Novel direct-current cascade high-voltage chained energy storage equipment

Abstract

The utility model discloses a novel direct-current cascade high-voltage chained energy storage device, relates to the technical field of power electronic converters, and aims to solve the technical problems of double-frequency alternating-current component, battery loss increase and service life reduction caused by a power module in the current high-voltage cascade alternating-current three-phase chained energy storage device. The direct-current chain type energy storage power module is used for supplying power to equipment and connected to a + / -10kv direct-current bus, the two energy storage reactors are used for realizing grouping access of a battery cluster, are connected in series and boosted to be merged into the direct-current bus, and are connected in series with the direct-current chain type energy storage power module, and the converter subsystems play roles in energy storage and energy exchange. The DC chain type energy storage power module has no frequency doubling AC component of high-voltage chain type energy storage, is more beneficial to reducing the loss of the battery and prolonging the service life, avoids the shutdown of the whole system caused by a single battery core, and improves the reliability of system operation.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronic converters, and more specifically to a novel direct current cascade high-voltage chain energy storage device. Background Art

[0002] According to the technical requirements of the chain energy storage DC / DC converter products of the supporting project of the national key R&D project "Off-grid wind / solar / hydrogen fuel cell DC interconnection and stable control technology", a modular topology structure is adopted, and the battery cluster and the chain converter module are matched in mechanical and electrical interfaces to realize the direct exchange of energy between the battery pack and the ±10kV system. When connected to the grid, it has two-way control of active power in the power mode, and the high-voltage side DC bus voltage control undertakes the voltage support during off-grid operation to maintain the stability of the DC bus voltage.

[0003] Current state of the art:

[0004] 1. The existing high-voltage cascade AC three-phase chain energy storage has a 2-fold frequency AC shunt caused by the power module, which increases the battery loss and reduces the service life;

[0005] 2. Existing equipment and high-voltage cascade AC energy storage equipment have resulted in a waste of power devices. The partitioned fixed method has also increased the use of DC cables, while also increasing the risk of ground faults due to laying DC cables, greatly increasing costs and manufacturing difficulty.

[0006] 3. Traditional high-voltage cascade energy storage equipment needs to be boosted by a transformer and cannot be directly connected to the DC bus voltage through a converter series connection, and cannot perform energy exchange, which reduces system efficiency;

[0007] 4. Traditional high-voltage cascade energy storage equipment only has the function of following the grid and cannot operate independently of the grid.

[0008] In view of this, we propose a new type of DC cascade high-voltage chain energy storage device. Utility Model Content

[0009] The purpose of this utility model is to overcome the shortcomings of the existing technology, meet the actual needs, and provide a new type of DC cascade high-voltage chain energy storage device to solve the technical problems of the current high-voltage cascade AC three-phase chain energy storage, which has a 2-fold frequency AC shunt caused by the power module, increases battery loss, and reduces service life.

[0010] In order to solve the above technical problems, the utility model provides the following technical solutions: a novel DC cascade high-voltage chain energy storage device, comprising:

[0011] DC bus, used to power equipment;

[0012] A DC chain energy storage power module connected to a ±10kv DC busbar realizes grouped access of battery clusters, series voltage boosting and integration into the DC busbar;

[0013] Two energy storage reactors connected in series to the DC chain energy storage power module play the role of energy storage and energy exchange;

[0014] A plurality of converter subsystems connected in series, wherein two ends of the converter subsystems are respectively connected in series to corresponding energy storage reactors, and the converter subsystems adopt a DC link converter topology structure, which is composed of a half-bridge arm module and an LC filter to form a non-isolated DCDC chain topology;

[0015] A battery subsystem connected in parallel to the converter subsystem includes a plurality of battery clusters for realizing chain energy storage.

[0016] Compared with the high-voltage cascade AC three-phase chain energy storage in the utility model, which has a 2-fold AC component caused by the power module, the DC energy storage converter mentioned in the device has no 2-fold AC component, and the use of DC DCDC conversion is beneficial to reducing battery loss and increasing service life.

[0017] Preferably, the DC chain energy storage power module includes an incoming circuit breaker, an isolating switch, a contactor, a sampling system, a pre-charging circuit, and a grounding switch. The incoming circuit breaker, isolating switch, contactor, sampling system, pre-charging circuit, and grounding switch are connected in series in sequence and connected to the energy storage reactor.

[0018] Preferably, the half-bridge arm module comprises two half-bridge IGBT power modules, the input side of the half-bridge IGBT power module is connected to a battery cluster, and the output side of the half-bridge IGBT power module is connected in series and connected to a ±10kV DC bus.

[0019] Preferably, the LC filter includes a supporting capacitor C1, a series inductor L1, a connecting switch KM1, a pre-charging switch KM2, a pre-charging resistor R1 and a fuse FU. The supporting capacitor C1 leads out a negative input voltage connected in series with the inductor L1, and the supporting capacitor C1 leads out a positive input voltage connected to the battery cluster through the connecting switch KM1, the pre-charging switch KM2, the pre-charging resistor R1 and the fuse FU to output a positive voltage to the battery subsystem 7.

[0020] Preferably, the two half-bridge IGBT power modules are connected in series to share the ±10kV bus voltage, and the battery cluster is charged and discharged through the BOOST / BUCK step-up and step-down mode to complete energy exchange.

[0021] Preferably, the sampling system includes two grounding modules respectively connected to the +10KV bus and the -10KV bus, and a converter M1 and a converter M34 connected in series between the two grounding modules. The two grounding modules cooperate with the converter M1 and the converter M34 to form four measurement points: positive pole-to-ground voltage collection, negative pole-to-ground voltage collection, positive pole output current, and negative pole output current.

[0022] Compared with the prior art, the beneficial effects of the utility model are:

[0023] 1. Compared with the high-voltage cascade AC three-phase chain energy storage, which has a 2-fold AC component caused by the power module, the DC energy storage converter mentioned in this device has no 2-fold AC component. The use of DC DCDC conversion is beneficial to reducing battery loss and increasing service life;

[0024] 2. Compared with existing equipment and high-voltage cascade AC energy storage equipment, this equipment uses a half-bridge arm module, which can save one-half of the power devices, and the half-bridge arm module and the battery cluster are fixed on the same bracket, which saves DC cables and reduces the risk of ground faults due to laying DC cables, greatly saving costs and reducing manufacturing difficulty.

[0025] 3. Compared with traditional high-voltage cascade energy storage equipment, this device does not need to be boosted by a transformer, but can be directly connected to the DC bus voltage through a converter series connection to achieve energy exchange and improve system efficiency;

[0026] 4. Compared with traditional high-voltage cascade energy storage equipment which only has the function of following the grid, this equipment can operate without the grid, establish the DC bus voltage, and assume the voltage support function when the DC bus fails and loses power. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the topological circuit principle diagram of the utility model;

[0028] Figure 2 This is a schematic diagram of the sampling configuration of the DC cascade high-voltage circuit measurement points in the utility model.

[0029] Figure 3 This is a schematic diagram of the topological structure of the converter subsystem in the utility model.

[0030] Description of the numbers in the figure:

[0031] 1. Incoming circuit breaker; 2. Isolating switch; 3. Contactor; 4. Sampling system; 5. Energy storage reactor; 6. Converter subsystem; 7. Battery subsystem; 8. Pre-charging circuit; 9. Grounding switch. DETAILED DESCRIPTION

[0032] like Figures 1 to 3As shown, the utility model relates to a novel DC cascade high-voltage chain energy storage device, comprising:

[0033] DC bus, used to power equipment;

[0034] A DC chain energy storage power module connected to a ±10kv DC busbar realizes grouped access of battery clusters, series voltage boosting and integration into the DC busbar;

[0035] Two energy storage reactors 5 connected in series to the DC chain energy storage power module play the role of energy storage and energy exchange;

[0036] A plurality of converter subsystems 6 connected in series, wherein two ends of the converter subsystem 6 are respectively connected in series to corresponding energy storage reactors 5, and the converter subsystem 6 adopts a DC link converter topology structure, which is composed of a half-bridge arm module and an LC filter to form a non-isolated DCDC link topology;

[0037] The battery subsystem 7 is connected in parallel to the converter subsystem 6, and the battery subsystem 7 includes a plurality of battery clusters for realizing chain energy storage.

[0038] Compared with the high-voltage cascade AC three-phase chain energy storage in the utility model, which has a 2-fold AC component caused by the power module, the DC energy storage converter mentioned in the device has no 2-fold AC component, and the use of DC DCDC conversion is beneficial to reducing battery loss and increasing service life.

[0039] In an embodiment of the utility model, the DC chain energy storage power module includes an incoming circuit breaker 1, an isolating knife 2, a contactor 3, a sampling system 4, a pre-charging circuit 8, and a grounding knife 9. The incoming circuit breaker 1, the isolating knife 2, the contactor 3, the sampling system 4, the pre-charging circuit 8, and the grounding knife 9 are connected in series in sequence and connected to the energy storage inductor 5.

[0040] In an embodiment of the utility model, the half-bridge arm module includes two half-bridge IGBT power modules, the input side of the half-bridge IGBT power module is connected to a battery cluster, and the output side of the half-bridge IGBT power module is connected in series and connected to a ±10kV DC bus.

[0041] In an embodiment of the utility model, the LC filter includes a supporting capacitor C1, a series inductor L1, a connecting switch KM1, a pre-charging switch KM2, a pre-charging resistor R1 and a fuse FU. The supporting capacitor C1 leads out a negative input voltage connected in series with the inductor L1, and the supporting capacitor C1 leads out a positive input voltage connected to the battery cluster through the connecting switch KM1, the pre-charging switch KM2, the pre-charging resistor R1 and the fuse FU to output a positive voltage to the battery subsystem 7.

[0042] In an embodiment of the utility model, two half-bridge IGBT power modules are connected in series to share the ±10kV bus voltage, and the battery cluster is charged and discharged through the BOOST / BUCK step-up and step-down mode to complete energy exchange.

[0043] In an embodiment of the utility model, the sampling system 4 includes two grounding modules respectively connected to the +10KV bus and the -10KV bus, and a converter M1 and a converter M34 connected in series between the two grounding modules. The two grounding modules cooperate with the converter M1 and the converter M34 to form four measurement points: positive pole-to-ground voltage collection, negative pole-to-ground voltage collection, positive pole output current, and negative pole output current.

[0044] Working principle: A new type of DC cascade high-voltage chain energy storage device, specifically including the following contents: Based on the architecture of DC cascade high-voltage chain energy storage, this device is designed and optimized with the back of the DC bus. First, on the basis of the existing AC cascade energy storage, the converter module is optimized through control technology. Each submodule of the converter subsystem topology circuit contains a half-bridge arm module and an LC filter to reduce the voltage and current ripple on the energy storage battery side. The converter adopts a non-isolated DCDC chain topology and adopts the lower tube of the half-bridge to form a BOOST / BUCK operation mode, which is directly connected to the DC bus system. Its battery subsystem 7 is dispersed in each converter subsystem 6 and connected in parallel next to the capacitor to avoid concentrated accumulation of battery cells in the DC.

[0045] The operation status of DC cascade high-voltage chain energy storage equipment is divided into grid-connected operation and off-grid operation. Grid-connected operation works in power mode and can receive power instructions from the monitoring system or energy management system. Off-grid operation provides voltage support for the bus and works in constant voltage or constant current mode. The converter is the key equipment for energy exchange between the energy storage component and the power grid, and can realize the control and management of the charging and discharging of the energy storage component.

[0046] The DC cascade high-voltage chain energy storage device receives the power and off-grid voltage instructions issued by the monitoring system, implements current closed-loop control, generates the required modulation wave, and sends it to each sub-module controller.

[0047] Submodule converter: Receives the modulation wave sent by the energy storage converter control layer, generates trigger pulses according to the carrier, drives the IGBT to turn on and off, and sends the power module related information to the energy storage converter device for operation status evaluation and fault diagnosis and processing.

[0048] In the grid-connected operation mode, the power PI control loop output is superimposed on the output of the module SOC balanced control to form a modulated wave signal with the goal of controlling the total port input / output current. The controller uses analog standardized control to achieve standardization of control parameters.

[0049] The current loop consists of two parts: the outer current loop and the inner current loop. The outer current loop uses PI to ensure the accuracy of the output current, and the inner current loop uses a DC deadbeat inner loop to ensure the dynamic response speed of fault processing.

[0050] In the off-grid operation mode, with the goal of controlling the bus voltage, the voltage PI control loop outputs the superposition module SOC balanced control to form a modulated wave signal.

[0051] The voltage outer loop includes a command feedforward plus a voltage feedback accumulator. The voltage feedback updates data every 0.01s to compensate for voltage deviations caused by impedance, etc., while ensuring system stability.

[0052] In order to achieve complete control, protection and measurement of chain equipment, electrical quantity measurements were carried out at each necessary node, namely DC sampling 4, bidirectional sampling of DC side current and voltage, 4 groups of equipment measurement points, the measurement point is the DC output bus, and the detailed points are: positive pole to ground voltage collection, negative pole to ground voltage collection, positive pole output current, negative pole output current.

[0053] The working process of the equipment mainly starts from the primary circuit topology. The equipment as a whole is composed of the incoming circuit breaker 1, the isolating knife 2, the pre-charging circuit 8, the sampling system 4 and the converter subsystem 6. The converter subsystem 6 is composed of multiple converters. The startup process is as follows:

[0054] 1. The incoming circuit breaker 1 is in the open state, the grounding switch 9 is in the open position, and the isolating switch 2 is in the closed position;

[0055] 2. The equipment has no fault alarms and meets the startup permission conditions;

[0056] 3. The bus voltage is normal and a one-key start command is issued;

[0057] 4. Close the incoming circuit breaker 1 and the pre-charge switch R1, and charge the converter through the pre-charge circuit 8. If the converter reaches the set value within 3 seconds and the unit is in the ready state and there is no fault, proceed to the next step, otherwise trip the switch;

[0058] 5. Comprehensively connect switch KM1 and unplug the pre-charge resistor R1, then after checking that the switch status is normal, execute the next part of the pre-charge switch R1 instruction;

[0059] 6. Execute the pre-charge switch R1 command, and if the status returns to normal, proceed to the next step of the device unlock command;

[0060] 7. Equipment detection unlocking conditions: the converter is ready, the incoming circuit breaker 1 is closed, there is no fault, and the equipment is in the locked state. If the above conditions are met, the equipment will be unlocked and enter the standby state; if the unlocking conditions are not met, all switches will be tripped.

[0061] 8. The device unlocking is working properly;

[0062] 9. Shutdown process: Send the shutdown process, first lock the PWM pulse, and then open all switches.

[0063] Invest in battery subsystem 7:

[0064] 1. Check that the battery subsystem 7 has no faults and the switch in the converter is in the open state;

[0065] 2. Close the inverter connection switch KM1 and make the battery and module voltages close to each other through the pre-charging resistor;

[0066] 3. Close the pre-charge switch KM2, unplug the pre-charge resistor R1, and put the battery into the entire system;

[0067] 4. The equipment receives the dispatch instruction and performs charging and discharging operation.

[0068] The model of fuse FU is RS306-01-T5Z-160A1250V_AC1250V_160; the model of connecting switch KM1 is EVHB150A-24B_IXT; the model of pre-charge switch KM2 is EVH50A24S_IXT; the model of pre-charge resistor R1 is RXLG-200W / 200R, the model of supporting capacitor C1 is DCLSY 1100-420; the model of series inductor L1 is DCR-0090-0M20-1.0DC_90A / 0.2mH

[0069] The embodiments of the present invention disclose preferred embodiments, but are not limited thereto. A person skilled in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. However, as long as they do not deviate from the spirit of the present invention, they are all within the protection scope of the present invention.

Claims

1. A novel DC cascade high-voltage chain energy storage device, characterized in that: include: DC bus, used to power equipment; A DC chain energy storage power module connected to a ±10kv DC busbar realizes grouped access of battery clusters, series voltage boosting and integration into the DC busbar; Two energy storage reactors (5) connected in series to the DC chain energy storage power module play the role of energy storage and energy exchange; A plurality of converter subsystems (6) connected in series, wherein two ends of the converter subsystem (6) are respectively connected in series to corresponding energy storage reactors (5), and the converter subsystem (6) adopts a DC link converter topology structure, and is composed of a half-bridge arm module and an LC filter, forming a non-isolated DCDC link topology; A battery subsystem (7) connected in parallel to the converter subsystem (6), wherein the battery subsystem (7) comprises a plurality of battery clusters for realizing chain energy storage.

2. A novel DC cascade high-voltage chain energy storage device according to claim 1, characterized in that: The DC chain energy storage power module comprises an incoming line circuit breaker (1), an isolating knife (2), a contactor (3), a sampling system (4), a pre-charging circuit (8), and a grounding knife (9); the incoming line circuit breaker (1), the isolating knife (2), the contactor (3), the sampling system (4), the pre-charging circuit (8), and the grounding knife (9) are sequentially connected in series and connected to an energy storage reactor (5).

3. A novel DC cascade high-voltage chain energy storage device according to claim 1, characterized in that: The half-bridge arm module comprises two half-bridge IGBT power modules, the input side of the half-bridge IGBT power module is connected to a battery cluster, and the output side of the half-bridge IGBT power module is connected in series and connected to a ±10kV DC bus.

4. A novel DC cascade high-voltage chain energy storage device according to claim 3, characterized in that: The LC filter comprises a supporting capacitor C1, a series inductor L1, a connecting switch KM1, a pre-charging switch KM2, a pre-charging resistor R1 and a fuse FU. The supporting capacitor C1 leads out a negative input voltage connected in series with the inductor L1, and the supporting capacitor C1 leads out a positive input voltage connected to the battery cluster through the connecting switch KM1, the pre-charging switch KM2, the pre-charging resistor R1 and the fuse FU to output a positive voltage to the battery subsystem (7).

5. A novel DC cascade high-voltage chain energy storage device according to claim 4, characterized in that: The two half-bridge IGBT power modules are connected in series to share the ±10kV bus voltage, and the battery cluster is charged and discharged through the BOOST / BUCK step-up and step-down mode to complete energy exchange.

6. A novel DC cascade high-voltage chain energy storage device according to claim 2, characterized in that: The sampling system (4) comprises two grounding modules respectively connected to the +10KV bus and the -10KV bus, and a converter M1 and a converter M34 connected in series between the two grounding modules. The two grounding modules cooperate with the converter M1 and the converter M34 to form four measurement points for positive pole-to-ground voltage collection, negative pole-to-ground voltage collection, positive pole output current, and negative pole output current.

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