Overvoltage protection circuit for high-capacity capacitor of energy storage equipment

Abstract

The invention discloses a high-capacity capacitor overvoltage protection circuit of energy storage equipment, which comprises an overvoltage detection unit, a control unit, a protection execution unit and at least one group of capacitor units, and is characterized in that the overvoltage detection unit is used for monitoring the voltage of the capacitor units in real time; the control unit judges whether the voltage information exceeds a preset overvoltage threshold value or not according to the voltage information provided by the overvoltage detection unit; the protection execution unit is used for executing protection measures when the control unit judges that the voltage exceeds the preset overvoltage threshold value; the protection execution unit is used for realizing safe discharge of the capacitor unit, the protection execution unit further comprises at least one energy transfer unit, and the energy transfer unit is used for transferring electric energy under the overvoltage condition; the scheme has the remarkable beneficial effects of improving the safety and stability of the power system, prolonging the service life of the capacitor, reducing the maintenance cost, enhancing the flexibility of the power system and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of electrical equipment protection, and in particular relates to an overvoltage protection circuit for a large-capacity capacitor of an energy storage device. Background Art

[0002] Battery Energy Storage System (BESS) is a system that uses batteries as energy storage carriers to store and supply electrical energy for a certain period of time. With the rapid development of the new energy industry, battery energy storage technology has become an important part of the energy field. Battery energy storage systems have broad application prospects in many fields. Battery energy storage systems can balance the peak and valley power of the power system, improve the stability of the power grid, reduce power grid losses, and reduce energy costs. In the event of sudden power failures or power outages, it can also serve as a backup power source to provide emergency power support for cities and industrial areas. Battery energy storage systems can be combined with distributed energy systems such as photovoltaic power generation and wind power generation to balance energy supply and demand and improve the utilization rate of distributed energy. Battery energy storage systems are also an important source of power for portable electronic devices such as smartphones, tablets, and laptops.

[0003] The working principle of the battery energy storage system in the prior art is mainly based on the charging and discharging process of the battery. During the charging process, an external power source applies voltage to the battery, which increases the chemical energy inside the battery, and the electrical energy is converted into chemical energy and stored in the battery. During the discharge process, the chemical energy inside the battery is converted back into electrical energy and released through an external circuit. The battery energy storage system is mainly composed of the following parts: battery system, which includes battery cells, battery modules, battery racks / clusters, etc.; power conversion system, which is the energy storage converter, is a bidirectional DC-AC inverter; battery management system, which is responsible for the intelligent management and maintenance of each battery unit; however, the overvoltage protection scheme of the prior art is not reasonably set, and when an overvoltage fault occurs, it is easy to cause the energy storage equipment to be damaged due to the fault, and the fault range is large.

[0004] Therefore, the present invention provides a large-capacity capacitor overvoltage protection circuit for energy storage equipment, which is used to solve the problems raised by the above background technology. Summary of the invention

[0005] In view of the problems raised by the above background technology, the purpose of the present invention is to provide a large-capacity capacitor overvoltage protection circuit for energy storage equipment.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0007] A large-capacity capacitor overvoltage protection circuit for an energy storage device comprises an overvoltage detection unit, a control unit and a protection execution unit, and also comprises at least one group of capacitor units, wherein the overvoltage detection unit is used to monitor the voltage of the capacitor unit in real time, and the control unit determines whether the voltage exceeds a preset overvoltage threshold value based on the voltage information provided by the overvoltage detection unit; the protection execution unit is used to execute protection measures when the control unit determines that the voltage exceeds the preset overvoltage threshold value; the protection execution unit is used to realize the safe discharge of the capacitor unit, and the protection execution unit also comprises at least one energy transfer unit, and the energy transfer unit is used to transfer electric energy in the case of overvoltage.

[0008] It is further defined that each capacitor unit includes at least one capacitor, the protection execution unit includes at least one discharge resistor, relay or MOS tube, and the energy transfer unit transfers electrical energy to a safe storage or consumption device in the event of an overvoltage.

[0009] It is further defined that the protection measures include power cut-off, discharge or energy transfer.

[0010] It is further defined that the plurality of groups of large capacitor units are connected in series or in parallel. Such a design can meet different energy storage requirements.

[0011] It is further defined that the overvoltage detection unit includes at least one voltage sensor for collecting a voltage signal of the capacitor unit in real time and transmitting it to the control unit.

[0012] It is further defined that the control unit includes a microprocessor or a programmable logic controller, which is used to process the voltage signal according to a preset algorithm and issue a control instruction to the protection execution unit.

[0013] It is further defined that the protection execution unit further includes a voltage limiting diode, which is connected in parallel across the capacitor, and when the capacitor voltage exceeds a threshold of the voltage limiting diode, the diode is turned on. Such a design can limit the further increase of the capacitor voltage.

[0014] It is further defined that it also includes an energy recovery unit, wherein the energy recovery unit is used to recover electric energy during the discharge process of the capacitor and store it in a backup power supply or return it to the power grid.

[0015] Further defined, also includes an overvoltage protection method, comprising the following steps:

[0016] Step 1: real-time monitoring of the voltage of the capacitor unit by the overvoltage detection unit;

[0017] Step 2: The control unit receives the voltage signal and determines whether it exceeds the overvoltage threshold according to a preset algorithm; specifically, the preset algorithm includes a comparison algorithm, a difference algorithm or a slope algorithm;

[0018] Step 3: If the voltage exceeds the threshold, the control unit sends a control instruction to the protection execution unit;

[0019] Step 4: The protection execution unit executes corresponding protection measures according to the control instruction, including cutting off power supply, discharging or energy transfer.

[0020] Further defined, in step 4, if a discharge measure is taken, the discharge process is implemented through a discharge resistor, a relay or a MOS tube. Such a design can ensure that the capacitor is safely discharged to a safe voltage level.

[0021] Beneficial effects of the present invention:

[0022] The present invention provides a large-capacity capacitor overvoltage protection circuit for energy storage equipment. Through timely overvoltage protection, the capacitor is prevented from being damaged by overvoltage, thereby avoiding possible power accidents and improving the safety of the power system. Through reasonable group voltage regulation and equipment adjustment strategies, it helps to maintain the voltage stability of the power system, ensure the normal operation of large-capacity capacitors, and improve the stability of the power system. Through effective overvoltage protection, the voltage shock to the capacitor is reduced, thereby extending its service life. Through real-time monitoring and control, potential safety hazards can be discovered and handled in a timely manner, reducing downtime and maintenance costs caused by capacitor damage.

[0023] In summary, this solution has significant beneficial effects in improving the safety and stability of the power system, extending the service life of capacitors, reducing maintenance costs, and enhancing the flexibility of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention can be further illustrated by the non-limiting examples given in the accompanying drawings;

[0025] Figure 1 A system module diagram of an embodiment of a large-capacity capacitor overvoltage protection circuit for an energy storage device of the present invention;

[0026] Figure 2 The present invention is a flowchart of the steps of an embodiment of a large-capacity capacitor overvoltage protection circuit of an energy storage device.

[0027] The main component symbols are explained as follows: overvoltage detection unit 101, control unit 102, protection execution unit 103, capacitor unit 104, energy transfer unit 105, energy recovery unit 106. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0030] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] like Figure 1 As shown, a large-capacity capacitor overvoltage protection circuit of an energy storage device of the present invention includes an overvoltage detection unit 101, a control unit 102 and a protection execution unit 103, and also includes at least one group of capacitor units 104, the overvoltage detection unit 101 is used to monitor the voltage of the capacitor unit 104 in real time, and the control unit 102 determines whether it exceeds a preset overvoltage threshold based on the voltage information provided by the overvoltage detection unit 101; the protection execution unit 103 is used to execute protection measures when the control unit 102 determines that the voltage exceeds the preset overvoltage threshold; the protection execution unit 103 is used to achieve safe discharge of the capacitor unit 104, and the protection execution unit 103 also includes at least one energy transfer unit 105, and the energy transfer unit 105 is used to transfer electric energy in the case of overvoltage.

[0032] In practical applications of this embodiment, each capacitor unit 104 includes at least one capacitor, the protection execution unit 103 includes at least one discharge resistor, relay or MOS tube, and the energy transfer unit 105 transfers electrical energy to a safe storage or consumption device in the event of overvoltage.

[0033] In practical applications of this embodiment, the protection measures include cutting off power supply, discharging or energy transfer.

[0034] In the practical application of this embodiment, the plurality of groups of large capacitor units 104 are connected in series or in parallel. Such a design can meet different energy storage requirements.

[0035] In practical applications of this embodiment, the overvoltage detection unit 101 includes at least one voltage sensor for collecting the voltage signal of the capacitor unit 104 in real time and transmitting it to the control unit 102 .

[0036] In practical applications of this embodiment, the control unit 102 includes a microprocessor or a programmable logic controller, which is used to process the voltage signal according to a preset algorithm and issue a control instruction to the protection execution unit 103 .

[0037] In the practical application of this embodiment, the protection execution unit 103 further includes a voltage limiting diode, which is connected in parallel across the capacitor. When the capacitor voltage exceeds the threshold of the voltage limiting diode, the diode is turned on. Such a design can limit the further increase of the capacitor voltage.

[0038] In practical applications of this embodiment, an energy recovery unit 106 is also included. The energy recovery unit 106 is used to recover electric energy during the discharge process of the capacitor and store it in a backup power supply or return it to the power grid.

[0039] In practical applications of this embodiment, an overvoltage protection method is also included, including the following steps:

[0040] Step 1: Real-time monitoring of the voltage of the capacitor unit 104 by the overvoltage detection unit 101

[0041] Step 2: The control unit 102 receives the voltage signal and determines whether it exceeds the overvoltage threshold according to a preset algorithm; specifically, the preset algorithm includes a comparison algorithm, a difference algorithm or a slope algorithm;

[0042] Step 3: If the voltage exceeds the threshold, the control unit 102 sends a control instruction to the protection execution unit 103;

[0043] Step 4: The protection execution unit 103 executes corresponding protection measures according to the control instruction, including cutting off power supply, discharging or energy transfer.

[0044] Specifically, the protection measures that can be adopted in this embodiment include overvoltage protection strategy, group voltage regulation strategy, equipment adjustment strategy and capacity adjustment strategy;

[0045] Overvoltage protection strategy: When the voltage across the capacitor exceeds its rated voltage, the overvoltage protection device will quickly cut off the connection between the capacitor and the power supply to prevent the capacitor from being damaged due to overvoltage.

[0046] Group voltage regulation strategy: Appropriately group the capacitors and use group switching to adjust the voltage to meet different voltage requirements.

[0047] Equipment adjustment strategy: Adjust the tap of the main transformer to reduce the voltage of the substation bus to reduce the overvoltage shock on the capacitor.

[0048] Capacity adjustment strategy: When the voltage is too high, the capacity of the capacitor can be reduced. At the same time, some capacitors can be moved to a suitable compensation location to avoid capacitor overload.

[0049] In the practical application of this embodiment, in step 4, if a discharge measure is taken, the discharge process is realized through a discharge resistor, a relay or a MOS tube. Such a design can ensure that the capacitor is safely discharged to a safe voltage level.

[0050] Embodiment 1 uses a comparison algorithm as an application of this embodiment: real-time monitoring of the voltage across the capacitor unit and direct comparison with a preset overvoltage threshold. The overvoltage threshold is set to a specific value. When the monitored voltage value is greater than the threshold, it can be judged as exceeding the overvoltage threshold. In the overvoltage protection circuit of this scheme, voltage data is continuously collected and compared with a fixed threshold. In this embodiment, for example, when the detected voltage signal V1 ≥ 200V (the set overvoltage threshold), the protection action is executed.

[0051] Embodiment 2:

[0052] As an application of this embodiment, the difference algorithm is used to calculate the difference between the current voltage and the normal working voltage or the average voltage. If the difference exceeds the preset allowable range, it is considered that the overvoltage threshold is exceeded. For example, the normal working voltage is 100V, and the allowable range of the difference is set to 20V. When the difference between the actual monitored voltage and 100V is greater than 20V, it is determined to exceed the overvoltage threshold.

[0053] Embodiment three:

[0054] As an application of this embodiment, the slope algorithm is used to analyze the slope of the voltage over time. If the slope of the voltage rise continues to exceed the set slope threshold for a period of time, it indicates that an overvoltage condition has occurred. For example, the voltage rises rapidly from 100V to 150V in a very short period of time. By calculating the slope of the voltage rise during this period of time and comparing it with the set slope threshold, it is determined whether the overvoltage threshold is exceeded.

[0055] Embodiment 4:

[0056] As an application of this embodiment, a statistical algorithm is used to perform statistical analysis on voltage data within a period of time. This embodiment calculates the average value and variance statistics of the voltage. When the voltage average value and variance exceed the corresponding preset thresholds, it is judged to exceed the overvoltage threshold. For example, the threshold of the voltage average value is set to 120V. If the average value calculated from the voltage data collected within a certain period of time is greater than 120V, it is considered to exceed the overvoltage threshold.

[0057] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A large-capacity capacitor overvoltage protection circuit for energy storage equipment, characterized in that: The invention comprises an overvoltage detection unit (101), a control unit (102) and a protection execution unit (103), and also comprises at least one group of capacitor units (104). The overvoltage detection unit (101) is used to monitor the voltage of the capacitor unit (104) in real time. The control unit (102) determines whether the voltage exceeds a preset overvoltage threshold value based on the voltage information provided by the overvoltage detection unit (101). The protection execution unit (103) is used to execute protection measures when the control unit (102) determines that the voltage exceeds the preset overvoltage threshold value. The protection execution unit (103) is used to realize the safe discharge of the capacitor unit (104). The protection execution unit (103) also comprises at least one energy transfer unit (105). The energy transfer unit (105) is used to transfer electric energy in the case of overvoltage.

2. The large-capacity capacitor overvoltage protection circuit of an energy storage device according to claim 1, characterized in that: Each capacitor unit (104) includes at least one capacitor, the protection execution unit (103) includes at least one discharge resistor, relay or MOS tube, and the energy transfer unit (105) transfers electrical energy to a safe storage or consumption device in the event of overvoltage.

3. The large-capacity capacitor overvoltage protection circuit of an energy storage device according to claim 1, characterized in that: The protection measures include power cut-off, discharge or energy transfer.

4. The large-capacity capacitor overvoltage protection circuit of an energy storage device according to claim 1, characterized in that: The multiple groups of large capacitor units (104) are connected in series or in parallel.

5. The large-capacity capacitor overvoltage protection circuit of an energy storage device according to claim 1, characterized in that: The overvoltage detection unit (101) comprises at least one voltage sensor, which is used to collect the voltage signal of the capacitor unit (104) in real time and transmit it to the control unit (102).

6. The large-capacity capacitor overvoltage protection circuit of an energy storage device according to claim 1, characterized in that: The control unit (102) comprises a microprocessor or a programmable logic controller, which is used to process the voltage signal according to a preset algorithm and issue a control instruction to the protection execution unit (103).

7. The large-capacity capacitor overvoltage protection circuit of an energy storage device according to claim 2, characterized in that: The protection execution unit (103) also includes a voltage limiting diode, which is connected in parallel at both ends of the capacitor. When the capacitor voltage exceeds a threshold value of the voltage limiting diode, the diode is turned on.

8. The large-capacity capacitor overvoltage protection circuit of an energy storage device according to claim 1, characterized in that: The invention also comprises an energy recovery unit (106), wherein the energy recovery unit (106) is used to recover electric energy during the discharge process of the capacitor and store the electric energy in a backup power source or return the electric energy to a power grid.

9. The large-capacity capacitor overvoltage protection circuit of an energy storage device according to claim 1, characterized in that: Also included is an overvoltage protection method, comprising the following steps: Step 1: monitoring the voltage of the capacitor unit (104) in real time through the overvoltage detection unit (101); Step 2: The control unit (102) receives the voltage signal and determines whether it exceeds the overvoltage threshold according to a preset algorithm; specifically, the preset algorithm includes a comparison algorithm, a difference algorithm or a slope algorithm; Step 3: If the voltage exceeds the threshold, the control unit (102) sends a control instruction to the protection execution unit (103); Step 4: The protection execution unit (103) executes corresponding protection measures according to the control instruction, including cutting off power supply, discharging or energy transfer.

10. The large-capacity capacitor overvoltage protection circuit of an energy storage device according to claim 9, characterized in that: In step 4, if discharging measures are taken, the discharging process is realized through a discharging resistor, a relay or a MOS tube.

Images