Zero-harmonic networking type energy storage converter and control method and equipment thereof

Abstract

The invention relates to a zero-harmonic networking type energy storage converter and a control method and equipment thereof. The method comprises the following steps: acquiring an energy storage voltage output by an energy storage element in real time; determining an operation mode of the energy storage element as a discharge mode according to the energy storage voltage, and obtaining a three-phase voltage output by the zero harmonic distortion module; processing the three-phase voltage by adopting Park transformation to obtain a direct-current voltage effective value; processing the direct-current voltage effective value by adopting a PWM (Pulse Width Modulation) technology to obtain a first duty ratio signal, and obtaining a first voltage output by the energy storage power supply module; if the first voltage is not smaller than the working voltage, processing the first voltage by adopting a three-level inverter to obtain a second voltage; and performing zero harmonic distortion processing on the second voltage to obtain a voltage output to the load after harmonic cancellation. According to the control method, the voltage output by the energy storage power supply module and the three-level inverter is subjected to zero-harmonic distortion processing through the zero-harmonic distortion module, so that the voltage output to the load is zero-harmonic, and the quality of electric energy output to the load is improved.

Description

Technical Field

[0001] The present application relates to the technical field of converters, and in particular to a zero-harmonic grid-type energy storage converter and a control method and device thereof. Background Art

[0002] In the power grid, with the continuous increase in installed capacity of wind power and photovoltaic power, the proportion of distributed renewable energy in the power system is gradually increasing. The high proportion of grid-connected devices and their decentralized installation methods will bring harmonic oscillation problems and suppression difficulties to the power system, resulting in weak grid support characteristics and reduced safety and stability. To address this problem, the power grid has introduced grid-connected energy storage converters. Because they can solve the problem of renewable energy consumption, they are considered key equipment for building a new power system. They adopt reasonable control strategies such as droop control, virtual synchronization control, matching control, and virtual oscillator control, giving the power system the characteristics of a voltage source, capable of actively building and maintaining stable output voltage, frequency, and low distortion rate, providing stable support for the power grid.

[0003] Existing grid-type energy storage converters are used in practical applications. One end of the grid-type energy storage converter is connected to a DC battery pack, and the other end is connected to the AC power grid. The grid-type energy storage converter is mainly composed of a DC-AC converter, with a large proportion of power electronic equipment. The output voltage waveform has a certain distortion rate, resulting in a decrease in power quality. This is usually solved by control methods. The commonly used control methods and equipment for grid-type energy storage converters are very complex, which increases the difficulty of building the grid-type energy storage converter system. The system complexity also increases, and the analysis becomes more difficult. In addition, the battery capacity cannot be infinite, and it cannot maintain permanent energy transmission to the power grid. The battery also requires an additional system for charging or battery replacement, which increases the cost of the entire power system and causes energy waste. Summary of the Invention

[0004] The present application provides a zero-harmonic grid-type energy storage converter and its control method and device, which are used to solve the technical problem that the voltage output by the existing grid-type energy storage converter contains harmonics, resulting in a decrease in the power quality of the output voltage.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] On the one hand, a control method for a zero-harmonic grid-type energy storage converter is provided, which is applied to the zero-harmonic grid-type energy storage converter. The zero-harmonic grid-type energy storage converter includes an energy storage power supply module, a first control module, a three-level inverter, a zero harmonic distortion module, and a second control module. The output end of the energy storage power supply module is respectively connected to the input end of the second control module and the input end of the three-level inverter, the output end of the three-level inverter is connected to the input end of the zero harmonic distortion module, the output end of the second control module is also connected to the input end of the three-level inverter, the output end of the zero harmonic distortion module is respectively connected to the load and the input end of the first control module, the output end of the first control module is connected to the input end of the energy storage power supply module, and the energy storage power supply module includes an energy storage element. The control method includes the following steps:

[0007] Acquiring the energy storage voltage output by the energy storage element in real time; determining the operation mode of the energy storage element according to the energy storage voltage;

[0008] If the operation mode of the energy storage element is the discharge mode, obtaining the three-phase voltage output by the zero harmonic distortion module; processing the three-phase voltage using Park transformation to obtain the effective value of the DC voltage;

[0009] The effective value of the DC voltage is processed using PWM modulation technology to obtain a first duty cycle signal; the operation of the switch tube in the energy storage power supply module is controlled according to the first duty cycle signal to obtain a first voltage output by the energy storage power supply module;

[0010] If the first voltage is not less than the operating voltage of the three-level inverter, processing the first voltage using the three-level inverter to obtain a second voltage;

[0011] The second voltage is subjected to zero harmonic distortion processing to obtain a voltage output to the load after harmonic cancellation.

[0012] Preferably, before the first voltage is processed by the three-level inverter to obtain the second voltage, the control method of the zero-harmonic grid-type energy storage converter further includes:

[0013] Processing the first voltage using SPWM modulation technology to obtain a second duty cycle signal;

[0014] The operation of the switch tube in the three-level inverter is controlled according to the second duty cycle signal, thereby controlling the output voltage of the three-level inverter to obtain a second voltage.

[0015] Preferably, the three-phase voltage is processed by Park transformation to obtain the effective value of the DC voltage, which includes:

[0016] Comparing the three-phase voltage with a set three-phase voltage reference value to obtain a three-phase voltage difference;

[0017] Convert the three-phase voltage difference by the Park transformation to obtain a voltage dq value;

[0018] A DC voltage effective value is obtained from the voltage dq value.

[0019] Preferably, the control method of the zero harmonic grid-type energy storage converter further includes:

[0020] If the operation mode of the energy storage element is the charging mode, controlling the first control module to not operate;

[0021] Comparing the energy storage voltage with a set reference voltage to obtain an energy storage voltage difference;

[0022] Processing the energy storage voltage difference using SPWM modulation technology to obtain a third duty cycle signal; controlling the operation of a switch in the three-level inverter according to the third duty cycle signal, thereby controlling the reverse output voltage of the three-level inverter to obtain a reverse voltage;

[0023] The load provides the energy storage element with a charging power supply of the reverse voltage through the zero harmonic distortion module and the three-level inverter.

[0024] In a second aspect, a zero-harmonic grid-type energy storage converter is provided, comprising an energy storage power supply module, a first control module, a three-level inverter, a zero harmonic distortion module, and a second control module. The output end of the energy storage power supply module is respectively connected to the input end of the second control module and the input end of the three-level inverter, the output end of the three-level inverter is connected to the input end of the zero harmonic distortion module, the output end of the second control module is also connected to the input end of the three-level inverter, the output end of the zero harmonic distortion module is respectively connected to the load and the input end of the first control module, the output end of the first control module is connected to the input end of the energy storage power supply module, and the energy storage power supply module includes an energy storage element; the first control module is used to obtain a first duty cycle signal according to the control method of the zero-harmonic grid-type energy storage converter described above, and control the operation of the switch tube in the energy storage power supply module according to the first duty cycle signal; the second control module is used to obtain a second duty cycle signal according to the control method of the zero-harmonic grid-type energy storage converter described above, and control the operation of the switch tube in the three-level inverter according to the second duty cycle signal.

[0025] Preferably, the first control module includes a first voltage detection submodule, a voltage comparison submodule, a Parker conversion submodule and a PWM modulation submodule connected in sequence;

[0026] The first voltage detection submodule is used to obtain the three-phase voltage output by the zero harmonic distortion module;

[0027] The voltage comparison submodule is used to compare the three-phase voltage with a set three-phase voltage reference value to obtain a three-phase voltage difference;

[0028] The Parker transformation submodule is configured to convert the three-phase voltage difference through the Parker transformation to obtain a voltage dq value; and to obtain a DC voltage effective value from the voltage dq value;

[0029] The PWM modulation submodule is used to process the effective value of the DC voltage using the PWM modulation technology to obtain a first duty cycle signal.

[0030] Preferably, the second control module includes a second voltage detection submodule and an SPWM modulation submodule;

[0031] The second voltage detection submodule is used to obtain the first voltage output by the energy storage power supply module;

[0032] The SPWM modulation submodule is configured to compare the first voltage as a feedback voltage signal with its built-in sinusoidal reference voltage signal to generate a second duty cycle signal; or

[0033] The SPWM modulation submodule is used to compare the energy storage voltage with a set reference voltage to obtain an energy storage voltage difference; and generate a third duty cycle signal based on the energy storage voltage difference as a feedback voltage signal and comparing it with its built-in sinusoidal reference voltage signal.

[0034] Preferably, the energy storage and power supply module further includes a first inductor, a first switching tube, a first parasitic diode, a second switching tube, a second parasitic diode, and a first capacitor. The positive electrode of the energy storage element is connected to the first end of the first inductor, and the negative electrode of the energy storage element is respectively connected to the second end of the second switching tube, the second end of the first capacitor, and the positive electrode of the second parasitic diode. The second end of the first inductor is respectively connected to the first end of the second switching tube, the positive electrode of the first parasitic diode, the second end of the first switching tube, and the negative electrode of the second parasitic diode. The first end of the first switching tube is respectively connected to the negative electrode of the first parasitic diode and the first end of the first capacitor. The output end of the energy storage and power supply module is also connected to the input end of the three-level inverter via a knife switch. The output end of the energy storage and power supply module is also connected to the second voltage detection submodule of the second control module.

[0035] Preferably, the zero harmonic distortion module includes a three-winding transformer for offsetting specific harmonics, the three-winding transformer including a triangular secondary winding element, a Y-shaped secondary winding element and a triangular primary winding element, the triangular winding element being connected to the first output end of the three-level inverter, the input end of the Y-shaped secondary winding element being connected to the second output end of the three-level inverter, and the triangular primary winding element being connected to the load; the triangular secondary winding element being used to provide a low harmonic voltage for the load and to form a third harmonic circulating current inside the triangular secondary winding element to prevent the low harmonic voltage from entering the load; the Y-shaped secondary winding element being used to provide neutral point access and cooperate with the triangular secondary winding element to achieve harmonic magnetic potential offset; the triangular primary winding element being used to block the zero-sequence harmonic current from propagating to the load side and provide a harmonic circulating current path.

[0036] In another aspect, a terminal device is provided, comprising a processor and a memory;

[0037] The memory is used to store program code and transmit the program code to the processor;

[0038] The processor is used to execute the above-mentioned control method of the zero-harmonic grid-type energy storage converter according to the instructions in the program code.

[0039] The zero-harmonic grid-type energy storage converter and its control method and device, the control method of the zero-harmonic grid-type energy storage converter is applied to the zero-harmonic grid-type energy storage converter, the zero-harmonic grid-type energy storage converter includes an energy storage power supply module, a first control module, a three-level inverter, a zero harmonic distortion module and a second control module, the output end of the energy storage power supply module is respectively connected to the input end of the second control module and the input end of the three-level inverter, the output end of the three-level inverter is connected to the input end of the zero harmonic distortion module, the output end of the second control module is also connected to the input end of the three-level inverter, the output end of the zero harmonic distortion module is respectively connected to the load and the input end of the first control module, the output end of the first control module is connected to the input end of the energy storage power supply module, and the energy storage power supply module includes an energy storage element. The control method includes obtaining the energy storage voltage output by the energy storage element in real time; determining the operation mode of the energy storage element according to the energy storage voltage; if the operation mode of the energy storage element is the discharge mode, obtaining the three-phase voltage output by the zero harmonic distortion module; processing the three-phase voltage using Park transformation to obtain the effective value of the DC voltage; processing the effective value of the DC voltage using PWM modulation technology to obtain a first duty cycle signal; controlling the operation of the switching tube in the energy storage power supply module according to the first duty cycle signal to obtain the first voltage output by the energy storage power supply module; if the first voltage is not less than the operating voltage of the three-level inverter, processing the first voltage using the three-level inverter to obtain a second voltage; performing zero harmonic distortion processing on the second voltage to obtain a voltage output to the load after harmonic cancellation.

[0040] It can be seen from the above technical solutions that the present application has the following advantages: the control method of the zero-harmonic grid-type energy storage converter performs zero-harmonic distortion processing on the voltage output by the energy storage power supply module and the three-level inverter through the zero-harmonic distortion module, so that the voltage output to the load is zero-harmonic, thereby improving the quality of the power output to the load and solving the technical problem that the voltage output by the existing grid-type energy storage converter has harmonics, resulting in a decrease in the power quality of the output voltage.

[0041] The zero-harmonic grid-type energy storage converter performs zero-harmonic distortion processing on the voltage delivered to the load through a three-level inverter and a zero-harmonic distortion module, allowing the zero-harmonic grid-type energy storage converter to provide voltage to the load with high power quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0043] Figure 1This is a flowchart of the steps of the control method of the zero-harmonic grid-type energy storage converter according to the embodiment of the present application;

[0044] Figure 2 A topology flow chart of a zero-harmonic grid-type energy storage converter in a control method of a zero-harmonic grid-type energy storage converter according to an embodiment of the present application;

[0045] Figure 3 This is a schematic diagram of the terminal device described in an embodiment of the present application. DETAILED DESCRIPTION

[0046] In order to make the purpose, features, and advantages of the invention of this application more obvious and easy to understand, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the embodiments described below are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0047] In the description of the embodiments of the present application, 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 the indicated technical features. Therefore, 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 application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0048] In the embodiments of the present application, unless otherwise expressly specified or limited, the terms "installed," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections, electrical connections; direct connections, or indirect connections through an intermediate medium; internal connections between two components, or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0049] Patent terms used in this application:

[0050] Pulse-Width Modulation (PWM) is a very effective technology that uses the digital output of a microprocessor to control analog circuits. It modulates the width of a series of pulses to obtain the required waveform (including shape and amplitude). That is, by changing the proportion of the on-time to the total time, that is, the duty cycle, the purpose of adjusting the voltage and frequency is achieved.

[0051] Sinusoidal Pulse Width Modulation (SPWM) modulates the pulses within each sinusoidal cycle using a natural or regular width modulation technique. This modulates the pulses into a sequence with a phase angle and area equivalent to a sine wave, resulting in a sinusoidal current output with equal amplitude and unequal width. The carrier ratio is the ratio of the fundamental wave (sinusoidal modulating wave) per cycle to the total number of pulses in the modulated output.

[0052] The embodiments of the present application provide a zero-harmonic grid-type energy storage converter and its control method and device, which solve the technical problem that the voltage output by the existing grid-type energy storage converter contains harmonics, resulting in a decrease in the power quality of the output voltage.

[0053] Example 1:

[0054] Figure 1 This is a flowchart of the steps of the control method of the zero harmonic grid-type energy storage converter described in the embodiment of the present application. Figure 2 This is a topology flow chart of the zero-harmonic grid-type energy storage converter in the control method of the zero-harmonic grid-type energy storage converter described in an embodiment of the present application.

[0055] like Figure 2 As shown, an embodiment of the present application provides a control method for a zero-harmonic grid-type energy storage converter, which is applied to a zero-harmonic grid-type energy storage converter. The zero-harmonic grid-type energy storage converter includes an energy storage power supply module 10, a first control module 20, a three-level inverter 30, a zero harmonic distortion module 40, and a second control module 50. The output end of the energy storage power supply module 10 is respectively connected to the input end of the second control module 20 and the input end of the three-level inverter 30. The output end of the three-level inverter 30 is connected to the input end of the zero harmonic distortion module 40. The output end of the second control module 50 is also connected to the input end of the three-level inverter 30. The output end of the zero harmonic distortion module 40 is respectively connected to the load 60 (such as a power grid) and the input end of the first control module 20. The output end of the first control module 20 is connected to the input end of the energy storage power supply module 10. The energy storage power supply module 10 includes an energy storage element 11.

[0056] It should be noted that the structure of the three-level inverter 30 is a relatively mature technology in this field, and this embodiment will not further elaborate on the structure of the three-level inverter 30. In this embodiment, the energy storage element 11 can be selected as a battery pack.

[0057] like Figure 1 As shown, the control method of the zero harmonic grid-type energy storage converter includes the following steps:

[0058] S1. Acquire the energy storage voltage output by the energy storage element in real time; determine the operation mode of the energy storage element according to the energy storage voltage.

[0059] It should be noted that in step S1, the energy storage voltage V output by the energy storage element is first obtained in real time. in , if the energy storage voltage V in Greater than the minimum voltage V of the energy storage element min When the energy storage element operates in discharge mode, if the energy storage voltage V in Less than the minimum voltage V of the energy storage element min When , the operation mode of the energy storage element is charging mode.

[0060] S2. If the energy storage element is operating in discharge mode, obtain the three-phase voltage output by the zero harmonic distortion module; process the three-phase voltage using Park transformation to obtain the effective value of the DC voltage.

[0061] It should be noted that in step S2, the operating mode of the energy storage element is determined according to step S1 to obtain the three-phase voltage V output by the zero harmonic distortion module in the zero harmonic grid-type energy storage converter. a 、V b and V c , for the three-phase voltage V a 、V b and V c The DC voltage effective value V1 is obtained by processing, which provides data for subsequently obtaining the first duty cycle signal for controlling the energy storage power supply module.

[0062] S3. Process the effective value of the DC voltage using PWM modulation technology to obtain a first duty cycle signal; control the operation of the switch tube in the energy storage power supply module according to the first duty cycle signal to obtain the first voltage output by the energy storage power supply module.

[0063] It should be noted that in step S3, the first duty cycle signal for controlling the operation of the switch tube in the energy storage power supply module is generated using the PWM modulation technology based on the DC voltage effective value V1 obtained in step S2. The operation of the energy storage power supply module is controlled based on the first duty cycle signal. The voltage output by the energy storage power supply module after operation is obtained and recorded as the first voltage, providing data for the subsequent step of starting the three-level inverter to output a second voltage corresponding to the first voltage. In this embodiment, the DC voltage effective value V1 is input into the PWM modulation technology and compared with the sawtooth wave set in the PWM modulation technology, and then the switching tube (such as the first switching tube S) in the energy storage power supply module is directly generated. 1和 A first duty cycle signal for turning on and off the second switch tube S2).

[0064] S4. If the first voltage is not less than the operating voltage of the three-level inverter, process the first voltage using the three-level inverter to obtain a second voltage.

[0065] It should be noted that in step S4, the first voltage in step S3 is not less than the operating voltage V of the three-level inverter.w In this case, the three-level inverter processes the first voltage and outputs a voltage recorded as a second voltage, providing the second voltage with harmonics for output to a load in a subsequent step.

[0066] S5. Perform zero harmonic distortion processing on the second voltage to obtain a voltage output to the load after harmonics are canceled.

[0067] It should be noted that in step S5, the second voltage obtained in step S4 is subjected to zero harmonic distortion processing to obtain a voltage output to the load after harmonic cancellation, allowing the zero-harmonic grid-type energy storage converter to provide high power quality voltage to the load. In this embodiment, the second voltage output by the three-level inverter is subjected to zero harmonic distortion processing by the zero harmonic distortion module to obtain a voltage with a high-quality voltage waveform.

[0068] The present application provides a control method for a zero-harmonic grid-type energy storage converter, which is applied to a zero-harmonic grid-type energy storage converter. The zero-harmonic grid-type energy storage converter includes an energy storage power supply module, a first control module, a three-level inverter, a zero harmonic distortion module, and a second control module. The output end of the energy storage power supply module is respectively connected to the input end of the second control module and the input end of the three-level inverter. The output end of the three-level inverter is connected to the input end of the zero harmonic distortion module. The output end of the second control module is also connected to the input end of the three-level inverter. The output end of the zero harmonic distortion module is respectively connected to the load and the input end of the first control module. The output end of the first control module is connected to the input end of the energy storage power supply module. The energy storage power supply module includes an energy storage element. The control method includes obtaining the energy storage voltage output by the energy storage element in real time; determining the operation mode of the energy storage element according to the energy storage voltage; if the operation mode of the energy storage element is the discharge mode, obtaining the three-phase voltage output by the zero harmonic distortion module; processing the three-phase voltage using Park transformation to obtain the effective value of the DC voltage; processing the effective value of the DC voltage using PWM modulation technology to obtain a first duty cycle signal; controlling the operation of the switching tube in the energy storage power supply module according to the first duty cycle signal to obtain the first voltage output by the energy storage power supply module; if the first voltage is not less than the operating voltage of the three-level inverter, processing the first voltage using the three-level inverter to obtain a second voltage; performing zero harmonic distortion processing on the second voltage to obtain a voltage output to the load after harmonic cancellation. The control method of the zero-harmonic grid-type energy storage converter performs zero-harmonic distortion processing on the voltage output by the energy storage power supply module and the three-level inverter through a zero-harmonic distortion module, so that the voltage output to the load is zero-harmonic, thereby improving the quality of the power output to the load and solving the technical problem that the voltage output by the existing grid-type energy storage converter has harmonics, resulting in a decrease in the power quality of the output voltage.

[0069] In one embodiment of the present application, before the first voltage is processed by a three-level inverter to obtain the second voltage, the control method of the zero-harmonic grid-type energy storage converter further includes:

[0070] Processing the first voltage using SPWM modulation technology to obtain a second duty cycle signal;

[0071] The operation of the switch tube in the three-level inverter is controlled according to the second duty cycle signal, thereby controlling the output voltage of the three-level inverter to obtain a second voltage.

[0072] It should be noted that when the first voltage output by the energy storage power supply module reaches the operating voltage V w When the first voltage is output, the three-level inverter begins operation, and the second control module then begins operation. The first voltage output by the energy storage power supply module is collected and modulated using SPWM technology to output a second duty cycle signal, which controls the switches of the three-level inverter and, in turn, controls the second voltage output by the three-level inverter. In this embodiment, SPWM modulation technology refers to controlling the three-level inverter by combining first voltage feedback with SPWM regulation technology. This can be understood as: collecting the output first voltage as a feedback signal, and using SPWM modulation technology to compare the feedback signal with a sinusoidal reference signal to generate a second duty cycle signal that drives the switches in the three-level inverter.

[0073] In one embodiment of the present application, the three-phase voltage is processed using Park transformation to obtain the effective value of the DC voltage, which includes:

[0074] Compare the three-phase voltage with the set three-phase voltage reference value to obtain the three-phase voltage difference;

[0075] The three-phase voltage difference is converted by Park transformation to obtain the voltage dq value;

[0076] Get the DC voltage RMS value from the voltage dq value.

[0077] It should be noted that the three-phase voltage V a 、V b and V c Respectively with the three-phase voltage reference value V ref Perform difference calculation and obtain the three voltage differences u a 、u b and u c The three-phase voltage difference u abc The three-phase voltage difference u is converted into abc Convert and get the voltage dq value u dq ; From the voltage dq value u dq Extract the effective value to get the DC voltage effective value V1. Taking phase a as an example, the Park transformation formula is:

[0078]

[0079]

[0080] Where, T dq is the transformation matrix of Park transformation, and θ is the phase angle of phase a voltage.

[0081] In one embodiment of the present application, the control method of the zero harmonic grid-type energy storage converter further includes:

[0082] If the operation mode of the energy storage element is the charging mode, controlling the first control module to not operate;

[0083] Compare the energy storage voltage with the set reference voltage to obtain the energy storage voltage difference;

[0084] The energy storage voltage difference is processed using an SPWM modulation technique to obtain a third duty cycle signal; the operation of a switch in the three-level inverter is controlled according to the third duty cycle signal, thereby controlling the reverse output voltage of the three-level inverter to obtain a reverse voltage;

[0085] The load provides a charging power supply with a reverse voltage to the energy storage element through a zero harmonic distortion module and a three-level inverter.

[0086] It should be noted that when the operation mode of the energy storage element is the charging mode, the energy storage voltage V in With the reference voltage V set o The comparison obtains the energy storage voltage difference u. The second control module operates, and the energy storage voltage difference u is modulated using SPWM technology to output a third duty cycle signal, which controls the operation of the switch tube in the three-level inverter, thereby controlling the three-level inverter to output a reverse voltage. The grid provides a charging power supply with a reverse voltage to the energy storage element through the zero harmonic distortion module and the three-level inverter, charging the energy storage element and realizing reverse energy transmission.

[0087] Example 2:

[0088] like Figure 2As shown, the embodiment of the present application provides a zero harmonic grid-type energy storage converter, including an energy storage power supply module 10, a first control module 20, a three-level inverter 30, a zero harmonic distortion module 40 and a second control module 50, the output end of the energy storage power supply module 10 is respectively connected to the input end of the second control module 20 and the input end of the three-level inverter 30, the output end of the three-level inverter 30 is connected to the input end of the zero harmonic distortion module 40, the output end of the second control module 50 is also connected to the input end of the three-level inverter 30, and the output end of the zero harmonic distortion module 40 is respectively connected to the load 60 (such as the power supply module 60). The first control module 20 is connected to the input end of the energy storage power supply module 10, and the output end of the first control module 20 is connected to the input end of the energy storage power supply module 10. The energy storage power supply module 10 includes an energy storage element 11. The first control module 20 is used to obtain a first duty cycle signal according to the control method of the zero-harmonic grid-type energy storage converter, and control the operation of the switch tube in the energy storage power supply module 10 according to the first duty cycle signal. The second control module 50 is used to obtain a second duty cycle signal according to the control method of the zero-harmonic grid-type energy storage converter, and control the operation of the switch tube in the three-level inverter 30 according to the second duty cycle signal.

[0089] It should be noted that the control method for the zero-harmonic grid-type energy storage converter has been described in Example 1 and will not be repeated in this example. The zero-harmonic grid-type energy storage converter uses a three-level inverter and a zero-harmonic distortion module to perform zero-harmonic distortion processing on the voltage delivered to the load, allowing the zero-harmonic grid-type energy storage converter to provide high power quality voltage to the load.

[0090] like Figure 2 As shown, in the embodiment of the present application, the first control module 20 includes a first voltage detection submodule 21, a voltage comparison submodule 22, a Parker conversion submodule 23 and a PWM modulation submodule 24 connected in sequence;

[0091] The first voltage detection submodule 21 is used to obtain the three-phase voltage output by the zero harmonic distortion module 40;

[0092] The voltage comparison submodule 22 is used to compare the three-phase voltage with the set three-phase voltage reference value to obtain the three-phase voltage difference;

[0093] The Parker transformation submodule 23 is used to transform the three-phase voltage difference by Parker transformation to obtain the voltage dq value; and to obtain the DC voltage effective value from the voltage dq value;

[0094] The PWM modulation submodule 24 is configured to process the effective value of the DC voltage using a PWM modulation technique to obtain a first duty cycle signal.

[0095] It should be noted that the first voltage detection submodule 21 can be a three-phase voltage sensor to obtain the three-phase voltage output by the zero harmonic distortion module 40. The contents of the first voltage detection submodule 21, the voltage comparison submodule 22, the Parker conversion submodule 23, and the PWM modulation submodule 24 have been described in the control method of the zero-harmonic grid-type energy storage converter in Example 1 and will not be further described in this embodiment.

[0096] like Figure 2 As shown, in the embodiment of the present application, the second control module 50 includes a second voltage detection submodule 51 and an SPWM modulation submodule 52;

[0097] A second voltage detection submodule 51 is used to obtain a first voltage output by the energy storage and power supply module 10;

[0098] The SPWM modulation submodule 52 is configured to compare the first voltage as a feedback voltage signal with its built-in sinusoidal reference voltage signal to generate a second duty cycle signal; or

[0099] The SPWM modulation submodule 52 is used to compare the energy storage voltage with the set reference voltage to obtain the energy storage voltage difference; and generate a third duty cycle signal based on the energy storage voltage difference as a feedback voltage signal and comparing it with its built-in sinusoidal reference voltage signal.

[0100] It should be noted that the second voltage detection submodule 51 can be selected as a voltage sensor to obtain the first voltage output by the energy storage power supply module 10. The contents of the second voltage detection submodule 51 and the SPWM modulation submodule 52 have been described in the control method of the zero-harmonic grid-type energy storage converter in Example 1 and will not be further described in this embodiment.

[0101] like Figure 2 As shown, in the embodiment of the present application, the energy storage power supply module 10 further includes a first inductor L1, a first switch tube S1, a first parasitic diode D 11 , the second switch tube S2, the second parasitic diode D 22 The positive electrode of the energy storage element 11 is connected to the first end of the first inductor L1, and the negative electrode of the energy storage element 11 is connected to the second end of the second switch tube S2, the second end of the first capacitor C1 and the second parasitic diode D 22 The second end of the first inductor L1 is connected to the first end of the second switch tube S2 and the first parasitic diode D 11 The positive electrode, the second end of the first switch tube S1 and the second parasitic diode D 22 The first end of the first switch tube S1 is connected to the negative electrode of the first parasitic diode D 11the output end of the energy storage power supply module 10 is also connected to the input end of the three-level inverter 30 through the knife switch T1, and the output end of the energy storage power supply module 10 is also connected to the second voltage detection submodule 51 of the second control module 50.

[0102] It should be noted that the first switch S1 and the second switch S2 can both be triodes, with the emitter of the triode serving as the second end of the first switch S1 and the second switch S2, the base of the triode serving as the control end of the first switch S1 and the second switch S2, and the collector of the triode serving as the first end of the first switch S1 and the second switch S2. The control end of the first switch S1 and the control end of the second switch S2 are both connected to the first control module 20.

[0103] like Figure 2 As shown, in an embodiment of the present application, the zero harmonic distortion module 40 includes a three-winding transformer for offsetting specific harmonics. The three-winding transformer includes a triangular secondary winding element, a Y-shaped secondary winding element, and a triangular primary winding element. The triangular winding element is connected to the first output terminal of the three-level inverter 30, the input terminal of the Y-shaped secondary winding element is connected to the second output terminal of the three-level inverter 30, and the triangular primary winding element is connected to the load 60; the triangular secondary winding element is used to provide a low harmonic voltage to the load and form a third harmonic circulating current inside the triangular secondary winding element to prevent the low harmonic voltage from entering the load; the Y-shaped secondary winding element is used to provide neutral point access and cooperate with the triangular secondary winding element to achieve harmonic magnetic potential offset; the triangular primary winding element is used to block the zero-sequence harmonic current from propagating to the load side and provide a harmonic circulating current path.

[0104] It should be noted that the triangular secondary winding element includes the first winding R △1 , the second winding R △2 and the third winding R △3 ; The Y-shaped secondary winding element includes the fourth winding R Y1 、The fifth winding R Y2 and the sixth winding R Y3 The triangular primary winding element includes the seventh winding R △a11 、The eighth winding R △22 and the ninth winding R Y△33 ; The first winding R △1 The first end of the second winding R △b The first end and the third winding R △c The first end of the second winding R △b The first end of the first winding R △1 The first end and the third winding R △c The second end of the fourth winding R Y1 The first end of the fifth winding RY2 The first end and the sixth winding R Y3 The first end of the seventh winding R △a11 The first end of the eighth winding R △22 The first end and the ninth winding R Y△33 In this embodiment, the zero harmonic distortion module 40 utilizes a special three-winding transformer structure. This three-winding transformer structure essentially utilizes the phase configuration and magnetic circuit coupling characteristics of the transformer windings to actively cancel specific harmonics (especially the third harmonic and its multiples), thereby achieving zero harmonic voltage distortion processing for voltage harmonics.

[0105] In the embodiment of the present application, the three-winding transformer of the zero-harmonic grid-type energy storage converter is combined with the three-level inverter 30. Since the phase shift between the two is 30 degrees, harmonic cancellation can be performed according to the first formula. The first formula is Odd or positive number.

[0106] Example 3:

[0107] Figure 3 This is a schematic diagram of the terminal device described in an embodiment of the present application.

[0108] like Figure 3 As shown, an embodiment of the present application provides a terminal device, including a processor and a memory;

[0109] A memory, configured to store program codes and transmit the program codes to a processor;

[0110] A processor is used to execute the control method of the zero-harmonic grid-type energy storage converter according to the instructions in the program code.

[0111] It should be noted that the processor is configured to execute the steps of the aforementioned control method embodiment of a zero-harmonic grid-type energy storage converter according to the instructions in the program code. Alternatively, the processor implements the functions of the modules / units in the aforementioned system / device embodiments when executing the computer program.

[0112] For example, a computer program may be divided into one or more modules / units, one or more of which are stored in a memory and executed by a processor to complete the present application. One or more modules / units may be a series of computer program instruction segments capable of performing specific functions, and the instruction segments are used to describe the execution process of the computer program in a terminal device.

[0113] Terminal devices can be computing devices such as desktop computers, laptops, PDAs, and cloud servers. Terminal devices may include, but are not limited to, processors and memory. Those skilled in the art will appreciate that this does not constitute a limitation on terminal devices and may include more or fewer components than shown, or a combination of certain components, or different components. For example, terminal devices may also include input / output devices, network access devices, buses, and the like.

[0114] The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0115] Memory can be an internal storage unit of a terminal device, such as a hard drive or memory. It can also be an external storage device, such as a plug-in hard drive, a SmartMedia Card (SMC), a Secure Digital (SD) card, or a flash memory card. Furthermore, memory can include both internal and external storage units. Memory is used to store computer programs and other programs and data required by the terminal device. Memory can also be used to temporarily store data that has been output or is about to be output.

[0116] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0117] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0118] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0119] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0120] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes various media that can store program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0121] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A control method for a zero-harmonic grid-type energy storage converter, applied to a zero-harmonic grid-type energy storage converter, characterized in that: The zero-harmonic grid-type energy storage converter includes an energy storage power supply module, a first control module, a three-level inverter, a zero harmonic distortion module, and a second control module. The output end of the energy storage power supply module is respectively connected to the input end of the second control module and the input end of the three-level inverter. The output end of the three-level inverter is connected to the input end of the zero harmonic distortion module. The output end of the second control module is also connected to the input end of the three-level inverter. The output end of the zero harmonic distortion module is respectively connected to the load and the input end of the first control module. The output end of the first control module is connected to the input end of the energy storage power supply module. The energy storage power supply module includes an energy storage element. The control method includes the following steps: Acquiring the energy storage voltage output by the energy storage element in real time; determining the operation mode of the energy storage element according to the energy storage voltage; If the operation mode of the energy storage element is the discharge mode, obtaining the three-phase voltage output by the zero harmonic distortion module; processing the three-phase voltage using Park transformation to obtain the effective value of the DC voltage; The effective value of the DC voltage is processed using PWM modulation technology to obtain a first duty cycle signal; the operation of the switch tube in the energy storage power supply module is controlled according to the first duty cycle signal to obtain a first voltage output by the energy storage power supply module; If the first voltage is not less than the operating voltage of the three-level inverter, processing the first voltage using the three-level inverter to obtain a second voltage; The second voltage is subjected to zero harmonic distortion processing to obtain a voltage output to the load after harmonic cancellation.

2. The control method of the zero harmonic grid-type energy storage converter according to claim 1, characterized in that: Before processing the first voltage using the three-level inverter to obtain the second voltage, the control method further includes: Processing the first voltage using SPWM modulation technology to obtain a second duty cycle signal; The operation of the switch tube in the three-level inverter is controlled according to the second duty cycle signal, thereby controlling the output voltage of the three-level inverter to obtain a second voltage.

3. The control method of the zero harmonic grid-type energy storage converter according to claim 1, characterized in that: The three-phase voltage is processed by Park transformation to obtain the effective value of the DC voltage, which includes: Comparing the three-phase voltage with a set three-phase voltage reference value to obtain a three-phase voltage difference; Convert the three-phase voltage difference by the Park transformation to obtain a voltage dq value; A DC voltage effective value is obtained from the voltage dq value.

4. The control method of the zero harmonic grid-type energy storage converter according to any one of claims 1 to 3, characterized in that: Also includes: If the operation mode of the energy storage element is the charging mode, controlling the first control module to not operate; Comparing the energy storage voltage with a set reference voltage to obtain an energy storage voltage difference; Processing the energy storage voltage difference using SPWM modulation technology to obtain a third duty cycle signal; controlling the operation of a switch in the three-level inverter according to the third duty cycle signal, thereby controlling the reverse output voltage of the three-level inverter to obtain a reverse voltage; The load provides the energy storage element with a charging power supply of the reverse voltage through the zero harmonic distortion module and the three-level inverter.

5. A zero harmonic grid-type energy storage converter, characterized in that: The invention comprises an energy storage power supply module, a first control module, a three-level inverter, a zero harmonic distortion module, and a second control module. The output end of the energy storage power supply module is respectively connected to the input end of the second control module and the input end of the three-level inverter. The output end of the three-level inverter is connected to the input end of the zero harmonic distortion module. The output end of the second control module is also connected to the input end of the three-level inverter. The output end of the zero harmonic distortion module is respectively connected to the load and the input end of the first control module. The output end of the first control module is connected to the input end of the energy storage power supply module. The energy storage power supply module includes an energy storage element. The first control module is configured to obtain a first duty cycle signal according to the control method of the zero harmonic grid-type energy storage converter according to any one of claims 1 to 4, and control the operation of the switch tube in the energy storage power supply module according to the first duty cycle signal. The second control module is configured to obtain a second duty cycle signal according to the control method of the zero harmonic grid-type energy storage converter according to claim 2, and control the operation of the switch tube in the three-level inverter according to the second duty cycle signal.

6. The zero harmonic grid-type energy storage converter according to claim 5, characterized in that: The first control module includes a first voltage detection submodule, a voltage comparison submodule, a Parker conversion submodule and a PWM modulation submodule connected in sequence; The first voltage detection submodule is used to obtain the three-phase voltage output by the zero harmonic distortion module; The voltage comparison submodule is used to compare the three-phase voltage with a set three-phase voltage reference value to obtain a three-phase voltage difference; The Parker transformation submodule is configured to convert the three-phase voltage difference through the Parker transformation to obtain a voltage dq value; and to obtain a DC voltage effective value from the voltage dq value; The PWM modulation submodule is used to process the effective value of the DC voltage using the PWM modulation technology to obtain a first duty cycle signal.

7. The zero harmonic grid-type energy storage converter according to claim 5, characterized in that: The second control module includes a second voltage detection submodule and an SPWM modulation submodule; The second voltage detection submodule is used to obtain the first voltage output by the energy storage power supply module; The SPWM modulation submodule is configured to compare the first voltage as a feedback voltage signal with its built-in sinusoidal reference voltage signal to generate a second duty cycle signal; or The SPWM modulation submodule is used to compare the energy storage voltage with a set reference voltage to obtain an energy storage voltage difference; and generate a third duty cycle signal based on the energy storage voltage difference as a feedback voltage signal and comparing it with its built-in sinusoidal reference voltage signal.

8. The zero harmonic grid-type energy storage converter according to claim 5, characterized in that: The energy storage and power supply module also includes a first inductor, a first switching tube, a first parasitic diode, a second switching tube, a second parasitic diode and a first capacitor. The positive electrode of the energy storage element is connected to the first end of the first inductor, and the negative electrode of the energy storage element is respectively connected to the second end of the second switching tube, the second end of the first capacitor and the positive electrode of the second parasitic diode. The second end of the first inductor is respectively connected to the first end of the second switching tube, the positive electrode of the first parasitic diode, the second end of the first switching tube and the negative electrode of the second parasitic diode. The first end of the first switching tube is respectively connected to the negative electrode of the first parasitic diode and the first end of the first capacitor. The output end of the energy storage and power supply module is also connected to the input end of the three-level inverter through a knife switch. The output end of the energy storage and power supply module is also connected to the second voltage detection submodule of the second control module.

9. The zero harmonic grid-type energy storage converter according to claim 5, characterized in that: The zero harmonic distortion module includes a three-winding transformer for offsetting specific harmonics. The three-winding transformer includes a triangular secondary winding element, a Y-shaped secondary winding element, and a triangular primary winding element. The triangular winding element is connected to the first output terminal of the three-level inverter, the input terminal of the Y-shaped secondary winding element is connected to the second output terminal of the three-level inverter, and the triangular primary winding element is connected to the load; the triangular secondary winding element is used to provide a low harmonic voltage for the load and form a third harmonic circulating current inside the triangular secondary winding element to prevent the low harmonic voltage from entering the load; the Y-shaped secondary winding element is used to provide neutral point access and cooperate with the triangular secondary winding element to achieve harmonic magnetic potential offset; the triangular primary winding element is used to block the zero-sequence harmonic current from propagating to the load side, providing a harmonic circulating current path.

10. A terminal device, characterized in that: including a processor and a memory; The memory is used to store program code and transmit the program code to the processor; The processor is used to execute the control method of the zero-harmonic grid-type energy storage converter according to any one of claims 1 to 4 according to the instructions in the program code.

Images