Cascaded high-voltage direct-hanging energy storage and consumption integrated device and system and control method

Abstract

The invention belongs to the technical field of direct-current power transmission, and discloses a cascaded high-voltage direct-hanging energy storage and consumption integrated device and system and a control method.The device comprises a plurality of energy storage modules and a plurality of energy consumption modules, the energy storage modules are connected to a direct-current bus after being connected in parallel, and the energy consumption modules are connected to the direct-current bus after being connected in parallel; the device is used for absorbing or dissipating surplus power on a direct-current bus. The cascade type high-voltage direct-hanging energy storage and consumption integrated device comprises a bridge arm composed of a plurality of energy storage modules C and a bridge arm composed of a plurality of energy consumption modules H, power flow control over a direct-current bus is achieved, meanwhile, loss is basically avoided in a steady state, and power transmission is easy to analyze and control. The limitation that an energy storage scheme or an energy consumption scheme is singly used in a current actual input project is broken through, the direct current bus power transmission adjusting capacity is achieved, almost no loss exists in the adjusting process, power transmission is easy to analyze and control, and the equipment reliability is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of direct current power transmission, and in particular relates to a cascaded high-voltage direct-mounted energy storage and consumption integrated device, system and control method. Background Art

[0002] As the proportion of new energy power generation such as photovoltaic and wind power increases, due to its intermittent, volatile and random characteristics, the direct grid connection of such new energy power will affect the voltage and frequency stability control of the power system, and will not be able to balance the power grid's absorption and transmission capabilities, and will also bring great pressure to the stable operation of the power grid in the access area. Therefore, energy storage and energy consumption systems are introduced into the power system to reduce peaks and fill valleys, control system stability, control power quality, improve power supply reliability, etc., so that it can meet the technical requirements of grid connection.

[0003] So far, various forms of energy storage have been explored and developed, which can be mainly divided into physical energy storage, electromagnetic energy storage and chemical energy storage. Among the many energy storage technologies, pumped storage is the most widely used form of energy storage, and chemical battery energy storage technology has made the fastest progress. Based on the various advantages of chemical battery energy storage, lithium battery technology is also given priority. Battery energy storage systems have high energy density, high power density, no moving parts, no special requirements for site and geographical conditions, and good dynamic characteristics. They are suitable for applications such as smoothing power fluctuations in wind farms or photovoltaic power stations, frequency and peak regulation of urban power grids, and emergency protection of important loads.

[0004] As the scale of renewable energy power plants expands and the demand for peak and frequency regulation of urban power grids increases, battery energy storage systems are also developing towards large capacity and high access voltage. Energy storage solutions have also evolved from multi-pulse GTO to two- and three-level battery energy storage, and finally derived into transformer boost, MMC-BESS and cascade battery energy storage systems.

[0005] The traditional transformer boost energy storage system connects the low-voltage DC battery pack to the high-voltage power grid. The connection of the power frequency transformer is conducive to suppressing common-mode interference and protecting the energy storage system, but it also brings difficulties to the optimization design of the efficiency, volume, cost and other aspects of the large-capacity energy storage PCS. There are two technical solutions for high-voltage battery energy storage PCS (power conversion system, the full name in English is Power Conversion System) that do not use power frequency boost transformers. One is to use a high-voltage battery pack and the other is the energy storage PCS boost solution; the former is subject to battery technology, battery detection and balancing technology, and the output voltage of the battery pack mostly does not exceed 1KV, which is difficult to apply to large-capacity energy storage systems. The latter is to connect the low-voltage DC battery pack to the high-voltage power grid through the boost capability of the converter, including DC converter boost and cascade topology boost. The DC converter boost generally adopts a bipolar topology. The first stage uses a large-capacity medium-high frequency isolation high boost ratio converter to boost the battery pack, and the second stage realizes direct grid connection. However, the control strategy is complicated due to the use of multi-stage converters, and multi-stage power conversion also affects the efficiency of the energy storage PCS. Summary of the invention

[0006] The purpose of the present invention is to provide a cascaded high-voltage direct-mounted energy storage and energy consumption integrated device, system and control method to solve the problem that traditional technology is not suitable for large-capacity energy storage and has low energy storage efficiency.

[0007] To achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a cascaded high-voltage direct-mounted energy storage and energy consumption integrated device, comprising a plurality of energy storage modules and a plurality of energy consumption modules, wherein the plurality of energy storage modules are connected in parallel to a DC bus, and the plurality of energy consumption modules are connected in parallel to the DC bus, and the plurality of energy storage modules and the plurality of energy consumption modules are alternately connected in parallel to absorb or dissipate surplus power on the DC bus; The energy storage module includes a plurality of cascaded energy storage half-bridge sub-modules and a DC inductor, wherein the plurality of energy storage half-bridge sub-modules are cascaded and connected in series with the DC inductor; The energy consumption module includes a plurality of energy consumption sub-modules and an energy consumption resistor. The plurality of energy consumption sub-modules are cascaded and connected in series with the energy consumption resistor.

[0008] Furthermore, the energy storage half-bridge submodule includes a first power switching device, a second power switching device, a first capacitor and an energy storage element, the energy storage element is connected in parallel with the first capacitor, the emitter of the first power switching device is connected to the collector of the second power switching device, and the DC positive port of the energy storage submodule is led out at the connection point, the collector of the first power switching device is connected to one end of the first capacitor, the emitter of the second power switching device is connected to the other end of the first capacitor, and the DC negative port of the energy storage submodule is led out at the connection point.

[0009] Further, the first power switch device and the second power switch device are insulated gate bipolar transistors, metal-oxide semiconductor field effect transistors or silicon carbide metal oxide semiconductor field effect transistors.

[0010] Furthermore, the energy consumption sub-module includes a thyristor, a third power switch device, a second capacitor, a fourth power switch device and a current limiting resistor. The collector of the third power switch device is connected to the anode of the thyristor, and the DC positive port of the energy consumption sub-module is led out at the connection point. The cathode of the thyristor is connected to the collector of the fourth power switch device, and the connection point is connected to one end of the second capacitor. The emitter of the third power switch device is connected to the other end of the second capacitor and is led out at the connection point as the DC negative port of the energy consumption sub-module. The DC negative port of the energy consumption sub-module is connected to the fourth power switch device, and a current limiting resistor is connected in series in the connected line.

[0011] Furthermore, the third power switch device and the fourth power switch device are insulated gate bipolar transistors, metal-oxide semiconductor field effect transistors or silicon carbide metal oxide semiconductor field effect transistors.

[0012] In a second aspect, the present invention provides a cascade type high voltage direct-mounted energy storage and energy consumption integrated system, including the cascade type high voltage direct-mounted energy storage and energy consumption integrated device.

[0013] Furthermore, the energy storage half-bridge submodule includes a first power switching device, a second power switching device, a first capacitor and an energy storage element, the energy storage element is connected in parallel with the first capacitor, the emitter of the first power switching device is connected to the collector of the second power switching device, and the DC positive port of the energy storage submodule is led out at the connection point, the collector of the first power switching device is connected to one end of the first capacitor, the emitter of the second power switching device is connected to the other end of the first capacitor, and the DC negative port of the energy storage submodule is led out at the connection point.

[0014] Further, the first power switch device and the second power switch device are insulated gate bipolar transistors, metal-oxide semiconductor field effect transistors or silicon carbide metal oxide semiconductor field effect transistors.

[0015] Furthermore, the energy consumption sub-module includes a thyristor, a third power switch device, a second capacitor, a fourth power switch device and a current limiting resistor. The collector of the third power switch device is connected to the anode of the thyristor, and the DC positive port of the energy consumption sub-module is led out at the connection point. The cathode of the thyristor is connected to the collector of the fourth power switch device, and the connection point is connected to one end of the second capacitor. The emitter of the third power switch device is connected to the other end of the second capacitor and is led out at the connection point as the DC negative port of the energy consumption sub-module. The DC negative port of the energy consumption sub-module is connected to the fourth power switch device, and a current limiting resistor is connected in series in the connected line.

[0016] Furthermore, the third power switch device and the fourth power switch device are insulated gate bipolar transistors, metal-oxide semiconductor field effect transistors or silicon carbide metal oxide semiconductor field effect transistors.

[0017] In a third aspect, the present invention provides a control method for a cascaded high-voltage direct-mounted energy storage and energy consumption integrated device, comprising the following steps: Obtain the surplus power on the DC bus through a power meter to determine the size of the surplus power; If the surplus power is less than the preset value, the bridge arm of the energy storage module is turned on to absorb energy; if the surplus power is greater than the preset value, the bridge arm of the energy consumption module is turned on to dissipate energy.

[0018] Furthermore, when the energy storage in the energy storage module is saturated, the current in the bridge arm of the energy storage module is reversed, and the energy consumption module is turned on for dissipation.

[0019] Compared with the prior art, the present invention has the following technical effects: The cascaded high-voltage direct-mounted energy storage and energy consumption integrated device described in the present invention includes a bridge arm composed of several energy storage modules and a bridge arm composed of several energy consumption modules. The bridge arm realizes the power flow control of the DC bus, and there is basically no loss in the steady state, and the power transmission is easy to analyze and control. Through the alternating parallel connection of several energy storage modules and several energy consumption modules, the flexible absorption or dissipation of surplus power on the DC bus is realized. The energy storage module is composed of several cascaded energy storage half-bridge sub-modules and a DC inductor. This structure improves the flexibility and efficiency of energy storage; the energy consumption module is composed of several energy consumption sub-modules and an energy consumption resistor, which ensures the effective dissipation of surplus power. The overall design improves the power regulation capability and energy utilization efficiency of the system, and is suitable for occasions where the DC bus power needs to be flexibly adjusted. It can be suitable for multiple scenarios of flexible interconnected power transmission. The system can work in multiple operating modes. When the energy storage module is running, the line transmission power can be adjusted to absorb surplus power, improve the energy utilization rate of the wind farm, and reduce energy efficiency waste. When the line monitoring bus voltage rises too much, the energy consumption module is put into use to provide a reliable discharge circuit for the entire line. The excess power on the line is dissipated through the energy consumption resistor, which can ensure the stable operation of the entire flexible interconnection system. Therefore, the device has low-cost fault ride-through capability, reduces the steady-state fluctuation of DC voltage during faults, ensures the stability of wind farm transmission power, and can quickly restore power transmission after the fault is cleared. At the same time, the number of modules of the integrated energy storage and energy consumption device can be reasonably configured according to the output power of the wind farm. When a system fault occurs, the coordinated operation of the energy storage module and the energy consumption module can ensure the stable operation of the system, and it can still work normally after the fault is removed, with high reliability. At the same time, the number of modules of the integrated energy storage and energy consumption device can be reasonably configured according to the system capacity.

[0020] The energy storage half-bridge submodule of the present invention realizes efficient conversion and storage of electric energy through a combination of a first power switch device, a second power switch device, a first capacitor and an energy storage element. This structure enables the energy storage submodule to flexibly control its output voltage and current to meet the system's precise requirements for DC bus power regulation. The use of insulated gate bipolar transistors, metal-oxide semiconductor field effect transistors or silicon carbide metal oxide semiconductor field effect transistors as power switching devices improves the switching speed and efficiency of the energy storage half-bridge submodule. These devices have the advantages of low loss, high withstand voltage and high switching speed, and are suitable for high-voltage and high-frequency power electronics applications.

[0021] The energy dissipation submodule of the present invention realizes effective dissipation of electric energy through the combination of thyristor, third power switch device, second capacitor, fourth power switch device and current limiting resistor. This structure enables the energy dissipation submodule to flexibly control its dissipated power, ensuring that the system can operate stably when the surplus power is too large. The power switch device in the energy dissipation submodule is the same as the power switch device in the energy storage half-bridge submodule, and the power switch device in the energy dissipation submodule also adopts a high-efficiency, high-voltage, high-frequency device type, which improves the performance and reliability of the energy dissipation submodule.

[0022] The cascaded high-voltage direct-mounted energy storage and energy consumption integrated system of the present invention integrates a cascaded high-voltage direct-mounted energy storage and energy consumption integrated device, realizing flexible regulation and efficient utilization of DC bus power. The system has a reasonable design and compact structure, and is suitable for various occasions requiring DC bus power regulation, such as wind farms, photovoltaic power stations, etc.

[0023] The energy storage half-bridge submodule in the system has the same structure as the energy storage half-bridge submodule in the device, which ensures the energy storage performance and power regulation capability of the system after integration. This design enables the system to fully utilize the advantages of the energy storage module and improve energy utilization efficiency and system stability.

[0024] The energy consumption submodules in the system are the same as those in the device, which ensures the dissipation performance and stability of the system after integration. This design enables the system to effectively dissipate energy when the surplus power is too large, ensuring the safe operation of the system.

[0025] The control method of the cascaded high-voltage direct-mounted integrated energy storage and energy consumption device of the present invention monitors the surplus power on the DC bus in real time, and controls the on and off of the energy storage module and the energy consumption module according to the size of the surplus power. This method realizes the flexible adjustment and efficient utilization of the DC bus power, and improves the response speed and stability of the system. The control method is simple and easy to implement, and is suitable for various occasions requiring DC bus power regulation. When the energy storage in the energy storage module is saturated, the control strategy dissipates the energy by reversing the bridge arm current of the energy storage module and turning on the energy consumption module. This strategy avoids the problem of overcharging of the energy storage module, and ensures the safe operation and long-term stability of the energy storage module. At the same time, this strategy also improves the reliability and safety of the system, and reduces equipment damage and failures caused by overcharging.

[0026] The modular design allows for flexible combination according to different usage requirements and scenarios, and modules can be easily added or removed for quick adjustment without large-scale modification of the entire device. When an energy-consuming device fails, the modular design makes troubleshooting and repair easier, and individual replacement or repair will not affect the normal operation of other modules, reducing maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the structure of the present invention Figure 2 The structure diagram of the half-bridge submodule of the energy storage module C in each bridge arm of the present invention is Figure 3 The submodule structure diagram of the energy consumption module H in each bridge arm of the present invention is Figure 4 The working principle diagram of the present invention is in: 1. A first power switch device; 2. A second power switch device; 3. A first capacitor; 4. An energy storage element; 5. A thyristor; 6. A third power switch device; 7. A second capacitor; 8. A fourth power switch device; 9. A current limiting resistor. DETAILED DESCRIPTION

[0028] Related terms explanation: IGBT: (Insulated Gate Bipolar Transistor) Insulated Gate Bipolar Transistor, a power semiconductor device; MOSFET: Metal-Oxide-Semiconductor Field-Effect Transistor, a transistor that uses electric field effect to control conduction and shutdown; SiC MOSFET: Silicon Carbide Metal Oxide Semiconductor Field-Effect Transistor (SiC Metal-Oxide-Semiconductor Field-Effect Transistor) is a power semiconductor device based on silicon carbide (SiC) material.

[0029] SOC: System on Chip refers to the integration of multiple electronic systems or components (such as processors, memory, interfaces, etc.) on a single chip.

[0030] VSC: Voltage Source Converter. A voltage source converter is a power electronic device that converts electrical energy from a power source (such as a battery, wind farm, etc.) into the required voltage and current form to meet the needs of a specific load or grid.

[0031] KCL: Kirchhoff's Current Law In a circuit, the sum of the currents flowing into a node is equal to the sum of the currents flowing out of the node. This law applies to any node in the circuit and is the basis of circuit analysis.

[0032] The present invention is further described below in conjunction with the accompanying drawings: Example 1, please refer to Figure 1 The present invention provides a cascade type high voltage direct-mounted energy storage and energy consumption integrated device, comprising a plurality of energy storage modules and a plurality of energy consumption modules, wherein the plurality of energy storage modules are connected in parallel to a DC bus, and the plurality of energy consumption modules are connected in parallel to the DC bus, and the plurality of energy storage modules and the plurality of energy consumption modules are alternately connected in parallel to absorb or dissipate surplus power on the DC bus; The energy storage module includes a plurality of cascaded energy storage half-bridge sub-modules and a DC inductor, wherein the plurality of energy storage half-bridge sub-modules are cascaded and connected in series with the DC inductor; The energy consumption module includes a plurality of energy consumption sub-modules and an energy consumption resistor. The plurality of energy consumption sub-modules are cascaded and connected in series with the energy consumption resistor.

[0033] The present invention provides a cascaded high-voltage direct-mounted energy storage and energy consumption integrated device, which integrates two functions of energy storage and energy consumption and can flexibly absorb or dissipate surplus power on a DC bus.

[0034] By alternately connecting several energy storage modules and several energy consumption modules in parallel, the device can dynamically adjust the ratio of energy storage and energy consumption according to actual needs, thereby improving the flexibility and adaptability of the system.

[0035] The energy storage module consists of several cascaded energy storage half-bridge sub-modules and a DC inductor. This structure enables the energy storage module to efficiently store and release electrical energy.

[0036] The cascaded energy storage half-bridge submodules can be expanded or reduced according to actual needs, which improves the scalability and flexibility of the energy storage module.

[0037] The addition of DC inductance helps to smooth the output current of the energy storage module and improve the stability of the system.

[0038] The energy dissipation module is composed of a plurality of energy dissipation sub-modules and an energy dissipation resistor. This structure enables the energy dissipation module to effectively dissipate the surplus power on the DC bus.

[0039] The cascade connection of several energy-consuming submodules can be flexibly adjusted according to the demand for dissipated power, thereby improving the adaptability and efficiency of the energy-consuming modules.

[0040] As the core component of the energy dissipation module, the energy dissipation resistor can stably dissipate electrical energy and prevent the system from malfunctioning due to excessive surplus power.

[0041] In summary, the cascaded high-voltage direct-mounted energy storage and energy consumption integrated device described in this paragraph has significant technical effects. By integrating the two functions of energy storage and energy consumption, the device can flexibly manage the surplus power on the DC bus, improving the flexibility and adaptability of the system. At the same time, the design of the energy storage module and the energy consumption module also fully considers the scalability, flexibility and stability, making the device widely applicable and reliable in practical applications.

[0042] Embodiment 2, the present invention provides a cascaded high-voltage direct-mounted energy storage and energy consumption integrated device, specifically including: an energy storage module and an energy consumption module, which realize three functions in total: when there is a small amount of surplus power on the DC bus, the bridge arm of the energy storage module is turned on to absorb energy; when there is a large amount of surplus power on the DC bus (caused by a receiving end fault), the bridge arm of the energy consumption module is turned on to dissipate energy; when the energy storage in the energy storage module is too saturated, the current of the bridge arm of the energy storage module is reversed, and the energy consumption module is turned on to dissipate energy, thereby ensuring the safe and reliable operation of the energy storage module.

[0043] The cascaded high-voltage direct-mounted energy storage and energy consumption integrated device includes a bridge arm composed of i energy storage modules C and a bridge arm composed of j energy consumption absorption modules H, where i is the number of energy storage module bridge arms and j is the number of energy consumption module bridge arms; each energy storage module C is composed of n cascaded c A half-bridge sub-module is connected in series with a DC inductor LC; each energy consumption module H consists of n h sub-module and an energy dissipation resistor R h Connected in series; The bridge arms of each energy storage module are composed of n cIt is formed by cascading several half - bridge sub - modules and connecting them in series with one DC inductor. Each energy - consuming module arm is formed by cascading n h sub - modules and connecting them in series with one energy - consuming resistor.

[0044] As Figure 2 shown, the half - bridge energy - storage sub - module structure on the energy - storage module arm is composed of a first power switch device 1, a second power switch device 2, a first capacitor 3, and an energy - storage element 4. Among them, the energy - storage element 4 is in parallel with the first capacitor 3. The emitter of the first power switch device 1 is connected to the collector of the second power switch device 2, and at the same time, the DC positive port of the energy - storage sub - module is led out from this connection point. The collector of the first power switch device 1 is connected to one end of the first capacitor 3, and the emitter of the second power switch device 2 is connected to the other end of the first capacitor 3. At the same time, the DC negative port of the energy - storage sub - module is led out from this connection point. The power switch device can be selected from IGBT, MOSFET, and SiC MOSFET.

[0045] The first power switch device 1 and the second power switch device 2 are composed of two switching tubes T 1 and T 2 with anti - parallel diodes D1 and D2. The switching tubes can be selected from IGBT, MOSFET, and SiC MOSFET. After the two switching tubes T1 and T2 are connected in series, they are connected in parallel with the first capacitor 3 and the energy - storage battery.

[0046] As Figure 3 shown, the energy - consuming sub - module structure on the energy - consuming module arm is composed of a thyristor 5, a third power switch device 6, a second capacitor 7, a fourth power switch device 8, and a current - limiting resistor 9. Among them, the collector of the third power switch device 6 is connected to the anode of the thyristor 5, and at the same time, the DC positive port of the energy - consuming sub - module is led out from this connection point. The cathode of the thyristor 5 is connected to the collector of the fourth power switch device 8. This connection point is connected to one end of the second capacitor 7. The emitter of the third power switch device 6 is connected to the other end of the second capacitor 7. After this connection point is led out, it serves as the DC negative port of the energy - consuming sub - module and is connected to the fourth power switch device 8. A current - limiting resistor 9 is connected in series in the connected line. The power switch device can be selected from IGBT, MOSFET, and SiC MOSFET.

[0047] The third power switch device 6 and the fourth power switch device 8 are composed of two switching tubes T 1 and T 2 with anti - parallel diodes D1 and D2. The switching tubes can be selected from IGBT, MOSFET, and SiC MOSFET. The switching tube T 1 is connected in reverse series with the thyristor 5 and then connected in parallel with the second capacitor 7 and the switching tube T 2 . The switching tube T 2Connected in series with current limiting resistor 9.

[0048] like Figure 1 As shown, the device can flexibly absorb surplus power in the line through i energy storage module bridge arms on the DC bus. These energy storage module bridge arms are composed of several cascaded energy storage half-bridge sub-modules and a DC inductor, which are connected in parallel to the DC bus to dynamically adjust the size of the absorbed power according to system requirements. When surplus power appears in the line, the energy storage module bridge arm will respond quickly and convert the excess electrical energy into energy in the energy storage element 4 for storage, thereby effectively avoiding the impact of excess power on the system.

[0049] At the same time, the device can also reliably dissipate excess power in the line through the j energy-dissipating module bridge arms on the DC bus. The energy-dissipating module bridge arm consists of several energy-dissipating sub-modules and an energy-dissipating resistor, which are also connected in parallel to the DC bus and adjust the rate of power dissipation according to the size of the surplus power and the operating status of the system. When the surplus power in the line exceeds a certain threshold, the energy-dissipating module bridge arm will start and convert the excess electrical energy into heat energy through the energy-dissipating resistor and dissipate it, thereby ensuring that the system will not fail or become unstable due to excess power.

[0050] The design of this cascaded high-voltage direct-mounted energy storage and energy consumption integrated device not only improves the flexibility and adaptability of the system, but also ensures the stable operation of the entire flexible interconnected system. By accurately controlling the flow of the DC bus, the device can effectively balance the power distribution in the system, optimize energy utilization efficiency, reduce system losses, and improve system reliability and safety.

[0051] Example 3, see Figure 1 The present invention provides a cascade type high voltage direct hanging energy storage and energy consumption integrated device including i+j bridge arms, wherein i bridge arms are i energy storage modules C, and j bridge arms are j energy consumption modules H. Each energy storage module C is composed of n cascaded c A half-bridge submodule and a DC inductor L C Each energy consumption module H consists of n h submodules and energy dissipation resistors R h The power flow control of the DC bus is achieved by controlling the power of i+j bridge arms on the DC bus.

[0052] refer to Figure 4 , VSC0 is constant power control, VSC1 is constant voltage control, for the cascaded high voltage direct hanging device, the voltage of the energy storage module C and the energy consumption module H submodule is clamped, the value is V dc , I 0 VSC0 provides a certain value, and based on Kirchhoff's current law KCL, we have I 0 +I ci+I hj =I dc (i=1,2,3; j=1,2,3), I 0 is the fixed current provided by VSC0, I ci is the current through the energy storage module C, I hj is the current passing through the energy consumption module H.

[0053] In addition, I ci and I hj The input and output of the control module can be controlled by the corresponding control strategy, and the control I ci and I hj The value of I dc , and then complete the control of the DC bus current. The number of modules of the energy storage and energy consumption integrated device can be reasonably configured according to the output power of the wind farm.

[0054] For the cascade type high-voltage direct-mounted energy storage and consumption integrated device, the control strategy is as follows: When the device monitors the DC bus voltage V dc When the circuit is raised due to surplus power (usually, V ref <V dc <1.05V ref ), turn on the energy storage module bridge arm to absorb the surplus power, and restore the DC bus voltage to the reference voltage V ref , take the difference between the two, V ref -V dc The reference power P is obtained through the PI controller ref , then with the rated power P dc Subtract and get the surplus power P △ , at this time the surplus power in the line is P △ (P △ =P c ). c and the bridge arm voltage V c Divide by, and get the modulation current I c , which is then input into the carrier phase shift modulation to achieve the effect of the energy storage module bridge arm absorbing surplus power and the DC bus voltage recovery. Then for the i energy storage module bridge arms, more optimization can be made on this basis, and the energy absorbed by the bridge arms of different energy storage modules can be reasonably allocated. The charging rate of the energy storage module is automatically adjusted according to the allocated surplus power, so as to achieve the optimal design at the cost of the energy storage element 4.

[0055] When a lot of power is stored in the line (1.05V ref <V dc ), the bridge arm of the energy storage module may not be able to meet the demand of power flow control, and the bridge arm of the energy consumption module is turned on to absorb power.△ Allocation on demand, △ =P c +P h ,P c is the power allocated to the energy storage module, P h is the power allocated to the energy consumption module, P c and the bridge arm voltage V c Divide, P h and the bridge arm voltage V h Divide them to get the modulation current I c and I h , and then input into the carrier phase shift modulation, so as to achieve the coordinated control of the energy storage module bridge arm and the energy consumption module bridge arm to absorb excess power and maintain the stability of the DC bus voltage. Similarly, for j energy storage module bridge arms, the energy absorbed by the bridge arms of different energy consumption modules is reasonably allocated, that is, the energy consumption power is regulated, and the optimal design is performed on the cost of energy consumption components. To achieve the best energy consumption effect. At the same time, it is also possible to consider combining some intelligent control algorithms to adjust the energy consumption strategy in real time according to the operating status of the system to ensure the stable operation of the system.

[0056] In order to better improve the energy utilization efficiency, the energy absorbed by the energy storage element 4 is utilized. When the SOC state of the energy storage element 4 is monitored to be good, the energy of the energy storage element 4 can be released to the DC bus, thereby forming an output power together with the transmitting end VSC0 to be received by the receiving end VSC1, thereby achieving constant power operation of the receiving end VSC1. This current loop aims to improve the energy utilization rate as much as possible and ensure the high efficiency of flexible DC power transmission.

[0057] In the integrated coordinated control of the energy storage module bridge arm and the energy consumption module bridge arm, the overcharge problem of the energy storage module bridge arm is also taken into consideration. The solution to this problem not only relies on the above method: the energy storage module bridge arm outputs energy, controls the battery discharge state, and improves energy utilization; it can also realize energy self-consumption through the reliable discharge circuit provided by the energy consumption module bridge arm. At this time, P c +P h =0,P c is the power allocated to the energy storage module, P h In order to allocate power to the energy consumption module, the self-consumption capacity of the energy storage and consumption circuit can also be independently adjusted, which effectively solves the overcharging problem of the energy storage element 4 and overcomes the disadvantage of the inconvenient discharge operation of the existing solution.

[0058] The present invention discloses a cascaded high-voltage direct-mounted energy storage and energy consumption integrated device, a bridge arm composed of i energy storage buffer modules C, and a bridge arm composed of j energy consumption absorption modules H. The i+j bridge arms are used to realize the power flow control of the DC bus. At the same time, there is basically no loss in the steady state, and the power transmission is easy to analyze and control, and it has the ability to adjust the power transmission of the DC bus. In addition, the device adopts a modular design, and the system can work in multiple operating modes. When a system failure occurs, the coordinated operation of the energy storage and energy consumption modules can ensure the stable operation of the system, and it can still work normally after the fault is removed, with high reliability. At the same time, the number of modules of the energy storage and energy consumption integrated device can be reasonably configured according to the system capacity.

[0059] The above description is only a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art can make several modifications without departing from the concept of the present invention. Figure 1 and Figure 4 All modifications and improvements belong to the protection scope of the present invention.

Claims

1. Cascade type high voltage direct hanging energy storage and energy consumption integrated device, characterized in that: It includes a plurality of energy storage modules and a plurality of energy consumption modules. The plurality of energy storage modules are connected in parallel to a DC bus. The plurality of energy consumption modules are connected in parallel to a DC bus. The plurality of energy storage modules and the plurality of energy consumption modules are alternately connected in parallel to absorb or dissipate surplus power on the DC bus. The energy storage module includes a plurality of cascaded energy storage half-bridge sub-modules and a DC inductor, wherein the plurality of energy storage half-bridge sub-modules are cascaded and connected in series with the DC inductor; The energy consumption module includes a plurality of energy consumption sub-modules and an energy consumption resistor. The plurality of energy consumption sub-modules are cascaded and connected in series with the energy consumption resistor.

2. The cascade type high voltage direct hanging energy storage and energy consumption integrated device according to claim 1, characterized in that: The energy storage half-bridge submodule includes a first power switch device, a second power switch device, a first capacitor and an energy storage element. The energy storage element is connected in parallel with the first capacitor. The emitter of the first power switch device is connected to the collector of the second power switch device. The DC positive port of the energy storage submodule is led out at the connection point. The collector of the first power switch device is connected to one end of the first capacitor, the emitter of the second power switch device is connected to the other end of the first capacitor, and the DC negative port of the energy storage submodule is led out at the connection point.

3. The cascade type high voltage direct hanging energy storage and energy consumption integrated device according to claim 2 is characterized in that: The first power switch device and the second power switch device are insulated gate bipolar transistors, metal-oxide semiconductor field effect transistors or silicon carbide metal oxide semiconductor field effect transistors.

4. The cascade type high voltage direct hanging energy storage and energy consumption integrated device according to claim 1, characterized in that: The energy consumption submodule comprises a thyristor, a third power switch device, a second capacitor, a fourth power switch device and a current limiting resistor. The collector of the third power switch device is connected to the anode of the thyristor, and a DC positive port of the energy consumption submodule is led out at a connection point. The cathode of the thyristor is connected to the collector of the fourth power switch device, and the connection point is connected to one end of the second capacitor. The emitter of the third power switch device is connected to the other end of the second capacitor and is led out at the connection point as a DC negative port of the energy consumption submodule. The DC negative port of the energy consumption submodule is connected to the fourth power switch device, and a current limiting resistor is connected in series in the connected line.

5. The cascade type high voltage direct hanging energy storage and energy consumption integrated device according to claim 4 is characterized in that: The third power switch device and the fourth power switch device are insulated gate bipolar transistors, metal-oxide semiconductor field effect transistors or silicon carbide metal oxide semiconductor field effect transistors.

6. A cascaded high-voltage direct-mounted energy storage and energy consumption integrated system, characterized in that: It comprises a cascaded high-voltage direct-mounted integrated energy storage and consumption device as described in any one of claims 1 to 5.

7. The cascade type high voltage direct hanging energy storage and energy consumption integrated system according to claim 6, characterized in that: The energy storage half-bridge submodule includes a first power switch device, a second power switch device, a first capacitor and an energy storage element. The energy storage element is connected in parallel with the first capacitor. The emitter of the first power switch device is connected to the collector of the second power switch device. The DC positive port of the energy storage submodule is led out at the connection point. The collector of the first power switch device is connected to one end of the first capacitor, the emitter of the second power switch device is connected to the other end of the first capacitor, and the DC negative port of the energy storage submodule is led out at the connection point.

8. The cascade type high voltage direct hanging energy storage and energy consumption integrated system according to claim 7, characterized in that: The first power switch device and the second power switch device are insulated gate bipolar transistors, metal-oxide semiconductor field effect transistors or silicon carbide metal oxide semiconductor field effect transistors.

9. The cascade type high voltage direct hanging energy storage and energy consumption integrated system according to claim 6, characterized in that: The energy consumption submodule comprises a thyristor, a third power switch device, a second capacitor, a fourth power switch device and a current limiting resistor. The collector of the third power switch device is connected to the anode of the thyristor, and a DC positive port of the energy consumption submodule is led out at a connection point. The cathode of the thyristor is connected to the collector of the fourth power switch device, and the connection point is connected to one end of the second capacitor. The emitter of the third power switch device is connected to the other end of the second capacitor and is led out at the connection point as a DC negative port of the energy consumption submodule. The DC negative port of the energy consumption submodule is connected to the fourth power switch device, and a current limiting resistor is connected in series in the connected line.

10. The cascade type high voltage direct hanging energy storage and energy consumption integrated system according to claim 9, characterized in that: The third power switch device and the fourth power switch device are insulated gate bipolar transistors, metal-oxide semiconductor field effect transistors or silicon carbide metal oxide semiconductor field effect transistors.

11. A control method for a cascaded high-voltage direct-mounted energy storage and energy consumption integrated device, characterized in that: The cascaded high-voltage direct-mounted energy storage and energy consumption integrated device according to any one of claims 1 to 5 comprises the following steps: Obtain the surplus power on the DC bus and determine the size of the surplus power; If the surplus power is less than the preset value, the bridge arm of the energy storage module is turned on to absorb energy; if the surplus power is greater than the preset value, the bridge arm of the energy consumption module is turned on to dissipate energy.

12. The control method of the cascade type high voltage direct hanging energy storage and energy consumption integrated device according to claim 11, characterized in that: When the energy storage in the energy storage module is saturated, the current in the bridge arm of the energy storage module reverses and turns on the energy consumption module for dissipation.

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