Network-configuration type hybrid energy storage converter based on energy storage battery and super capacitor and control method thereof

Abstract

The application provides a network-constructing type hybrid energy storage converter based on energy storage batteries and super capacitors, comprising three variable current modules with the same structure, and the three variable current modules correspond to three phases A, B and C respectively, each variable current module is connected to the corresponding phase line through a bridge arm inductor, and the three variable current modules are connected to form a star structure; the variable current module comprises a plurality of sub-modules with the same structure, the plurality of sub-modules are sequentially connected in cascade, the positive end of the sub-module at the head end is connected to the corresponding phase line through a bridge arm inductor, and the negative end of the sub-module at the tail end is connected to a neutral point; the sub-module comprises an H-bridge circuit, a capacitor C, an energy storage battery module and a super capacitor module, the midpoint of the upper bridge arm of the H-bridge circuit is used as the positive end of the sub-module and is connected to the corresponding phase line through a bridge arm inductor, the midpoint of the lower bridge arm of the H-bridge circuit is used as the negative end of the sub-module, and the capacitor C is connected in parallel with the H-bridge circuit; the positive end of the energy storage battery module and the super capacitor module is connected to the positive end of the capacitor C, and the negative end of the energy storage battery module and the super capacitor module is connected to the negative end of the capacitor C.

Description

Technical Field

[0001] This invention relates to a power equipment and its control method, and more particularly to a grid-type hybrid energy storage converter based on energy storage batteries and supercapacitors and its control method. Background Technology

[0002] Large-scale renewable energy power plants are mostly located at the end of the power grid, with weak grid connection strength. The system has inertia / frequency and voltage stability issues. Grid-based control technology can simulate the characteristics of synchronous generators, actively construct voltage and frequency, and improve the stability of renewable energy under weak grid conditions. It is one of the mainstream solutions to solve the grid connection stability of renewable energy.

[0003] Existing grid-based control technologies have low capacity and are insufficient to support the stable operation of the entire power station. Currently, grid-based SVG, static condensers, and grid-based energy storage are being added to the 35 kV or 220 kV collection points of new energy power stations. However, grid-based SVG does not have an energy storage unit and is mainly used to support grid voltage, making it difficult to provide significant inertia / frequency support capabilities. Static condensers are equipped with supercapacitor energy storage units, which can provide significant inertia and voltage support capabilities, but due to the low energy density of supercapacitors, they are difficult to provide long-term frequency support capabilities. Grid-based energy storage is equipped with energy storage battery units, which can provide voltage support and long-term frequency support capabilities, but due to the low power density and cycle life of energy storage batteries, they are not suitable for frequent instantaneous power support and have weak inertia support capabilities.

[0004] Therefore, in order to solve the above-mentioned technical problems, it is urgent to propose a new technical approach. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a grid-type hybrid energy storage converter based on energy storage batteries and supercapacitors and its control method. In the converter, H-bridge circuits, supercapacitor modules and energy storage battery modules are used to form several sub-modules and form a star-shaped cascaded structure, thereby providing the power grid with short-term fast inertia support and long-term frequency support, thus effectively ensuring the operational stability of the power grid system.

[0006] The present invention provides a grid-type hybrid energy storage converter based on energy storage batteries and supercapacitors, including three converter modules with the same structure, and the three converter modules correspond to the three phases A, B and C respectively. Each converter module is connected to the corresponding phase line through a bridge arm inductor, and the three converter modules are connected to form a star structure.

[0007] The converter module includes several sub-modules with the same structure, which are cascaded in sequence. The positive terminal of the first sub-module is connected to the corresponding phase line through a bridge arm inductor, and the negative terminal of the last sub-module is connected to the neutral point.

[0008] The submodule includes an H-bridge circuit, a capacitor C, an energy storage battery module, and a supercapacitor module. The midpoint of the upper arm of the H-bridge circuit serves as the positive terminal of the submodule and is connected to the corresponding phase line through the arm inductance. The midpoint of the lower arm of the H-bridge circuit serves as the negative terminal of the submodule. The capacitor C is connected in parallel with the H-bridge circuit. The positive terminals of the energy storage battery module and the supercapacitor module are connected to the positive terminal of the capacitor C, and the negative terminals of the energy storage battery module and the supercapacitor module are connected to the negative terminal of the capacitor C.

[0009] Furthermore, the supercapacitor module includes a supercapacitor, IGBT Q7, IGBT Q8, and inductor L. SC ;

[0010] The collector of IGBT Q7 is connected to the positive terminal of capacitor C, serving as the positive terminal of the supercapacitor module. The emitter of IGBT Q7 is connected to the collector of IGBT Q8. The emitter of IGBT Q8 is connected to the negative terminal of the supercapacitor and the negative terminal of capacitor C. The positive terminal of the supercapacitor is connected through inductor L. SC The collector of IGBT Q8 is connected; the gates of IGBT Q7 and IGBT Q8 respectively receive PWM control signals.

[0011] Furthermore, the energy storage battery module includes an energy storage battery, IGBT Q5, IGBT Q6, and inductor L. B ;

[0012] The collector of IGBT Q5 is connected to the positive terminal of capacitor C, serving as the positive terminal of the energy storage battery module. The emitter of IGBT Q5 is connected to the collector of IGBT Q6. The emitter of IGBT Q6 is connected to the negative terminal of the energy storage battery and the negative terminal of capacitor C. The positive terminal of the energy storage battery is connected through inductor L. B The collector of IGBT Q6 is connected to IGBT Q5 and IGBT Q6 respectively, and PWM control signals are input to them.

[0013] Accordingly, the present invention also provides a control method based on the above-described grid-type hybrid energy storage converter, characterized by comprising the following steps:

[0014] S1. Determine the operating parameters of the i-th submodule in the grid-type hybrid energy storage converter, wherein the operating parameters include the active power reference value P. ref Reactive power reference value Q ref Voltage reference value U ref The voltage reference value u of the supercapacitor module cref and the active power reference value P of the energy storage battery module brefi ;

[0015] S2. Determine the phase angle and amplitude of the virtual internal potential, the current reference value of the supercapacitor module, and the current reference value of the energy storage battery module based on the operating parameters of the grid-type hybrid energy storage converter;

[0016] S3. Generate a PWM control signal for controlling the H-bridge circuit based on the phase angle and amplitude of the virtual internal potential, generate a PWM control signal for controlling the supercapacitor module based on the current reference value of the supercapacitor, and generate a PWM control signal for controlling the energy storage battery module based on the current reference value of the energy storage battery.

[0017] Furthermore, determining the phase angle and amplitude of the virtual internal potential based on the operating parameters of the grid-type hybrid energy storage converter specifically includes:

[0018] ; ;

[0019] Where: θ represents the phase angle of the virtual internal potential, P ref P represents the active power reference value of the i-th submodule. e Let J represent the actual output active power of the i-th submodule, J represent the virtual moment of inertia, ω0 represent the rated angular velocity of the power grid system, D represent the damping coefficient, kq represent the droop coefficient, and Q represent the sag coefficient. ref Q represents the reactive power reference value. e This represents the actual reactive power output of the i-th submodule.

[0020] Furthermore, the generation of PWM control signals for controlling the H-bridge circuit based on the phase angle and amplitude of the virtual internal potential specifically includes:

[0021] The voltage of each phase line is evenly distributed to each sub-module of the corresponding converter module, and the evenly distributed voltage of each sub-module is converted into a direct-axis component u. d and cross-axis component u q ;

[0022] Calculate the direct-axis voltage deviation ∆u d :

[0023] ;

[0024] Direct axis voltage deviation ∆u d The input is processed by the PI controller to obtain the direct-axis current reference value i. dref :

[0025] ;

[0026] Where: K p,d K i,d These represent the proportional and integral coefficients of the PI controller, respectively.

[0027] The cross-axis component u q The quadrature-axis voltage deviation ∆u is obtained by comparing it with 0. q :

[0028] ;

[0029] The quadrature-axis voltage deviation ∆u q The input is processed by the PI controller to obtain the quadrature axis current reference value i. qref :

[0030] ;

[0031] Calculate the reference values ​​for direct-axis current and quadrature-axis current and compare them with the actual direct-axis current value i. d and cross-axis current value i q deviation ∆i d and ∆i q :

[0032] ;

[0033] Based on deviation ∆i d and ∆i q The voltage control command u is obtained by inputting it into the PI controller. ctrld and u ctrlq :

[0034] ;

[0035] Where: K p,id and K p,iq K i,id and K i,iq These represent the proportional and integral coefficients of the corresponding PI controller, respectively.

[0036] Using the phase angle θ of the virtual internal potential as a reference angle, the voltage control command u is applied. ctrld and u ctrlq Transforming to a three-phase coordinate system, we obtain the voltage modulation waveform U of the H-bridge circuit. mod And the voltage modulation waveform U mod The PWM control signal for the H-bridge circuit is generated by single-pole frequency doubling carrier phase shift modulation.

[0037] Furthermore, the generation of PWM control signals for controlling the supercapacitor module based on the supercapacitor's current reference value specifically includes:

[0038] The voltage reference value u of the i-th submodule supercapacitor module cref The actual voltage u of the supercapacitor module ci The difference is used to obtain the supercapacitor voltage deviation ∆u ci :

[0039] ;

[0040] Voltage deviation ∆u ci The current reference value i of the supercapacitor module is obtained by inputting it into the PI controller. sciref ;

[0041] Use the current reference value i sciref Compared with the actual output current i of the supercapacitor sci The difference is then input to the PI controller to obtain the control command signal u. ctrlc :

[0042] ;

[0043] For control command signal u ctrlc Complementary modulation is used to generate the PWM control signal for the supercapacitor module.

[0044] Furthermore, a PWM control signal for controlling the energy storage battery module is generated based on the current reference value of the energy storage battery:

[0045] Based on the active power reference value P of the energy storage battery brefi With the port voltage V of the energy storage battery bi Determine the current reference value i of the energy storage battery bref :

[0046] ;

[0047] Use the current reference value i bref Compared with the actual output current i of the energy storage battery bi The difference is then input into the PI controller to obtain the control command u. ctrlb :

[0048] ;

[0049] Control command u ctrlb Complementary modulation is used to generate the PWM control signal for the energy storage battery module.

[0050] The beneficial effects of this invention are as follows: By using an H-bridge circuit, a supercapacitor module, and an energy storage battery module to form several sub-modules and a star-shaped cascaded structure in the converter, it is possible to provide short-term rapid inertia support and long-term frequency support for the power grid, thereby effectively ensuring the operational stability of the power grid system.

[0051] Furthermore, by using bidirectional Buck / Boost converters in the energy storage battery module and the supercapacitor module to isolate the supercapacitor and the energy storage battery, it is possible to ensure deep discharge of the supercapacitor and avoid the impact of capacitor frequency double-frequency fluctuations on the cycle life of the energy storage battery.

[0052] Through the control process, the system voltage, frequency, and inertia can be automatically adjusted, enabling the entire power grid system to operate continuously and stably. Attached Figure Description

[0053] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0054] Figure 1 This is a topological diagram of the present invention.

[0055] Figure 2 This is a topology diagram of the submodules of the present invention.

[0056] Figure 3 This is a schematic diagram of the process of the present invention.

[0057] Figure 4 This is a schematic diagram of the H-bridge circuit control of the present invention.

[0058] Figure 5 This is a schematic diagram of the control of the supercapacitor module and energy storage battery module of the present invention. Detailed Implementation

[0059] The present invention will be further described in detail below:

[0060] like Figure 1 As shown: The present invention provides a grid-type hybrid energy storage converter based on energy storage batteries and supercapacitors, including three converter modules with the same structure (the same topology and the same number of sub-modules). The three converter modules correspond to the three phases A, B and C respectively. The positive terminal of each converter module is connected to the corresponding phase line through the bridge arm inductor, and the negative terminals of the three converter modules are connected to the same point (called the neutral point or 0 potential point) to form a star structure.

[0061] The converter module includes several structurally identical sub-modules, which are cascaded sequentially. The positive terminal of the first sub-module (referring to the sub-module connected to the phase line of the power grid) is connected to the corresponding phase line through a bridge arm inductor, and the negative terminal of the last sub-module (the sub-module connected to the center point is called the last terminal module) is connected to the neutral point. All sub-modules are completely identical in electrical parameters, which facilitates modular and redundant design. It is easy to adjust the rated voltage and capacity by increasing or decreasing the number of sub-modules, thereby meeting the needs of different operating environments.

[0062] The submodule includes an H-bridge circuit, a capacitor C, an energy storage battery module, and a supercapacitor module. The midpoint of the upper arm of the H-bridge circuit serves as the positive terminal of the submodule, connected to the corresponding phase line via the arm inductance. The midpoint of the lower arm of the H-bridge circuit serves as the negative terminal of the submodule. The capacitor C is connected in parallel with the H-bridge circuit. The positive terminals of the energy storage battery module and the supercapacitor module are connected to the positive terminal of the capacitor C, and the negative terminals of the energy storage battery module and the supercapacitor module are connected to the negative terminal of the capacitor C. The H-bridge circuit is composed of four IGBTs (Insulated Gate Bipolar Transistors), a prior art circuit structure. The capacitor C serves as a filter and stabilizes the voltage. Through the above structure, the converter uses an H-bridge circuit, a supercapacitor module, and an energy storage battery module to form several submodules and a star-cascaded structure, thereby providing short-term rapid inertia support and long-term frequency support for the power grid, effectively ensuring the operational stability of the power grid system.

[0063] In this embodiment, as Figure 2 As shown: The supercapacitor module includes a supercapacitor, IGBT Q7, IGBT Q8, and inductor L. SC ;

[0064] The collector of IGBT Q7 is connected to the positive terminal of capacitor C, serving as the positive terminal of the supercapacitor module. The emitter of IGBT Q7 is connected to the collector of IGBT Q8. The emitter of IGBT Q8 is connected to the negative terminal of the supercapacitor and the negative terminal of capacitor C. The positive terminal of the supercapacitor is connected through inductor L. SC The collector of IGBT Q8 is connected; the gates of IGBT Q7 and IGBT Q8 respectively receive PWM control signals.

[0065] The energy storage battery module includes an energy storage battery, IGBT Q5, IGBT Q6, and inductor L. B The energy storage battery uses lithium batteries.

[0066] The collector of IGBT Q5 is connected to the positive terminal of capacitor C, serving as the positive terminal of the energy storage battery module. The emitter of IGBT Q5 is connected to the collector of IGBT Q6. The emitter of IGBT Q6 is connected to the negative terminal of the energy storage battery and the negative terminal of capacitor C. The positive terminal of the energy storage battery is connected through inductor L. B The collector of IGBT Q6 is connected to IGBT Q5, and PWM control signals are input to IGBT Q6 respectively. Figure 2 As can be seen from this: IGBT Q7, IGBT Q8, and inductor L SC This forms a bidirectional Buck / Boost converter, consisting of IGBT Q5, IGBT Q6, and inductor L. BSimilarly, it forms a bidirectional Buck / Boost converter, thereby isolating the supercapacitor and energy storage battery from the H-bridge circuit and the supercapacitor and energy storage battery. This can ensure the deep discharge of the supercapacitor and avoid the impact of the capacitor's second harmonic frequency fluctuation on the cycle life of the energy storage battery. At the same time, it provides greater inertia, frequency and voltage support capabilities, making its active support technology advantages for new energy power plants more obvious.

[0067] Accordingly, the present invention also provides a control method based on the above-described grid-type hybrid energy storage converter, characterized by comprising the following steps:

[0068] S1. Determine the operating parameters of the i-th submodule in the grid-type hybrid energy storage converter, wherein the operating parameters include the active power reference value P. ref Reactive power reference value Q ref Voltage reference value U ref The voltage reference value u of the supercapacitor module cref and the active power reference value P of the energy storage battery module brefi ;

[0069] S2. Determine the phase angle and amplitude of the virtual internal potential, the current reference value of the supercapacitor module, and the current reference value of the energy storage battery module based on the operating parameters of the grid-type hybrid energy storage converter;

[0070] S3. Generate a PWM control signal for controlling the H-bridge circuit based on the phase angle and amplitude of the virtual internal potential, generate a PWM control signal for controlling the supercapacitor module based on the current reference value of the supercapacitor, and generate a PWM control signal for controlling the energy storage battery module based on the current reference value of the energy storage battery.

[0071] Specifically: such as Figures 4-5 As shown: Determining the phase angle and amplitude of the virtual internal potential based on the operating parameters of a grid-type hybrid energy storage converter specifically includes:

[0072] ; ;

[0073] Where: θ represents the phase angle of the virtual internal potential, P ref P represents the active power reference value of the i-th submodule. e Let J represent the actual output active power of the i-th submodule, J represent the virtual moment of inertia, ω0 represent the rated angular velocity of the power grid system, D represent the damping coefficient, kq represent the droop coefficient, and Q represent the sag coefficient. ref Q represents the reactive power reference value. e This represents the actual reactive power output of the i-th submodule.

[0074] The generation of PWM control signals for controlling the H-bridge circuit based on the phase angle and amplitude of the virtual internal potential specifically includes:

[0075] The voltage of each phase line is evenly distributed to each sub-module of the corresponding converter module, and the evenly distributed voltage of each sub-module is converted into a direct-axis component u. d and cross-axis component u q For example, if phase A has a phase voltage of M, then dividing the phase voltage by N (the number of sub-modules contained in each converter module) gives the voltage division of each sub-module under phase A.

[0076] Calculate the direct-axis voltage deviation ∆u d :

[0077] ;

[0078] Direct axis voltage deviation ∆u d The input is processed by the PI controller to obtain the direct-axis current reference value i. dref :

[0079] ;

[0080] Where: K p,d K i,d These represent the proportional and integral coefficients of the PI controller, respectively.

[0081] The cross-axis component u q The quadrature-axis voltage deviation ∆u is obtained by comparing it with 0. q :

[0082] ;

[0083] The quadrature-axis voltage deviation ∆u q The input is processed by the PI controller to obtain the quadrature axis current reference value i. qref :

[0084] ;

[0085] Calculate the reference values ​​for direct-axis current and quadrature-axis current and compare them with the actual direct-axis current value i. d and cross-axis current value i q deviation ∆i d and ∆i q :

[0086] ;

[0087] Based on deviation ∆i d and ∆i q The voltage control command u is obtained by inputting it into the PI controller. ctrld and u ctrlq :

[0088] ;

[0089] Where: K p,id and K p,iq K i,id and K i,iq These represent the proportional and integral coefficients of the corresponding PI controller, respectively.

[0090] Using the phase angle θ of the virtual internal potential as a reference angle, the voltage control command u is applied. ctrld and u ctrlq Transforming to a three-phase coordinate system, we obtain the voltage modulation waveform U of the H-bridge circuit. mod And the voltage modulation waveform U mod A unipolar frequency-doubled carrier phase-shift modulation is used to generate the PWM control signal for the H-bridge circuit. This PWM control signal is used to control the on / off state of the four IGBTs in the H-bridge circuit. Specifically, the voltage control command u... ctrld and u ctrlq The transformation from the DQ coordinate system (also known as the rotating coordinate system) to the three-phase coordinate system (stationary coordinate system) is an existing process. θ is used as the reference angle during the transformation, which will not be elaborated here. Single-pole frequency-doubled carrier phase-shift modulation (CPS-SPWM) is also an existing technology, which will not be elaborated here.

[0091] The PI controllers mentioned above are different; although they are all PI controllers, their proportional coefficients and integral coefficients are different.

[0092] The generation of PWM control signals for controlling the supercapacitor module based on the supercapacitor's current reference value specifically includes:

[0093] The voltage reference value u of the i-th submodule supercapacitor module cref The actual voltage u of the supercapacitor module ci The difference is used to obtain the supercapacitor voltage deviation ∆u ci :

[0094] ;

[0095] Voltage deviation ∆u ci The current reference value i of the supercapacitor module is obtained by inputting it into the PI controller. sciref ;

[0096] Use the current reference value i sciref Compared with the actual output current i of the supercapacitor sci The difference is then input to the PI controller to obtain the control command signal u. ctrlc :

[0097] ;

[0098] For control command signal u ctrlc Complementary modulation is used to generate the PWM control signal for the supercapacitor module.

[0099] A PWM control signal for controlling the energy storage battery module is generated based on the current reference value of the energy storage battery.

[0100] Based on the active power reference value P of the energy storage battery brefi With the port voltage V of the energy storage battery bi Determine the current reference value i of the energy storage battery bref :

[0101] ;

[0102] Use the current reference value i bref Compared with the actual output current i of the energy storage battery bi The difference is then input into the PI controller to obtain the control command u. ctrlb :

[0103] ;

[0104] Control command u ctrlb Complementary modulation is used to generate the PWM control signal for the energy storage battery module. This complementary modulation refers to generating corresponding PWM control signals that enable complementary conduction of the two IGBTs in both the energy storage battery module and the supercapacitor module. Taking the supercapacitor module as an example, when the PWM control signal controls Q7 and Q8, Q8 is off when Q7 is on, and vice versa, thus forming a complementary conduction mechanism. Through this method, factors such as system inertia and damping coefficient are considered during control, enabling spontaneous responses to system voltage, frequency, and inertia, ensuring the continuous and stable operation of the entire power grid system.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A grid-type hybrid energy storage converter based on energy storage batteries and supercapacitors, characterized in that: It includes three identical converter modules, which correspond to phases A, B and C respectively. Each converter module is connected to the corresponding phase line through a bridge arm inductor, and the three converter modules are connected to form a star structure. The converter module includes several sub-modules with the same structure, which are cascaded in sequence. The positive terminal of the first sub-module is connected to the corresponding phase line through a bridge arm inductor, and the negative terminal of the last sub-module is connected to the neutral point. The submodule includes an H-bridge circuit, a capacitor C, an energy storage battery module, and a supercapacitor module. The midpoint of the upper arm of the H-bridge circuit serves as the positive terminal of the submodule and is connected to the corresponding phase line through the arm inductance. The midpoint of the lower arm of the H-bridge circuit serves as the negative terminal of the submodule. The capacitor C is connected in parallel with the H-bridge circuit. The positive terminals of the energy storage battery module and the supercapacitor module are connected to the positive terminal of the capacitor C, and the negative terminals of the energy storage battery module and the supercapacitor module are connected to the negative terminal of the capacitor C.

2. The grid-type hybrid energy storage converter based on energy storage batteries and supercapacitors according to claim 1, characterized in that: The supercapacitor module includes a supercapacitor, an IGBT Q7, an IGBT Q8, and an inductor L. SC ; The collector of IGBT Q7 is connected to the positive terminal of capacitor C, serving as the positive terminal of the supercapacitor module. The emitter of IGBT Q7 is connected to the collector of IGBT Q8. The emitter of IGBT Q8 is connected to the negative terminal of the supercapacitor and the negative terminal of capacitor C. The positive terminal of the supercapacitor is connected through inductor L. SC The collector of IGBT Q8 is connected; the gates of IGBT Q7 and IGBT Q8 respectively receive PWM control signals.

3. The grid-type hybrid energy storage converter based on energy storage batteries and supercapacitors according to claim 1, characterized in that: The energy storage battery module includes an energy storage battery, IGBT Q5, IGBT Q6, and inductor L. B ; The collector of IGBT Q5 is connected to the positive terminal of capacitor C, serving as the positive terminal of the energy storage battery module. The emitter of IGBT Q5 is connected to the collector of IGBT Q6. The emitter of IGBT Q6 is connected to the negative terminal of the energy storage battery and the negative terminal of capacitor C. The positive terminal of the energy storage battery is connected through inductor L. B The collector of IGBT Q6 is connected to IGBT Q5 and IGBT Q6 respectively, and PWM control signals are input to them.

4. A control method for a grid-type hybrid energy storage converter based on any one of claims 1-3, characterized in that: Includes the following steps: S1. Determine the operating parameters of the i-th submodule in the grid-type hybrid energy storage converter, wherein the operating parameters include the active power reference value P. ref Reactive power reference value Q ref Voltage reference value U ref The voltage reference value u of the supercapacitor module cref and the active power reference value P of the energy storage battery module brefi ; S2. Determine the phase angle and amplitude of the virtual internal potential, the current reference value of the supercapacitor module, and the current reference value of the energy storage battery module based on the operating parameters of the grid-type hybrid energy storage converter; S3. Generate a PWM control signal for controlling the H-bridge circuit based on the phase angle and amplitude of the virtual internal potential, generate a PWM control signal for controlling the supercapacitor module based on the current reference value of the supercapacitor, and generate a PWM control signal for controlling the energy storage battery module based on the current reference value of the energy storage battery.

5. The control method for the grid-type hybrid energy storage converter according to claim 4, characterized in that: The determination of the phase angle and amplitude of the virtual internal potential based on the operating parameters of the grid-type hybrid energy storage converter specifically includes: ； ； Where: θ represents the phase angle of the virtual internal potential, P ref P represents the active power reference value of the i-th submodule. e Let J represent the actual output active power of the i-th submodule, J represent the virtual moment of inertia, ω0 represent the rated angular velocity of the power grid system, D represent the damping coefficient, kq represent the droop coefficient, and Q represent the sag coefficient. ref Q represents the reactive power reference value. e This represents the actual reactive power output of the i-th submodule.

6. The control method for the grid-type hybrid energy storage converter according to claim 5, characterized in that: The generation of PWM control signals for controlling the H-bridge circuit based on the phase angle and amplitude of the virtual internal potential specifically includes: The voltage of each phase line is evenly distributed to each sub-module of the corresponding converter module, and the evenly distributed voltage of each sub-module is converted into a direct-axis component u. d and cross-axis component u q ; Calculate the direct-axis voltage deviation ∆u d : ； Direct axis voltage deviation ∆u d The input is processed by the PI controller to obtain the direct-axis current reference value i. dref : ； Where: K p,d K i,d These represent the proportional and integral coefficients of the PI controller, respectively. The cross-axis component u q The quadrature-axis voltage deviation ∆u is obtained by comparing it with 0. q : ； The quadrature-axis voltage deviation ∆u q The input is processed by the PI controller to obtain the quadrature axis current reference value i. qref : ； Calculate the reference values ​​for direct-axis current and quadrature-axis current and compare them with the actual direct-axis current value i. d and cross-axis current value i q deviation ∆i d and ∆i q : ； Based on deviation ∆i d and ∆i q The voltage control command u is obtained by inputting it into the PI controller. ctrld and u ctrlq : ； Where: K p,id and K p,iq K i,id and K i,iq These represent the proportional and integral coefficients of the corresponding PI controller, respectively. Using the phase angle θ of the virtual internal potential as a reference angle, the voltage control command u is applied. ctrld and u ctrlq Transforming to a three-phase coordinate system, we obtain the voltage modulation waveform U of the H-bridge circuit. mod And the voltage modulation waveform U mod The PWM control signal for the H-bridge circuit is generated by single-pole frequency doubling carrier phase shift modulation.

7. The control method for the grid-type hybrid energy storage converter according to claim 5, characterized in that: The generation of PWM control signals for controlling the supercapacitor module based on the supercapacitor's current reference value specifically includes: The voltage reference value u of the i-th submodule supercapacitor module cref The actual voltage u of the supercapacitor module ci The difference is used to obtain the supercapacitor voltage deviation ∆u ci : ； Voltage deviation ∆u ci The current reference value i of the supercapacitor module is obtained by inputting it into the PI controller. sciref ; Use the current reference value i sciref Compared with the actual output current i of the supercapacitor sci The difference is then input to the PI controller to obtain the control command signal u. ctrlc : ； For control command signal u ctrlc Complementary modulation is used to generate the PWM control signal for the supercapacitor module.

8. The control method for the grid-type hybrid energy storage converter according to claim 5, characterized in that: A PWM control signal for controlling the energy storage battery module is generated based on the current reference value of the energy storage battery. Based on the active power reference value P of the energy storage battery brefi With the port voltage V of the energy storage battery bi Determine the current reference value i of the energy storage battery bref : ； Use the current reference value i bref Compared with the actual output current i of the energy storage battery bi The difference is then input into the PI controller to obtain the control command u. ctrlb : ； Control command u ctrlb Complementary modulation is used to generate the PWM control signal for the energy storage battery module.

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