Energy storage converter and overcurrent protection control method thereof

Abstract

The invention discloses an energy storage converter and an overcurrent protection control method thereof, and the energy storage converter comprises a DC power distribution module which comprises a DC fuse switch group which comprises a controllable fuse device connected between a DC input side and a DC bus side, the controllable fuse device is used for being controlled to disconnect the electric connection between the direct current input side and the direct current bus side; the current sampling module is connected with the direct current bus side and is used for sampling current flowing through the direct current bus side; and the control sampling module is connected with the current sampling module and the controllable fuse device and is used for controlling the controllable fuse device to be disconnected according to the sampling data of the current sampling module. According to the energy storage converter, when overcurrent occurs in the system, the sampling module is controlled to control the controllable fuse device to be disconnected, electric connection between the direct current input side and the direct current bus side can be rapidly disconnected, and system operation is safer and more reliable.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage converters, and in particular to an energy storage converter and an overcurrent protection control method therefor. Background Art

[0002] With the development of energy storage technology, the requirements for the cost and power density of energy storage systems are getting higher and higher. An energy storage converter (PCS, Power Conversion System) is an important part of an energy storage system. An energy storage converter is a device that controls the charging and discharging processes of a storage battery and performs AC-DC conversion. A fuse is usually integrated in the energy storage converter as a short-circuit protection, which is used to cut off the AC-side energy when the battery is short-circuited or cut off the battery energy when the energy storage converter bus is short-circuited, preventing the expansion of battery faults and ensuring the safety of the energy storage system. In the prior art, an energy storage converter often needs to be used in cooperation with a high-voltage box. Moreover, when the system performs overcurrent protection, the effective time of the fuse in the energy storage converter is relatively long, and the short-circuit peak energy is relatively high during the entire process from when the system detects overcurrent to when the fuse breaks, which easily causes damage to the internal materials or devices of the battery and brings potential safety hazards. Summary of the Invention

[0003] An embodiment of the present invention provides an energy storage converter and an overcurrent protection control method therefor, aiming to solve the problem that the effective time of the fuse is long during overcurrent protection of the existing energy storage converter.

[0004] In a first aspect, an embodiment of the present invention provides an energy storage converter, which includes:

[0005] A DC power distribution module, including a DC fuse switch group, the DC fuse switch group includes a controllable fuse device connected between a DC input side and a DC bus side, and the controllable fuse device is used to controllably disconnect the electrical connection between the DC input side and the DC bus side;

[0006] A current sampling module, connected to the DC bus side, for sampling the current flowing through the DC bus side;

[0007] A control sampling module, connected to the current sampling module and the controllable fuse device, for controlling the controllable fuse device to break according to the sampling data of the current sampling module.

[0008] In the energy storage converter provided by the embodiment of the present invention, the DC fuse switch group further includes a passive fuse device, and one of the controllable fuse device and the passive fuse device is connected between the positive pole of the DC input side and the positive pole of the DC bus side, and the other one is connected between the negative pole of the DC input side and the negative pole of the DC bus side.

[0009] In the energy storage converter provided by the embodiment of the present invention, the DC power distribution module further includes a mechanical on-off switch group, and the mechanical on-off switch group is connected between the DC input side and the DC fuse switch group. Among them, the mechanical on-off switch group is used to manually turn on and off the electrical connection between the DC input side and the DC bus side.

[0010] In the energy storage converter provided by the embodiment of the present invention, the mechanical on-off switch group includes a first disconnecting switch and a second disconnecting switch. The first disconnecting switch and the second disconnecting switch are respectively connected to the positive and negative poles of the DC input side, and both the controllable fusing device and the passive fusing device are respectively connected after the first disconnecting switch and the second disconnecting switch.

[0011] In the energy storage converter provided by the embodiment of the present invention, the DC power distribution module further includes a controlled on-off switch group, and the controlled on-off switch group is connected between the DC fuse switch group and the DC bus side. Among them, the controlled on-off switch group is used to turn on and off the electrical connection from the DC input side to the DC bus side under the control of the control and sampling module.

[0012] In the energy storage converter provided by the embodiment of the present invention, the controlled on-off switch group includes a first DC contactor and a second DC contactor. The first DC contactor is connected between the controllable fusing device and the DC bus side, and the second DC contactor is connected between the passive fusing device and the DC bus side. The control and sampling module is connected to the first DC contactor and the second DC contactor.

[0013] In the energy storage converter provided by the embodiment of the present invention, the control and sampling module includes a conversion unit, a comparison unit, and a trigger unit. The conversion unit is connected between the current sampling module and the comparison unit, and the trigger unit is connected to the comparison unit and the controllable fusing device. Among them, the conversion unit is used to convert the current sampled by the current sampling module into a comparison electrical signal, the comparison unit is used to calculate a comparison result based on the comparison electrical signal, and the trigger unit enables and drives the controllable fusing device to trip according to the comparison result.

[0014] In the energy storage converter provided by the embodiment of the present invention, the DC power distribution module further includes an EMC filtering unit, and the EMC filtering unit is connected between the DC input side and the DC fuse switch group. Among them, the EMC filtering unit is used to filter the current on the DC input side.

[0015] Second aspect, an embodiment of the present invention provides an overcurrent protection control method for an energy storage converter, which is applied to the energy storage converter described in the first aspect above. The method includes: obtaining the current on the DC bus side; comparing the current on the DC bus side with a preset threshold to obtain a detection result; when the detection result indicates overcurrent, controlling the controllable fusing device to disconnect the electrical connection between the DC input side and the DC bus side.

[0016] An embodiment of the present invention provides an energy storage converter and its overcurrent protection control method. The energy storage converter includes: a DC power distribution module, including a DC fuse switch group, the DC fuse switch group includes a controllable fusing device connected between the DC input side and the DC bus side, and the controllable fusing device is used to controllably disconnect the electrical connection between the DC input side and the DC bus side; a current sampling module, connected to the DC bus side, for sampling the current flowing through the DC bus side; a control sampling module, connected to the current sampling module and the controllable fusing device, for controlling the controllable fusing device to trip according to the sampling data of the current sampling module. The energy storage converter of the present application, through the combined cooperation of the current sampling module, the controllable fusing device, and the control sampling module, the control sampling module can control the controllable fuse to trip to quickly disconnect the electrical connection between the DC input side and the DC bus side when the current sampling module detects overcurrent, so as to prevent the expansion of the fault and make the system operation safer and more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a schematic structural diagram of the energy storage converter provided by the embodiment of the present invention;

[0019] Figure 2 It is a schematic structural diagram of the energy storage converter in an application scenario provided by the embodiment of the present invention;

[0020] Figure 3 It is a schematic flow chart of the steps of the method provided by the embodiment of the present invention;

[0021] Figure 4 It is a schematic flow chart of the sub-steps of the method provided by the embodiment of the present invention.

[0022] The reference numerals in the figures are as follows:

[0023] 10. DC power distribution module; 11. DC fuse switch group; 12. Mechanical on-off switch group; 13. Controlled on-off switch group; 20. Current sampling module; 30. Control sampling module; 31. Conversion unit; 32. Comparison unit; 33. Trigger unit; 40. DC soft start unit; 50. EMC filtering unit; 60. Power conversion module. Detailed implementation manners

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] The directional terms mentioned in the present invention, such as "upper", "lower", "front", "rear", "left", "right", "inner", "outer", "side", etc., are only references to the directions in the attached drawings. Therefore, the directional terms used are for explaining and understanding the present invention, rather than for limiting the present invention. In addition, in the drawings, structures that are similar or identical are denoted by the same reference numerals.

[0026] An energy storage converter is proposed in an embodiment of the present invention to solve the problem that the existing energy storage converter needs to be used in cooperation with a high-voltage box, resulting in a low system power density. The specific idea is as follows:

[0027] The overall energy storage converter includes a DC power distribution module 10, a current sampling module 20, and a control sampling module 30; the DC power distribution module 10 includes a DC fuse switch group 11, and the DC fuse switch group 11 includes a controllable fuse device connected between the DC input side and the DC bus side. The controllable fuse device is used to controllably disconnect the electrical connection between the DC input side and the DC bus side; the current sampling module 20 is connected to the DC bus side and is used to sample the current flowing through the DC bus side; the control sampling module 30 is connected to the current sampling module 20 and the controllable fuse device, and is used to control the controllable fuse device to trip according to the sampling data of the current sampling module 20.

[0028] To better understand the above technical solutions, the above technical solutions will be described in detail below with reference to the accompanying drawings of the specification and specific implementation manners.

[0029] The existing energy storage converter usually needs to be used in cooperation with a high-voltage box in the application of the energy storage system. The current of the battery comes out of the high-voltage box and then is connected to the energy storage converter. The independent high-voltage box not only occupies most of the space of the energy storage system, but also some of the switching devices in the high-voltage box have the same functions as the switching devices in the energy storage converter, resulting in a low overall power density of the energy storage system and a high system operation cost.

[0030] Please refer to Figure 1 and Figure 2 , the energy storage converter of the present application mainly includes a DC power distribution module 10, a current sampling module 20, and a control sampling module 30. In addition, it may also include a power conversion module 60 for realizing power conversion. The DC power distribution module 10 is one of the core components of the energy storage converter, which is mainly connected between the DC input side and the DC bus side. The electrical energy on the DC input side is transmitted to the DC bus side through the DC power distribution module 10. The DC power distribution module 10 includes a DC fuse switch group 11, which is composed of at least one controllable fuse device. The controllable fuse device is connected between the DC input side and the DC bus side, specifically, it can be connected between the positive pole of the DC input side and the positive pole of the DC bus side, or it can be connected between the negative pole of the DC input side and the negative pole of the DC bus side, such as Figure 1 and Figure 2As shown, at least one of K1 and K2 is a controlled fusing device. The DC input side is usually an energy storage device (such as a battery module) or a renewable energy power generation device (such as a photovoltaic array) connected to the energy storage converter, which is used to provide DC electrical energy. The DC bus side is the circuit on one side of the power conversion module 60, which is used to convert DC electrical energy into AC electrical energy and transmit it to the load or the power grid. The controlled fusing device is used to be controlled to quickly disconnect the circuit in case of abnormal conditions (such as overload or short circuit) to protect the system safety. The controlled fusing device can adopt circuit breakers with controllable breaking functions such as intelligent circuit breakers, electronic fuses (eFuses), and hybrid fuses. Compared with the passive breaking type of circuit breakers, the controlled fusing device has a faster breaking response speed. The process from receiving the control signal to breaking is usually in milliseconds, and it has better advantages in the overcurrent protection of the system. The current sampling module 20 is connected to the DC bus side and is used to sample the current flowing through the DC bus side, and can monitor the current flowing through the DC bus side in real time. This module is composed of a high-precision current sensor (such as a current Hall) and a signal conditioning circuit. The control sampling module 30 is connected to the current sampling module 20 and the controlled fusing device. The control sampling module 30 is the control core of the energy storage converter, responsible for receiving the sampling data of the current sampling module 20 and controlling the operation of the controlled fusing device according to the preset protection logic. The control sampling module 30 can control the controlled fusing device to break according to the sampling data of the current sampling module 20. Specifically, in the case of overcurrent or open circuit on the DC bus side, the control sampling module 30 controls the controlled fusing device to break, so that the power transmission loop of the system is disconnected to protect the system safety. In practical applications, the current sampling module 20 samples the current on the DC bus side in real time and sends the sampling data to the control sampling module 30. The control sampling module 30 compares the sampling data of the current with the set threshold and controls the controlled fusing device according to the comparison result. When the system is working normally, the current sampling module 20 monitors the current on the DC bus side in real time and transmits the data to the control sampling module 30. The control sampling module 30 determines that the current value is within the normal range and does not trigger any protection actions. When there is an overload or short circuit in the circuit of the system, the current in the power transmission loop increases, and the current on the DC bus side increases. The current sampling module 20 detects the abnormal current on the DC bus side. The control sampling module 30 compares the current with the preset threshold according to the preset protection logic and determines that the system has overcurrent and needs to disconnect the circuit. The control sampling module 30 sends a disconnection signal to the controlled fusing device to make it quickly break and disconnect the electrical connection between the DC input side and the DC bus side, preventing the fault from expanding. When the fault is eliminated, the system is restored to normal through the maintenance by the system operator. Thus, the energy storage converter can more reliably achieve the protection of the energy storage system by cooperating with the protection logic and improve the safety of the energy storage system.

[0031] Furthermore, the controllable fusing device adopts an intelligent circuit breaker with a reset function. Compared with an ordinary circuit breaker, it not only has a fast breaking response speed but also can be re-enabled by a reset or reset button after being triggered. In practical applications, when an overcurrent occurs in the system, the controllable fusing device quickly breaks to achieve system protection. After the system fault is eliminated and the repair is completed, the system operator can manually reset the controllable fusing device to restore the normal operation of the system without replacing the circuit-breaking device, which not only facilitates the restoration after system fault repair but also saves costs.

[0032] In one embodiment, referring to Figure 1 and Figure 2 , the DC fusing switch group 11 further includes a passive fusing device. One of the controllable fusing device and the passive fusing device is connected between the positive pole of the DC input side and the positive pole of the DC bus side, and the other one is connected between the negative pole of the DC input side and the negative pole of the DC bus side. In a specific implementation, the DC fusing switch group 11 further includes a passive fusing device, that is, the DC fusing switch group 11 is composed of a controllable fusing device and a passive fusing device. One of the controllable fusing device and the passive fusing device is connected between the positive pole of the DC input side and the positive pole of the DC bus side, and the other one is connected between the negative pole of the DC input side and the negative pole of the DC bus side. As shown in Figure 1 and Figure 2 , one of K1 and K2 is a controlled fusing device and the other one is a passive fusing device. In this embodiment, taking the case where the controllable fusing device is connected between the positive pole of the DC input side and the positive pole of the DC bus side, and the passive fusing device is connected between the negative pole of the DC input side and the negative pole of the DC bus side as an example, that is, K1 is the controlled fusing device and K2 is the passive fusing device in this embodiment. The passive fusing device does not require a control source to control the breaking action, and it realizes circuit breaking based on thermal accumulation fusing. The passive fusing device can adopt devices such as a thermal fuse and a fuse. The passive fusing device in this embodiment specifically adopts a thermal fuse. The fusing time of the passive fusing device is slower than that of the controllable fusing device, but the passive fusing device breaks based on the thermal effect. In the case of a fault in the control circuit part or the failure of the controllable fusing device, the passive fusing device can be used as a backup protection, which can reduce the system cost and further improve the safety of the energy storage system.

[0033] Furthermore, referring to Figure 1 and Figure 2, the DC power distribution module 10 further includes a mechanical on-off switch group 12, which is connected between the DC input side and the DC fuse switch group 11. Among them, the mechanical on-off switch group 12 is used to manually turn on and off the electrical connection between the DC input side and the DC bus side. In a specific implementation, the DC power distribution module 10 further includes a mechanical on-off switch group 12, which is connected between the DC input side and the DC fuse switch group 11, and can be specifically connected before the DC fuse switch group 11. It is used to manually turn on and off the electrical connection between the DC input side and the DC bus side. The mechanical on-off switch group 12 is usually composed of mechanical switches, usually isolating switches (knife switches). In the case of system anomalies (such as overload or short circuit), if the DC fuse switch group 11 is damaged and fails or the control circuit fails, system operators can directly manually disconnect the circuit through the mechanical on-off switch group 12 to protect the system safety manually and further improve the system security.

[0034] Furthermore, referring to Figure 1 and Figure 2 , the mechanical on-off switch group 12 includes a first isolating switch K3 and a second isolating switch K4. The first isolating switch K3 and the second isolating switch K4 are respectively connected to the positive and negative poles of the DC input side, and both the controllable fusing device and the passive fusing device are respectively connected after the first isolating switch K3 and the second isolating switch K4. In a specific implementation, the mechanical on-off switch group 12 is mainly composed of a first isolating switch K3 and a second isolating switch K4. The first isolating switch K3 is connected between the positive pole of the DC input side and the positive pole of the DC bus side, serving as a manual switch on the positive pole circuit of the system to manually disconnect the positive pole circuit of the system. The second isolating switch K4 is connected between the negative pole of the DC input side and the negative pole of the DC bus side, serving as a manual switch on the negative pole circuit of the system to manually disconnect the negative pole circuit of the system. In practical applications, in the case of system anomalies (such as overload or short circuit), if the DC fuse switch group 11 is damaged and fails or the control circuit fails, system operators can directly manually disconnect the circuit through the first isolating switch K3 and the second isolating switch K4 respectively to improve the system security.

[0035] In an embodiment, referring to Figure 1 and Figure 2, the DC power distribution module 10 further includes a controlled on-off switch group 13, which is connected between the DC fuse switch group 11 and the DC bus side. Among them, the controlled on-off switch group 13 is used to turn on and off the electrical connection from the DC input side to the DC bus side under the control of the control and sampling module 30. In a specific implementation, the DC power distribution module 10 further includes a controlled on-off switch group 13, which is connected between the DC fuse switch group 11 and the DC bus side, and is used to turn on and off the electrical connection from the DC input side to the DC bus side under the control of the control and sampling module 30. The controlled on-off switch group 13 is usually composed of an electric control switch, such as a DC contactor, a relay, etc. In practical applications, in the case of system abnormalities (such as overload or short circuit), if the DC fuse switch group 11 is damaged and fails, the control and sampling module 30 can issue a control signal through the cooperation of the control logic to turn off the circuit by the electrically controlled on-off switch group 13, further improving the safety of the system.

[0036] Further, referring to Figure 1 and Figure 2 , the controlled on-off switch group 13 includes a first DC contactor K5 and a second DC contactor K6. The first DC contactor K5 is connected between the controllable fuse device and the DC bus side, and the second DC contactor K6 is connected between the passive fuse device and the DC bus side. The control and sampling module 30 is connected to the first DC contactor K5 and the second DC contactor K6. In a specific implementation, the controlled on-off switch group 13 is mainly composed of a first DC contactor K5 and a second DC contactor K6. The first DC contactor K5 is connected between the positive output of the DC fuse switch group 11 and the positive pole of the DC bus side. As an electric control switch on the positive pole loop of the system, it can turn on and off the positive pole loop of the system under the control of the control and sampling module 30. The second DC contactor K6 is connected between the negative output of the DC fuse switch group 11 and the negative pole of the DC bus side. As an electric control switch on the negative pole loop of the system, it can turn on and off the negative pole loop of the system under the control of the control and sampling module 30. In practical applications, in the case of system abnormalities (such as overload or short circuit), if the DC fuse switch group 11 is damaged and fails, the control and sampling module 30 can issue a control signal through the cooperation of the control logic to turn off the circuit by the first DC contactor K5 and the second DC contactor K6 respectively, improving the safety of the system.

[0037] Even further, referring to Figure 1 and Figure 2, the DC power distribution module 10 further includes a DC soft start unit 40, and the DC soft start unit 40 is connected to at least one of the first DC contactor K5 and the second DC contactor K6. Among them, the DC soft start unit 40 is used to softly start the on / off of the first DC contactor K5 and the second DC contactor K6. In a specific implementation, the DC power distribution module 10 further includes a DC soft start unit 40, and the DC soft start unit 40 is connected to at least one of the first DC contactor K5 and the second DC contactor K6. In this embodiment, the DC soft start unit 40 is connected to the first DC contactor K5 as an example. In other embodiments, the DC soft start unit 40 can be connected to the second DC contactor K6. Since the first DC contactor K5 and the second DC contactor K6 are switching devices directly connected to the DC bus side, when the first DC contactor K5 or the second DC contactor K6 makes an on / off action, the inrush current is relatively large, and the DC soft start unit 40 can reduce the inrush current and achieve the soft start of the first DC contactor K5 or the second DC contactor K6. The DC soft start unit 40 is specifically designed using a capacitor and an inductor. Usually, the capacitor is connected in parallel at the input and output terminals of the first DC contactor K5 or the input and output terminals of the second DC contactor K6, and the inductor is connected in series between the output terminal of the first DC contactor K5 and the DC bus side. In practical applications, the DC fuse switch group 11 is in a conducting state. When the system is powered on, the first DC contactor K5 or the second DC contactor K6 is default in an off state. The current passes through the DC soft start unit 40 after passing through the DC fuse switch group 11 and is input to the DC bus side to charge the DC bus. Limited by the DC soft start unit 40, the charging current will not be too large. When the voltages on both sides are basically the same, the control and sampling module 30 then controls the first DC contactor K5 and the second DC contactor K6 to conduct, ensuring that the inrush currents of the first DC contactor K5 and the second DC contactor K6 are at a relatively low level, and the first DC contactor K5 and the second DC contactor K6 will not be damaged, improving the reliability of the system.

[0038] In one embodiment, referring to Figure 1 and Figure 2, the control sampling module 30 includes a conversion unit 31, a comparison unit 32, and a trigger unit 33. The conversion unit 31 is connected to the current sampling module 20 and the comparison unit 32, and the trigger unit 33 is connected to the comparison unit 32 and the controllable fusing device. Among them, the conversion unit 31 is used to convert the current sampled by the current sampling module 20 into a comparison electrical signal, the comparison unit 32 is used to calculate a comparison result based on the comparison electrical signal, and the trigger unit 33 enables and drives the controllable fusing device to trip according to the comparison result. In a specific implementation, the control sampling module 30 is mainly composed of a conversion unit 31, a comparison unit 32, and a trigger unit 33. In addition, it also includes other control sampling circuit units. The conversion unit 31 is connected to the current sampling module 20 and the comparison unit 32. The conversion unit 31 can specifically be a circuit for current-voltage conversion. The conversion unit 31 can convert the current sampled by the current sampling module 20 into a comparison electrical signal and send it to the comparison unit 32. The comparison electrical signal is specifically a voltage signal. The comparison unit 32 can calculate a comparison result based on the comparison electrical signal. The trigger unit 33 is connected to the comparison unit 32 and the controllable fusing device. The trigger unit 33 can send an enabling signal to the controllable fusing device according to the comparison result calculated by the comparison unit 32 to enable it, thereby driving the controllable fusing device to trip. In practical applications, through the joint cooperation of the conversion unit 31, the comparison unit 32, and the trigger unit 33, the reliability protection of the system can be achieved, and the safety of the system can be improved.

[0039] In one embodiment, referring to Figure 1 and Figure 2 , the DC power distribution module 10 further includes an EMC filtering unit 50. The EMC filtering unit 50 is connected between the DC input side and the DC fuse switch group 11. Among them, the EMC filtering unit 50 is used to filter the current on the DC input side. In a specific implementation, the DC power distribution module 10 further includes an EMC filtering unit 50. The EMC filtering unit 50 is connected between the DC input side and the DC fuse switch group 11. As the pre-stage circuit of the DC fuse switch group 11, the EMC filtering unit 50 is usually designed with components such as inductors and capacitors to filter the current on the DC input side. Its working principle mainly includes common-mode filtering and differential-mode filtering, suppressing electromagnetic interference of the post-stage circuit on the DC input side, improving electromagnetic compatibility, and making the system operation more reliable.

[0040] The energy storage converter provided by the embodiment of the present application integrally incorporates the corresponding power distribution switch devices of the high-voltage box, and can achieve power distribution output without externally connecting a high-voltage box, improving the power density of the energy storage system, reducing the operating cost of the energy storage system, and through the combined cooperation of the current sampling module, the controllable fuse device, and the control sampling module, the control sampling module can, when the current sampling module detects overcurrent, control the controllable fuse to break and quickly disconnect the electrical connection between the DC input side and the DC bus side to prevent the expansion of the fault, making the system operation safer and more reliable.

[0041] As Figure 3 shown, the present application provides an overcurrent protection control method for an energy storage converter. The method is applied to the energy storage converter described in the above embodiment, and the method includes steps: S110 - S130.

[0042] S110. Obtain the current on the DC bus side.

[0043] In specific implementation, the DC input side of the energy storage converter is usually connected to a battery module or a photovoltaic power generation module, and the electric energy generated by the battery module or the photovoltaic power generation module is distributed to a load or the power grid through the energy storage converter. When the energy storage converter is operating, it samples the current on the DC bus side in real time through the current sampling module, so as to obtain the current on the DC bus side in the energy storage converter in real time, and then compare it by the control sampling module. Specifically, when a short-circuit fault occurs between the battery module or the photovoltaic power generation module and the energy storage converter, or a short-circuit fault occurs inside the energy storage converter, or an overload or short-circuit occurs between the energy storage converter and the power grid or the load, the current on the DC bus side in the energy storage converter will increase, and the control sampling module judges whether the system has an overcurrent according to the change of the current on the DC bus side.

[0044] S120. Compare the current on the DC bus side with a preset threshold to obtain a detection result.

[0045] In specific implementation, the control sampling module obtains a detection result by comparing the current on the DC bus side with a preset threshold. Specifically, the preset threshold is the minimum current value in the overcurrent state of the system. Taking the preset threshold as the judgment standard for overcurrent, it judges whether the system meets the overcurrent condition, and further judges whether the system has an overcurrent, so as to obtain a detection result and take corresponding overcurrent protection measures according to the detection result.

[0046] In one embodiment, as Figure 4 shown, the step S120 includes steps S121 - S123.

[0047] S121. Compare the current on the DC bus side with a charging direction protection threshold and a discharging direction protection threshold.

[0048] In specific implementation, when the system is in the charging state, the energy storage converter converts the alternating current in the power grid into direct current and stores it in the battery module or other energy storage devices connected to the DC input side. In this state, the current on the DC bus side of the energy storage converter is the charging current. When the system is in the discharging state, the energy storage converter converts the direct current stored in the battery module into alternating current and supplies it to the power grid or load for use. During this process, the current on the DC bus side of the energy storage converter is the discharging current. When the energy storage converter is operating, it compares the current on the DC bus side with the charging direction protection threshold and the discharging direction protection threshold through the control sampling module. The charging direction protection threshold is the minimum overcurrent in the charging state of the system, and the discharging direction protection threshold is the minimum overcurrent in the discharging state of the system. Using the charging direction protection threshold and the discharging direction protection threshold as the judgment criteria for overcurrent in the charging and discharging states respectively, it is determined whether overcurrent occurs in the charging and discharging states of the system, and then the detection result is obtained to take corresponding overcurrent protection measures according to the detection result, realizing overcurrent protection in both the charging and discharging states of the system.

[0049] S122. Determine whether the current on the DC bus side is greater than the charging direction protection threshold or greater than the discharging direction protection threshold.

[0050] In specific implementation, the energy storage converter compares the current on the DC bus side with the charging direction protection threshold and the discharging direction protection threshold through the control sampling module. When the system is in the charging state, it takes the current on the DC bus side being greater than the charging direction protection threshold as a necessary condition for determining that the system has overcurrent. When the system is in the discharging state, it takes the current on the DC bus side being greater than the discharging direction protection threshold as a necessary condition for determining that the system has overcurrent.

[0051] S123. If the current on the DC bus side is greater than the charging direction protection threshold or greater than the discharging direction protection threshold, then determine that the detection result is overcurrent.

[0052] In specific implementation, when the current of the DC bus is greater than the charging direction protection threshold, it indicates that the current on the DC bus side is too large in the charging state of the system. The control sampling module determines that the system has overcurrent and the charging of the system is abnormal. It is necessary to promptly disconnect the electrical connection between the DC input side and the DC bus side to ensure the safety of the system. Similarly, when the current of the DC bus is greater than the discharging direction protection threshold, it indicates that the current on the DC bus side is too large in the discharging state of the system. The control sampling module determines that the detection result is overcurrent and the discharging of the system is abnormal. It is necessary to promptly disconnect the electrical connection between the DC input side and the DC bus side to ensure the safety of the system.

[0053] S130. When the detection result is overcurrent, control the controllable fusing device to disconnect the electrical connection between the DC input side and the DC bus side.

[0054] In specific implementation, the control sampling module compares the current on the DC bus side with a preset threshold value, and determines whether an overcurrent occurs in the system according to the comparison result. If the detection result is overcurrent, it indicates that the system is abnormal, which may be caused by a short-circuit fault between the battery module or the photovoltaic power generation module and the energy storage converter, or by a short-circuit fault inside the energy storage converter, or by an overload or short-circuit between the energy storage converter and the power grid or load. When the detection result is overcurrent, the energy storage converter controls the controllable fusing device to directly disconnect the electrical connection between the DC input side and the DC bus side through the control sampling module. The disconnection time of the electrical connection between the DC input side and the DC bus side can be achieved within 1 ms, effectively avoiding the system catching fire due to overcurrent and improving the safety of the system.

[0055] The method provided by the embodiment of the present application obtains the current on the DC bus side, compares the current on the DC bus side with a preset threshold value to obtain a detection result, and when the detection result is overcurrent, controls the controllable fusing device to disconnect the electrical connection between the DC input side and the DC bus side. In the case of overcurrent in the system, the electrical connection between the DC input side and the DC bus side of the energy storage converter can be quickly disconnected, improving the safety and reliability of the system.

[0056] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An energy storage converter, characterized in that: include: A DC power distribution module, comprising a DC fuse switch group, wherein the DC fuse switch group comprises a controllable fuse device connected between a DC input side and a DC bus side, wherein the controllable fuse device is used to controllably disconnect the electrical connection between the DC input side and the DC bus side; A current sampling module, connected to the DC bus side, and used to sample the current flowing through the DC bus side; A control sampling module is connected to the current sampling module and the controllable fuse device, and is used to control the controllable fuse device to disconnect according to the sampling data of the current sampling module.

2. The energy storage converter according to claim 1, characterized in that: The DC fuse switch group also includes a passive fuse device, one of the controllable fuse device and the passive fuse device is connected between the positive pole of the DC input side and the positive pole of the DC bus side, and the other is connected between the negative pole of the DC input side and the negative pole of the DC bus side.

3. The energy storage converter according to claim 2, characterized in that: The DC power distribution module also includes a mechanical on-off switch group, which is connected between the DC input side and the DC fuse switch group, wherein the mechanical on-off switch group is used to manually switch on and off the electrical connection between the DC input side and the DC bus side.

4. The energy storage converter according to claim 3, characterized in that: The mechanical on-off switch group includes a first isolating switch and a second isolating switch, wherein the first isolating switch and the second isolating switch are respectively connected to the positive pole and the negative pole of the DC input side, and the controllable fuse device and the passive fuse device are respectively connected after the first isolating switch and the second isolating switch.

5. The energy storage converter according to claim 2, characterized in that: The DC power distribution module also includes a controlled on-off switch group, which is connected between the DC fuse switch group and the DC bus side, wherein the controlled on-off switch group is used to switch on and off the electrical connection from the DC input side to the DC bus side under the control of the control sampling module.

6. The energy storage converter according to claim 5, characterized in that: The controlled on-off switch group includes a first DC contactor and a second DC contactor, the first DC contactor is connected between the controllable fuse device and the DC bus side, the second DC contactor is connected between the passive fuse device and the DC bus side, and the control sampling module connects the first DC contactor and the second DC contactor.

7. The energy storage converter according to any one of claims 1 to 6, characterized in that: The control sampling module includes a conversion unit, a comparison unit and a trigger unit, wherein the conversion unit is connected to the current sampling module and the comparison unit, and the trigger unit is connected to the comparison unit and the controllable fuse device, wherein the conversion unit is used to convert the current sampled by the current sampling module into a comparison electrical signal, the comparison unit is used to calculate a comparison result based on the comparison electrical signal, and the trigger unit enables driving the controllable fuse device to disconnect based on the comparison result.

8. The energy storage converter according to any one of claims 1 to 6, characterized in that: The DC power distribution module further includes an EMC filter unit, which is connected between the DC input side and the DC fuse switch group, wherein the EMC filter unit is used to filter the current on the DC input side.

9. An overcurrent protection control method for an energy storage converter, applied to the energy storage converter according to any one of claims 1 to 8, characterized in that: The method comprises: Get the current on the DC bus side; Comparing the current on the DC bus side with a preset threshold to obtain a detection result; When the detection result is overcurrent, the controllable fuse device is controlled to disconnect the electrical connection between the DC input side and the DC bus side.

10. The method according to claim 9, characterized in that The step of comparing the current on the DC bus side with a preset threshold to obtain a detection result comprises: Comparing the current on the DC bus side with a charging direction protection threshold and a discharging direction protection threshold; Determine whether the current on the DC bus side is greater than the charging direction protection threshold or greater than the discharging direction protection threshold; If the current on the DC bus side is greater than the charging direction protection threshold or greater than the discharging direction protection threshold, the detection result is determined to be overcurrent.

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