Power grid voltage intensity supporting type equipment and voltage intensity supporting method

Abstract

The invention provides power grid voltage intensity supporting equipment and a voltage intensity supporting method. The power grid voltage intensity supporting equipment comprises a converter valve, a high-voltage direct-current bus, an isolated direct-current converter module, a low-voltage direct-current bus and an energy storage module which are connected in sequence, the low-voltage direct-current bus is used as a low-voltage platform to access the energy storage module from a low potential; the isolated direct-current converter module is used for converting the low-voltage direct current output by the energy storage module into high-voltage direct current and outputting the high-voltage direct current to a high-voltage direct-current bus; one side of the converter valve is connected to a high-voltage alternating-current power grid, the other side of the converter valve is connected with the high-voltage direct-current bus, and the converter valve is used for inverting high-voltage direct current of the high-voltage direct-current bus into high-voltage alternating current and providing voltage support for the high-voltage alternating-current power grid. The stability of power grid operation is improved; and flexible configuration and low-potential independent installation of the energy storage module are realized through the isolated direct-current converter module, so that the system safety is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible AC power transmission and distribution equipment for power grids, and in particular to a power grid voltage strength supporting equipment and a voltage strength supporting method. Background Art

[0002] With the massive access of renewable energy sources such as wind and light to the power grid, the proportion of power electronic equipment in the power grid has gradually increased, resulting in a decrease in the voltage strength of the power grid and insufficient anti-interference. The traditional solution is to increase the short-circuit ratio of the power grid and enhance the voltage strength of the power grid by installing synchronous condensers. Synchronous condensers can provide short-circuit current and voltage support for the system, but condensers have problems such as long construction period, high cost, high loss, complex maintenance, and lack of flexibility.

[0003] Therefore, at present, power electronic grid-connected converter valves are combined with energy storage to construct grid voltage strength support equipment. In areas where there is a lack of voltage source support and low short-circuit ratio, this equipment can support the grid voltage strength during grid faults. It has the advantages of low cost, low loss, easy maintenance and strong controllability.

[0004] The existing grid voltage strength support equipment generally adopts grid-type control to show the external characteristics of voltage source, spontaneously respond to grid faults, and have high requirements for energy storage power. There are two technical routes for the design of grid voltage strength support equipment. One is to adopt low-voltage multi-stage boosting and grid-connected mode, which requires multiple groups of energy storage converters (Power Conversion System, PCS) to be connected to the grid after being boosted by multi-stage transformers. The parallel connection of multiple groups of energy storage PCS with voltage source characteristics is prone to cause problems such as circulating current and multi-machine oscillation, and there is a risk of multiple PCS overcurrent chain disconnection, resulting in decreased grid stability; the other is to adopt a high-voltage direct-hanging structure, mainly a cascade topology, to integrate the energy storage element into the DC side of the converter valve submodule, resulting in the energy storage element being placed at a high potential, and high requirements for battery insulation; and in this topology, the grid is coupled with the energy storage element, that is, the converter valve module directly connected to the grid is coupled with the energy storage module. Due to the number of converter valve modules, the energy storage element needs to be configured synchronously, resulting in poor configuration flexibility, redundant energy storage capacity, low utilization rate, and high cost of the device. In addition, the energy storage elements have the risk of fire, and the entire device has high fire protection requirements and low safety.

[0005] Therefore, the topological structure of the existing grid voltage strength support equipment has the following problems: the parallel connection of multiple energy storage PCSs in the low-voltage multi-stage boost grid-connected structure is prone to cause circulation and multi-machine oscillation problems, and there is a risk of multiple PCSs being disconnected from the grid due to overcurrent, resulting in a decrease in grid stability; in the high-voltage direct-hung energy storage structure, the DC side capacitors of the converter valve submodules are connected in parallel to the energy storage elements, and the configuration of the energy storage elements is limited by the number of converter valve modules, resulting in poor configuration flexibility, redundant energy storage capacity, and low device safety. Therefore, a grid voltage strength support equipment that can solve the above problems is needed. Summary of the invention

[0006] In order to overcome the above-mentioned deficiencies of the prior art, the present invention proposes a grid voltage strength support equipment, comprising:

[0007] A converter valve, a high-voltage DC bus, an isolated DC converter module, a low-voltage DC bus, and an energy storage module connected in sequence;

[0008] The low-voltage DC bus is used as a low-voltage platform to access the energy storage module from a low potential;

[0009] The isolated DC converter module is used to convert the low-voltage DC power output by the energy storage module into high-voltage DC power and output it to the high-voltage DC bus;

[0010] The converter valve is connected to the high-voltage AC power grid on one side and connected to the high-voltage DC bus on the other side, and is used to convert the high-voltage DC power of the high-voltage DC bus into high-voltage AC power, thereby providing stable voltage support for the high-voltage AC power grid.

[0011] Optionally, the isolated DC converter module includes a plurality of groups of isolated DC converters connected in sequence;

[0012] Each group of the isolated DC converters comprises a high-voltage DC side converter, a high-frequency transformer and a low-voltage DC side converter connected in sequence, wherein the high-frequency transformer is used to achieve electrical isolation between the low-voltage DC power and the high-voltage DC power;

[0013] The high-voltage DC side converters of each group of isolated DC converters are connected in series, and the lead wires after the series connection are connected to the high-voltage DC bus. The low-voltage DC side converters of each group of isolated DC converters are connected in parallel, and the lead wires after the parallel connection are connected to the low-voltage DC bus, so as to convert the low-voltage DC power in the low-voltage DC bus into high-voltage DC power and output it to the high-voltage DC bus.

[0014] Optionally, a DC capacitor is provided on the high-voltage DC bus;

[0015] The DC capacitor is used to charge and discharge itself through the isolated DC converter module based on the voltage change of the high-voltage DC bus, so as to maintain the voltage of the high-voltage DC bus constant.

[0016] Optionally, it further includes: a filter module connected between the converter valve and the high-voltage AC power grid;

[0017] The filter module includes one of the following: an L filter, an LC filter or an LCL filter.

[0018] Optionally, the converter valve includes one of the following: a two-level converter valve, a three-level converter valve, and a modular multi-level converter valve;

[0019] The two-level converter valve and the three-level converter valve are composed of insulated gate bipolar transistors connected in series;

[0020] The modular multi-level converter valve is composed of a plurality of sub-modules, and the sub-modules include a full-bridge, half-bridge or full-half hybrid bridge structure.

[0021] Optionally, the energy storage module includes a plurality of energy storage elements connected in parallel, and the number of the energy storage elements is configured according to the charging and discharging power requirements of the high-voltage AC power grid for the energy storage module.

[0022] Optionally, the energy storage element includes a supercapacitor and / or an energy storage battery.

[0023] Optionally, the equipment further includes a control module, wherein the control module is respectively connected to the high-voltage AC power grid, the energy storage module and the converter valve;

[0024] The control module includes a DC side energy storage voltage control link, an internal potential generation control link, and a voltage and current inner loop control link connected in sequence;

[0025] The energy storage voltage control link is used to generate an active power reference value according to the DC side energy storage voltage stability requirement, and use the active power reference value to control the charging and discharging of the energy storage module;

[0026] The internal potential generation control link is used to output the phase and amplitude of the internal potential of the supporting equipment according to the active power reference value, the reactive power reference value, the active power and reactive power of the supporting equipment connected to the grid, and adjust the active power and reactive power based on the phase and amplitude of the internal potential; the reactive power and active power are calculated based on the voltage and current of the high-voltage AC bus;

[0027] The voltage and current inner loop control link is used to generate a voltage reference value for the converter valve according to the phase and amplitude of the internal potential, and to generate a modulation signal for driving the converter valve based on the voltage reference value.

[0028] Based on the above inventive concept, the present invention proposes a voltage strength support method based on power grid voltage strength support equipment, comprising:

[0029] The energy storage module outputs low-voltage direct current, and the low-voltage direct current bus serves as a low-voltage platform to collect the low-voltage direct current output by the energy storage module;

[0030] The low voltage DC power is converted into high voltage DC power by an isolated DC converter and output to a high voltage DC bus, so as to maintain a constant voltage of the high voltage DC bus;

[0031] The high-voltage direct current is stably converted into the high-voltage alternating current required by the high-voltage alternating current grid through the converter valve, thereby achieving voltage strength support for the high-voltage alternating current grid.

[0032] Optionally, after the high-voltage direct current is stably converted into the high-voltage alternating current required by the high-voltage alternating current grid through the converter valve, the process further includes:

[0033] The high-voltage alternating current is filtered by a filtering module and then output to the high-voltage alternating current grid.

[0034] Optionally, the filtering module includes one of the following: an L filter, an LC filter or an LCL filter.

[0035] In another aspect, the present application further provides an electronic device, comprising: at least one processor and a memory; the memory and the processor are connected via a bus;

[0036] The memory is used to store one or more programs;

[0037] When the one or more programs are executed by the at least one processor, the voltage strength supporting method based on the grid voltage strength supporting equipment as described above is implemented.

[0038] On the other hand, the present application also provides a computer-readable storage medium having an execution program stored thereon, and when the execution program is executed, the voltage strength supporting method based on the grid voltage strength supporting equipment as described above is implemented.

[0039] Compared with the closest prior art, the present invention has the following beneficial effects:

[0040] The present invention provides a grid voltage strength support equipment and a voltage strength support method, comprising: a converter valve, a high-voltage DC bus, an isolated DC converter module, a low-voltage DC bus and an energy storage module connected in sequence; the low-voltage DC bus is used to serve as a low-voltage platform to access the energy storage module from a low potential; the isolated DC converter module is used to convert the low-voltage DC power output by the energy storage module into high-voltage DC power and output it to the high-voltage DC bus; one side of the converter valve is connected to the high-voltage AC grid, and the other side is connected to the high-voltage DC bus, and is used to convert the high-voltage DC power of the high-voltage DC bus into high-voltage AC power, so as to provide stable voltage support for the high-voltage AC grid; compared with the traditional 690V grid-connected low-voltage multi-stage boost and parallel The problem of power capacity being too large is solved by directly hanging the voltage strength support equipment of the present application on the high-voltage AC busbar, which can realize the high-power capacity design of a single set of equipment and avoid the problems of circulating current and transient oscillation caused by multiple sets of low-voltage equipment after being boosted and connected to the grid, thereby further maintaining the stability of the power grid; the isolated DC converter module is used to realize the access of the energy storage module from a low potential and the flexible configuration of the energy storage module, which is easy to expand the capacity of the energy storage module, and realizes the electrical isolation of the energy storage module from the high-voltage side of the power grid. The energy storage module is isolated from the converter valve, which is conducive to the safe operation of the energy storage module; the flexible configuration of the energy storage module improves the utilization rate of the energy storage module, reduces the redundancy of the energy storage capacity, and thereby improves the economy of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of the topological structure of a power grid voltage strength support type equipment provided by the present invention;

[0042] Figure 2 A schematic diagram of a two-level converter valve structure with IGBT series structure provided by the present invention;

[0043] Figure 3 A schematic diagram of a three-level converter valve structure with IGBT series structure provided by the present invention;

[0044] Figure 4 A schematic diagram of the structure of a modular multi-level converter valve provided by the present invention;

[0045] Figure 5 A schematic diagram of a topological structure of an isolated DC / DC converter provided by the present invention;

[0046] Figure 6 A schematic diagram of the topological structure of an isolated DC converter module provided by the present invention;

[0047] Figure 7 A schematic diagram of the structure of an energy storage module using multiple groups of supercapacitors connected in parallel provided by the present invention;

[0048] Figure 8A schematic diagram of the structure of an energy storage module provided by the present invention using multiple groups of energy storage batteries connected in parallel;

[0049] Fig. 9 A schematic flow chart of a voltage strength support method based on power grid voltage strength support equipment provided by the present invention;

[0050] Fig.10 A control block diagram of the support equipment provided by the present invention;

[0051] Fig.11 A waveform diagram providing frequency support for the support type equipment provided by the present invention;

[0052] Fig.12 A waveform diagram providing voltage support for the support type equipment provided by the present invention;

[0053] Fig.13 A waveform diagram of the voltage of the energy storage element controlled by the supporting equipment provided by the present invention;

[0054] Fig.14 A waveform diagram of the active reactive output of the supporting equipment provided by the present invention;

[0055] Fig.15 The present invention provides a schematic diagram of the structure of an electronic device. DETAILED DESCRIPTION

[0056] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0057] Example 1

[0058] The present invention provides a power grid voltage strength support type equipment, such as Figure 1 As shown, it includes: a converter valve, a high-voltage DC bus, an isolated DC converter module, a low-voltage DC bus and an energy storage module connected in sequence;

[0059] The low-voltage DC bus is used as a low-voltage platform to access the energy storage module from a low potential;

[0060] The isolated DC converter module is used to convert the low-voltage DC power output by the energy storage module into high-voltage DC power and output it to the high-voltage DC bus;

[0061] The converter valve is connected to a high-voltage AC power grid on one side and connected to the high-voltage DC bus on the other side, and is used to convert the high-voltage DC power of the high-voltage DC bus into high-voltage AC power during a power grid failure, thereby providing stable voltage support for the high-voltage AC power grid.

[0062] The supporting equipment provided in this solution is directly connected to the high-voltage AC busbar of the high-voltage AC grid, and is used to support the voltage of the high-voltage AC grid.

[0063] The converter valve is controlled by direct-to-alternating current conversion, the DC side of the converter valve is connected to a high-voltage direct current bus, and the AC side of the converter valve is directly connected to a high-voltage alternating current bus. The converter valve is connected to a high-voltage alternating current grid through the high-voltage alternating current bus. The high-voltage direct current output by the high-voltage direct current bus is converted into three-phase high-voltage alternating current through an inverter, and reactive power is output or absorbed during a grid voltage fault to maintain stable grid operation.

[0064] The converter valve includes one of the following: a two-level converter valve, a three-level converter valve, a multi-level converter valve and an MMC converter valve (Modular Multilevel Converter), and the two-level converter valve and the three-level converter valve are composed of insulated gate bipolar transistors (IGBT) connected in series, which can greatly reduce the number of semiconductor switch devices compared to the converter valve of the cascade H-bridge structure. Figure 2 As shown in the figure, it is a two-level converter valve with IGBT series structure. Each phase bridge arm adopts the structure of IGBT devices directly connected in series. The DC side of the converter valve is connected to the high-voltage DC bus, and the AC side outputs three phases A, B, and C to the high-voltage AC bus. Figure 3 As shown in the figure, it is a three-level converter valve with IGBT series structure. Each phase bridge arm adopts IGBT device direct series structure. Each phase bridge arm is clamped by two groups of diodes. The DC side is connected to the high-voltage DC bus, and the AC side outputs A, B, and C three phases to the high-voltage AC bus. Figure 4 As shown, a modular multi-level converter valve is provided, wherein each phase of the modular multi-level converter valve is divided into an upper bridge arm and a lower bridge arm, and a single bridge arm is formed by cascading multiple sub-modules (SM), and the sub-module includes a full-bridge, half-bridge or full-half hybrid bridge structure.

[0065] The supporting equipment is directly connected to the high-voltage AC busbar through the connection of the converter valve. Compared with the traditional topological structure of multiple groups of low-voltage equipment connected to the grid, it can realize the high-power capacity design of a single group of equipment, and avoid the problems of circulating current and transient oscillation caused by the low-voltage equipment after boosting and connecting to the grid, thereby maintaining the stability of the power grid.

[0066] Optionally, the converter valve is connected to the high-voltage AC busbar via a filter module, that is, the topological structure of the support equipment further includes: a filter module ( Figure 1 The filtering link in the process is used to reduce the harmonic interference generated during the commutation process and ensure the stable operation of the power system;

[0067] The filter module includes one of the following: an L filter, an LC filter or an LCL filter.

[0068] If a filter module is connected between the converter valve and the high-voltage AC bus, the AC side of the converter valve outputs three phases A, B, and C to the filter module, and then outputs to the high-voltage AC bus after filtering.

[0069] The isolated direct current converter module includes a plurality of groups of isolated direct current converters connected in sequence, namely, isolated DC / DC (Direct Current) converters;

[0070] like Figure 5 The figure shows the topological structure of an isolated DC / DC converter. Each group of the isolated DC converters includes a high-voltage DC side converter, a high-frequency transformer and a low-voltage DC side converter connected in sequence. The high-frequency transformer is used to achieve electrical isolation between low-voltage DC power and high-voltage DC power. The high-voltage DC side converter and the low-voltage DC side converter in the isolated DC converter of this embodiment are high-voltage DC side full-bridge converters and low-voltage DC side full-bridge converters.

[0071] like Figure 6 The figure shows a connection diagram between multiple groups of isolated DC / DC converters, that is, a topological structure diagram of an isolated DC converter module, in which the high-voltage DC side full-bridge converters of each group of isolated DC converters are connected in series, and the lead wires after the series connection are connected to the high-voltage DC bus; the low-voltage DC side full-bridge converters of each group of the isolated DC converters are connected in parallel, and the lead wires after the parallel connection are connected to the low-voltage DC bus, which are used to convert the low-voltage DC power in the low-voltage DC bus into high-voltage DC power and output it to the high-voltage DC bus.

[0072] The high-voltage DC bus is provided with a DC capacitor, which is used to charge and discharge itself through the isolated DC converter module based on the voltage change of the high-voltage DC bus, so as to maintain a constant voltage of the high-voltage DC bus.

[0073] The low-voltage DC bus is connected to an energy storage module, and the energy storage module includes a plurality of energy storage elements connected in parallel. The number of the energy storage elements can be flexibly configured according to the charging and discharging power requirements of the high-voltage AC power grid for the energy storage module.

[0074] Since the grid voltage strength support equipment has a high requirement for the charging and discharging power of the energy storage module, this solution adopts a high-rate charging and discharging type of energy storage element, which includes a supercapacitor and / or an energy storage battery, such as an energy storage lithium battery, such as Figure 7 As shown in FIG. , a storage module is formed by connecting multiple groups of supercapacitors in parallel; Figure 8 As shown, an energy storage module using multiple groups of energy storage batteries connected in parallel.

[0075] The equipment also includes a control module, which is connected to the high-voltage AC power grid, the energy storage module and the converter valve respectively;

[0076] like Fig. 9 As shown, the control module includes a DC side energy storage voltage control link, an internal potential generation control link, and a voltage and current inner loop control link connected in sequence;

[0077] The energy storage voltage control link is used to generate an active power reference value according to the DC side energy storage voltage stability requirement, and use the active power reference value to control the charging and discharging of the energy storage module;

[0078] The internal potential generation control link is used to output the phase and amplitude of the internal potential of the supporting equipment according to the active power reference value, the reactive power reference value, the active power and reactive power of the supporting equipment connected to the grid, and adjust the active power and reactive power based on the phase and amplitude of the internal potential; the reactive power and active power are calculated based on the voltage and current of the high-voltage AC bus;

[0079] The voltage and current inner loop control link is used to generate a voltage reference value for the converter valve according to the phase and amplitude of the internal potential, and to generate a modulation signal for driving the converter valve based on the voltage reference value.

[0080] The support equipment provided by this solution has energy storage elements connected from low potential to the low-voltage DC bus through an isolated DC / DC link, providing high-voltage DC power to the high-voltage DC bus, maintaining the voltage of the high-voltage DC bus constant, ensuring that the converter valve can stably and continuously output current during grid faults, and realizing the voltage support function of the grid voltage strength support equipment. The isolated DC converter module is used to realize the connection of the energy storage module from low potential and the flexible configuration of the energy storage module, which is easy to expand the capacity of the energy storage module, and realizes the electrical isolation of the energy storage module from the high-voltage side of the grid, which is conducive to the safe operation of the energy storage module; the flexible configuration of the energy storage module improves the utilization rate of the energy storage module, reduces the redundancy of energy storage capacity, and thus improves the economy of the equipment.

[0081] That is, the grid voltage strength supporting equipment provided by the present invention has the advantages of low-potential installation of energy storage elements, flexible configuration of energy storage capacity, easy expansion of high voltage and large capacity, and low equipment cost.

[0082] Example 2

[0083] Based on the above inventive concept, the present invention also provides a voltage strength support method based on power grid voltage strength support equipment, such as Fig.10 As shown, including:

[0084] S1, the energy storage module outputs low-voltage direct current, and the low-voltage direct current bus serves as a low-voltage platform to collect the low-voltage direct current output by the energy storage module;

[0085] S2, the low voltage DC power is converted into high voltage DC power through an isolated DC converter and output to a high voltage DC bus, so as to maintain a constant voltage of the high voltage DC bus;

[0086] S3. The high-voltage direct current is stably inverted into the high-voltage alternating current required by the high-voltage alternating current grid through a converter valve, thereby achieving voltage strength support for the high-voltage alternating current grid.

[0087] In step S3, after the high-voltage direct current is stably inverted into the high-voltage alternating current required by the high-voltage alternating current grid through the converter valve, the method further includes: filtering the high-voltage alternating current by using a filter module and then outputting the filtered current to the high-voltage alternating current grid.

[0088] The above-mentioned filter module includes one of the following: an L filter, an LC filter or an LCL filter.

[0089] This embodiment provides a control strategy for implementing the support method based on the grid voltage strength support type equipment. Specifically, Fig. 9 The control block diagram is shown as follows:

[0090] Obtain the voltage V of the high voltage AC grid abc and current I abc And perform dq decoupling dq / abc (abc represents three phases, dq represents dq coordinate system, which is a rotating coordinate system for decoupling three-phase voltage and current), based on the voltage V after dq decoupling dq and current I dq Perform power calculation to obtain the reactive power Q and active power P of the supporting equipment connected to the grid;

[0091] The reactive power-voltage Q / V control sub-link in the internal potential generation control link is based on the reactive power Q, the reactive power reference value Q ref and voltage reference value V ref Output control signal E, i.e., the amplitude of the potential inside the supporting equipment, for adjusting the reactive power Q;

[0092] The active power-frequency P / f control sub-link in the internal potential generation control link is used, based on the active power P and the active power reference value P output by the energy storage voltage control link. ref The output control parameter θ, i.e., the phase of the potential inside the supporting equipment, is used to adjust the active power P; the active power reference value output by the energy storage voltage control link is used to control the charging and discharging of the energy storage module;

[0093] The virtual admittance sub-link in the voltage and current inner loop control link is used to output the current reference value I in the dq coordinate system based on the control signal E and the control parameter θ. dqref ;

[0094] Through the current inner loop control sub-link in the voltage and current inner loop control link, based on the current reference value I in the dq coordinate system dqref , and converted again through the dq coordinate system to obtain the output voltage reference value U required by the supporting equipment ref , that is, the output voltage reference value of the converter valve, through which the modulation signal for driving the converter valve is generated.

[0095] Through this control strategy, the supporting equipment can adjust its own active power output during the frequency fluctuation of the high-voltage AC power grid to provide frequency support for the power grid (active power-frequency P / f control link); adjust its own reactive power output during the voltage drop of the power grid to provide strength support for the power grid (reactive power-voltage Q / v control link); it can also control the voltage of the subsequent energy storage element and actively output the required reactive power according to the instruction (energy storage voltage control link). Among them, the energy storage voltage control is achieved by outputting the active power reference value P ref To indicate the active power that needs to be absorbed or provided. Providing active power is charging, and absorbing active power is discharging. By controlling charging and discharging, the equipment can achieve the active setting and realize voltage control.

[0096] In the specific implementation process, the frequency support effect provided by the support equipment of the present application is as follows: Fig.11 As shown in the graphs Graphs, from top to bottom are the active power waveform Psvq output by the equipment and the grid frequency waveform fqrid, where Sec represents the time unit. When the grid frequency decreases, active power should be supplemented, and when the frequency increases, active power needs to be reduced. Fig.11 As shown, during the period when the grid frequency decreases, the equipment outputs active power to the grid, and during the period when the grid frequency increases, the device absorbs active power from the grid to achieve the expected control target.

[0097] The strength support effect provided by the support equipment of this application is as follows Fig.12 As shown in the figure, from top to bottom are the grid voltage waveform Usvg, the equipment output current waveform Isvg, the equipment internal capacitor voltage waveforms Usmfb and Usmhb, and the equipment reactive power waveform Qsvq. After the grid voltage drops, the equipment should respond quickly, increase the output current and improve the system strength. Fig.12It can be seen that after the grid voltage drops, the output current of the equipment increases rapidly, and the voltage fluctuation of the internal capacitor of the equipment becomes more obvious due to the increase in throughput power. After the grid voltage recovers, the output current of the equipment drops rapidly, and the capacitor voltage fluctuation drops accordingly, achieving the expected control target.

[0098] The supporting equipment of the present application controls the voltage of the energy storage element as follows Fig.13 As shown, the two curves are respectively the waveform of the energy storage element voltage Usc and the waveform of the energy storage element voltage reference value Usc ref. The device (support equipment) should have the function of controlling the voltage of the energy storage element within a certain range. Fig.13 It can be seen that when the voltage of the energy storage element is higher than the set lower limit, the voltage reference value of the energy storage element is the same as the actual voltage value of the energy storage element, that is, no control is performed; when the voltage of the energy storage element is lower than the set lower limit, the reference voltage maintains the set lower limit, and the actual voltage value of the energy storage element is quickly adjusted back to the normal range to achieve the expected control target.

[0099] The supporting equipment of this application actively outputs reactive power according to the instructions. Fig.14 As shown, from top to bottom are the device output reactive power waveform Usvg, the device output current waveform Isvg, the device internal capacitor voltage waveforms Usm fb and Usm hb, and the equipment reactive power waveform Qsvq; where Sec represents the time unit. When the device receives the instruction to change the reactive output from 0 to 100%, Fig.14 In the process, the reactive power output of the device rises to the specified value, and the output current rises accordingly. The voltage fluctuation of the capacitor inside the device becomes more obvious due to the increase in throughput power, and the device can continuously and stably output the required reactive power to achieve the expected control target.

[0100] Example 3

[0101] like Fig.15 As shown, the present invention also provides an electronic device, which may be a computer device, a single-chip device, an intelligent mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, the processor, and the transceiver component are connected via a bus; the memory may be used to store an execution program, and an exemplary execution program may include instructions; the processor is used to execute the instructions stored in the memory. The memory may also be used to store data, which may be called and / or modified when the instructions are executed.

[0102] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, and is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in a storage medium to implement corresponding method processes or corresponding functions, so as to implement the steps of the voltage strength support method based on grid voltage strength support equipment in the above-mentioned embodiment.

[0103] Example 4

[0104] Based on the same inventive concept, the present invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory), which is a memory device in the electronic device for storing programs and data. It can be understood that the storage medium here can include both the built-in storage medium in the electronic device and the extended storage medium supported by the electronic device. The storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more execution programs (including program codes). It should be noted that the storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk storage. The processor loads and executes one or more instructions stored in the storage medium, which can implement the steps of the voltage strength support method based on the power grid voltage strength support type equipment in the above embodiment.

[0105] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0106] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0107] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0108] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions are all within the protection scope of the claims to be approved.

Claims

1. A power grid voltage strength support equipment, characterized in that: include: A converter valve, a high-voltage DC bus, an isolated DC converter module, a low-voltage DC bus, and an energy storage module connected in sequence; The low-voltage DC bus is used as a low-voltage platform to access the energy storage module from a low potential; The isolated DC converter module is used to convert the low-voltage DC power output by the energy storage module into high-voltage DC power and output it to the high-voltage DC bus; The converter valve is connected to the high-voltage AC power grid on one side and connected to the high-voltage DC bus on the other side to convert the high-voltage DC power of the high-voltage DC bus into high-voltage AC power, thereby providing stable voltage support for the high-voltage AC power grid.

2. The device according to claim 1, characterized in that The isolated DC converter module includes a plurality of groups of isolated DC converters connected in sequence; Each group of the isolated DC converters comprises a high-voltage DC side converter, a high-frequency transformer and a low-voltage DC side converter connected in sequence, wherein the high-frequency transformer is used to achieve electrical isolation between the low-voltage DC power and the high-voltage DC power; The high-voltage DC side converters of each group of isolated DC converters are connected in series, and the lead wires after the series connection are connected to the high-voltage DC bus. The low-voltage DC side converters of each group of isolated DC converters are connected in parallel, and the lead wires after the parallel connection are connected to the low-voltage DC bus, so as to convert the low-voltage DC power in the low-voltage DC bus into high-voltage DC power and output it to the high-voltage DC bus.

3. The device according to claim 1, characterized in that: A DC capacitor is provided on the high-voltage DC bus; The DC capacitor is used to charge and discharge itself through the isolated DC converter module based on the voltage change of the high-voltage DC bus, so as to maintain the voltage of the high-voltage DC bus constant.

4. The device according to claim 1, characterized in that Also includes: A filter module connected between the converter valve and the high voltage AC power grid; The filter module includes one of the following: an L filter, an LC filter or an LCL filter.

5. The device according to claim 1 or 4, characterized in that: The converter valve includes one of the following: a two-level converter valve, a three-level converter valve, and a modular multi-level converter valve; The two-level converter valve and the three-level converter valve are composed of insulated gate bipolar transistors connected in series; The modular multi-level converter valve is composed of a plurality of sub-modules, and the sub-modules include a full-bridge, half-bridge or full-half hybrid bridge structure.

6. The apparatus according to claim 1, characterized in that The energy storage module includes a plurality of energy storage elements connected in parallel, and the number of the energy storage elements is configured according to the charging and discharging power requirements of the high-voltage AC power grid for the energy storage module.

7. The apparatus according to claim 6, characterized in that The energy storage element includes a super capacitor and / or an energy storage battery.

8. The apparatus according to claim 1, characterized in that It also includes a control module, which is connected to the high-voltage AC power grid, the energy storage module and the converter valve respectively; The control module includes a DC side energy storage voltage control link, an internal potential generation control link, and a voltage and current inner loop control link connected in sequence; The energy storage voltage control link is used to generate an active power reference value according to the DC side energy storage voltage stability requirement, and use the active power reference value to control the charging and discharging of the energy storage module; The internal potential generation control link is used to output the phase and amplitude of the internal potential of the supporting equipment according to the active power reference value, the reactive power reference value, the active power and reactive power of the supporting equipment connected to the grid, and adjust the active power and reactive power based on the phase and amplitude of the internal potential; the reactive power and active power are calculated based on the voltage and current of the high-voltage AC bus; The voltage and current inner loop control link is used to generate a voltage reference value for the converter valve according to the phase and amplitude of the internal potential, and to generate a modulation signal for driving the converter valve based on the voltage reference value.

9. A voltage strength support method based on power grid voltage strength support equipment, characterized in that: include: The energy storage module outputs low-voltage direct current, and the low-voltage direct current bus serves as a low-voltage platform to collect the low-voltage direct current output by the energy storage module; The low voltage DC power is converted into high voltage DC power by an isolated DC converter and output to a high voltage DC bus, so as to maintain a constant voltage of the high voltage DC bus; The high-voltage direct current is stably converted into the high-voltage alternating current required by the high-voltage alternating current grid through the converter valve, thereby achieving voltage strength support for the high-voltage alternating current grid.

10. The method according to claim 9, characterized in that After the high-voltage direct current is stably converted into the high-voltage alternating current required by the high-voltage alternating current grid through the converter valve, the method further includes: The high-voltage alternating current is filtered by a filtering module and then output to the high-voltage alternating current grid.

11. The method according to claim 10, characterized in that The filter module includes one of the following: an L filter, an LC filter or an LCL filter.

12. An electronic device, characterized in that: include: at least one processor and memory; The memory and the processor are connected via a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, the voltage strength supporting method based on the grid voltage strength supporting equipment as described in any one of claims 9 to 11 is implemented.

13. A computing device readable storage medium, characterized in that: An execution program is stored thereon, and when the execution program is executed, a voltage strength supporting method based on grid voltage strength supporting equipment as described in any one of claims 9 to 11 is implemented.

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