High-voltage direct-hanging type network configuration hybrid energy storage converter based on triangular structure and control method thereof

Abstract

The application provides a high-voltage direct-hanging type network-constructing hybrid energy storage converter based on a triangular structure and a control method thereof. In the converter, H-bridge circuits, super capacitor modules and energy storage battery modules are used to form a plurality of sub-modules and form a triangular structure, so that short-time rapid inertia support and long-time scale frequency support can be provided for a power grid, the system voltage, frequency and inertia can be correspondingly self-generated, and the entire power grid system can continuously and stably operate. By using bidirectional Buck / Boost converters in the energy storage battery modules and the super capacitor modules, the super capacitor and the energy storage battery are isolated, deep discharge of the super capacitor can be ensured, and the capacitor double-frequency fluctuation is avoided to affect the cycle life of the energy storage battery.

Description

Technical Field

[0001] This invention relates to a power equipment and control method, and more particularly to a high-voltage direct-connected grid-type hybrid energy storage converter based on a triangular structure and its control method. Background Technology

[0002] With the rapid development of renewable energy sources such as wind power and photovoltaics, and as traditional synchronous generator units are gradually replaced in the process of power system transformation, the system exhibits new characteristics of low inertia and weak damping, and the risks of inertia / frequency and voltage stability increase significantly.

[0003] Grid-based technology can simulate the characteristics of synchronous generators, provide voltage and frequency support, and actively participate in grid regulation. It is one of the main ways to solve the system stability problem caused by the high proportion of new energy access.

[0004] Currently, technologies such as grid-type SVG, static synchronous condensers, and grid-type energy storage have been promoted in practical engineering. Grid-type SVG can provide dynamic reactive power and transient voltage support, and can specifically solve grid voltage stability issues. However, due to the lack of energy storage units, it lacks inertia and frequency support capabilities. Static synchronous condensers are equipped with supercapacitors and have strong inertia and transient voltage support capabilities. However, due to the low energy density of supercapacitors, it is difficult to achieve long-term frequency support. Grid-type energy storage is equipped with electrochemical energy storage batteries, which can provide voltage support and long-term frequency support, effectively ensuring grid frequency stability. However, due to the low power density and cycle life of the energy storage batteries themselves, they cannot provide frequent instantaneous power support, and their inertia support capability is also relatively weak.

[0005] Therefore, in order to solve the above-mentioned technical problems, it is urgent to propose a new technical approach. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a high-voltage direct-connected grid-type hybrid energy storage converter and its control method based on a triangular structure. In the converter, an H-bridge circuit, a supercapacitor module, and an energy storage battery module are used to form several sub-modules and form a triangular structure, thereby providing the power grid with short-term rapid inertia support and long-term frequency support, thus effectively ensuring the operational stability of the power grid system.

[0007] The present invention provides a high-voltage direct-connected grid-type hybrid energy storage converter based on a triangular structure, comprising 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 triangular connection structure.

[0008] The converter module includes several sub-modules with the same structure. The sub-modules are cascaded in sequence. The positive end of the first sub-module is connected to the corresponding phase line through the bridge arm inductor. The negative end of the last sub-module is the common connection point between the corresponding phase line of the adjacent phase converter module and the bridge arm inductor.

[0009] 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.

[0010] Furthermore, the supercapacitor module includes a supercapacitor, IGBT Q7, IGBT Q8, and inductor L. SC ;

[0011] 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.

[0012] Furthermore, the energy storage battery module includes an energy storage battery, IGBT Q5, IGBT Q6, and inductor L. B ;

[0013] 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.

[0014] Accordingly, the present invention also provides a control method based on the above-described grid-type hybrid energy storage converter, comprising the following steps:

[0015] S1. Determine the operating parameters of the i-th submodule of the grid-type converter, the operating parameters including the active power reference value P. ref Reactive power reference value Q refThe voltage reference value of the supercapacitor, the actual voltage value of the supercapacitor, the active power reference value of the energy storage battery, the actual voltage value of the port, and the voltage reference value U. ref The phase angle θ of the virtual internal potential and the virtual internal potential are determined by the operating parameters of the i-th submodule.

[0016] S2. Obtain the three-phase voltage of the power grid and the three-phase output current of the converter, and obtain the voltage component u in the dq coordinate system based on the phase angle of the virtual internal potential. od u oq and current component i d i q ;

[0017] S3. Based on voltage component u od u oq Current component i d i q The phase angle θ of the virtual internal potential is used to determine the voltage modulation signal of the H-bridge circuit, and unipolar frequency doubling carrier phase shift modulation is used to modulate the voltage modulation signal to generate the PWM control signal of the H-bridge circuit.

[0018] S4. Determine the voltage control signal u of the supercapacitor module based on the supercapacitor's voltage reference value and actual voltage value. cmod Based on the voltage control signal u cmod Generate complementary PWM control signals to control the operation of the supercapacitor module;

[0019] S5. Determine the voltage control signal u of the energy storage battery module based on the reference value of the active power of the energy storage battery and the actual voltage value of the port. bmod Based on the voltage control signal u bmod Complementary PWM control signals are generated to control the operation of the energy storage battery module.

[0020] Furthermore, determining the phase angle θ of the virtual internal potential specifically includes:

[0021] Where: ω is the virtual angular velocity, and s represents the complex frequency domain;

[0022] ;

[0023] ;

[0024] Where: P e Let represent the actual active power of the i-th submodule, D represent the damping coefficient, J represent the virtual moment of inertia, and ω0 represent the rated angular velocity.

[0025] Furthermore, the three-phase voltage of the power grid and the three-phase output current of the converter are obtained, and the voltage component u in the dq coordinate system is obtained based on the phase angle of the virtual internal potential. od u oq and current component i d i q Specifically, it includes:

[0026] ;

[0027] ;

[0028] Where: i0 and u o0 These represent the zero-sequence components of the three-phase current and the three-phase voltage of the power grid, respectively.

[0029] Furthermore, step S3 specifically includes:

[0030] Calculate the reference value of reactive power Q ref The actual output reactive power Q of the i-th submodule e The deviation ΔQ between them:

[0031] ;

[0032] Determine the amplitude E of the virtual internal potential. ref :

[0033] ;

[0034] Where: k q This is the voltage droop factor;

[0035] The amplitude E of the virtual internal potential ref and voltage component u od and u oq The input to the PI controller yields the current command values ​​i for the d-axis and q-axis. rd and i rq :

[0036] ;

[0037] ;

[0038] Where: K pd K id K represents the proportional and integral coefficients of the PI controller, respectively; pq K iq These represent the proportional and integral coefficients of the PI controller, respectively.

[0039] The current command value i rd and i rq The voltage command value s is obtained by inputting it into the PI controller.d and s q :

[0040] ;

[0041] Where: K p,id and K p,iq K i,id and K i,iq These are the proportional and integral coefficients of the corresponding PI controller;

[0042] The voltage command value s d and s q Perform inverse Park transform to generate a three-phase voltage modulation signal:

[0043] .

[0044] Furthermore, step S4 specifically includes:

[0045] Calculate the reference value u of the supercapacitor in the i-th submodule. cref With respect to the actual voltage u of the supercapacitor ci The difference Δu c :

[0046] ;

[0047] Voltage deviation ∆u ci The current reference value i of the supercapacitor is obtained by inputting it into the PI controller. scref :

[0048] ;

[0049] Where: K scvp and K scvi These are the proportional and integral coefficients of the voltage outer loop PI controller, respectively.

[0050] Determine the current deviation signal :

[0051] ;

[0052] Where: i sci This indicates the actual output current of the supercapacitor;

[0053] Current deviation signal The voltage control signal u is obtained by inputting it into the PI controller. cmod The expression in the complex frequency domain:

[0054] ;

[0055] Where: K pc Kic These are the proportional and integral coefficients of the PI controller, respectively.

[0056] Furthermore, step S5 specifically includes:

[0057] The active power reference value P of the energy storage battery module brefi With the port voltage V of the energy storage battery bi Determine the current reference value i bref :

[0058] ;

[0059] Determine the current deviation Δi bi :

[0060] ; where: i bi This indicates the actual output current of the energy storage battery;

[0061] The current deviation Δi bi The voltage control signal u is obtained by inputting it into the PI controller. bmod The expression in the complex frequency domain:

[0062] ;

[0063] Where: K pb K ib These are the proportional and integral coefficients of the PI controller, respectively.

[0064] The beneficial effects of the present invention are as follows: Through the present invention, several sub-modules are constructed in the converter using H-bridge circuit, supercapacitor module and energy storage battery module and forming a triangular structure, thereby providing the power grid with short-term fast inertia support and long-term frequency support. It can spontaneously respond to system voltage, frequency and inertia, so that the entire power grid system can operate continuously and stably.

[0065] 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. Attached Figure Description

[0066] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0067] Figure 1 This is a schematic diagram of the structure of the present invention.

[0068] Figure 2 This is a schematic diagram of the submodule structure of the present invention.

[0069] Figure 3 This is a schematic diagram of the process of the present invention.

[0070] Figure 4 This is a schematic diagram of the H-bridge circuit control of the present invention.

[0071] 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

[0072] The present invention will be further described in detail below:

[0073] The present invention provides a high-voltage direct-connected grid-type hybrid energy storage converter based on a triangular structure, comprising three converter modules with the same structure (i.e., the same topology and the same number of sub-modules), 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 triangular connection structure.

[0074] 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 where the current converter module is connected to the corresponding phase line of the power grid) is connected to the corresponding phase line through a bridge arm inductor. The negative terminal of the last sub-module (referring to the sub-module where the current converter module is connected to the phase line of the adjacent converter module, for example: the negative terminal of the last terminal module of phase A is connected to the phase line of phase B, the negative terminal of the last terminal module of phase B is connected to the phase line of phase C, and the negative terminal of the last terminal module of phase C is connected to the phase line of phase A) is connected to the corresponding phase line of the adjacent phase converter module and the bridge arm. The common connection point between inductors; where each submodule is completely identical in electrical parameters, this facilitates modular and redundant design, and allows for adjustment of rated voltage and capacity by increasing or decreasing the number of submodules, thus meeting the needs of different operating environments; in the above, the midpoint of the upper arm of the H-bridge circuit is the common connection point between the emitter of IGBT Q1 and the collector of IGBT Q3, and the midpoint of the lower arm of the H-bridge circuit is the common connection point between the emitter of IGBT Q2 and the collector of IGBT Q4; the sequential cascading described above is illustrated with an example:

[0075] For example, if phase A has 3 sub-modules, then the positive terminal of sub-module 1 is connected to the corresponding phase line through an inductor (or reactor), the negative terminal of sub-module 1 is connected to the positive terminal of sub-module 2, the negative terminal of sub-module 2 is connected to the positive terminal of sub-module 3, and the negative terminal of sub-module 3 is connected to the phase line of phase B.

[0076] 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 voltage stabilizer. 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 triangular connection 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.

[0077] In this embodiment, as Figure 2 As shown: The supercapacitor module includes a supercapacitor, IGBT Q7, IGBT Q8, and inductor L. SC ;

[0078] 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.

[0079] The energy storage battery module includes an energy storage battery, IGBT Q5, IGBT Q6, and inductor L. B ;

[0080] 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.

[0081] Accordingly, the present invention also provides a control method based on the above-described grid-type hybrid energy storage converter, comprising the following steps:

[0082] S1. Determine the operating parameters of the i-th submodule of the grid-type converter, the operating parameters including the active power reference value P. ref Reactive power reference value Q ref The voltage reference value of the supercapacitor, the actual voltage value of the supercapacitor, the active power reference value of the energy storage battery, the actual voltage value of the port, and the voltage reference value U. ref The phase angle θ of the virtual internal potential and the virtual internal potential are determined by the operating parameters of the i-th submodule.

[0083] S2. Obtain the three-phase voltage of the power grid and the three-phase output current of the converter, and obtain the voltage component u in the dq coordinate system based on the phase angle of the virtual internal potential. od u oq and current component i d i q ;

[0084] S3. Based on voltage component u od u oq Current component i d i q The voltage modulation signal of the H-bridge circuit is determined by the phase angle θ of the virtual internal potential, and the voltage modulation signal is modulated by unipolar frequency doubling carrier phase shift modulation to generate the PWM control signal of the H-bridge circuit. This PWM control signal is used to control the operation of each IGBT in the H-bridge circuit. Among them, unipolar frequency doubling carrier phase shift modulation (CPS-SPWM) is also an existing technology and will not be described in detail here.

[0085] S4. Determine the voltage control signal u of the supercapacitor module based on the supercapacitor's voltage reference value and actual voltage value. cmod Based on the voltage control signal u cmod Generate complementary PWM control signals to control the operation of the supercapacitor module;

[0086] S5. Determine the voltage control signal u of the energy storage battery module based on the reference value of the active power of the energy storage battery and the actual voltage value of the port. bmod Based on the voltage control signal ubmod Complementary PWM control signals are generated to control the operation of the energy storage battery module. Of course, this also applies to the voltage control signal u. cmod and voltage control signal u bmod Before modulation, the two voltage control signals need to be inversely converted using PARK before modulation.

[0087] Specifically, such as Figures 4-5 As shown: Determining the phase angle θ of the virtual internal potential specifically includes:

[0088] Where: ω is the virtual angular velocity, and s represents the complex frequency domain;

[0089] ;

[0090] ;

[0091] Where: P e Let represent the actual active power of the i-th submodule, D represent the damping coefficient, J represent the virtual moment of inertia, and ω0 represent the rated angular velocity.

[0092] In this embodiment, the three-phase voltage of the power grid and the three-phase output current of the converter are obtained, and the voltage component u in the dq coordinate system is obtained based on the phase angle of the virtual internal potential. od u oq and current component i d i q Specifically, it includes:

[0093] ;

[0094] ;

[0095] Where: i0 and u o0 These represent the zero-sequence components of the three-phase current and the three-phase voltage of the power grid, respectively.

[0096] Step S3 specifically includes:

[0097] Calculate the reference value of reactive power Q ref The actual output reactive power Q of the i-th submodule e The deviation ΔQ between them:

[0098] ;

[0099] Determine the amplitude E of the virtual internal potential. ref :

[0100] ;

[0101] Where: k qThis is the voltage droop factor;

[0102] The amplitude E of the virtual internal potential ref and voltage component u od and u oq The input to the PI controller yields the current command values ​​i for the d-axis and q-axis. rd and i rq :

[0103] ;

[0104] ;

[0105] Where: K pd K id K represents the proportional and integral coefficients of the PI controller, respectively; pq K iq These represent the proportional and integral coefficients of the PI controller, respectively.

[0106] The current command value i rd and i rq The voltage command value s is obtained by inputting it into the PI controller. d and s q :

[0107] ;

[0108] Where: K p,id and K p,iq K i,id and K i,iq These are the proportional and integral coefficients of the corresponding PI controller;

[0109] The voltage command value s d and s q Perform inverse Park transform to generate three-phase voltage modulation signal s a s b and s c :

[0110] .

[0111] In this embodiment, step S4 specifically includes:

[0112] Calculate the reference value u of the supercapacitor in the i-th submodule. cref With respect to the actual voltage u of the supercapacitor ci The difference Δu c :

[0113] ;

[0114] Voltage deviation ∆u ciThe current reference value i of the supercapacitor is obtained by inputting it into the PI controller. scref :

[0115] ;

[0116] Where: K scvp and K scvi These are the proportional and integral coefficients of the voltage outer loop PI controller, respectively.

[0117] Determine the current deviation signal :

[0118] ;

[0119] Where: i sci This indicates the actual output current of the supercapacitor;

[0120] Current deviation signal The voltage control signal u is obtained by inputting it into the PI controller. cmod The expression in the complex frequency domain:

[0121] ;

[0122] Where: K pc K ic These are the proportional and integral coefficients of the PI controller, respectively.

[0123] Step S5 specifically includes:

[0124] The active power reference value P of the energy storage battery module brefi With the port voltage V of the energy storage battery bi Determine the current reference value i bref :

[0125] ;

[0126] Determine the current deviation Δi bi :

[0127] ; where: i bi This indicates the actual output current of the energy storage battery;

[0128] The current deviation Δi bi The voltage control signal u is obtained by inputting it into the PI controller. bmod The expression in the complex frequency domain:

[0129] ;

[0130] Where: K pb K ibThese are the proportional and integral coefficients of the PI controller, respectively.

[0131] For the IGBTs in energy storage batteries and supercapacitor modules, the generated PWM signals are complementary signals, enabling the two IGBTs in the energy storage battery module and the two IGBTs in the supercapacitor module to conduct in a complementary manner. Taking the supercapacitor module as an example, when the PWM control signal is generated to control Q7 and Q8, when Q7 is on, Q8 is off, and when Q8 is on, Q7 is off, thus forming a complementary conduction mechanism. Through the above method, the control takes into account factors such as system inertia and damping coefficient, and can spontaneously respond to system voltage, frequency, and inertia, enabling the entire power grid system to operate continuously and stably.

[0132] 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 high-voltage direct-connected grid-type hybrid energy storage converter based on a triangular structure, 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 delta connection structure. The converter module includes several sub-modules with the same structure. The sub-modules are cascaded in sequence. The positive end of the first sub-module is connected to the corresponding phase line through the bridge arm inductor. The negative end of the last sub-module is the common connection point between the corresponding phase line of the adjacent phase converter module and the bridge arm inductor. 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 high-voltage direct-connected grid-type hybrid energy storage converter based on a triangular structure 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 high-voltage direct-connected grid-type hybrid energy storage converter based on a triangular structure 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 of the grid-type converter, the operating parameters including the active power reference value P. ref Reactive power reference value Q ref The voltage reference value of the supercapacitor, the actual voltage value of the supercapacitor, the active power reference value of the energy storage battery, the actual voltage value at the port, and the voltage reference value U. ref The phase angle θ of the virtual internal potential and the virtual internal potential are determined by the operating parameters of the i-th submodule. S2. Obtain the three-phase voltage of the power grid and the three-phase output current of the converter, and obtain the voltage component u in the dq coordinate system based on the phase angle of the virtual internal potential. od u oq and current component i d i q ; S3. Based on voltage component u od u oq Current component i d i q The phase angle θ of the virtual internal potential is used to determine the voltage modulation signal of the H-bridge circuit, and unipolar frequency doubling carrier phase shift modulation is used to modulate the voltage modulation signal to generate the PWM control signal of the H-bridge circuit. S4. Determine the voltage control signal u of the supercapacitor module based on the supercapacitor's voltage reference value and actual voltage value. cmod Based on the voltage control signal u cmod Generate complementary PWM control signals to control the operation of the supercapacitor module; S5. Determine the voltage control signal u of the energy storage battery module based on the reference value of the active power of the energy storage battery and the actual voltage value of the port. bmod Based on the voltage control signal u bmod Complementary PWM control signals are generated to control the operation of the energy storage battery module.

5. The control method for the grid-type hybrid energy storage converter according to claim 4, characterized in that: Determining the phase angle θ of the virtual internal potential specifically includes: Where: ω is the virtual angular velocity, and s represents the complex frequency domain; ； ； Where: P e Let represent the actual active power of the i-th submodule, D represent the damping coefficient, J represent the virtual moment of inertia, and ω0 represent the rated angular velocity.

6. The control method for the grid-type hybrid energy storage converter according to claim 5, characterized in that: The three-phase voltage of the power grid and the three-phase output current of the converter are obtained, and the voltage component u in the dq coordinate system is obtained based on the phase angle of the virtual internal potential. od u oq and current component i d i q Specifically, it includes: ； ； Where: i0 and u o0 These represent the zero-sequence components of the three-phase current and the three-phase voltage of the power grid, respectively.

7. The control method for the grid-type hybrid energy storage converter according to claim 6, characterized in that: Step S3 specifically includes: Calculate the reference value of reactive power Q ref The actual output reactive power Q of the i-th submodule e The deviation ΔQ between them: ； Determine the amplitude E of the virtual internal potential ref : ； Where: k q This is the voltage droop factor; The amplitude E of the virtual internal potential ref and voltage component u od and u oq The input to the PI controller yields the current command values ​​i for the d-axis and q-axis. rd and i rq : ； ； Where: K pd K id K represents the proportional and integral coefficients of the PI controller, respectively; pq K iq These represent the proportional and integral coefficients of the PI controller, respectively. The current command value i rd and i rq The voltage command value s is obtained by inputting it into the PI controller. d and s q : ； Where: K p,id and K p,iq K i,id and K i,iq These are the proportional and integral coefficients of the corresponding PI controller; The voltage command value s d and s q Perform inverse Park transform to generate a three-phase voltage modulation signal: 。 8. The control method for the grid-type hybrid energy storage converter according to claim 4, characterized in that: Step S4 specifically includes: Calculate the reference value u of the supercapacitor in the i-th submodule. cref With respect to the actual voltage u of the supercapacitor ci The difference Δu c : ； Voltage deviation ∆u ci The current reference value i of the supercapacitor is obtained by inputting it into the PI controller. scref : ； Where: K scvp and K scvi These are the proportional and integral coefficients of the voltage outer loop PI controller, respectively. Determine the current deviation signal : ； Where: i sci This indicates the actual output current of the supercapacitor; Current deviation signal The voltage control signal u is obtained by inputting it into the PI controller. cmod The expression in the complex frequency domain: ； Where: K pc K ic These are the proportional and integral coefficients of the PI controller, respectively.

9. The control method for the grid-type hybrid energy storage converter according to claim 5, characterized in that: Step S5 specifically includes: The active power reference value P of the energy storage battery module brefi With the port voltage V of the energy storage battery bi Determine the current reference value i bref : ； Determine the current deviation Δi bi : ; where: i bi This indicates the actual output current of the energy storage battery; The current deviation Δi bi The voltage control signal u is obtained by inputting it into the PI controller. bmod The expression in the complex frequency domain: ； Where: K pb K ib These are the proportional and integral coefficients of the PI controller, respectively.

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