Rapid switching device and method based on digital energy reconstruction system

Abstract

The invention belongs to the technical field of new energy power system energy storage, and particularly relates to a rapid switching device and method based on a digital energy reconstruction system. The device comprises a digital energy reconstruction system and a switching loop. The digital energy reconstruction system is used for monitoring and managing the operation state of the battery cluster and controlling the on-off of the battery module as required; the switching loop realizes rapid control of energy exchange between the battery cluster and the power grid through series-parallel connection of the IGBT modules. Through series-parallel connection of the IGBT modules, switching and protection effects of a traditional switch in a direct-current system can be replaced, switching on and switching off of an electrical main loop of a digital energy reconstruction system can be achieved at the microsecond level through the IGBT, and system safety is protected in time; and the number of the input IGBTs can be intelligently controlled according to the system power, the loss can be effectively reduced, and the service life of the IGBTs can be prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage of new energy power systems, and in particular relates to a fast switching device and method based on a digital energy reconstruction system. Background Art

[0002] The main performance indicators of battery energy storage systems, such as efficiency, reliability and safety, are crucial to the safe operation and successful commercial deployment of energy storage systems. The digital energy reconstruction system discretizes and digitizes the battery analog energy flow, transforms the physical hard connection between battery cells into a flexible connection controlled by a program, and thus transforms the analog battery energy storage system into a digital battery energy storage system. This fundamentally solves the industry pain points in terms of safety and economy caused by the short board effect of the battery system, and thus achieves seamless integration with the information Internet industry. As a disruptive technology of the energy Internet, digital energy storage has transformative significance for the future development of the energy storage industry.

[0003] In the digital energy reconstruction system, the battery system is quickly put into use when in use, and is quickly cut out of the system in case of failure to protect the battery from damage. The traditional solution is to use a contactor or a fast switch based on traditional power electronics, such as a fast thyristor as a switch, but its response speed still cannot meet the technical requirements of digital battery energy storage. Summary of the invention

[0004] In order to overcome the problems in the prior art, the present invention proposes a fast switching device and method based on a digital energy reconstruction system.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] In a first aspect, the present invention provides a fast switching device based on a digital energy reconstruction system, including a digital energy reconstruction system and a switching circuit;

[0007] The digital energy reconstruction system is responsible for monitoring and managing the operating status of the battery cluster and controlling the on and off of the battery module as needed;

[0008] The switching circuit realizes rapid control of energy exchange between the battery cluster and the power grid through the series and parallel connection of IGBT modules.

[0009] Furthermore, the positive pole of the switching loop is connected to the battery cluster part in the digital energy reconstruction system; the negative pole of the switching loop is connected to the AC bus to realize energy exchange with the power grid.

[0010] Further, the digital energy reconstruction system includes an energy block and an energy control module. The energy block is a reconfigurable battery network. The energy control module is configured to obtain the operating parameters of each battery module in the energy block when the energy block is charging or discharging, and perform on-off control on each battery module by controlling the switches of each battery module in the energy block based on the obtained operating parameters.

[0011] Further, the IGBT module includes an insulated gate bipolar transistor and an anti-parallel diode.

[0012] Further, in the digital energy reconstruction system, the control of the number of IGBT modules input for different power levels includes:

[0013] Allocate 2 n / 2 IGBT modules on each of the battery cluster side and the AC bus side, where n ≥ 1;

[0014] If the operating power of the digital energy reconstruction system is P, the power P1 borne by each IGBT branch is:

[0015] P1 = P / (2 n / 2);

[0016] If the power ratio is m, 0 < m ≤ 100%, then calculate the number of IGBT branches n1 to be input, 1 ≤ n1 ≤ 2 n / 2, where n1 is the number of IGBT branches that need to be input simultaneously on the battery cluster side and the AC bus side:

[0017] n1 = mP / P1.

[0018] Further, if n1 is calculated to be a non-integer, round up to the nearest integer for branch input.

[0019] Further, in the switching circuit, the working current is increased by paralleling IGBT modules.

[0020] Further, in the switching circuit, the working voltage is increased by series connecting IGBT modules.

[0021] In a second aspect, the present invention provides a fast switching method based on a digital energy reconstruction system for implementing a fast switching device based on a digital energy reconstruction system described in the first aspect, including the following steps:

[0022] The digital energy reconstruction system starts to operate, and the energy control module continuously monitors the energy block, that is, the operating parameters of each battery module in the battery cluster;

[0023] According to the operating power P of the digital energy reconstruction system, calculate the power P1 that each branch can bear; according to the required power ratio m, calculate the number of IGBT modules n1 to be input;

[0024] According to the determined number n1 of IGBT modules to be put into use, a corresponding number of IGBT modules are put into use simultaneously on the battery cluster side and the AC bus side;

[0025] By connecting the IGBT modules in series and in parallel, the energy exchange between the battery cluster and the power grid can be quickly controlled.

[0026] Furthermore, the operating parameters of the battery module include voltage and current.

[0027] Compared with the prior art, the present invention has the following technical effects:

[0028] The present invention can replace the switching and protection functions of traditional switches in the DC system through the series and parallel connection of IGBT modules. The IGBT can realize the opening and closing of the electrical main circuit of the digital energy reconstruction system in microseconds, and timely protect the system safety. In addition, the present invention can intelligently control the number of IGBTs invested according to the system power, which can effectively reduce the loss and increase the life of the IGBT. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 It is a switching circuit diagram of the dual IGBTs in parallel of the present invention;

[0031] Figure 2 It is a topological diagram of a parallel switching circuit of multiple IGBT modules of the present invention;

[0032] Figure 3 This is a topological diagram of a series-parallel switching circuit of multiple IGBT modules of the present invention.

[0033] Figure 4 This is a flow chart of judging whether to start the IGBT under different power conditions according to the present invention. DETAILED DESCRIPTION

[0034] In order to further explain the technical means and effects taken by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the technical solutions proposed by the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments. The specific features, structures or characteristics in one or more embodiments may be combined in any suitable form. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by technicians in the technical field of the present invention.

[0035] Traditional switches, whether contactors or control methods based on switch devices such as thyristors, have a response time of milliseconds, and their response time increases with the increase of current. From the above description, it can be seen that traditional switches have a slow response time, and the response time increases with the increase of current, which cannot meet the requirements of the digital energy reconstruction system for fast action in microseconds. The present invention adopts a fast power electronic device, an insulated gate bipolar transistor, which is commonly known as IGBT, in a series-parallel manner to achieve rapid switching of battery clusters in the digital energy reconstruction system.

[0036] In this embodiment, refer to Figure 1-Figure 4 , provides a fast switching device based on a digital energy reconstruction system, including a digital energy reconstruction system and a switching circuit;

[0037] The digital energy reconstruction system is responsible for monitoring and managing the operating status of the battery cluster and controlling the on and off of the battery module as needed;

[0038] The switching circuit realizes rapid control of energy exchange between the battery cluster and the power grid through the series and parallel connection of IGBT modules; wherein the positive pole of the switching circuit is connected to the battery cluster part in the digital energy reconstruction system; the negative pole of the switching circuit is connected to the AC bus to realize energy exchange with the power grid.

[0039] In this embodiment, the digital energy reconstruction system includes an energy block and an energy control module, wherein the energy block is a reconfigurable battery network; the energy control module is used to obtain the operating parameters of each battery module in the energy block when the energy block is charging or discharging, and to control the on and off of each battery module by controlling the switch of each battery module in the energy block based on the acquired operating parameters.

[0040] When the energy block needs to discharge, the energy control module controls the opening and closing of the switching circuit according to the status information of the battery module to quickly and accurately transmit the energy in the battery cluster to the grid. When the energy block needs to be charged, the energy of the grid is transmitted to the battery cluster through the opposite process. In the event of a fault, the switching circuit can cut off the electrical connection between the battery side and the grid side within microseconds to protect the system safety.

[0041] In this implementation, the positive pole of the switching loop is connected to the battery block part of the digital energy reconstruction system, namely the BAT side, which includes complex power electronic control devices and software strategies to achieve differentiated inclusion of cascade battery utilization. The negative pole of the switching loop is connected to the AC bus, namely the PCS side, to achieve energy exchange with the grid.

[0042] Figure 1 This is the switching circuit when two IGBTs are connected in parallel. Figure 1 There are four bridge arms in the switching circuit, each of which includes an IGBT module, and the IGBT module includes an insulated gate bipolar transistor and an anti-parallel diode. The insulated gate bipolar transistor has the advantages of low driving power, fast switching speed, small on-state voltage drop and strong current carrying capacity. The anti-parallel diode can make the insulated gate bipolar transistor bidirectionally conductive, and at the same time can also protect the insulated gate bipolar transistor from being broken down by reverse high voltage. The two poles of the switching circuit constitute the two poles of the microsecond switching circuit, which are the positive pole of the switching circuit and the negative pole of the switching circuit.

[0043] The specific working logic of the switching circuit when dual IGBTs are connected in parallel is:

[0044] (1) IGBT modules are connected in parallel to increase current:

[0045] It can be regarded as IGBT module T1 and IGBT module T2 are connected in parallel, and IGBT module T3 and IGBT module T4 are connected in parallel; the current flows from the BAT side to the PCS side, the IGBT module T1 and IGBT module T4 flow through the diode, and the IGBT module T2 and IGBT module T3 flow through the insulated gate bipolar transistor; the current flows from the PCS side to the BAT side, the IGBT module T1 and IGBT module T4 flow through the insulated gate bipolar transistor, and the IGBT module T2 and IGBT module T3 flow through the diode; according to the size of the through-current, the number of IGBT modules to be turned on can be selected. If it is the rated current, all of them are turned on; if the current is lower than a certain value, the IGBT can be partially turned on;

[0046] (3) IGBT modules are connected in series to increase voltage:

[0047] IGBT module T1 and IGBT module T3 are connected in series, and IGBT module T2 and IGBT module T4 are connected in series; the BAT side is connected to the PCS side, which can be regarded as increasing the withstand voltage of the device; the above is a method of increasing the voltage and current of the dual IGBT module parallel switching circuit. According to different operating conditions, the IGBT can be selectively turned on alternately at low current, which reduces system losses and increases the operating life of the IGBT.

[0048] Figure 2 This is the topology diagram of the parallel switching circuit of multiple IGBT modules. Figure 3This is the topology diagram of the multi-IGBT module series-parallel switching circuit. Figure 2 and Figure 3 By connecting IGBT modules in series and in parallel, a higher operating voltage and current can be achieved. The microsecond response speed of the IGBT module can cut off the electrical connection between the BAT side and the PCS side more quickly in the event of a fault. At the same time, combined with precise sampling and control circuits, it can greatly improve the safety of the digital energy reconstruction system under different working conditions.

[0049] By connecting multiple modules in parallel in the current direction, a larger current flow can be achieved, such as Figure 2 As shown. Combined Figure 1 The operating logic shown is to increase the working current by connecting multiple modules in parallel in the current direction. Figure 2 In the n IGBT modules are connected in parallel, and the BAT side and PCS side are each allocated 2 n / 2 IGBT modules (n≥1), at this time the circuit can withstand the current increase in the same proportion.

[0050] As in Figure 1 In the equation, n=1, the maximum current flowing is A;

[0051] Figure 2 In the case of n=2, the maximum current flowing is 2A;

[0052] When n=3 / 4 / 5…, the current flowing increases in the same proportion;

[0053] Figure 2 In the scheme shown, under different current conditions, the IGBT modules can still be partially turned on according to the IGBT module parameters. At the same time, in this topology, the number of IGBT modules is greater, which is more effective in reducing losses and increasing IGBT life.

[0054] In practical applications, to control the number of IGBT modules used at different power levels, it is first necessary to determine the power that each IGBT module or branch can withstand; then, based on the total power demand and power ratio of the system, calculate the number of IGBT modules that need to be used. Specifically, the following steps may be included:

[0055] (1) Determine the power of each branch;

[0056] like Figure 2 As shown, in order to increase the topology flow capacity, 2 are allocated on the BAT side and the PCS side. n / 2 IGBT modules (n≥1), if the system operating power is P, then the power P1 that each branch can withstand is:

[0057] P1=P / (2 n / 2);

[0058] Figure 2 Each branch includes two IGBT switching tubes and two antiparallel diodes.

[0059] (2) Calculate the number of branches of the IGBT module to be put into operation;

[0060] In different power ranges, if the power ratio is m (0 < m ≤ 100%), the number of IGBT branches to be put into operation n1 (1 ≤ n1 ≤ 2 n / 2) can be calculated through the following formula. n1 is the number of IGBT branches that need to be put into operation on both the battery side and the PCS side:

[0061] n1 = mP / P1;

[0062] According to the above formula, if the calculated n1 is 1, that is, the minimum number of branches to be put into operation is 1, that is, 1 branch is put into operation on both the battery side and the PCS side. If the calculated n1 is a non-integer, it is necessary to round up to the nearest integer for branch input to ensure that the power capacity of the IGBT module put into operation is greater than the operating power and avoid IGBT overload damage. In the actual control process, to ensure the power loop, n1 ≥ 1 needs to be set during zero-power operation.

[0063] Combined with Figure 1 and Figure 2 topologies, it is extended to a general topology that can increase voltage and current simultaneously. As Figure 3 shown, by adjusting the number of parallel and series IGBT modules, the voltage and current can be increased in the same proportion.

[0064] In Figure 2 , the current direction can increase the current in the same proportion through the parallel connection of 2 n modules (n ≥ 1). In the vertical voltage direction, the voltage can be increased in the same proportion through the series connection of 2 n IGBT modules (n ≥ 1).

[0065] For example, in Figure 1 , when n = 1, the maximum circulating voltage is U; Figure 3 in n , when n = 2, the maximum operating voltage can be regarded as 2U; when n = 3 / 4 / 5..., the operating voltage increases in the same proportion. That is, through the parallel connection of 2 n modules in the current direction and the series connection of 2 n IGBT modules in the voltage direction, adjust the corresponding proportion according to the actual situation of the project to meet the requirements of the actual operating voltage and current.

[0066] The present invention can replace the traditional switches in the switching and protection functions of the DC system through the series and parallel connection of IGBT modules. The traditional switches, whether contactors or control methods based on switching devices such as thyristors, have a response time of milliseconds, and their response time is extended as the current increases. At the same time, due to technical bottlenecks, in a larger voltage and current environment, there are often no matching conventional products, and the technical parameters of new development or production cannot be guaranteed. The present invention can intelligently control the number of IGBTs invested according to the system capacity, which can effectively reduce losses and increase the life of IGBTs. The present invention is based on the current mainstream fast power electronic device insulated gate bipolar transistor, i.e., IGBT, which can realize the opening and closing of the electrical main circuit of the digital energy reconstruction system in microseconds, and timely protect the system safety.

[0067] Based on the same inventive concept, an embodiment of the present invention also provides a method for realizing a fast switching device based on a digital energy reconstruction system involved in the above-mentioned fast switching device based on a digital energy reconstruction system. The implementation scheme for solving the problem provided by the system is similar to the implementation scheme recorded in the above-mentioned method, so the specific limitations in one or more system embodiments provided below can refer to the above-mentioned limitations on a fast switching device based on a digital energy reconstruction system, and will not be repeated here.

[0068] In one embodiment, a fast switching method based on a digital energy reconstruction system is provided, comprising the following steps:

[0069] The digital energy reconstruction system starts to run, and the energy control module continuously monitors the energy block, that is, the operating parameters of each battery module in the battery cluster, wherein the operating parameters of the battery module include voltage and current;

[0070] According to the operating power P of the digital energy reconstruction system, calculate the power P1 that each branch can bear; according to the required power ratio m, calculate the number of IGBT modules that need to be invested;

[0071] According to the determined number of IGBT modules to be put into use, a corresponding number of IGBT modules are put into use simultaneously on the battery cluster side and the AC bus side;

[0072] By connecting the IGBT modules in series and in parallel, the energy exchange between the battery cluster and the power grid can be quickly controlled.

[0073] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A fast switching device based on a digital energy reconstruction system, characterized in that: Including digital energy reconstruction system and switching circuit; The digital energy reconstruction system is responsible for monitoring and managing the operating status of the battery module and controlling the on and off of the battery module as needed; The switching circuit realizes rapid control of energy exchange between the battery module and the power grid through the series and parallel connection of the IGBT modules.

2. A fast switching device based on a digital energy reconstruction system according to claim 1, characterized in that: The positive pole of the switching circuit is connected to the battery cluster part in the digital energy reconstruction system; the negative pole of the switching circuit is connected to the AC bus to realize energy exchange with the power grid.

3. According to claim 1, a fast switching device based on a digital energy reconstruction system is characterized in that: The digital energy reconstruction system includes an energy block and an energy control module, wherein the energy block is a reconfigurable battery network; the energy control module is used to obtain operating parameters of each battery module in the energy block when the energy block is charging or discharging, and to control the on and off of each battery module by controlling the switch of each battery module in the energy block based on the acquired operating parameters.

4. According to claim 1, a fast switching device based on a digital energy reconstruction system is characterized in that: The IGBT module includes an insulated gate bipolar transistor and an anti-parallel diode.

5. According to claim 1, a fast switching device based on a digital energy reconstruction system is characterized in that: In the digital energy reconstruction system, the control of the number of IGBT modules invested in different power levels includes: 2 is allocated on the battery cluster side and the AC bus side respectively. n / 2 IGBT modules, where n≥1; If the operating power of the digital energy reconstruction system is P, the power P1 that each branch can withstand is: P1=P / (2 n / 2); If the power ratio is m, calculate the number of IGBT branches n1, 1≤n1≤2 n / 2, n1 is the number of IGBT branches that need to be put into use simultaneously on the battery cluster side and the AC bus side: n1=mP / P1.

6. A fast switching device based on a digital energy reconstruction system according to claim 5, characterized in that: If the calculated n1 is not an integer, round it up to the nearest integer and put the branch into operation.

7. A fast switching device based on a digital energy reconstruction system according to claim 1, characterized in that: In the switching circuit, the operating current is increased by connecting the IGBT modules in parallel.

8. The fast switching device based on the digital energy reconstruction system according to claim 1 is characterized in that: In the switching circuit, the operating voltage is increased by connecting IGBT modules in series.

9. A fast switching method based on a digital energy reconstruction system, used to implement a fast switching device based on a digital energy reconstruction system according to any one of claims 1 to 8, characterized in that: The following steps are involved: The digital energy reconstruction system starts to operate, and the energy control module continuously monitors the energy block, that is, the operating parameters of each battery module in the battery cluster; According to the operating power P of the digital energy reconstruction system, calculate the power P1 that each branch can bear; according to the required power ratio m, calculate the number of IGBT modules that need to be invested; According to the determined number of IGBT modules to be put into operation, a corresponding number of branches are put into operation at the battery cluster side and the AC bus side at the same time; By connecting the IGBT modules in series and in parallel, the energy exchange between the battery cluster and the power grid can be quickly controlled.

10. A fast switching method based on a digital energy reconstruction system according to claim 9, characterized in that: The operating parameters of the battery module include voltage and current.

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