Power regulation control method of multi-phase energy storage inverter and multi-phase energy storage system

Abstract

The present invention discloses a power regulation control method and a multiphase energy storage system of a multiphase energy storage inverter based on bus voltage control, including: obtaining the active power of the current phase of the power grid; performing a first closed-loop regulation on the active power of the current phase of the power grid, the feedback signal is the active power of the current phase of the power grid, the target signal is zero, and the first closed-loop output value is output; the effective value of the power grid voltage of each phase is obtained to determine the bus reference voltage of the current phase; the bus voltage of the current phase is performed a second closed-loop regulation, the feedback signal is the instantaneous sampling value of the bus voltage of the current phase, the target signal is the bus reference voltage of the current phase, and the second closed-loop output value is output; according to the first and second closed-loop output values, the control current of the current phase is determined to perform power regulation control. The present invention not only makes full use of photovoltaic energy, but also makes the state of the energy storage battery more stable, thereby improving the life of the energy storage battery.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage systems, and in particular to a power regulation control method of a multi-phase energy storage inverter based on bus voltage control and a multi-phase energy storage system. Background Art

[0002] The three-phase energy storage system is a common energy storage model. Figure 1 The three-phase energy storage system topology shown is a common form, wherein the three-phase energy storage system includes an energy storage battery 10, a three-phase energy storage inverter 20, a photovoltaic grid-connected inverter 30, a three-phase grid 40 and a load 50, wherein the three-phase energy storage inverter 20 is composed of a bidirectional DC BUCK-BOOST 21 and a three-way T-type three-level inverter circuit 22, wherein the N line (neutral line) is drawn from the positive and negative bus capacitor terminals, allowing for unbalanced inverter output. Among them, the three-phase energy storage inverter 20 can use the electric energy stored in the energy storage battery 10 to power the load 50, and can also use the three-phase grid 40 and the photovoltaic grid-connected inverter 30 to charge the energy storage battery. In particular, when the energy storage battery 10 is full, charging the energy storage battery 10 will be prohibited. At this time, the common control method of the three-phase energy storage inverter 20 is that the target power of the R / S / T three-phase of the three-phase energy storage inverter 20 is only allowed to be in the discharge direction, and the charging target is allowed to be responded to when the power decreases.

[0003] However, this control method has the following disadvantages: (1) When the load 50 connected to the AC side of a phase is less than the photovoltaic energy output of the phase, and the load 50 connected to other phases is greater than the photovoltaic energy output of that phase, because the three-phase energy storage inverter 20 only responds to the discharge target power when the energy storage battery 10 is fully charged, it is impossible to use the photovoltaic energy in the phase with surplus photovoltaic energy to the phase with insufficient photovoltaic energy, resulting in the problem of not fully utilizing the photovoltaic energy load, resulting in reduced economic benefits. (2) In order to supply power to the load 50 in the phase with a load greater than the output of the photovoltaic grid-connected inverter 30, the power of the energy storage battery 10 is required. The discharge of the energy storage battery 10 will cause the battery power to decrease, thereby causing the energy storage battery 10 to exit the fully charged state and allow the three-phase energy storage inverter 20 to respond to the charging target again. During the whole process, the SOC (State-of-Charge) of the energy storage battery is constantly changing, giving users a sense of system instability. At the same time, the frequent charging and discharging of the energy storage battery 10 will also affect the life of the energy storage battery 10.

[0004] The disclosure of the above background technology content is only used to assist in understanding the concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of the present application. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes a power regulation control method of a multi-phase energy storage inverter based on bus voltage control and a multi-phase energy storage system, which can fully utilize photovoltaic energy on the one hand, and on the other hand, the state of the energy storage battery is more stable, thereby improving the life of the energy storage battery.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention discloses a power regulation control method for a multi-phase energy storage inverter based on bus voltage control, comprising sequentially controlling the bus voltage of each phase of the multi-phase energy storage inverter, comprising the following steps:

[0008] S1: Get the active power of the current phase of the grid;

[0009] S2: performing a first closed-loop regulation on the active power of the power grid of the current phase, wherein the feedback signal of the first closed-loop regulation is the active power of the power grid of the current phase obtained in step S1, the target signal is zero, and the output is the first closed-loop output value;

[0010] S3: Obtain the effective value of each phase grid voltage, and determine the bus reference voltage of the current phase according to the effective value of each phase grid voltage;

[0011] S4: performing a second closed-loop regulation on the bus voltage of the current phase, wherein the feedback signal of the second closed-loop regulation is the instantaneous sampling value of the bus voltage of the current phase, the target signal is the bus reference voltage of the current phase obtained in step S3, and the output is the second closed-loop output value;

[0012] S5: determining a control current of a current phase according to the first closed-loop output value and the second closed-loop output value;

[0013] S6: Perform power regulation control based on the control current of the current phase obtained in step S5 as the control target.

[0014] Preferably, step S2 further comprises obtaining a maximum discharge current of the current phase and a minimum charge current of the current phase, wherein the maximum discharge current is a positive number and the minimum charge current is a negative number;

[0015] The first closed-loop output value includes a signed number, wherein when the first closed-loop output value is a positive number, it indicates discharging, and when the first closed-loop output value is a negative number, it indicates charging;

[0016] When performing the first closed-loop adjustment, the first closed-loop output value is limited to a first preset range; the first preset range is less than or equal to the maximum discharge current of the current phase and greater than or equal to the minimum charging current of the current phase.

[0017] Preferably, step S3 comprises: obtaining the effective value of each phase grid voltage, and determining the bus reference voltage of the current phase according to the first closed-loop output value obtained in step S2 and the effective value of each phase grid voltage.

[0018] Preferably, step S3 specifically includes:

[0019] Get the effective value of each phase grid voltage and The product of the maximum value of the effective value of each phase grid voltage is taken as the voltage base value, where K is the adjustment coefficient, and 1<K<1.2;

[0020] When the first closed-loop output value is a negative number, the bus reference voltage of the current phase is determined as the sum of the voltage base value and the voltage adjustment value; when the first closed-loop output value is a non-negative number, the bus reference voltage of the current phase is determined as the difference between the voltage base value and the voltage adjustment value.

[0021] Preferably, the voltage regulation value is 5% to 20% of the effective value of the grid voltage.

[0022] Preferably, step S5 specifically includes:

[0023] S51: Determine whether the first closed-loop output value is a negative number. When the first closed-loop output value is a negative number, it indicates that the first closed-loop output is in a charging direction, and then execute step S52; otherwise, it indicates that the first closed-loop output is in a discharging direction, and then execute step S57:

[0024] S52: Determine whether the second closed-loop output value is a negative number. When the second closed-loop output value is a negative number, it indicates that the second closed-loop output is in a charging direction, and then execute step S53; otherwise, it indicates that the second closed-loop output is in a discharging direction, and then execute step S54:

[0025] S53: determining the control current of the current phase to be 0, and clearing the integral amount in the first closed-loop regulation process in step S2;

[0026] S54: Determine whether the second closed-loop output value is greater than the absolute value of the first closed-loop output value, if yes, execute step S55; otherwise, execute step S56;

[0027] S55: determining the control current of the current phase as the first closed-loop output value, and assigning the integral value in the second closed-loop adjustment process in step S4 to the opposite number of the first closed-loop output value;

[0028] S56: determining the control current of the current phase as the opposite number of the second closed-loop output value, and assigning the integral value in the first closed-loop regulation process in step S2 to the opposite number of the second closed-loop output value;

[0029] S57: Determine whether the second closed-loop output value is a positive number. If the second closed-loop output value is a positive number, it indicates that the second closed-loop output is in a discharging direction, and then execute step S53; otherwise, it indicates that the second closed-loop output is in a charging direction, and then execute step S58;

[0030] S58: Determine whether the first closed-loop output value is greater than the absolute value of the second closed-loop output value; if so, execute step S56; otherwise, execute step S55.

[0031] Preferably, the first closed-loop regulation in step S2 and the second closed-loop regulation in step S4 both adopt PI regulation or PID regulation.

[0032] In a second aspect, the present invention discloses a multi-phase energy storage system, including an energy storage battery, a multi-phase energy storage inverter, a photovoltaic system and a multi-phase power grid, wherein the multi-phase energy storage inverter is respectively connected to the energy storage battery, the photovoltaic system and the multi-phase power grid, and the multi-phase energy storage inverter is used to execute the power regulation control method of the multi-phase energy storage inverter based on bus voltage control described in the first aspect.

[0033] In a third aspect, the present invention discloses a computer-readable storage medium, in which a computer program is stored, wherein the computer program is configured to be executable by a processor to execute the power regulation control method of a multi-phase energy storage inverter based on bus voltage control as described in the first aspect.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: the power regulation control method of the multi-phase energy storage inverter based on bus voltage control and the multi-phase energy storage system proposed in the present invention can make the power of the phase corresponding to the high bus reference voltage flow to the phase corresponding to the low bus reference voltage by performing closed-loop regulation on the active power of each phase of the power grid and the bus voltage of each phase respectively; thereby achieving the effect of using the photovoltaic grid-connected inverter connected to the three-phase energy storage system as much as possible to power the load, and realizing the effect of improving the utilization rate of the photovoltaic grid-connected inverter; at the same time, the bus voltage control method of the three-phase energy storage inverter proposed in the present invention is combined with the effectiveness of the photovoltaic grid-connected inverter algorithm that is usually used preferentially in the multi-phase energy storage system, which also greatly reduces the charging and discharging working time of the energy storage battery, increases the service life of the energy storage battery, and improves the life of the energy storage battery; and the reduction of the charging and discharging time of the energy storage battery further presents more stable battery status information to the user, such as a more stable SOC display value, which increases the user's recognition of product stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is the topological structure diagram of the three-phase energy storage system;

[0036] Figure 2It is a flow chart of power regulation control of a multi-phase energy storage inverter based on bus voltage control disclosed in Embodiment 1 of the present invention;

[0037] Figure 3 It is a control block diagram of power regulation of a multi-phase energy storage inverter based on bus voltage control disclosed in Embodiment 1 of the present invention. DETAILED DESCRIPTION

[0038] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope and application of the present invention.

[0039] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it can be directly on the other component or indirectly on the other component. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, connection can be used for both fixing and circuit / signal communication.

[0040] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0042] like Figure 2 and Figure 3 As shown, the first embodiment of the present invention discloses a power regulation control method of a multi-phase energy storage inverter based on bus voltage control, comprising sequentially controlling the bus voltage of each phase of the multi-phase energy storage inverter, including the following steps:

[0043] S1: Get the active power of the current phase of the grid;

[0044] S2: Perform a first closed-loop regulation on the active power of the current phase of the power grid, the feedback signal of the first closed-loop regulation is the active power of the current phase of the power grid obtained in step S1, the target signal is zero, and the output is the first closed-loop output value.

[0045] like Figure 3 As shown, the active power of the current phase grid is P act , the target signal is P ref , the first closed-loop output value is Out1.

[0046] The first closed-loop regulation may adopt conventional PI (Proportion Integration) regulation or PID (Proportion Integration Differentiation) regulation.

[0047] The principle of PI regulation or PID regulation is: input error signal, that is, the difference between target signal (set value) and feedback signal (actual value), and output control signal through PI regulation / PID regulation. In this application, the control signal output by the first closed-loop regulation is recorded as the first closed-loop output value.

[0048] Among them, P is a proportional control unit, which adjusts the control amount according to the proportion of the error; I is an integral control unit, which adjusts the control amount according to the time integral of the error; as the adjustment time increases, the integral control unit will generate an integral term, which is referred to as the integral amount in the following text. D is a differential control unit, which adjusts the control amount according to the rate of change of the error.

[0049] To facilitate the expression of the direction of the current, the current when the energy storage inverter is discharging is expressed as a positive number, and the current when the energy storage inverter is charging is expressed as a negative number.

[0050] This step also includes: obtaining the maximum discharge current of the current phase and the minimum charging current of the current phase, wherein the maximum discharge current is a positive number and the minimum charging current is a negative number; limiting the first closed-loop output value within a first preset range when performing the first closed-loop adjustment. Correspondingly, the first closed-loop output value contains a signed number, wherein when the first closed-loop output value is a positive number, it indicates that the energy storage inverter is discharging, and when the first closed-loop output value is a negative number, it indicates that the energy storage inverter is charging; the first preset range is less than or equal to the maximum discharge current of the current phase and greater than or equal to the minimum charging current of the current phase; that is, limiting the first closed-loop output value within the first preset range when performing the first closed-loop adjustment. For example, during the first closed-loop adjustment process, when the first closed-loop output value is greater than the maximum discharge current of the current phase, the first closed-loop output value is assigned to the maximum discharge current of the current phase; when the first closed-loop output value is less than the minimum charging current of the current phase, the first closed-loop output value is assigned to the minimum charging current of the current phase.

[0051] Among them, the maximum discharge current and minimum charge current of the current phase are important parameters to measure the performance of the inverter, which reflect the ability of the inverter under different working conditions. These two parameters are not only affected by the design and manufacturing process of the inverter, but also directly affected by the operating temperature of the key components inside the inverter.

[0052] The maximum discharge current of the current phase refers to the maximum current value that the current phase circuit can safely provide when the inverter is outputting power. This value usually determines the maximum output power of the inverter in the current phase. As the temperature rises, the on-resistance of key semiconductor devices (such as IGBT, MOSFET, etc.) inside the inverter will increase, which will cause greater power consumption and heat generation, thereby limiting the maximum discharge current capacity. To prevent overheating and device damage, the inverter may reduce its output current, or trigger a protection mechanism to shut down the output in extreme cases.

[0053] The minimum charging current of the current phase refers to the minimum current value that the current phase circuit can safely receive when the inverter is in the energy storage system (such as a battery pack) charging mode. This value affects the charging efficiency and speed of the inverter. Under low temperature conditions, the internal resistance of the battery increases, resulting in a decrease in charging efficiency. In addition, the electronic components inside the inverter may also exhibit different characteristics at low temperatures, such as an increase in on-resistance, which also affects the minimum charging current. Under high temperature conditions, although the internal resistance of the battery decreases, excessively high temperatures may cause the battery to overheat and affect the battery life. Therefore, the inverter may adjust the minimum charging current to protect the battery.

[0054] S3: Obtain the effective value of each phase grid voltage, and determine the bus reference voltage of the current phase according to the effective value of each phase grid voltage;

[0055] Furthermore, this step includes: obtaining the effective value of each phase grid voltage, and determining the bus reference voltage of the current phase according to the first closed-loop output value obtained in step S2 and the effective value of each phase grid voltage.

[0056] Wherein, step S3 specifically includes:

[0057] S31: Get the effective value of each phase grid voltage and The product of the maximum value of the effective value of each phase grid voltage is taken as the voltage base value, where K is the adjustment coefficient, and 1<K<1.2.

[0058] S32: When the first closed-loop output value is a negative number, the bus reference voltage of the current phase is determined as the sum of the voltage base value and the voltage adjustment value; when the first closed-loop output value is a non-negative number, the bus reference voltage of the current phase is determined as the difference between the voltage base value and the voltage adjustment value; wherein the voltage adjustment value is preferably about 5% to 20% of the effective value of the grid voltage. For example, if the effective value of the grid voltage is 230V, the voltage adjustment value is preferably between 10V and 40V.

[0059] S4: performing a second closed-loop regulation on the bus voltage of the current phase, wherein the feedback signal of the second closed-loop regulation is the instantaneous sampling value of the bus voltage of the current phase, the target signal is the bus reference voltage of the current phase obtained in step S3, and the output is the second closed-loop output value;

[0060] The second closed-loop regulation adopts the same PI regulation or PID regulation as step S2.

[0061] like Figure 3 As shown, U act is the instantaneous sampling value of the bus voltage of the current phase, U ref is the bus reference voltage of the current phase, and the second closed-loop output value is Out2.

[0062] S5: Determine the control current of the current phase according to the first closed-loop output value and the second closed-loop output value;

[0063] like Figure 3 As shown, according to the first closed-loop output value Out1 and the second closed-loop output value Out2, the control current of the current phase can be determined, and this current is the reference current, that is, I ref .

[0064] Wherein, step S5 specifically includes:

[0065] S51: Determine whether the first closed-loop output value is a negative number. When the first closed-loop output value is a negative number, it indicates that the first closed-loop output is in a charging direction, and then execute step S52; otherwise, it indicates that the first closed-loop output is in a discharging direction, and then execute step S57:

[0066] S52: Determine whether the second closed-loop output value is a negative number. When the second closed-loop output value is a negative number, it indicates that the second closed-loop output is in the charging direction, and then execute step S53; otherwise, it indicates that the second closed-loop output is in the discharging direction, and then execute step S54:

[0067] S53: determining the control current of the current phase to be 0, and clearing the integral amount in the first closed-loop regulation process in step S2;

[0068] S54: Determine whether the second closed-loop output value is greater than the absolute value of the first closed-loop output value. If yes, execute step S55; otherwise, execute step S56;

[0069] S55: determining the control current of the current phase as the first closed-loop output value, and assigning the integral value in the second closed-loop regulation process in step S4 to the opposite number of the first closed-loop output value;

[0070] S56: determining the control current of the current phase as the opposite number of the second closed-loop output value, and assigning the integral value in the first closed-loop regulation process in step S2 to the opposite number of the second closed-loop output value;

[0071] S57: Determine whether the second closed-loop output value is a positive number. If the second closed-loop output value is a positive number, it indicates that the second closed-loop output is in a discharging direction, and then execute step S53; otherwise, it indicates that the second closed-loop output is in a charging direction, and then execute step S58;

[0072] S58: Determine whether the first closed-loop output value is greater than the absolute value of the second closed-loop output value; if so, execute step S56; otherwise, execute step S55.

[0073] S6: Perform power regulation control based on the control current of the current phase obtained in step S5 as the control target.

[0074] like Figure 3 As shown, PI regulation or PID regulation can be used for power regulation. The control current I ref and the actual current I of the current phase act As input, the closed-loop output Out3 is used, and PWM (Pulse Width Modulation) control is performed according to the output value to achieve power regulation.

[0075] Since the grid voltage is basically stable, it can be considered that the current regulation will be directly reflected in the power. From the above description, it can be seen that the first closed-loop regulation and the second closed-loop regulation together constitute the front link of the power regulation control.

[0076] The power regulation control method of a multi-phase energy storage inverter based on bus voltage control in the first embodiment of the present invention can be applied to a three-phase energy storage inverter or a two-phase energy storage inverter.

[0077] The following is a detailed description of the power regulation control method of the multi-phase energy storage inverter based on bus voltage control disclosed in Example 1 of the present invention in combination with a specific embodiment. In this specific embodiment, the power regulation control method of the multi-phase energy storage inverter based on bus voltage control disclosed in Example 1 is applied to, for example, Figure 1 A three-phase energy storage inverter 20 in the three-phase energy storage system is shown.

[0078] In order to solve the two problems mentioned in the background technology, when the energy storage battery is fully charged, a power regulation control method of a multi-phase energy storage inverter based on bus voltage control is introduced, in which the bidirectional DC module (bidirectional DC BUCK-BOOST 21) adopts an independent control mode, and only the Boost switch tube is allowed to perform closed-loop regulation of the bus voltage. The bus reference voltage of the bidirectional DC module is: Max((R_Rms* *2*K),(S_Rms* *2*K),(T_Rms* *2*K)), where R_Rms is the effective value of the R-phase grid voltage, S_Rms is the effective value of the S-phase grid voltage, T_Rms is the effective value of the T-phase grid voltage, where K is a regulation coefficient greater than 1 and less than 1.2. In a specific example, K is 1.06, R_Rms is 230V, S_Rms is 231V, and T_Rms is 232V, then the bus reference voltage of the bidirectional DC module is 695V.

[0079] The R phase, S phase, and T phase of the three-phase energy storage inverter 20 are controlled separately, and the R phase algorithm is as follows:

[0080] A1: Calculation of active power of R phase grid.

[0081] The R-phase grid voltage and the R-phase grid current are collected by the sampling circuit, and the R-phase grid active power is calculated and recorded as R_Power. In a specific example, the value of R_Power is 1000W;

[0082] A2: Perform closed-loop regulation on the active power of the R-phase grid.

[0083] In this step, the closed-loop regulation adopts the PID regulation method, in which the feedback signal is the active power of the R-phase power grid output in step A1, the target signal is zero, and the output is the first closed-loop output value R_Power_PI_Out. In a specific example, ignoring the specific regulation process of PID, it can be considered that the newly generated first closed-loop output value is the current value added on the basis of the original current, which is equal to (0-1000W) / 230V= -4.35A. Assuming that this is the initial call, the value of R_Power_PI_Out at this time is -4.35A, where R_Power_PI_Out is a signed number, the positive sign represents discharge in the direction of the power grid, and the negative sign represents the need to charge to the BUS bus terminal.

[0084] In the process of closed-loop regulation of the active power of the R-phase grid, it is required that R_Power_PI_Out cannot be greater than the maximum discharge current of the R-phase, and R_Power_PI_Out cannot be less than the minimum charging current of the R-phase. For example, when R_Power_PI_Out is greater than the maximum discharge current of the R-phase, R_Power_PI_Out is assigned to the maximum discharge current of the R-phase; when R_Power_PI_Out is less than the minimum charging current of the R-phase, R_Power_PI_Out is assigned to the minimum charging current of the R-phase.

[0085] Normally, the maximum discharge current of each phase of the three-phase energy storage inverter 20 is the same, and the minimum charging current of each phase of the three-phase energy storage inverter 20 is also the same, so the maximum discharge current and the minimum charging current of the three-phase energy storage inverter can be obtained in this step as the maximum discharge current of the R phase and the minimum charging current of the R phase, respectively. Among them, the "maximum discharge current" is a positive number, and the "minimum charging current" is a negative number.

[0086] A3: Generates R-phase bus reference voltage.

[0087] If R_Power_PI_Out is negative, the R-phase bus reference voltage is R_V_BusBas+V1; if R_Power_PI_Out is non-negative, the R-phase bus reference voltage is R_V_BusBas-V1. The base value of the R-phase bus reference voltage R_V_BusBas is equal to Max((R_Rms* *2*K),(S_Rms* *2*K),(T_Rms* *2*K)), R_Rms is the effective value of the R-phase grid voltage, S_Rms is the effective value of the S-phase grid voltage, T_Rms is the effective value of the T-phase grid voltage, wherein K is a regulation coefficient greater than 1 and less than 1.2, and in a specific example, K is 1.06; the voltage regulation value V1 ranges from 10V to 40V, and in a specific example, V1 is 20V. In combination with the above specific embodiments of the present invention, at this time R_Power_PI_Out = -4.35A, then the current bus voltage reference is 695V + 20V = 715V.

[0088] A4: Perform closed-loop regulation on the R-phase bus voltage.

[0089] In this step, the closed-loop regulation adopts the PID regulation mode, in which the feedback signal is the instantaneous sampling value of the bus voltage (this value is obtained by the system in real time), the target signal is the R-phase bus reference voltage output in step A3, and the output is recorded as the second closed-loop output value R_Bus_PI_Out. In the embodiment of the present invention, the R-phase bus voltage needs to be stabilized at around 715V, ignoring the specific regulation process of PID, and the final output R_Bus_PI_Out is +3.5A.

[0090] A5: Generates R phase control current.

[0091] When R_Power_PI_Out is negative (indicating that R phase needs to be charged): If R_Bus_PI_Out is negative (indicating that the actual bus voltage is already higher than the target bus voltage of R phase), the R phase control current is assigned to 0 (when the actual bus voltage of R phase is already higher than the target bus voltage of R phase, R phase should not continue to charge the bus, so the control current is assigned to 0, which means that the bus will no longer be charged, otherwise the bus voltage will continue to increase), and at the same time, the integral amount in the closed-loop regulation of the active power of the R phase grid in step A2 is cleared (to avoid interference with the next regulation call). If R_Bus_PI_Out is non-negative (indicating that the actual bus voltage has not yet reached or has just reached the target bus voltage of phase R), if R_Bus_PI_Out > abs(R_Power_PI_Out), the R-phase control current is assigned to R_Power_PI_Out, and the integral value in the closed-loop regulation of the R-phase bus voltage is assigned to (-R_Power_PI_Out) (to avoid interference with the next regulation call); if R_Bus_PI_Out ≤ abs(R_Power_PI_Out), the R-phase control current is assigned to -R_Bus_PI_Out, and the integral value in the closed-loop regulation of the R-phase grid active power is assigned to (-R_Bus_PI_Out) (to avoid interference with the next regulation call).

[0092] When R_Power_PI_Out is non-negative (indicating that the R phase needs to be discharged): If R_Bus_PI_Out is positive (indicating that the actual bus voltage has not yet reached the target bus voltage of the R phase), the R phase control current is assigned to 0 (when the R phase actual bus voltage has not yet reached the target bus voltage of the R phase, the R phase should not continue to discharge, so the control current is assigned to 0, which means that the bus of this phase will no longer discharge, otherwise the bus voltage will continue to be lowered), and at the same time, the integral amount in the closed-loop regulation of the active power of the R phase power grid in step A2 is cleared. If R_Bus_PI_Out is not positive (indicating that the actual bus voltage has just reached or is higher than the target bus voltage of phase R), if R_Power_PI_Out > abs(R_Bus_PI_Out), the R-phase control current is assigned to (-R_Bus_PI_Out), and the integral value in the closed-loop regulation of the R-phase grid active power is assigned to (-R_Bus_PI_Out); if R_Power_PI_Out ≤ abs(R_Bus_PI_Out), the R-phase control current is assigned to R_Power_PI_Out, and the integral value in the closed-loop regulation of the R-phase bus voltage is assigned to (-R_Power_PI_Out).

[0093] In combination with the specific test example of the present invention, the above conditions that R_Power_PI_Out (-4.35A) is negative and R_Bus_PI_Out (+3.5A) is non-negative are met, and R_Bus_PI_Out ≤ abs(R_Power_PI_Out) is further met, then the control current of the R phase is assigned to -3.5A.

[0094] A6: R phase control current response.

[0095] The R-phase inverter unit performs power regulation control with the R-phase control current output in step A5 as the control target.

[0096] Among them, the S phase algorithm is as follows:

[0097] B1: Calculation of active power of S-phase power grid.

[0098] The S-phase grid voltage and the S-phase grid current are collected by the sampling circuit, and the S-phase grid active power is calculated and recorded as S_Power. In a specific example, the value of S_Power is -500W;

[0099] B2: Perform closed-loop regulation on the active power of the S-phase power grid.

[0100] In this step, the closed-loop regulation adopts the PID regulation method, in which the feedback signal is the active power of the S-phase power grid output in step B1, the target signal is zero, and the output is the first closed-loop output value S_Power_PI_Out. In a specific example, ignoring the specific regulation process of PID, it can be considered that the newly generated first closed-loop output value is the current value added on the basis of the original current, which is equal to (0+500W) / 231V= +2.17A. Assuming that this is the initial call, the value of S_Power_PI_Out at this time is +2.17, where S_Power_PI_Out is a signed number, the positive sign represents discharge in the direction of the power grid, and the negative sign represents the need to charge to the BUS bus terminal.

[0101] In the process of closed-loop regulation of the active power of the S-phase power grid, it is required that S_Power_PI_Out cannot be greater than the maximum discharge current of the S-phase, and S_Power_PI_Out cannot be less than the minimum charging current of the S-phase. For example, when S_Power_PI_Out is greater than the maximum discharge current of the S-phase, S_Power_PI_Out is assigned to the maximum discharge current of the S-phase; when S_Power_PI_Out is less than the minimum charging current of the S-phase, S_Power_PI_Out is assigned to the minimum charging current of the S-phase.

[0102] Normally, the maximum discharge current of each phase of the three-phase energy storage inverter 20 is the same, and the minimum charging current of each phase of the three-phase energy storage inverter 20 is also the same, so the maximum discharge current and the minimum charging current of the three-phase energy storage inverter can be obtained in this step as the maximum discharge current of the S phase and the minimum charging current of the S phase, respectively. Among them, the "maximum discharge current" is a positive number, and the "minimum charging current" is a negative number.

[0103] B3: Generate S-phase bus reference voltage.

[0104] If S_Power_PI_Out is negative, the S-phase bus reference voltage is S_V_BusBas+V1; if S_Power_PI_Out is non-negative, the S-phase bus reference voltage is S_V_BusBas-V1. The basic value of the S-phase bus reference voltage S_V_BusBas is equal to Max((R_Rms* *2*K),(S_Rms* *2*K),(T_Rms* *2*K)), R_Rms is the effective value of the R-phase grid voltage, S_Rms is the effective value of the S-phase grid voltage, T_Rms is the effective value of the T-phase grid voltage, wherein K is a regulation coefficient greater than 1 and less than 1.2, and in a specific example, K is 1.06; the voltage regulation value V1 ranges from 10V to 40V, and in a specific example, V1 is 20V. In combination with the above specific embodiments of the present invention, at this time, S_Power_PI_Out is +2.17A, and the current bus voltage reference is 695V-20V=675V.

[0105] B4: Perform closed-loop regulation on the S-phase bus voltage.

[0106] In this step, the closed-loop regulation adopts the PID regulation mode, in which the feedback signal is the instantaneous sampling value of the bus voltage (this value is obtained by the system in real time), the target signal is the S-phase bus reference voltage output in step B3, and the output is recorded as the second closed-loop output value S_Bus_PI_Out. In the embodiment of the present invention, the S-phase bus voltage needs to be stabilized at around 675V, ignoring the specific regulation process of PID, and the final output S_Bus_PI_Out is -10A.

[0107] B5: Generates S-phase control current.

[0108] When S_Power_PI_Out is negative (indicating that S phase needs to be charged): If S_Bus_PI_Out is negative (indicating that the actual bus voltage is already higher than the target bus voltage of S phase), the S phase control current is assigned to 0 (when the actual bus voltage of S phase is already higher than the target bus voltage of S phase, S phase should not continue to charge the bus, so the control current is assigned to 0, which means that the bus will no longer be charged, otherwise the bus voltage will continue to increase), and at the same time, the integral amount in the closed-loop regulation of the active power of the S phase power grid in step B2 is cleared. If S_Bus_PI_Out is non-negative (indicating that the actual bus voltage has not yet reached or has just reached the target bus voltage of the S phase), if S_Bus_PI_Out > abs(S_Power_PI_Out), the S phase control current is assigned to S_Power_PI_Out, and the integral value in the closed-loop regulation of the S phase bus voltage is assigned to (-S_Power_PI_Out); if S_Bus_PI_Out ≤ abs(S_Power_PI_Out), the S phase control current is assigned to -S_Bus_PI_Out, and the integral value in the closed-loop regulation of the S phase grid active power is assigned to (-S_Bus_PI_Out).

[0109] When S_Power_PI_Out is non-negative (indicating that the S phase needs to be discharged): If S_Bus_PI_Out is positive (indicating that the actual bus voltage has not yet reached the target bus voltage of the S phase), the S phase control current is assigned to 0 (when the S phase actual bus voltage has not yet reached the target bus voltage of the S phase, the S phase should not continue to discharge, so the control current is assigned to 0, which means that the bus of this phase will no longer discharge, otherwise the bus voltage will continue to be lowered), and at the same time, the integral amount in the closed-loop regulation of the active power of the S phase power grid in step B2 is cleared. If S_Bus_PI_Out is not positive (indicating that the actual bus voltage has just reached or is higher than the target bus voltage of the S phase), if S_Power_PI_Out > abs(S_Bus_PI_Out), the S phase control current is assigned to (-S_Bus_PI_Out), and the integral value in the closed-loop regulation of the S phase grid active power is assigned to (-S_Bus_PI_Out); if S_Power_PI_Out ≤ abs(S_Bus_PI_Out), the S phase control current is assigned to S_Power_PI_Out, and the integral value in the closed-loop regulation of the S phase bus voltage is assigned to (-S_Power_PI_Out).

[0110] In combination with the specific test example of the present invention, the above conditions that S_Power_PI_Out (+2.17A) is positive and S_Bus_PI_Out (-10A) is non-positive are met, and S_Power_PI_Out ≤ abs(S_Bus_PI_Out) is further met, then the control current of the S phase is assigned to +2.17A.

[0111] B6: S phase control current response.

[0112] The S-phase inverter unit performs power regulation control with the S-phase control current output in step B5 as the control target.

[0113] Among them, the T phase algorithm is as follows:

[0114] C1: Calculation of active power of T-phase grid.

[0115] The T-phase grid voltage and the T-phase grid current are collected by the sampling circuit, and the active power of the T-phase grid is calculated and recorded as T_Power. In a specific example, the value of T_Power is -305W;

[0116] C2: Perform closed-loop regulation on the active power of the T-phase grid.

[0117] In this step, the closed-loop regulation adopts the PID regulation method, in which the feedback signal is the active power of the T-phase power grid output in step C1, the target signal is zero, and the output is the first closed-loop output value T_Power_PI_Out. In a specific example, ignoring the specific regulation process of PID, it can be considered that the newly generated first closed-loop output value is the current value added on the basis of the original current, which is equal to (0+305W) / 232V= +1.32A. Assuming that this is the initial call, the value of T_Power_PI_Out at this time is +1.32A, where T_Power_PI_Out is a signed number, the positive sign represents discharge to the power grid, and the negative sign represents the need to charge to the BUS bus terminal.

[0118] In the process of closed-loop regulation of the active power of the T-phase grid, it is required that T_Power_PI_Out cannot be greater than the maximum discharge current of the T-phase, and T_Power_PI_Out cannot be less than the minimum charging current of the T-phase. For example, when T_Power_PI_Out is greater than the maximum discharge current of the T-phase, T_Power_PI_Out is assigned to the maximum discharge current of the T-phase; when T_Power_PI_Out is less than the minimum charging current of the T-phase, T_Power_PI_Out is assigned to the minimum charging current of the T-phase.

[0119] Normally, the maximum discharge current of each phase of the three-phase energy storage inverter 20 is the same, and the minimum charging current of each phase of the three-phase energy storage inverter 20 is also the same, so the maximum discharge current and the minimum charging current of the three-phase energy storage inverter can be obtained in this step as the maximum discharge current of the T phase and the minimum charging current of the T phase, respectively. Among them, the "maximum discharge current" is a positive number, and the "minimum charging current" is a negative number.

[0120] C3: Generates T-phase bus reference voltage.

[0121] If T_Power_PI_Out is negative, the T-phase bus reference voltage is T_V_BusBas+V1; if T_Power_PI_Out is non-negative, the T-phase bus reference voltage is T_V_BusBas-V1. The basic theoretical value of the T-phase bus reference voltage T_V_BusBas is equal to Max((R_Rms* *2*K),(S_Rms* *2*K),(T_Rms* *2*K)), R_Rms is the effective value of the R-phase grid voltage, S_Rms is the effective value of the S-phase grid voltage, T_Rms is the effective value of the T-phase grid voltage, wherein K is a regulation coefficient greater than 1 and less than 1.2, and in a specific example, K is 1.06; the voltage regulation value V1 has a value range of 10V-40V, and in a specific example, V1 is 20V. In combination with the above specific embodiments of the present invention, at this time, T_Power_PI_Out is +1.32A, and the current bus voltage reference is 695V-20V=675V.

[0122] C4: Perform closed-loop regulation on the T-phase bus voltage.

[0123] In this step, the closed-loop regulation adopts the PID regulation mode, in which the feedback signal is the instantaneous sampling value of the bus voltage (this value is obtained by the system in real time), the target signal is the T-phase bus reference voltage output in step B3, and the output is recorded as the second closed-loop output value T_Bus_PI_Out. In the embodiment of the present invention, the T-phase bus voltage needs to be stabilized at around 675V, ignoring the specific regulation process of PID, and the final output T_Bus_PI_Out is -10A.

[0124] C5: Generates T-phase control current.

[0125] When T_Power_PI_Out is negative (indicating that phase T needs to be charged): If T_Bus_PI_Out is negative (indicating that the actual bus voltage is already higher than the target bus voltage of phase T), the control current of phase T is assigned to 0 (when the actual bus voltage of phase T is already higher than the target bus voltage of phase T, phase T should not continue to charge the bus, so the control current is assigned to 0, which means that the bus will no longer be charged, otherwise the bus voltage will continue to increase), and at the same time, the integral amount in the closed-loop regulation of the active power of the T-phase power grid in step C2 is cleared. If T_Bus_PI_Out is non-negative (indicating that the actual bus voltage has not yet reached or has just reached the target bus voltage of phase S), if T_Bus_PI_Out > abs(T_Power_PI_Out), the T-phase control current is assigned to T_Power_PI_Out, and the integral value in the closed-loop regulation of the T-phase bus voltage is assigned to (-T_Power_PI_Out); if T_Bus_PI_Out ≤ abs(T_Power_PI_Out), the T-phase control current is assigned to -T_Bus_PI_Out, and the integral value in the closed-loop regulation of the T-phase grid active power is assigned to (-T_Bus_PI_Out).

[0126] When T_Power_PI_Out is non-negative (indicating that phase T needs to be discharged): If T_Bus_PI_Out is positive (indicating that the actual bus voltage has not yet reached the target bus voltage of phase T), the control current of phase T is assigned to 0 (when the actual bus voltage of phase T has not yet reached the target bus voltage of phase T, phase T should not continue to discharge, so the control current is assigned to 0, which means that the bus of this phase will no longer discharge, otherwise the bus voltage will continue to be lowered), and at the same time, the integral amount in the closed-loop regulation of the active power of the T-phase power grid in step C2 is cleared. If T_Bus_PI_Out is not positive (indicating that the actual bus voltage has just reached or is higher than the target bus voltage of phase T), if T_Power_PI_Out > abs(T_Bus_PI_Out), the T-phase control current is assigned to (-T_Bus_PI_Out), and the integral value in the closed-loop regulation of the active power of the T-phase power grid is assigned to (-T_Bus_PI_Out); if T_Power_PI_Out ≤ abs(T_Bus_PI_Out), the T-phase control current is assigned to T_Power_PI_Out, and the integral value in the closed-loop regulation of the T-phase bus voltage is assigned to (-T_Power_PI_Out).

[0127] In combination with the specific test example of the present invention, the above conditions that T_Power_PI_Out (+1.32A) is positive and T_Bus_PI_Out (-10A) is non-positive are met, and T_Power_PI_Out ≤ abs(T_Bus_PI_Out) is further met, then the control current of the T phase is assigned to +1.32A.

[0128] C6: T phase control current response.

[0129] The T-phase inverter unit performs power regulation control with the T-phase control current output in step C5 as the control target.

[0130] Combining the specific embodiments of the control logic of the R phase, S phase, and T phase in the above three-phase energy storage inverter, it can be seen that in this embodiment, the R phase photovoltaic is greater than the load (R_Power=1000W), the S phase photovoltaic is less than the load (S_Power=-500W), and the T phase photovoltaic is less than the load (S_Power=-305W). First: the R phase recognizes that this phase has the ability to charge through the R phase grid active power closed-loop regulation, so the R phase bus reference voltage at this time will be higher than the bus reference voltage of the bidirectional DC module; second: the S / T phase recognizes that this phase needs to draw power from the bus voltage through the S / T phase grid power closed-loop regulation, so the S / T phase bus reference voltage at this time will be lower than the bus reference voltage of the bidirectional DC module. Based on the above, it can be seen that the bus reference voltage of the R phase is the highest, so it is determined that the power of the S / T phase is obtained from the R phase first, and the level of the bus reference voltage in the present invention determines the flow direction of energy, that is, the bus voltage control method of the present invention makes the power of the phase corresponding to the high bus reference voltage flow to the phase corresponding to the low bus reference voltage; combined with the above embodiments, it can be seen that the R phase charges the system with a current target of about 3.5A, the S phase supplies power to the outside of the system at about 2.17A, and the T phase supplies power to the outside of the system at about 1.32A, and the R phase does not participate in the entire process of transmitting energy to the S / T phase, thereby achieving The effect of using the photovoltaic grid-connected inverter connected to the three-phase energy storage system to power the load as much as possible is improved, which improves the utilization rate of the photovoltaic grid-connected inverter; at the same time, the bus voltage control method of the three-phase energy storage inverter proposed in the present invention is combined with the effectiveness of the photovoltaic grid-connected inverter algorithm that is usually used preferentially in the multi-phase energy storage system, which also greatly reduces the charging and discharging working time of the energy storage battery, increases the service life of the energy storage battery, and improves the life of the energy storage battery; and the reduction of the charging and discharging time of the energy storage battery further presents more stable battery status information to the user, such as a more stable SOC display value, which increases the user's recognition of product stability.

[0131] Embodiment 2 of the present invention discloses a multiphase energy storage system, including an energy storage battery, a multiphase energy storage inverter, a photovoltaic grid-connected inverter and a multiphase power grid, wherein the multiphase energy storage inverter is respectively connected to the energy storage battery, the photovoltaic grid-connected inverter and the multiphase power grid, and the multiphase energy storage inverter is used to execute the power regulation control method of the multiphase energy storage inverter based on bus voltage control in the above-mentioned embodiment 1.

[0132] Embodiment 3 of the present invention discloses a computer-readable storage medium, in which a computer program is stored, wherein the computer program is configured to be run by a processor to execute the power regulation control method of the multi-phase energy storage inverter based on bus voltage control in the above-mentioned embodiment 1. For example, the computer-readable storage medium can be stored in the multi-phase energy storage inverter.

[0133] Optionally, the computer-readable storage medium may include, but is not limited to, various media that can store computer programs, such as a USB flash drive, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk.

[0134] The background section of the present invention may contain background information about the problem or environment of the present invention, rather than describing the prior art by others. Therefore, the content contained in the background section is not an admission by the applicant that the prior art is available.

[0135] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, it can also make several substitutions or modifications to these described embodiments, and these substitutions or modifications should be regarded as belonging to the protection scope of the present invention. In the description of this specification, the description of reference terms "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, in the absence of mutual contradiction, the technical personnel in this field can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and modifications can be made herein without departing from the scope defined by the attached claims.

Claims

1. A power regulation control method for a multi-phase energy storage inverter based on bus voltage control, characterized in that: The method comprises sequentially controlling the bus voltage of each phase of the multi-phase energy storage inverter, comprising the following steps: S1: Get the active power of the current phase of the grid; S2: performing a first closed-loop regulation on the active power of the power grid of the current phase, wherein the feedback signal of the first closed-loop regulation is the active power of the power grid of the current phase obtained in step S1, the target signal is zero, and the output is the first closed-loop output value; S3: Obtain the effective value of each phase grid voltage, and determine the bus reference voltage of the current phase according to the effective value of each phase grid voltage; S4: performing a second closed-loop regulation on the bus voltage of the current phase, wherein the feedback signal of the second closed-loop regulation is the instantaneous sampling value of the bus voltage of the current phase, the target signal is the bus reference voltage of the current phase obtained in step S3, and the output is the second closed-loop output value; S5: determining a control current of a current phase according to the first closed-loop output value and the second closed-loop output value; S6: Perform power regulation control based on the control current of the current phase obtained in step S5 as the control target.

2. The method according to claim 1, characterized in that Step S2 also includes obtaining a maximum discharge current of the current phase and a minimum charge current of the current phase, wherein the maximum discharge current is a positive number and the minimum charge current is a negative number; The first closed-loop output value includes a signed number, wherein when the first closed-loop output value is a positive number, it indicates discharging, and when the first closed-loop output value is a negative number, it indicates charging; When performing the first closed-loop adjustment, the first closed-loop output value is limited to a first preset range; the first preset range is less than or equal to the maximum discharge current of the current phase and greater than or equal to the minimum charging current of the current phase.

3. The method according to claim 1, characterized in that Step S3 includes: obtaining the effective value of each phase grid voltage, and determining the bus reference voltage of the current phase according to the first closed-loop output value obtained in step S2 and the effective value of each phase grid voltage.

4. The method according to claim 3, characterized in that Step S3 specifically includes: Get the effective value of each phase grid voltage and The product of the maximum value of the effective value of each phase grid voltage is taken as the voltage base value, where K is the adjustment coefficient, and 1<K<1.2; When the first closed-loop output value is a negative number, the bus reference voltage of the current phase is determined as the sum of the voltage base value and the voltage adjustment value; when the first closed-loop output value is a non-negative number, the bus reference voltage of the current phase is determined as the difference between the voltage base value and the voltage adjustment value.

5. The method according to claim 4, characterized in that The voltage regulation value is 5% to 20% of the effective value of the grid voltage.

6. The method according to claim 1, characterized in that Step S5 specifically includes: S51: Determine whether the first closed-loop output value is a negative number. When the first closed-loop output value is a negative number, it indicates that the first closed-loop output is a charging current value, and then execute step S52; otherwise, it indicates that the first closed-loop output is in a discharging direction, and then execute step S57: S52: Determine whether the second closed-loop output value is a negative number. When the second closed-loop output value is a negative number, it indicates that the second closed-loop output is in a charging direction, and then execute step S53; otherwise, it indicates that the second closed-loop output is in a discharging direction, and then execute step S54: S53: determining the control current of the current phase to be 0, and clearing the integral amount in the first closed-loop regulation process in step S2; S54: Determine whether the second closed-loop output value is greater than the absolute value of the first closed-loop output value, if yes, execute step S55; otherwise, execute step S56; S55: determining the control current of the current phase as the first closed-loop output value, and assigning the integral value in the second closed-loop adjustment process in step S4 to the opposite number of the first closed-loop output value; S56: determining the control current of the current phase as the opposite number of the second closed-loop output value, and assigning the integral value in the first closed-loop regulation process in step S2 to the opposite number of the second closed-loop output value; S57: Determine whether the second closed-loop output value is a positive number. If the second closed-loop output value is a positive number, it indicates that the second closed-loop output is in a discharging direction, and then execute step S53; otherwise, it indicates that the second closed-loop output is in a charging direction, and then execute step S58; S58: Determine whether the first closed-loop output value is greater than the absolute value of the second closed-loop output value; if so, execute step S56; otherwise, execute step S55.

7. The method according to claim 1, characterized in that The first closed-loop regulation in step S2 and the second closed-loop regulation in step S4 both adopt PI regulation or PID regulation.

8. A multiphase energy storage system, characterized in that: It includes an energy storage battery, a multi-phase energy storage inverter, a photovoltaic grid-connected inverter and a multi-phase power grid, wherein the multi-phase energy storage inverter is respectively connected to the energy storage battery, the photovoltaic grid-connected inverter and the multi-phase power grid, and the multi-phase energy storage inverter is used to execute the power regulation control method of the multi-phase energy storage inverter based on bus voltage control as described in any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that: A computer program is stored in the computer-readable storage medium, wherein the computer program is configured to be executable by a processor to execute the power regulation control method of a multi-phase energy storage inverter based on bus voltage control as described in any one of claims 1 to 7.

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