Uninterruptible power supply and control method thereof

Abstract

The invention discloses an uninterruptible power supply and a control method thereof. The uninterruptible power supply comprises a plurality of inverter systems which are connected in parallel; the control method comprises the following steps: calculating a direct-current voltage reference value of each inverter system according to an active power set value of an uninterruptible power supply and a charge state of a battery in each inverter system; based on the output voltage amplitude reference value and the output voltage amplitude acquisition value of the uninterruptible power supply, obtaining a first electromotive force adjusting value of each inverter system; and generating a driving signal of the grid-connected inverter in each inverter system based on the DC voltage reference value and the electromotive force first adjustment value. According to the invention, rapid adjustment of the voltage of the grid-connected inverter is realized, reactive ring current is prevented, and static voltage indifference control of the uninterruptible power supply is realized.

Description

Technical Field

[0001] The present application relates to the technical field of uninterruptible power supply, and in particular to an uninterruptible power supply and a control method thereof. Background Art

[0002] As users' requirements for power quality continue to increase, UPS (Uninterruptible Power Supply) has gradually become the first choice for electrical equipment in various industries. As an uninterruptible power supply, UPS is widely used in production control, power substation, and various computer application systems.

[0003] Performance and reliability issues of transmission and distribution equipment, the mutual influence of various complex power equipment, the increase of nonlinear power equipment, natural disasters and human factors make it difficult for the municipal power grid to ensure stable and reliable output of high-quality electric energy. At the same time, some key equipment has very high requirements for power quality, otherwise it will cause huge or even irreparable losses.

[0004] The application of UPS can solve this contradiction: first, UPS can play an isolation role, which can effectively suppress interference such as grid surges, spikes, noise, etc., thereby improving the power supply of equipment; second, UPS can provide uninterrupted power supply, ensuring the reliability of power supply when the grid fails. Therefore, UPS plays a vital role in computer and its network, communication, finance, electricity, transportation, national defense, and other departments. The output of general UPS is provided by the inverter. For example, when the online UPS is working, its output is always provided by the inverter. Therefore, for UPS, adopting an efficient and feasible inverter control solution is the key to ensuring the safety and reliability of power supply.

[0005] In high-power application scenarios, multiple inverters are often required to be connected in parallel to achieve uninterrupted power supply to the load. The parallel connection methods of UPS systems are divided into three categories: centralized control, master-slave control, and droop control. For centralized control, the computing power and communication requirements of the processor are very high. When there is a problem with the processor or communication, it will affect the operation of the entire system; for master-slave control, the master controller and the slave controller are not in the same position. When the slave controller fails, the system is not affected, but once the master controller fails, it will still affect the entire system; for droop control, the output voltage amplitude and frequency are affected by the operating power, which in turn affects the static performance of the system. Summary of the invention

[0006] In view of this, the purpose of the present application is to provide an uninterruptible power supply and a control method thereof, so as to achieve rapid regulation of the grid-connected inverter voltage, prevent reactive circulating current, and achieve zero-difference control of the static voltage of the uninterruptible power supply.

[0007] The technical solutions adopted by this application to solve the above technical problems are as follows:

[0008] On one hand, the present application provides a control method for an uninterruptible power supply, wherein the uninterruptible power supply includes a plurality of inverter systems connected in parallel; the control method includes:

[0009] According to the active power setting value of the uninterruptible power supply and the charge state of the battery in each inverter system, a DC voltage reference value of each inverter system is calculated;

[0010] Based on the output voltage amplitude reference value and the output voltage amplitude acquisition value of the uninterruptible power supply, a first adjustment value of the electromotive force of each inverter system is obtained;

[0011] Based on the DC voltage reference value and the first adjustment value of the electromotive force, a driving signal of the grid-connected inverter in each inverter system is generated.

[0012] In one example, based on the output voltage amplitude reference value and the output voltage amplitude acquisition value of the uninterruptible power supply, the first adjustment value of the electromotive force of each inverter system is obtained, including:

[0013] According to the output voltage amplitude reference value and the output voltage amplitude acquisition value, an output voltage deviation value of the uninterruptible power supply is obtained;

[0014] After the output voltage deviation value is adjusted through the proportional-integral link, the first adjustment value of the electromotive force is obtained.

[0015] In one example, based on the DC voltage reference value and the first adjustment value of the electromotive force, generating a driving signal of a grid-connected inverter in each inverter system includes:

[0016] Determining a virtual electromotive force and an output phase of each inverter system based on a DC voltage reference value and a first electromotive force adjustment value;

[0017] After the virtual electromotive force and output phase are regulated by voltage and current double closed loop, the modulation voltage is obtained;

[0018] The modulation voltage is PWM modulated to generate a drive signal.

[0019] In one example, based on a DC voltage reference value and a first electromotive force adjustment value, determining a virtual electromotive force and an output phase of each inverter system includes:

[0020] Based on the first adjustment value of the electromotive force, a virtual electromotive force of each inverter system is obtained;

[0021] Based on the DC voltage reference value and the first adjustment value of the electromotive force, the output phase of each inverter system is obtained.

[0022] The difference between the output voltage amplitude acquisition value and the first preset unit is amplified by the voltage deviation control coefficient to obtain the second adjustment value of the electromotive force of each inverter system;

[0023] After the first adjustment value of the electromotive force and the second adjustment value of the electromotive force are superimposed, the total deviation of the electromotive force of each inverter system is obtained;

[0024] After superimposing the total electromotive force deviation and the electromotive force reference value, the virtual electromotive force is obtained.

[0025] In one example, based on the DC voltage reference value and the first adjustment value of the electromotive force, the output phase of each inverter system is obtained, including:

[0026] Based on the DC voltage reference value, the DC voltage acquisition value and the frequency reference value, the phase angle of each inverter system is obtained;

[0027] The difference between the output voltage amplitude acquisition value and the first preset unit is amplified by the voltage deviation control coefficient to obtain the second adjustment value of the electromotive force of each inverter system;

[0028] After the first adjustment value of the electromotive force and the second adjustment value of the electromotive force are superimposed, the total deviation of the electromotive force of each inverter system is obtained;

[0029] Based on the total electromotive force deviation of each inverter system, a first phase angle deviation of each inverter system is obtained;

[0030] Based on the DC voltage reference value and the second preset unit, obtaining a second phase angle deviation of each inverter system;

[0031] An output phase is obtained based on the phase angle, the first phase angle deviation, and the second phase angle deviation.

[0032] In one example, based on the DC voltage reference value, the DC voltage acquisition value, and the frequency reference value, the phase angle of each inverter system is obtained, including:

[0033] Obtaining a first DC voltage deviation value of each inverter system according to a DC voltage reference value and a DC voltage acquisition value;

[0034] After the first DC voltage deviation value passes through an integral link with negative feedback, an output frequency deviation value of each inverter system is obtained;

[0035] The output frequency deviation value and the frequency reference value are superimposed to obtain the output frequency value of each inverter system;

[0036] The output frequency value is adjusted through the integral link to obtain the phase angle.

[0037] In one example, based on the total electromotive force deviation of each inverter system, a first phase angle deviation of each inverter system is obtained, including:

[0038] The total electromotive force deviation is amplified by the electromotive force phase angle feedforward coefficient to obtain the first phase angle deviation.

[0039] In one example, based on the DC voltage reference value and the second preset unit, obtaining the second phase angle deviation of each inverter system includes:

[0040] Obtaining a second DC voltage deviation value of each inverter system according to the DC voltage reference value and a second preset unit;

[0041] The second DC voltage deviation value is amplified by the DC voltage phase angle feedforward coefficient to obtain a second phase angle deviation.

[0042] On the other hand, the present application provides an uninterruptible power supply, which includes a plurality of inverter systems connected in parallel; the uninterruptible power supply also includes a control unit, the control unit includes a memory and a processor, the memory is configured to store a computer program, and the processor implements a control method of the uninterruptible power supply when executing the computer program.

[0043] The uninterruptible power supply and control method thereof provided in the embodiment of the present application adopt energy management: according to the active power setting value of the uninterruptible power supply and the charge state of the battery in each inverter system, a DC voltage reference value of each inverter system is calculated; and inverter control: based on the output voltage amplitude reference value and the output voltage amplitude acquisition value of the uninterruptible power supply, a first electromotive force adjustment value of each inverter system is obtained; based on the DC voltage reference value and the first electromotive force adjustment value, a drive signal of the grid-connected inverter in each inverter system is generated; by controlling the voltage in coordination with energy management and inverter control, rapid adjustment of the grid-connected inverter voltage is achieved, reactive circulation is prevented, and zero-difference control of the static voltage of the uninterruptible power supply is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A schematic diagram of an uninterruptible power supply provided in an embodiment of the present application;

[0045] Figure 2 A schematic diagram of a control method for an uninterruptible power supply provided in an embodiment of the present application;

[0046] Figure 3 A schematic diagram of the control structure of an uninterruptible power supply provided in an embodiment of the present application;

[0047] Figure 4 A schematic diagram of the control structure of a grid-connected inverter provided in an embodiment of the present application;

[0048] Figure 5 Schematic diagram of the voltage and current dual closed-loop control structure provided in an embodiment of the present application.

[0049] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0050] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer and more understandable, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0051] Variables and their definitions involved in the embodiments of this application:

[0052] P ref : Inverter output power setting value

[0053] SOC: State of charge of the DC battery

[0054] V dc_ref 、V dc : Reference value and acquisition value of inverter DC side voltage

[0055] U PCCm_ref : Reference value of UPS output voltage amplitude

[0056] U PCCm : The collected value of UPS output voltage amplitude

[0057] ΔU PCCm : UPS output voltage comparison value

[0058] PI: Proportional Integral Regulator

[0059] ΔE ref1 : The first adjustment value of the inverter's electromotive force

[0060] ΔE ref2 : The second adjustment value of the inverter's electromotive force

[0061] ΔE: total inverter electromotive force deviation

[0062] E: Virtual electromotive force of the inverter

[0063] ΔV dc1 : DC voltage first deviation value

[0064] ΔV dc2 : DC voltage second deviation value

[0065] Integral link from DC voltage deviation to frequency deviation

[0066] K D : The slope coefficient between the inverter AC frequency and DC voltage.

[0067] Δω: inverter output frequency deviation value

[0068] ω ref : Inverter output frequency reference value

[0069] ω: inverter output frequency

[0070] θ: inverter phase angle

[0071] Δθ1: First phase angle deviation

[0072] Δθ2: Second phase angle deviation

[0073] θ E : Output phase of the inverter

[0074] LPF: Low Pass Filter

[0075] Points

[0076] E ref_pu : Electromotive force reference value

[0077] K Ethe : Electromotive force-phase angle feedforward coefficient

[0078] K ue : Voltage deviation control coefficient

[0079] K Vthe : DC voltage-phase angle feedforward coefficient

[0080] e g_a 、e g_b 、e g_c : The values ​​of the inverter modulation voltage a-axis, b-axis and c-axis

[0081] U g_dq : The acquisition value of the inverter output voltage dq axis

[0082] i g_dqref : Reference value of inverter output current dq axis

[0083] i g_dq : The acquisition value of the inverter output current dq axis

[0084] e g_dq : dq axis value of inverter modulation voltage

[0085] Figure 1 It is a schematic diagram of an uninterruptible power supply provided in an embodiment of the present application.

[0086] like Figure 1As shown, the output end of the uninterruptible power supply (shown as PCC in the figure) is connected to the load and / or connected to the power grid through an isolation inductor L, and the uninterruptible power supply includes a plurality of inverter systems connected in parallel (shown as Q1 to Qn in the figure); each of the plurality of inverter systems includes a grid-connected inverter VSC and a battery, the DC side of the grid-connected inverter is connected to the battery, and the AC side of the grid-connected inverter is connected to the output end of the uninterruptible power supply.

[0087] Each inverter system also includes a filter inductor Z l 、Filter capacitor C l , transformer T and DC bus capacitor C dc Filter inductor Z l 、Filter capacitor C l The transformer T is connected to the AC side of the grid-connected inverter, and the AC side of the grid-connected inverter is connected to the AC side of the grid-connected inverter through the filter inductor Z l , transformer T is connected to the output end of the uninterruptible power supply, and filter capacitor C l One end is connected to the filter inductor Z l Between the transformer T, the filter capacitor C l The other end of the DC bus capacitor C dc It is connected to the DC side of the grid-connected inverter, that is, connected between the positive and negative DC busbars of the grid-connected inverter.

[0088] Furthermore, the uninterruptible power supply also includes a control unit, the control unit includes a memory and a processor, the memory is configured to store a computer program, and the processor implements the control method of the uninterruptible power supply when executing the computer program.

[0089] In a specific implementation, the control unit includes an energy management system for unified energy management of multiple inverter systems connected in parallel. Usually, an uninterruptible power supply has only one energy management system. The control unit also includes an inverter controller, which is used to individually control each inverter system. In a preferred implementation, multiple inverter systems connected in parallel correspond to multiple inverter controllers, and each inverter controller individually controls a corresponding inverter system.

[0090] The energy management system can calculate the DC voltage reference value of each inverter system based on the active power setting value of the uninterruptible power supply and the state of charge (SOC) of the battery in each inverter system; and obtain the first electromotive force adjustment value of each inverter system based on the output voltage amplitude reference value and output voltage amplitude acquisition value of the uninterruptible power supply. The inverter controller can control the grid-connected inverter using grid-type control based on the DC voltage reference value and the first electromotive force adjustment value given by the energy management system.

[0091] The voltage control of the inverter controller on the grid-connected inverter can achieve rapid voltage regulation and prevent reactive circulating current, but the control of the inverter controller alone cannot achieve static zero-difference control of the terminal voltage of the uninterruptible power supply. The energy management system has a long communication cycle with the grid-connected inverter, and the control speed is insufficient, but it can achieve static zero-difference control of the terminal voltage of the uninterruptible power supply. The present application adopts the coordinated voltage control of the energy management system and the inverter controller, which can simultaneously achieve rapid voltage regulation, reasonable reactive power distribution, and static voltage zero-difference control.

[0092] like Figure 2 As shown, the control method of the uninterruptible power supply provided in the embodiment of the present application includes the following steps:

[0093] S11, calculating a DC voltage reference value of each inverter system according to the active power setting value of the uninterruptible power supply and the charge state of the battery in each inverter system; and obtaining a first electromotive force adjustment value of each inverter system based on the output voltage amplitude reference value and the output voltage amplitude acquisition value of the uninterruptible power supply;

[0094] S12: Generate a drive signal for the grid-connected inverter in each inverter system based on the DC voltage reference value and the first adjustment value of the electromotive force.

[0095] In one example, obtaining the first adjustment value of the electromotive force of each inverter system based on the output voltage amplitude reference value and the output voltage amplitude acquisition value of the uninterruptible power supply includes:

[0096] Obtaining an output voltage deviation value of the uninterruptible power supply according to the output voltage amplitude reference value and the output voltage amplitude acquisition value;

[0097] After the output voltage deviation value is adjusted through a proportional-integral link, the first adjustment value of the electromotive force is obtained.

[0098] like Figure 3 As shown, according to the active power setting value P of the uninterruptible power supply set and the state of charge SOC of the battery in each inverter system, and the DC voltage reference value V of each inverter system is obtained through the calculation link Calculatedc_ref .

[0099] The output voltage amplitude reference value U of the uninterruptible power supply PCCm_ref The output voltage amplitude acquisition value U of the uninterruptible power supply PCCm The output voltage deviation value ΔU of the uninterruptible power supply is obtained by subtracting PCCm , the output voltage deviation value ΔU of the uninterruptible power supply PCCm After the proportional integral link PI adjustment, the first adjustment value ΔE of the electromotive force of each inverter system is obtained. ref1 .

[0100] In one example, the step of generating a driving signal of the grid-connected inverter in each inverter system based on a DC voltage reference value and a first adjustment value of an electromotive force includes:

[0101] Determining a virtual electromotive force and an output phase of each inverter system based on the DC voltage reference value and the first electromotive force adjustment value;

[0102] The virtual electromotive force and the output phase are subjected to a voltage-current double closed loop to obtain a modulation voltage;

[0103] The modulation voltage is PWM modulated to generate the drive signal.

[0104] In one example, determining the virtual electromotive force and output phase of each inverter system based on the DC voltage reference value and the first electromotive force adjustment value includes:

[0105] Based on the first adjustment value of the electromotive force, a virtual electromotive force of each inverter system is obtained;

[0106] Based on the DC voltage reference value and the first adjustment value of the electromotive force, the output phase of each inverter system is obtained.

[0107] In one example, based on the first adjustment value of the electromotive force, the virtual electromotive force of each inverter system is obtained, including:

[0108] The difference between the output voltage amplitude acquisition value and the first preset unit is amplified by the voltage deviation control coefficient to obtain the second adjustment value of the electromotive force of each inverter system;

[0109] After the first electromotive force adjustment value and the second electromotive force adjustment value are superimposed, a total electromotive force deviation of each inverter system is obtained;

[0110] The virtual electromotive force is obtained by superimposing the total electromotive force deviation and the electromotive force reference value.

[0111] In one example, obtaining the output phase of each inverter system based on the DC voltage reference value and the first adjustment value of the electromotive force includes:

[0112] Based on the DC voltage reference value, the DC voltage acquisition value and the frequency reference value, a phase angle of each inverter system is obtained;

[0113] The difference between the output voltage amplitude acquisition value and the first preset unit is amplified by the voltage deviation control coefficient to obtain the second adjustment value of the electromotive force of each inverter system;

[0114] After the first electromotive force adjustment value and the second electromotive force adjustment value are superimposed, a total electromotive force deviation of each inverter system is obtained;

[0115] Based on the total electromotive force deviation of each inverter system, a first phase angle deviation of each inverter system is obtained;

[0116] Based on the DC voltage reference value and a second preset unit, obtaining a second phase angle deviation of each inverter system;

[0117] The output phase is obtained based on the phase angle, the first phase angle deviation, and the second phase angle deviation.

[0118] In one example, based on the DC voltage reference value, the DC voltage acquisition value, and the frequency reference value, the phase angle of each inverter system is obtained, including:

[0119] Obtaining a first DC voltage deviation value of each inverter system according to the DC voltage reference value and the DC voltage acquisition value;

[0120] After the first DC voltage deviation value passes through an integral link with negative feedback, an output frequency deviation value of each inverter system is obtained;

[0121] Superimposing the output frequency deviation value and the frequency reference value to obtain an output frequency value of each inverter system;

[0122] The output frequency value is adjusted through an integral link to obtain the phase angle.

[0123] In one example, based on the total electromotive force deviation of each inverter system, a first phase angle deviation of each inverter system is obtained, including:

[0124] The total electromotive force deviation is amplified by the electromotive force phase angle feedforward coefficient to obtain the first phase angle deviation.

[0125] In one example, based on the DC voltage reference value and the second preset unit, obtaining the second phase angle deviation of each inverter system includes:

[0126] Obtaining a second DC voltage deviation value of each inverter system according to the DC voltage reference value and the second preset unit;

[0127] The second DC voltage deviation value is amplified by a DC voltage phase angle feed-forward coefficient to obtain the second phase angle deviation.

[0128] like Figure 4 As shown, according to the DC voltage reference value V dc_ref And DC voltage acquisition V dc , and obtain the first DC voltage deviation value ΔV dc1 ; The first DC voltage deviation value ΔV dc1 Through the negative feedback K D The integral part After that, the output frequency deviation value Δω is obtained; the output frequency deviation value Δω is added to the frequency reference value to obtain the output frequency value ω, and the output frequency value ω is obtained by the integral link. Then the phase angle θ is obtained.

[0129] The first preset unit 1 and the output voltage amplitude acquisition value U of the uninterruptible power supply PCCm Make the difference, and then pass the voltage deviation control coefficient K ue After the amplification link, the second adjustment value of the electromotive force ΔE is obtained ref2 . The first adjustment value of electromotive force ΔE ref1 and the second adjustment value of electromotive force ΔE ref2 After summing, the total electromotive force deviation ΔE is obtained. The total electromotive force deviation ΔE is summed with the electromotive force reference value to obtain the virtual electromotive force E.

[0130] The total deviation of electromotive force ΔE is calculated by the electromotive force phase angle feedforward coefficient K Ethe After amplification, the first phase angle deviation Δθ1 is obtained.

[0131] DC voltage reference value V dc_ref Subtract the second preset unit 1 to obtain the second DC voltage deviation value ΔV dc2 ; The second DC voltage deviation value ΔV dc2 After being amplified by the DC voltage phase angle feed-forward coefficient, the second phase angle deviation Δθ2 is obtained.

[0132] The sum of Δθ1, Δθ2 and θ gives the output phase θ E .

[0133] Figure 5 This is a schematic diagram of voltage and current dual closed-loop control. Figure 5 As shown, the virtual electromotive force E and the inverter AC voltage dq axis acquisition value U g_dq After the voltage control loop is adjusted, the inverter current dq axis reference value i is obtained. g_dqref ; The current dq axis reference value i of the inverterg_dqref The AC current value i of the inverter g_dq After being adjusted by the current control loop, the inverter modulation voltage dq axis reference value e is obtained. g_dref ;e g_dref Combined with the inverter output phase θ E , after Park transformation, the modulation voltage e is obtained g_a 、e g_b and e g_c ; Modulation voltage e g_a 、e g_b and e g_c After PWM modulation, a driving signal for the grid-connected inverter is generated.

[0134] The preferred embodiments of the present application are described above with reference to the accompanying drawings, but the scope of the present application is not limited thereby. Any modification, equivalent substitution and improvement made by a person skilled in the art without departing from the scope and essence of the present application shall be within the scope of the present application.

Claims

1. A method for controlling an uninterruptible power supply, characterized in that: The uninterruptible power supply includes a plurality of inverter systems connected in parallel; the control method includes: Calculating a DC voltage reference value of each inverter system according to the active power setting value of the uninterruptible power supply and the charge state of the battery in each inverter system; Based on the output voltage amplitude reference value and the output voltage amplitude acquisition value of the uninterruptible power supply, a first adjustment value of the electromotive force of each inverter system is obtained; Based on the DC voltage reference value and the first adjustment value of the electromotive force, a driving signal of the grid-connected inverter in each inverter system is generated.

2. The control method of the uninterruptible power supply according to claim 1, characterized in that: The step of obtaining the first adjustment value of the electromotive force of each inverter system based on the output voltage amplitude reference value and the output voltage amplitude acquisition value of the uninterruptible power supply comprises: Obtaining an output voltage deviation value of the uninterruptible power supply according to the output voltage amplitude reference value and the output voltage amplitude acquisition value; After the output voltage deviation value is adjusted through a proportional-integral link, the first adjustment value of the electromotive force is obtained.

3. The control method of the uninterruptible power supply according to claim 1, characterized in that: The step of generating a driving signal of the grid-connected inverter in each inverter system based on the DC voltage reference value and the first electromotive force adjustment value comprises: Determining a virtual electromotive force and an output phase of each inverter system based on the DC voltage reference value and the first electromotive force adjustment value; The virtual electromotive force and the output phase are regulated by voltage and current double closed loops to obtain a modulation voltage; The modulation voltage is PWM modulated to generate the drive signal.

4. The control method of the uninterruptible power supply according to claim 3, characterized in that: The step of determining the virtual electromotive force and output phase of each inverter system based on the DC voltage reference value and the first electromotive force adjustment value comprises: Based on the first adjustment value of the electromotive force, a virtual electromotive force of each inverter system is obtained; Based on the DC voltage reference value and the first adjustment value of the electromotive force, the output phase of each inverter system is obtained.

5. The control method of the uninterruptible power supply according to claim 4, characterized in that: The step of obtaining the virtual electromotive force of each inverter system based on the first electromotive force adjustment value comprises: The difference between the output voltage amplitude acquisition value and the first preset unit is amplified by the voltage deviation control coefficient to obtain the second adjustment value of the electromotive force of each inverter system; After the first electromotive force adjustment value and the second electromotive force adjustment value are superimposed, a total electromotive force deviation of each inverter system is obtained; The virtual electromotive force is obtained by superimposing the total electromotive force deviation and the electromotive force reference value.

6. The control method of the uninterruptible power supply according to claim 4, characterized in that: Based on the DC voltage reference value and the first electromotive force adjustment value, the output phase of each inverter system is obtained, including: Based on the DC voltage reference value, the DC voltage acquisition value and the frequency reference value, a phase angle of each inverter system is obtained; The difference between the output voltage amplitude acquisition value and the first preset unit is amplified by the voltage deviation control coefficient to obtain the second adjustment value of the electromotive force of each inverter system; After the first electromotive force adjustment value and the second electromotive force adjustment value are superimposed, a total electromotive force deviation of each inverter system is obtained; Based on the total electromotive force deviation of each inverter system, a first phase angle deviation of each inverter system is obtained; Based on the DC voltage reference value and a second preset unit, obtaining a second phase angle deviation of each inverter system; The output phase is obtained based on the phase angle, the first phase angle deviation, and the second phase angle deviation.

7. The control method of the uninterruptible power supply according to claim 6, characterized in that: The obtaining the phase angle of each inverter system based on the DC voltage reference value, the DC voltage acquisition value and the frequency reference value includes: Obtaining a first DC voltage deviation value of each inverter system according to the DC voltage reference value and the DC voltage acquisition value; After the first DC voltage deviation value passes through an integral link with negative feedback, an output frequency deviation value of each inverter system is obtained; Superimposing the output frequency deviation value and the frequency reference value to obtain an output frequency value of each inverter system; The output frequency value is adjusted through an integral link to obtain the phase angle.

8. The control method of the uninterruptible power supply according to claim 6, characterized in that: The obtaining of the first phase angle deviation of each inverter system based on the total electromotive force deviation of each inverter system includes: The total electromotive force deviation is amplified by the electromotive force phase angle feedforward coefficient to obtain the first phase angle deviation.

9. The control method of the uninterruptible power supply according to claim 6, characterized in that: The obtaining of a second phase angle deviation of each inverter system based on the DC voltage reference value and a second preset unit includes: Obtaining a second DC voltage deviation value of each inverter system according to the DC voltage reference value and the second preset unit; The second DC voltage deviation value is amplified by a DC voltage phase angle feed-forward coefficient to obtain the second phase angle deviation.

10. An uninterruptible power supply, characterized in that: The uninterruptible power supply includes a plurality of inverter systems connected in parallel; the uninterruptible power supply also includes a control unit, the control unit includes a memory and a processor, the memory is configured to store a computer program, and the processor implements the control method of the uninterruptible power supply according to any one of claims 1 to 9 when executing the computer program.

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