in the photovoltaic converter.

[0038] B2. Reference instructions for calculating photovoltaic current limits: DC bus voltage u bus Reference to DC bus voltage first command u pv_ref The difference is calculated to obtain a second difference. This second difference is then processed by the outer loop of the second PI regulator to perform proportional-integral calculations, resulting in the photovoltaic current limit reference command I. pv_reflimit As shown in the following formula: Δu pv =u pv_ref -u bus (8); I pv_reflimit =(k pv_p +k pv_i ∫)Δu pv (9); In one specific embodiment of this application, the proportional coefficient and integral coefficient of the second PI regulator of the bus voltage loop of the photovoltaic converter are the same as the proportional coefficient and integral coefficient of the first PI regulator.

[0039] B3. Calculate the reference command value I for the inner loop current of the photovoltaic converter inductor. pv_refact : Reference the DC bus current to the first instruction I pv_ref and Photovoltaic Current Limit Reference Directive I pv_reflimit Perform a logical minimum operation to obtain the minimum value, and get the reference command value I of the inner loop current of the photovoltaic converter inductor current. pv_refact As shown in the following formula: I pv_refact =min(I pv_ref I pv_reflimit (10). B4. Calculate the PWM pulse drive duty cycle D of the photovoltaic converter. pv : The first inductor current i of the photovoltaic converter lpv And the inner loop current reference command value I of photovoltaic inductor current pv_refact The difference is calculated to obtain a third difference value. This third difference value is then processed by the third PI arithmetic unit through a proportional-integral inner loop operation to obtain the PWM pulse drive duty cycle D of the photovoltaic converter. pv The calculation formula for controlling the operation of the photovoltaic converter is as follows: Δipv =I pv_refact -i lpv (11); D pv =(k Ipv_p +k Ipv_i ∫)Δi pv (12); In the formula, D pv k represents the duty cycle of the PWM pulse drive. Ipv_p k represents the proportional gain of the inner current loop in a photovoltaic converter. Ipv_i This represents the integral coefficient of the inner current loop in the photovoltaic converter.

[0040] Step S4, the control method of the battery converter BATDC, as follows: Figure 5 As shown, it includes the following steps: C1. Calculate the battery protection current limit: Set the outer loop value of the battery voltage and battery input port voltage v bat The difference is calculated to obtain the fourth difference value. This fourth difference value is then processed by the outer loop of the fourth PI regulator for battery voltage protection to perform proportional-integral calculations, resulting in the battery protection current limit value I. bat_protect_limit As shown in the following formula: I bat_protect_limit =(k bat_p +k bat_i ∫)Δv bat (14); In the formula, k bat_p k represents the proportional gain of the PI converter in the battery converter. bat_i This represents the integral coefficient of the PI converter in the battery converter.

[0041] C2. Calculate the battery current reference command limit I for the battery converter in different operating modes. bat_ref_aclimit : Based on the grid power, load power, and the operating mode of the residential energy storage inverter, the reference command limit I for the battery current of the battery converter is calculated. bat_ref_aclimit The operating modes of residential energy storage inverters include self-consumption mode, battery priority mode, and peak shaving and valley filling mode.

[0042] D1. In self-consumption mode, the battery current reference command limit I bat_ref_aclimit The calculation method is as follows: The fifth difference is obtained by calculating the difference between the expected total mains power and the total three-phase mains power: erro1[k]=P set -P gridsum (15); The battery current reference command limit at the current time k is equal to the battery current reference command limit at the previous time k-1 plus the fifth difference at the current time minus the fifth difference at the previous time, as shown in the following formula: Save the fifth difference value at the current time step as the fifth difference value at the next time step: erro1[k-1]=erro1[k] (17). In equations (16) and (17), represents assigning the value on the right side of the equal sign to the value on the left side of the equal sign.

[0043] P set P represents the expected total mains power output issued by the host computer or dispatcher. gridsum This indicates the total power of the three-phase mains electricity.

[0044] When the residential inverter prevents backflow P set equals 0, k bat_p k is the proportional coefficient of the incremental PI regulator in the battery converter. bat_i This is the integral coefficient of the incremental PI controller.

[0045] D2. Battery current reference command limit I during battery priority mode or peak shaving and valley filling charging. bat_ref_aclimit The calculation method is as follows: I bat_ref_aclimit =I bat_charge (18); That is, the battery current reference command limit I bat_ref_aclimit It equals the charging current.

[0046] D3. During peak shaving and valley filling discharge, the battery current reference command limit I bat_ref_aclimit The calculation method is as follows: I bat_ref_aclimit =I bat_Discharge (19); That is, the battery current reference command limit I bat_ref_aclimit It equals the discharge current.

[0047] C3. Calculate the inner loop reference command I for the output battery current of the battery converter. bat_ref .

[0048] DC bus voltage u bus Reference to DC bus voltage second command u bat_ref The difference is calculated to obtain the sixth difference value. This sixth difference value is then processed by the fifth PI regulator to perform proportional-integral calculations, resulting in the inner loop reference command I for the output battery current. bat_ref As shown in the following formula: Δu bat =ubus -u bat_ref (20); I bat_ref =(k bat_p +k bat_i ∫)Δu bat (twenty one); In the formula, k bat_p k represents the proportional gain of the PI regulator in the battery converter. bat_i This represents the integral coefficient of the PI regulator in the battery converter.

[0049] C4. Calculate the reference command value I for the output inductor current and inner loop current of the battery converter. bat_refact : to I bat_protect_limit I bat_ref_aclimit and I bat_ref Perform a logical minimum operation to obtain the minimum value, which will be used as the reference command value I for the inner loop current of the battery inductor. bat_refact As shown in the following formula: I bat_refact =min(I bat_ref I bat_ref_aclimit I bat_protect_limit ) (twenty two). Specifically, first I bat_ref_aclimit and I bat_ref Perform a logical minimum operation to obtain the first minimum value, then multiply the first minimum value by I. bat_protect_limit Perform a logical minimum operation to obtain the second minimum value, and use the second minimum value as the reference command value I for the inner loop current of the battery inductor current. bat_refact .

[0050] C5. Calculate the PWM pulse drive duty cycle D of the battery converter. bat : Reference command value I for battery inductor current inner loop current bat_refact The current i of the second inductor lbat The difference is calculated to obtain the seventh difference value. This seventh difference value is then processed by the sixth PI arithmetic unit for proportional-integral calculation to obtain the PWM pulse drive duty cycle D of the battery converter. bat The calculation formula for controlling the operation of the battery converter is as follows: Δi bat =I bat_refact -i lbat (twenty three); D bat =(k Ibat_p +k Ibat_i ∫)Δi bat (twenty four); In the formula, k Ibat_pk represents the proportional gain of the inner current loop of the battery converter. Ibat_i This represents the integral coefficient of the inner current loop of the battery converter.

[0051] Step S5, the control method of the AC / DC inverter, such as... Figure 6 As shown, it includes the following steps: E1. Calculate the current inner loop reference command limit for AC / DC inverters under different operating modes: According to the power P of each phase of the power grid grida P gridb P gridc and the power P of each phase electrical load Loada P Loadb P Loadc Based on the operating mode of the residential energy storage inverter, the current inner loop reference command limit I of the AC / DC inverter is calculated. inv_ref_limit .

[0052] F1. When the residential energy storage inverter operates in self-consumption mode, the inverter current inner loop reference command limit I... inv_ref_limit The calculation method is as follows: erro2[k]=P setx -P gridx (25); erro2[k-1]=erro2[k] (27). In equation (25), x represents any one of the three phases A / B / C, and P setx This represents the power per phase issued by the host computer or dispatcher. When the residential inverter is protected against reverse current, P... setx Equals 0. k inv_p k is the proportional coefficient of the incremental seventh PI regulator in the AC / DC inverter. inv_i This is the integral coefficient of the incremental PI regulator in the AC / DC inverter.

[0053] In equations (26) and (27), represents assigning the value on the right side of the equal sign to the value on the left side of the equal sign.

[0054] k represents the current time, and k-1 represents the previous time.

[0055] F2. When the residential energy storage inverter is operating in battery priority mode or peak-shaving and valley-filling charging mode, the inverter current inner loop reference command limit I... inv_ref_limit The calculation method is as follows: I inv_ref_limit =I grid_charge (28); That is, the inverter current inner loop reference command limit I inv_reflimit It equals the charging current.

[0056] F3. The operating mode of the residential energy storage inverter is during peak shaving and valley filling discharge, with the inverter current inner loop reference command limit I. inv_ref_limit The calculation method is as follows: I inv_ref_limit =I grid_Discharge (29); That is, the inverter current inner loop reference command limit I inv_reflimit It equals the discharge current.

[0057] E2. Reference instructions for calculating inverter current limits: The outer loop reference command u of the AC / DC inverter bus voltage inv_ref With DC bus voltage u bus The difference is calculated to obtain the eighth difference value. This eighth difference value is then processed by the eighth PI regulator of the AC / DC inverter for proportional-integral calculation to obtain the inverter current limit reference command I. inv_ref As shown in the following formula: Δu inv =u bus -u inv_ref (30); I inv_ref =(k inv_p +k inv_i ∫)Δu inv (31); In the formula, k inv_p k represents the proportional gain of the eighth PI regulator in an AC / DC inverter. inv_i This represents the integral coefficient of the PI regulator in an AC / DC inverter.

[0058] E3. Calculate the reference command value I for the inner loop current of the AC / DC inverter. inv_refact ; to I inv_ref_limit and I inv_ref Perform a logical minimum operation to obtain the minimum value, which will be used as the reference command value I for the inner loop current of the AC / DC inverter. inv_refact As shown in the following formula: I inv_refact =min(I inv_ref_limit I inv_ref (32); E4. Calculate the PWM control signal D for each phase of the AC / DC inverter. invx : The reference command value I for the inner loop current. inv_refact The current i of each phase output inductor of the AC / DC inverter is respectively related to the current i of each phase output inductor. la i lb i lc By taking the difference, we obtain the ninth difference value Δi. linvxThe ninth difference is processed by proportional resonance (PR) control to obtain the PWM control signals D for each phase of the AC / DC inverter. invx As described below: Δi linvx =k inv_x ×I inv_refact -i lx (33); In the formula, x represents any one of the three phases A, B, and C, w0 represents the resonant frequency of the proportional resonant controller, and k inv_p k represents the proportional coefficient of the proportional resonant controller. inv_r w represents the resonant point gain of the proportional resonant controller. c k represents the bandwidth of the proportional resonant controller at resonance. inv_x The current coefficient for each phase is determined based on the three-phase load ratio, and the calculation formula is as follows: k inv_a :k inv_b :k inv_c =P Loada :P Loadb :P Loadc (34). An embodiment of the present invention provides a residential energy storage inverter control terminal device based on DC bus control. The terminal device of this embodiment includes: a processor, a memory, and a computer program stored in the memory and executable on the processor, such as a program for calculating the inner loop current. When the processor executes the computer program, it implements the method described in this application.

[0059] Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the above-described device embodiments.

[0060] For example, the computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing specific functions, which describe the execution process of the computer program in the DC bus-based residential energy storage inverter control terminal device. For example, the computer program can be divided into multiple modules, each with the following specific functions: 1. Photovoltaic converter control module, used for calculating the duty cycle of photovoltaic control pulses; 2. Battery converter control module, used for calculating battery control pulse duty cycle; 3. AC / DC inverter control module, used for calculating the duty cycle of AC / DC control pulses.

[0061] The residential energy storage inverter control terminal device based on DC bus control can be a computing device such as a desktop computer, laptop, handheld computer, or cloud server. The residential energy storage inverter control terminal device based on DC bus control may include, but is not limited to, a processor and a memory. Those skilled in the art will understand that the above examples are merely examples of the residential energy storage inverter control terminal device based on DC bus control and do not constitute a limitation on the residential energy storage inverter control terminal device based on DC bus control. It may include more or fewer components than illustrated, or combine certain components, or different components. For example, the residential energy storage inverter control terminal device based on DC bus control may also include input / output devices, network access devices, buses, etc.

[0062] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the DC bus-based residential energy storage inverter control terminal equipment, connecting all parts of the equipment via various interfaces and lines.

[0063] The memory can be used to store the computer program and / or modules. The processor implements various functions of the DC bus-based residential energy storage inverter control terminal device by running or executing the computer program and / or modules stored in the memory and calling the data stored in the memory. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created according to the use of the mobile phone (such as audio data, phonebook, etc.). In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital card (SD) card, flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0064] The module / unit integrated into the residential energy storage inverter control terminal equipment based on DC bus control, if implemented as a software functional unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0065] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A control strategy for a residential energy storage inverter based on DC bus control, wherein the residential energy storage inverter includes a photovoltaic converter, a battery converter, and an AC / DC inverter, characterized in that: This includes sampling the port voltage and inductor current of each converter, calculating the basic parameters of each converter in the residential energy storage inverter, setting the priority of the DC bus voltage reference command for each converter, performing proportional-integral calculations within each converter based on the internal sampled voltage of the DC bus and the basic parameters of each converter to obtain the current inner loop reference command value of each converter, then subtracting the current inner loop reference command value from the current value of each converter to obtain the difference, calculating the control pulse duty cycle of each converter based on the difference, and then driving and controlling each converter.

2. The control strategy for a residential energy storage inverter based on DC bus control according to claim 1, characterized in that: During battery discharge, the DC bus voltage reference first command of the photovoltaic converter has the highest priority, the DC bus voltage reference second command of the battery converter has the second highest priority, and the DC bus voltage reference third command of the AC / DC inverter has the lowest priority. During battery charging, the DC bus voltage reference first command of the photovoltaic converter has the highest priority, the DC bus voltage reference third command of the AC / DC inverter has the second highest priority, and the DC bus voltage reference second command of the battery converter has the lowest priority.

3. The control strategy for a residential energy storage inverter based on DC bus control according to claim 1, characterized in that: The first input voltage and the first inductor current of the photovoltaic converter are collected. After calculation by the outer loop of the first PI regulator of the photovoltaic converter voltage, the first reference command for the DC bus current is obtained. Based on the first reference command for the DC bus voltage of the photovoltaic converter and the internal sampling voltage of the DC bus, the outer loop of the second PI regulator of the photovoltaic converter voltage is calculated to obtain the photovoltaic current limit reference command. Based on the first reference command for the DC bus current and the photovoltaic current limit reference command, the inner loop current reference command value of the photovoltaic converter inductor current is obtained. Combined with the photovoltaic inductor current, the inner loop of the third PI regulator of the current is calculated to obtain the photovoltaic PWM pulse drive duty cycle.

4. The control strategy for a residential energy storage inverter based on DC bus control according to claim 2, characterized in that: The control strategy for photovoltaic converters includes the following steps: B1. Based on the first input voltage and the first inductor current, the photovoltaic voltage reference setpoint is calculated using the photovoltaic maximum power point tracking algorithm; B2. Compare the photovoltaic voltage reference setpoint with the first input voltage ν pv Calculate the difference to obtain the first difference; B3. Perform the first proportional integral operation on the first difference to obtain the first reference command for the DC bus current; B4. Set the photovoltaic DC bus voltage to reference the first instruction u. pv_ref With DC bus voltage u bus Take the difference to obtain the second difference; B5. Perform the second proportional integral operation on the second difference to obtain the photovoltaic current limit reference instruction; B6. Calculate the minimum value between the DC bus current reference first command and the photovoltaic current limit reference command, and use it as the inner loop current reference command value of the photovoltaic converter inductor current. B7. Calculate the difference between the inner loop current reference command value of the photovoltaic converter inductor current and the first inductor current in the converter to obtain the third difference value. B8. Perform a third proportional-integral inner loop operation on the third difference to obtain the PWM pulse drive duty cycle of the photovoltaic converter.

5. The control strategy for a residential energy storage inverter based on DC bus control according to claim 1, characterized in that: In the battery converter, the lower limit of battery discharge voltage and the upper limit of battery charging voltage are obtained based on the battery input port voltage and inductor current. During discharge, the lower limit of the discharge voltage is used as the given value for the outer loop of the battery voltage; during charging, the upper limit of the charging voltage is used as the given value for the outer loop of the battery voltage.

6. The control strategy for a residential energy storage inverter based on DC bus control according to claim 5, characterized in that: Based on the outer loop setpoint of the battery voltage and the battery access port voltage, the battery protection current limit is obtained. Based on the grid power, load power, and the operating mode of the residential energy storage inverter, the battery current reference command limit of the battery converter is calculated. Based on the DC bus voltage and the second reference command for the battery DC bus voltage, the inner loop reference command for the output battery current is calculated. The smallest value among the battery protection current limit, the battery current reference command limit, and the inner loop reference command for the output battery current is logically taken to obtain the inner loop current reference command value for the battery inductor current. The difference between the inner loop current reference command value for the battery inductor current and the battery inductor current is calculated, and then a proportional-integral inner loop operation is performed on the difference to obtain the PWM pulse drive duty cycle of the battery converter.

7. The control strategy for a residential energy storage inverter based on DC bus control according to claim 6, characterized in that: The operating modes of residential energy storage inverters include self-consumption mode, battery priority mode, and peak shaving and valley filling mode. Under different operating modes, the reference command limit for the battery current of the battery converter is calculated based on the grid power and load power, including the following steps: D1. In self-consumption mode, the battery current reference command limit I bat_ref_aclimit The calculation method is as follows: erro1[k]=P set -P gridsum (15); erro1[k-1]=erro1[k](17); In the formula, P set P represents the expected total mains power output issued by the host computer or dispatcher. gridsum This indicates the total power of the three-phase mains electricity; k bat_p k represents the proportional coefficient of the incremental first PI regulator in the battery converter. bat_i is the integral coefficient of the incremental first PI controller; k represents the current time, and k-1 represents the previous time. D2. Battery current reference command limit I during battery priority mode or peak shaving and valley filling charging. bat_ref_aclimit The calculation method is as follows: I bat_ref_aclimit =I bat_charge (18); I bat_charge Indicates the charging current; D3. During peak shaving and valley filling discharge, the battery current reference command limit I bat_ref_aclimit The calculation method is as follows: I bat_ref_aclimit =I bat_Discharge (19); I bat_Discharge This represents the discharge current.

8. The control strategy for a residential energy storage inverter based on DC bus control according to claim 6, characterized in that: The control strategy for the battery converter includes the following steps: C1. Calculate the difference between the outer loop setpoint of the battery voltage and the voltage at the battery input port to obtain the fourth difference value. Then, perform the fourth difference value through the outer loop calculation of the fourth PI regulator of the battery voltage protection to obtain the battery protection current limit value. C2. Based on the grid power and load power, calculate the battery current reference command limit I for the battery converter in different operating modes. bat_ref_aclimit : C3. Calculate the difference between the DC bus voltage and the battery DC bus voltage referenced by the second instruction to obtain the sixth difference value; perform the fifth proportional-integral operation on the sixth difference value to obtain the inner loop reference instruction for the output battery current; C4. Perform a logical minimum operation on the battery protection current limit, battery current reference command limit, and output battery current inner loop reference command to obtain the minimum value, which is used as the battery inductor current inner loop current reference command value. C5. The difference between the inner loop current reference command value of the battery inductor current and the battery inductor current is obtained as the seventh difference value. The seventh difference value is then processed by the sixth proportional-integral operation to obtain the PWM pulse drive duty cycle of the battery converter.

9. The control strategy for a residential energy storage inverter based on DC bus control according to claim 1, characterized in that: In an AC / DC inverter, the inverter current inner loop reference command limit is calculated based on the grid power and load power of each phase under different operating modes. The inverter current limit reference command is obtained by performing proportional-integral calculations based on the AC / DC inverter bus voltage outer loop reference command and the DC bus voltage. The minimum value is obtained by logically subtracting the inverter current inner loop reference command limit and the inverter current limit reference command, and this minimum value is used as the inverter current inner loop reference command value for the AC / DC inverter. The PWM control signal for the AC / DC inverter is then calculated based on the inverter inner loop current reference command value and the inverter's output inductor current.

10. A residential energy storage inverter control strategy based on DC bus control according to claim 9, characterized in that: The control strategy includes the following steps: E1. Calculate the inverter current inner loop reference command limit for different operating modes based on the grid power and load power of each phase. E2. The difference between the outer loop reference command of the AC / DC inverter bus voltage and the DC bus voltage is used to obtain the eighth difference value. The eighth difference value is then used for the seventh proportional-integral operation to obtain the inverter current limit reference command. E3. Logically take the minimum value of the inverter current inner loop reference command limit and the inverter current limit reference command, and use the minimum value as the inverter current inner loop current reference command value. E4. The inner loop current reference command value of the inverter is compared with the output inductor current of each phase of the inverter to obtain the ninth difference value of each phase. The ninth difference value of each phase is processed by proportional resonance control to obtain the PWM control signal of each phase of the AC / DC inverter.

11. The control strategy for a residential energy storage inverter based on DC bus control according to claim 9, characterized in that: The calculation methods for the inverter current inner loop reference command limit under different operating modes are as follows: F1. In self-consumption mode, the inverter current inner loop reference command limit I inv_ref_limit The calculation method is as follows: erro2[k]=P setx -P gridx (25); erro2[k-1]=erro2[k](27); In equation (25), x represents any one of the three phases A / B / C, and P setx This represents the power per phase issued by the host computer or dispatcher. When the residential inverter is protected against reverse current, P... setx equals 0; k inv_p k is the proportional coefficient of the AC / DC inverter incremental seventh PI controller. inv_i represents the integral coefficient of the AC / DC inverter incremental PI regulator; k represents the current time, and k-1 represents the previous time. F2, during battery priority mode or peak shaving and valley filling charging, the inverter current inner loop reference command limit I inv_ref_limit The calculation method is as follows: I inv_ref_limit =I grid_charge (28); I grid_charge Indicates the charging current; F3. The operating mode of the residential energy storage inverter is during peak shaving and valley filling discharge, with the inverter current inner loop reference command limit I. inv_ref_limit The calculation method is as follows: I inv_ref_limit =I grid_Discharge (29); I grid_Discharge This represents the discharge current.

12. A residential energy storage inverter control terminal based on DC bus control, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, it implements the method as described in any one of claims 1-11.

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