Network construction type SVG device of integrated super capacitor, control method thereof and medium

Abstract

The invention relates to the technical field of power electronic equipment, in particular to a network construction type SVG (static var generator) device of an integrated super capacitor, a control method of the network construction type SVG device and a medium, and the network construction type SVG device comprises three network construction type static var generator branches which are connected to a three-phase alternating-current bus in a triangular form, each network-forming static var generator branch comprises an inductor and a plurality of super-capacitance bridging modules which are connected in series, and the inductor is used for smoothing current waveforms of the super-capacitance bridging modules; the super-capacitor bridging module comprises a plurality of full-bridge sub-modules and a plurality of super-capacitor sub-modules which are connected in series; the super-capacitor sub-module comprises a full-bridge super-capacitor sub-module, an interface circuit and a super-capacitor unit; and the super-capacitor sub-module is used for regulating and controlling the energy storage state according to the charging and discharging instruction. According to the invention, through integration of the super capacitor and a network construction control strategy, dynamic reactive compensation and voltage support of a power grid system are realized, system inertia is enhanced, and stability of a power system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic equipment, and in particular to a supercapacitor-integrated meshed SVG device and a control method and medium thereof. Background Art

[0002] In the current power system, with the widespread application of new energy and power electronics technology, the stability of traditional power systems has gradually decreased. At the same time, as synchronous generators with rotational inertia are gradually replaced by new energy power sources with low inertia, the power system has the characteristics of low inertia and weak damping. This change requires the power system to have additional active power support in addition to reactive power compensation to suppress fluctuations in system frequency and ensure the stable operation of the power grid.

[0003] Static Var Generator (SVG) uses power electronic devices to achieve reactive power compensation for the system. It has the advantages of dynamic compensation and fast response. It is increasingly widely used in power systems and can effectively support system voltage and improve the stability of power systems. However, the existing SVG device is limited by the energy stored in its capacitor. When dealing with system frequency fluctuations caused by active power changes, it is difficult to provide sufficient inertia support and reactive power support in the system, which limits its function to a certain extent. At the same time, supercapacitors, as energy storage elements with high power density, can quickly absorb and release high power in a short time and are not limited by the principle of chemical reaction. This makes the application of supercapacitors in power systems have broad prospects. Integrating supercapacitors into existing SVG devices can significantly improve the inertia reserve of SVG devices, thereby enhancing their support capacity in power systems. However, in practical applications, how to effectively integrate supercapacitors into SVG devices and design reasonable control strategies to achieve inertia and reactive power support for power systems is still a major problem currently faced. Summary of the invention

[0004] The object of the present invention is to provide a supercapacitor-integrated meshing type SVG device and a control method and medium thereof, which can realize dynamic reactive power compensation and voltage support for the power grid system by integrating supercapacitors and meshing control strategies, while enhancing system inertia.

[0005] In order to solve the above technical problems, the present invention provides a mesh-type SVG device with integrated supercapacitor and a control method and medium thereof.

[0006] In a first aspect, the present invention provides a meshed SVG device with integrated supercapacitors, comprising a meshed control system and three meshed static VAR generator branches connected in a triangle form to a three-phase AC bus, each meshed static VAR generator branch comprising at least one inductor and a plurality of supercapacitor bridge modules connected in series, wherein the inductor is used to smooth the current waveform of the supercapacitor bridge module;

[0007] The supercapacitor bridging module includes a plurality of full-bridge submodules and a plurality of supercapacitor submodules connected in series;

[0008] The supercapacitor submodule comprises a full-bridge supercapacitor submodule, an interface circuit and a supercapacitor unit; the full-bridge supercapacitor submodule is cascade-connected to the supercapacitor unit via the interface circuit; the supercapacitor submodule is used to regulate its energy storage state according to the received charge and discharge instructions.

[0009] In a further embodiment, the full-bridge supercapacitor module includes a DC capacitor, a first switch module, a second switch module, a third switch module, a fourth switch module, a first bypass switch, and a turning thyristor;

[0010] The first switch module and the second switch module are connected in series to form a first switch branch, the third switch module and the fourth switch module are connected in series to form a second switch branch, and the first switch branch, the second switch branch and the DC capacitor are connected in parallel;

[0011] The first bypass switch and the turning thyristor are connected in parallel with the second switch module and the fourth switch module.

[0012] In a further embodiment, the interface circuit includes a first circuit breaker, a second circuit breaker, a first fuse and a bidirectional DC-DC converter; the bidirectional DC-DC converter is connected in parallel with the supercapacitor unit;

[0013] The positive terminal of the DC capacitor is connected to the positive terminal of the supercapacitor unit through the first fuse and the first circuit breaker connected in series in sequence; the negative terminal of the DC capacitor is connected to the negative terminal of the supercapacitor unit through the second circuit breaker;

[0014] One end of the bidirectional DC-DC converter is connected to a connection point between the first circuit breaker and the supercapacitor unit, and the other end of the bidirectional DC-DC converter is connected to a connection point between the second circuit breaker and the supercapacitor unit.

[0015] In a further embodiment, the supercapacitor unit comprises a plurality of supercapacitors connected in cascade.

[0016] In a further implementation scheme, the networked control system is used to respond to active and reactive output instructions, generate state control instructions for each of the supercapacitor bridge modules using various networked control strategies, and control the switching state of the full-bridge submodule and the charging and discharging state of the supercapacitor submodule according to the state control instructions. The networked control strategies include active-frequency control strategy, reactive-voltage control strategy, internal potential control strategy and current inner loop control strategy.

[0017] In a further embodiment, the networked control system includes an inertia reserve input module;

[0018] The inertia reserve investment module is used to make a difference between the voltage modulation wave reference value and the voltage modulation wave actual value to obtain the voltage modulation wave deviation value, and generate the ultra-capacity bridge module investment quantity through a proportional-integral regulator according to the voltage modulation wave deviation value and a preset investment quantity upper limit value.

[0019] In a further embodiment, the number of super-capacity bridging modules put into use is not greater than the upper limit of the super-capacity bridging modules allowed to be put into use.

[0020] In a second aspect, the present invention provides a control method for a meshed SVG device with integrated supercapacitors, using the meshed SVG device with integrated supercapacitors as described above, the control method comprises the following steps:

[0021] In response to the active and reactive power output instructions, determining an active power reference value and a reactive power reference value of the meshed SVG device according to the operating state of the meshed SVG device;

[0022] According to the active power deviation value between the active power reference value and the active power actual value, active power-frequency control is performed using a proportional-integral control algorithm to obtain a virtual internal potential phase angle;

[0023] According to the reactive power deviation value between the reactive power reference value and the reactive power actual value, and the AC voltage deviation value between the AC voltage reference value and the AC voltage actual value, reactive-voltage control is performed using a proportional-integral control algorithm to obtain a virtual internal potential amplitude;

[0024] generating an internal potential control instruction according to the virtual internal potential phase angle and the virtual internal potential amplitude;

[0025] Converting the internal potential control instruction into a current inner loop control reference value, wherein the current inner loop control reference value includes a current direct axis component reference value and a current quadrature axis component reference value;

[0026] The actual value of the current direct-axis component and the actual value of the current quadrature-axis component of the supercapacitor bridge module are collected, and a state control instruction of each supercapacitor bridge module is generated according to the current inner-loop control reference value; the state control instruction includes a switch state instruction of the full-bridge submodule and a charge and discharge instruction of the supercapacitor submodule.

[0027] In a further embodiment, the step of converting the inner potential control instruction into a current inner loop control reference value comprises:

[0028] According to the voltage direct-axis component deviation value between the voltage direct-axis component at the common coupling point and the virtual internal potential amplitude, a reference value of the current direct-axis component is generated by using a proportional-integral control algorithm;

[0029] A current quadrature-axis component reference value is generated by using a proportional-integral control algorithm according to a voltage quadrature-axis component deviation value between a common coupling point voltage quadrature-axis component and a preset common coupling point voltage quadrature-axis reference value.

[0030] In a further embodiment, the step of collecting the actual value of the current direct-axis component and the actual value of the current quadrature-axis component of the ultra-capacitor bridge module and generating the state control instruction of each ultra-capacitor bridge module according to the current inner loop control reference value includes:

[0031] According to the direct-axis component deviation value between the current direct-axis component reference value and the actual value of the current direct-axis component of the super-capacitor bridge module, and the quadrature-axis component deviation value between the current quadrature-axis component reference value and the actual value of the current quadrature-axis component of the super-capacitor bridge module, a current inner-loop control is performed using a proportional-integral control algorithm to generate a current inner-loop control output result;

[0032] Converting the current inner loop control output result into a bridge arm voltage modulation waveform through Park transformation;

[0033] According to the bridge arm voltage modulation waveform, a pulse width modulation method is used to generate a state control instruction for each super-capacitor bridge module.

[0034] In a third aspect, the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0035] The present invention provides a meshing type SVG device with integrated supercapacitor and its control method and medium. The meshing type SVG device includes a meshing type control system and three meshing type static VAR generator branches connected in a triangle form on a three-phase AC bus. Each meshing type static VAR generator branch includes at least one inductor and a plurality of supercapacitor bridge modules connected in series. The inductor is used to smooth the current waveform of the supercapacitor bridge module. The supercapacitor bridge module includes a plurality of full-bridge submodules and a plurality of supercapacitor submodules connected in series. The supercapacitor submodule includes a full-bridge supercapacitor submodule, an interface circuit and a supercapacitor unit. The full-bridge supercapacitor submodule is cascade-connected with the supercapacitor unit through the interface circuit. Compared with the prior art, the meshing type SVG device can provide reactive power compensation and active inertia support by integrating supercapacitor submodules and meshing control strategies, meet the dual needs of reactive power compensation and active power support of the power system after the access of new energy, effectively resist the system frequency fluctuation caused by the change of active power, and improve the stability of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the structure of a meshed SVG device with integrated supercapacitors provided in an embodiment of the present invention;

[0037] Figure 2 is a schematic diagram of the structure of a supercapacitor submodule provided by an embodiment of the present invention;

[0038] Figure 3 is a control block diagram of a network control strategy provided by an embodiment of the present invention;

[0039] Figure 4 It is a logic block diagram of an inertia reserve input module provided by an embodiment of the present invention;

[0040] Figure 5 It is a flow chart of a control method of a meshed SVG device with integrated supercapacitors provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The following specifically illustrates the implementation mode of the present invention in conjunction with the accompanying drawings. The embodiments are provided for illustrative purposes only and cannot be understood as limiting the present invention. The accompanying drawings are provided for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0042] refer to Figure 1 The embodiment of the present invention provides a mesh-type SVG device with integrated supercapacitor, such as Figure 1As shown, the meshed SVG device includes a meshed control system and three meshed static VAR generator branches connected to a three-phase AC bus in a triangle form, each meshed static VAR generator branch includes at least one inductor L1 and a plurality of supercapacitor bridge modules 11 connected in series, the supercapacitor bridge module includes a plurality of full-bridge submodules 12 and a plurality of supercapacitor submodules 13 connected in series, the full-bridge submodule and the supercapacitor submodule together construct a bridge arm voltage to achieve a bidirectional flow of voltage and current; the supercapacitor submodule is used to control its energy storage state according to the received charge and discharge instructions, to achieve a fast power response and energy storage of the meshed SVG device, to support internal potential control and current inner loop control; the ratio between the full-bridge submodule and the supercapacitor submodule can be determined according to the required inertia support capacity, wherein the inductor L1 is used in the meshed SVG device to smooth the current waveform of the supercapacitor bridge module 11, to play a role of filtering and energy storage, thereby effectively reducing harmonics, and storing and releasing energy to support the stable operation of the power grid.

[0043] like Figure 2 As shown, the supercapacitor submodule includes a full-bridge supercapacitor submodule 21, an interface circuit 22 and a supercapacitor unit 23. The full-bridge supercapacitor submodule 21 is cascade-connected with the supercapacitor unit 23 through the interface circuit 22. The supercapacitor unit includes a plurality of cascade-connected supercapacitors SC. In this embodiment, the full-bridge supercapacitor submodule includes a DC capacitor C1, a first switch module S1, a second switch module S2, a third switch module S3, a fourth switch module S4, a first bypass switch K1 and a turning thyristor T1; the first switch module S1 and the second switch module S2 are connected in series to form a first switch branch, the third switch module S3 and the fourth switch module S4 are connected in series to form a second switch branch, the first switch branch, the second switch branch and the DC capacitor C1 are connected in parallel; the first bypass switch K1 and the turning thyristor T1 are connected in parallel with the second switch module S2 and the fourth switch module S4.

[0044] In this embodiment, the interface circuit includes a first circuit breaker QF1, a second circuit breaker QF2, a first fuse F1 and a bidirectional DC-DC converter (DC / DC converter); the bidirectional DC-DC converter is connected in parallel with the supercapacitor unit to achieve voltage adjustment of the supercapacitor unit; the positive terminal of the DC capacitor C1 is connected to the positive terminal of the supercapacitor unit through the first fuse F1 and the first circuit breaker QF1 connected in series in sequence; the negative terminal of the DC capacitor C1 is connected to the negative terminal of the supercapacitor unit through the second circuit breaker QF2; one end of the bidirectional DC-DC converter is connected to the connection point between the first circuit breaker QF1 and the supercapacitor unit, and the other end of the bidirectional DC-DC converter is connected to the connection point between the second circuit breaker QF2 and the supercapacitor unit.

[0045] In this embodiment, the meshing control system is used to respond to active and reactive output instructions, generate state control instructions for each of the supercapacitor bridge modules using various meshing control strategies, and control the switching state of the full-bridge submodule and the charging and discharging state of the supercapacitor submodule according to the state control instructions. The various meshing control strategies include active-frequency control strategy, reactive-voltage control strategy, internal potential control strategy, and current inner loop control strategy.

[0046] Specifically, the meshing type SVG device proposed in this embodiment includes multiple meshing control strategies, such as Figure 3 As shown in the figure, multiple network control strategies include active-frequency control strategy, reactive-voltage control strategy, internal potential control strategy and current inner loop control strategy; among them, the active-frequency control strategy calculates the active power deviation by comparing the active power reference value Pref with the active power actual value P, and then uses the proportional integral (PI) control algorithm to control the active power and frequency of the power deviation value, and generates a virtual internal potential phase angle θ, thereby changing the active power exchange between the SVG device and the power grid, and realizing the support and regulation of the power grid frequency. Figure 3 Where, ω is the virtual angular velocity of the internal potential output by the meshed SVG device; J is the virtual moment of inertia coefficient; K is the active voltage adjustment coefficient; Δw is the virtual angular velocity difference of the internal potential; ω0 is the rated angular velocity of the system; ΔE is the difference between the actual value of the virtual internal potential amplitude and the reference value of the virtual internal potential amplitude; E0 is the reference value of the virtual internal potential amplitude; u cd is the grid-side voltage d-axis reference value; u cq is the q-axis reference value of the grid-side voltage.

[0047] The reactive power-voltage control strategy uses the proportional integral (PI) control algorithm to regulate the reactive power deviation between the reactive power reference value Qref and the reactive power actual value Q, as well as the AC voltage deviation between the AC voltage reference value Uref and the AC voltage actual value U, so as to determine the virtual internal potential amplitude E, thereby changing the reactive power exchange between the SVG device and the power grid, and achieving support and regulation of the grid voltage.

[0048] The internal potential control strategy compares the direct-axis component u of the voltage at the point of common connection (PCC) sd The voltage d-axis (direct axis) component deviation value is calculated from the virtual internal potential amplitude E, and the voltage d-axis component deviation value is processed through the proportional integral (PI) control link to generate the current d-axis component reference value i d_ref Similarly, this embodiment compares the quadrature-axis component u of the common coupling point voltage sq The voltage q-axis (quadrature axis) component deviation value is obtained from its reference value. The voltage q-axis component deviation value is processed through the PI control link to generate the current q-axis component reference value i q_ref By controlling the potential inside the grid-forming SVG device, the output current and power of the grid-forming SVG device can be controlled, thereby achieving rapid response and precise regulation of the grid current.

[0049] The input of the current inner loop control strategy includes the current d-axis component reference value i d_ref The actual value of the current d-axis component i d , and the current q-axis component reference value i q_ref The actual value of the current q-axis component i q These input values ​​are processed through the PI control link to obtain the current inner loop control output result, and the current inner loop control output result is converted into the bridge arm voltage modulation waveform u through dq / abc coordinate transformation jref , where j = a, b, c; to achieve accurate control of the output current of the meshed SVG device, the current d-axis component reference value i output based on the internal potential control strategy of this embodiment d_ref and the current q-axis component reference value i q_ref , use the PI controller to adjust the actual value i of the current d-axis component of the SVG device d and the actual value of the current q-axis component i q By adjusting the output voltage and current of the ultra-capacitor bridge module, the actual output current of the SVG device is made consistent with the reference value, thereby achieving rapid response and precise regulation of the grid current; it should be noted that the reference phase angle based on which the dq / abc conversion is based does not rely on the phase-locked loop (PLL), but is directly determined by the active-frequency control strategy.

[0050] This embodiment uses multiple grid-forming control strategies to enable the grid-forming SVG device to simulate the grid-forming capability of a synchronous generator, and achieve precise control of active and reactive power in the grid, so that the grid-forming SVG device can effectively support and adjust the frequency and voltage of the grid, provide the necessary active and reactive support for the power system, and improve the stability and operating efficiency of the grid.

[0051] In this embodiment, the meshed control system includes an inertia reserve investment module; the inertia reserve investment module is used to subtract the voltage modulation wave reference value and the voltage modulation wave actual value to obtain a voltage modulation wave deviation value, and generate the number of super-capacity bridge modules invested according to the voltage modulation wave deviation value and a preset upper limit of the number of investments through a proportional-integral regulator (PI regulator); the number of super-capacity bridge modules invested is not greater than the upper limit of the super-capacity bridge modules allowed to be invested.

[0052] In the supercapacitor-based SVG device, in order to accurately control the output voltage and current, this embodiment requires a reference value U based on the input voltage modulation wave. dcref And the actual value of the voltage modulation wave U dc Determine the number of super-capacity bridge modules to be invested, such as Figure 4 As shown, this embodiment first compares U dcref and U dc , calculate the number of modules n that should be invested nconduct , which represents the number of submodules that need to be activated in order to achieve the desired output voltage and current under the current grid demand and SVG device status. This embodiment needs to ensure that the calculated number of super-capacitor bridge modules (n nconduct ) is less than or equal to the upper limit value n of the super-capacity bridge module allowed to be put into use max , to prevent exceeding the maximum capacity of the system design; in order to determine the super-capacitor bridge module to be put into or cut out, this embodiment needs to sort all the super-capacitor bridge modules from high to low according to their capacitance voltage. When the meshed SVG device needs to perform a discharge operation, the input is sorted as 1, 2, ..., n nconduct The super-capacitor bridge modules are more efficient in providing the required discharge current due to their higher capacitor voltage. When the grid-type SVG device needs to perform a charging operation, the input is ranked as Nn nconduct +1, Nn nconduct+2, ..., N super-capacitor bridge modules, where N represents the total number of super-capacitor bridge modules in the meshing type SVG device. These super-capacitor bridge modules are more suitable for receiving charging current due to their lower capacitor voltage, thereby maintaining the voltage balance of the entire device. In this way, the meshing type SVG device proposed in this embodiment can accurately control the number of super-capacitor bridge modules according to the actual needs of the power grid and the voltage state of the super-capacitor bridge modules, thereby optimizing the operating efficiency and response speed of the device, ensuring that the SVG device can flexibly adapt to the needs of the power grid, especially when the power grid voltage and frequency fluctuate, and can provide more stable and effective reactive support.

[0053] The embodiment of the present invention provides a meshed SVG device with integrated supercapacitor, the meshed SVG device includes a meshed control system and three meshed static VAR generator branches connected in a triangle form on a three-phase AC bus, each meshed static VAR generator branch includes at least one inductor and several supercapacitor bridge modules connected in series, the inductor is used to smooth the current waveform of the supercapacitor bridge module; the supercapacitor bridge module includes multiple full-bridge submodules and multiple supercapacitor submodules connected in series; the supercapacitor submodule includes a full-bridge supercapacitor submodule, an interface circuit and a supercapacitor unit; the full-bridge supercapacitor submodule is cascade-connected with the supercapacitor unit through the interface circuit; the supercapacitor submodule is used to regulate its energy storage state according to the received charge and discharge instructions. Compared with the prior art, the meshed SVG device proposed in this embodiment can realize reactive power compensation and inertia support at the same time by integrating supercapacitor energy storage elements and meshed control strategies, meet the dual needs of reactive power and active power support of the power system after the access of new energy, effectively resist the system frequency fluctuation caused by active power changes, and improve the stability of the power system.

[0054] In one embodiment, Figure 5 As shown, an embodiment of the present invention provides a control method for a meshed SVG device with integrated supercapacitors, and the control method uses the meshed SVG device with integrated supercapacitors as described above, and includes the following steps:

[0055] S1 in response to active and reactive output instructions, according to the operating state of the network-type SVG device to determine the network-type SVG device active power reference value and reactive power reference value;

[0056] S2. According to the active power deviation value of the active power reference value and the actual active power value, the active power - frequency control is performed using a proportional integral control algorithm to obtain a virtual internal potential phase angle;

[0057] S3. According to the reactive power deviation value between the reactive power reference value and the actual reactive power value, and the AC voltage deviation value between the AC voltage reference value and the actual AC voltage value, a proportional-integral control algorithm is used for reactive-voltage control to obtain a virtual internal potential amplitude;

[0058] S4. Generate an internal potential control instruction according to the virtual internal potential phase angle and the virtual internal potential amplitude;

[0059] S5. Converting the inner potential control command into a current inner loop control reference value, the current inner loop control reference value including a current direct-axis component reference value and a current quadrature-axis component reference value;

[0060] S6. Collect the actual value of the current direct-axis component and the actual value of the current quadrature-axis component of the supercapacitor bridge module, and generate a state control instruction for each supercapacitor bridge module according to the current inner loop control reference value; the state control instruction includes the switch state instruction of the full-bridge submodule and the charge and discharge instruction of the supercapacitor submodule.

[0061] In this embodiment, the step of converting the inner potential control instruction into a current inner loop control reference value includes:

[0062] According to the direct axis component u of the common coupling point voltage sd The voltage direct axis component deviation value between the virtual internal potential amplitude E and the reference value i of the current direct axis component is generated by using the proportional integral control algorithm. d_ref ;

[0063] According to the quadrature-axis component u of the voltage at the common coupling point sq The voltage quadrature-axis component deviation value between the preset common coupling point voltage quadrature-axis reference value is used to generate the current quadrature-axis component reference value i by using the proportional-integral control algorithm. q_ref .

[0064] Specifically, in response to the received active and reactive output instructions, the present embodiment determines the active power reference value Pref and the reactive power reference value Qref of the meshed SVG device according to the operating state of the meshed SVG device, and acquires data such as the active power actual value P, the reactive power actual value Q and the AC voltage actual value U by real-time monitoring the actual operating state of the meshed SVG device; according to the active power deviation value between the active power reference value Pref and the active power actual value P, the proportional integral control algorithm is used to perform active-frequency control to obtain a virtual internal potential phase angle θ; according to the reactive power deviation value between the reactive power reference value Qref and the reactive power actual value Q, and the AC voltage deviation value between the AC voltage reference value Uref and the AC voltage actual value U, the proportional integral control algorithm is used to perform reactive-voltage control to obtain a virtual internal potential amplitude E; according to the virtual internal potential phase angle θ and the virtual internal potential amplitude E, an internal potential control instruction is generated; the internal potential control instruction is converted into a current inner loop control reference value, and the current inner loop control reference value includes a current d-axis component reference value i d_ref and the current q-axis component reference value i q_ref ; Collect the actual value i of the current d-axis component of the super-capacitor bridge module d And the actual value of the current q-axis component i q , and according to the current inner loop control reference value, the actual value i of the current d-axis component of the super-capacitor bridge module d And the actual value of the current q-axis component i q Generate state control instructions for each supercapacitor bridge module; the state control instructions include switch state instructions for the full-bridge submodule and charge and discharge instructions for the supercapacitor submodule, determine the switch state (on or off) of the full-bridge submodule and the charge and discharge state of the supercapacitor submodule according to the state control instructions, and execute corresponding action instructions, change the output voltage and current of the supercapacitor bridge module by adjusting the switch state of the full-bridge submodule, and maintain or adjust its energy storage state by controlling the charge and discharge of the supercapacitor submodule.

[0065] In this embodiment, the step of collecting the actual value of the current direct-axis component and the actual value of the current quadrature-axis component of the ultra-capacitor bridge module, and generating the state control instruction of each ultra-capacitor bridge module according to the current inner loop control reference value includes:

[0066] According to the direct-axis component deviation value between the current direct-axis component reference value and the actual value of the current direct-axis component of the super-capacitor bridge module, and the quadrature-axis component deviation value between the current quadrature-axis component reference value and the actual value of the current quadrature-axis component of the super-capacitor bridge module, a current inner-loop control is performed using a proportional-integral control algorithm to generate a current inner-loop control output result;

[0067] The current inner loop control output result is converted into a bridge arm voltage modulation waveform through Park transformation (dq / abc coordinate transformation);

[0068] According to the bridge arm voltage modulation waveform, a pulse width modulation method is used to generate a state control instruction for each super-capacitor bridge module.

[0069] Specifically, in this embodiment, according to the current d-axis component reference value i d_ref The actual value i of the current d-axis component of the supercapacitor bridge module d The d-axis component deviation value and the current q-axis component reference value i q_ref The actual value i of the current q-axis component of the supercapacitor bridge module q The q-axis component deviation value between the two is used to perform current inner loop control using a proportional integral control algorithm to generate a current inner loop control output result; the current inner loop control output result is converted into a bridge arm voltage modulation waveform u through a dq / abc coordinate transformation jref ; According to the bridge arm voltage modulation waveform u jref , the pulse width modulation method is used to generate the state control instructions of each super-capacitor bridge module; it should be noted that the bridge arm voltage modulation waveform u jref The voltage waveform required to be generated by each bridge arm in the mesh-type SVG device is as follows: jref Determine the switch state command of the full-bridge submodule, and use the PWM (pulse width modulation) method to modulate the bridge arm voltage waveform u jref Converted into switch state instructions to control the on and off of the switch devices (such as IGBT) in the full-bridge sub-module, so that the output voltage waveform generated by the full-bridge sub-module is as close as possible to the bridge arm voltage modulation waveform u jref At the same time, this embodiment can modulate the waveform u according to the bridge arm voltage jref The waveform and size of the supercapacitor can be used to calculate the charging and discharging state, rate and duration of the supercapacitor, thereby realizing the charging and discharging control of the supercapacitor.

[0070] It should be noted that the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0071] For the specific definition of the control method of a mesh-type SVG device with integrated supercapacitor, please refer to the above-mentioned definition of a mesh-type SVG device with integrated supercapacitor, which will not be repeated here. A person of ordinary skill in the art can appreciate that the various modules and steps described in conjunction with the embodiments disclosed in this application can be implemented in hardware, software, or a combination of both. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0072] The embodiment of the present invention provides a control method for a meshed SVG device with integrated supercapacitors, the control method comprising: determining an active power reference value and a reactive power reference value according to the operating state of the meshed SVG device; performing active power-frequency control using a proportional-integral control algorithm according to an active power deviation value between the active power reference value and the active power actual value, and obtaining a virtual internal potential phase angle; performing reactive power-voltage control using a proportional-integral control algorithm according to a reactive power deviation value between the reactive power reference value and the reactive power actual value, and an AC voltage deviation value between the AC voltage reference value and the AC voltage actual value, and obtaining a virtual internal potential amplitude; generating an internal potential control instruction according to the virtual internal potential phase angle and the virtual internal potential amplitude; converting the internal potential control instruction into a current inner loop control reference value, the current inner loop control reference value including a current direct-axis component reference value and a current quadrature-axis component reference value; collecting the actual value of the current direct-axis component and the actual value of the current quadrature-axis component of the supercapacitor bridge module, and generating a state control instruction for each supercapacitor bridge module according to the current inner loop control reference value. Compared with the prior art, this embodiment can simultaneously realize reactive power compensation and inertia support by integrating supercapacitor energy storage elements and grid control strategies, meet the dual needs of the power system for reactive power and active power support after the access of new energy, effectively resist the system frequency fluctuations caused by active power changes, and improve the stability of the power system.

[0073] In one embodiment, the present invention provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the above method are implemented.

[0074] The above-mentioned embodiments only express several preferred implementation modes of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in the technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be regarded as the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be based on the protection scope of the claims.

Claims

1. A mesh-type SVG device with integrated supercapacitor, characterized in that: It includes a grid-type control system and three grid-type static VAR generator branches connected to a three-phase AC bus in a triangle form, each grid-type static VAR generator branch includes at least one inductor and a plurality of super-capacitor bridge modules connected in series, and the inductor is used to smooth the current waveform of the super-capacitor bridge module; The supercapacitor bridging module includes a plurality of full-bridge submodules and a plurality of supercapacitor submodules connected in series; The supercapacitor submodule comprises a full-bridge supercapacitor submodule, an interface circuit and a supercapacitor unit; the full-bridge supercapacitor submodule is cascade-connected to the supercapacitor unit via the interface circuit; the supercapacitor submodule is used to regulate its energy storage state according to the received charge and discharge instructions.

2. The SVG device with integrated supercapacitor as claimed in claim 1, characterized in that: The full-bridge supercapacitor module includes a DC capacitor, a first switch module, a second switch module, a third switch module, a fourth switch module, a first bypass switch and a turning thyristor; The first switch module and the second switch module are connected in series to form a first switch branch, the third switch module and the fourth switch module are connected in series to form a second switch branch, and the first switch branch, the second switch branch and the DC capacitor are connected in parallel; The first bypass switch and the turning thyristor are connected in parallel with the second switch module and the fourth switch module.

3. The mesh-type SVG device with integrated supercapacitor according to claim 2, characterized in that: The interface circuit includes a first circuit breaker, a second circuit breaker, a first fuse and a bidirectional DC-DC converter; the bidirectional DC-DC converter is connected in parallel with the supercapacitor unit; The positive terminal of the DC capacitor is connected to the positive terminal of the supercapacitor unit through the first fuse and the first circuit breaker connected in series in sequence; the negative terminal of the DC capacitor is connected to the negative terminal of the supercapacitor unit through the second circuit breaker; One end of the bidirectional DC-DC converter is connected to a connection point between the first circuit breaker and the supercapacitor unit, and the other end of the bidirectional DC-DC converter is connected to a connection point between the second circuit breaker and the supercapacitor unit.

4. The mesh-type SVG device with integrated supercapacitor according to claim 1, characterized in that: The supercapacitor unit includes a plurality of supercapacitors connected in cascade.

5. The mesh-type SVG device with integrated supercapacitor according to claim 1, characterized in that: The networked control system is used to respond to active and reactive output instructions, generate state control instructions for each supercapacitor bridge module using various networked control strategies, and control the switching state of the full-bridge submodule and the charging and discharging state of the supercapacitor submodule according to the state control instructions. The networked control strategies include active-frequency control strategy, reactive-voltage control strategy, internal potential control strategy and current inner loop control strategy.

6. The mesh-type SVG device with integrated supercapacitor according to claim 1, characterized in that: The networked control system includes an inertia reserve input module; The inertia reserve investment module is used to make a difference between the voltage modulation wave reference value and the voltage modulation wave actual value to obtain the voltage modulation wave deviation value, and generate the ultra-capacity bridge module investment quantity through a proportional-integral regulator according to the voltage modulation wave deviation value and a preset investment quantity upper limit value.

7. The mesh-type SVG device with integrated supercapacitor according to claim 6, characterized in that: The number of super-capacity bridge modules put into use is not greater than the upper limit of the super-capacity bridge modules allowed to be put into use.

8. A control method for a meshed SVG device with integrated supercapacitor, characterized in that: Using the meshed SVG device with integrated supercapacitor as claimed in any one of claims 1 to 7, the control method comprises the following steps: In response to the active and reactive power output instructions, determining an active power reference value and a reactive power reference value of the meshed SVG device according to the operating state of the meshed SVG device; According to the active power deviation value between the active power reference value and the active power actual value, active power-frequency control is performed using a proportional-integral control algorithm to obtain a virtual internal potential phase angle; According to the reactive power deviation value between the reactive power reference value and the reactive power actual value, and the AC voltage deviation value between the AC voltage reference value and the AC voltage actual value, reactive-voltage control is performed using a proportional-integral control algorithm to obtain a virtual internal potential amplitude; generating an internal potential control instruction according to the virtual internal potential phase angle and the virtual internal potential amplitude; Converting the internal potential control instruction into a current inner loop control reference value, wherein the current inner loop control reference value includes a current direct axis component reference value and a current quadrature axis component reference value; The actual value of the current direct-axis component and the actual value of the current quadrature-axis component of the supercapacitor bridge module are collected, and a state control instruction of each supercapacitor bridge module is generated according to the current inner-loop control reference value; the state control instruction includes a switch state instruction of the full-bridge submodule and a charge and discharge instruction of the supercapacitor submodule.

9. The control method of a meshed SVG device with integrated supercapacitor according to claim 8, characterized in that: The step of converting the inner potential control instruction into a current inner loop control reference value comprises: According to the voltage direct-axis component deviation value between the voltage direct-axis component at the common coupling point and the virtual internal potential amplitude, a reference value of the current direct-axis component is generated by using a proportional-integral control algorithm; A current quadrature-axis component reference value is generated by using a proportional-integral control algorithm according to a voltage quadrature-axis component deviation value between a common coupling point voltage quadrature-axis component and a preset common coupling point voltage quadrature-axis reference value.

10. The control method of a meshed SVG device with integrated supercapacitor according to claim 8, characterized in that: The step of collecting the actual value of the direct-axis component of the current and the actual value of the quadrature-axis component of the current of the super-capacitor bridge module, and generating the state control instruction of each super-capacitor bridge module according to the current inner loop control reference value comprises: According to the direct-axis component deviation value between the current direct-axis component reference value and the actual value of the current direct-axis component of the super-capacitor bridge module, and the quadrature-axis component deviation value between the current quadrature-axis component reference value and the actual value of the current quadrature-axis component of the super-capacitor bridge module, a current inner-loop control is performed using a proportional-integral control algorithm to generate a current inner-loop control output result; Converting the current inner loop control output result into a bridge arm voltage modulation waveform through Park transformation; According to the bridge arm voltage modulation waveform, a pulse width modulation method is used to generate a state control instruction for each super-capacitor bridge module.

11. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed, the method according to any one of claims 8 to 10 is implemented.

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