Charging and discharging protection system for battery pack of energy storage power station

Abstract

The invention discloses a charging and discharging protection system for a battery pack of an energy storage power station, and relates to the technical field of battery charging and discharging protection, and the system comprises an electromagnetic pulse protection device which is arranged on an electromagnetic sensitive circuit of the energy storage power station and is used for shielding the interference of electromagnetic pulses on the electromagnetic sensitive circuit; the charging and discharging protection device is connected with a battery pack and a single battery of the energy storage power station, and is used for acquiring real-time temperature, real-time voltage and real-time current of the battery pack and the single battery of the energy storage power station, and controlling the charging and discharging of the energy storage power station based on the real-time temperature, the real-time voltage and the real-time current of the battery pack and the single battery of the energy storage power station; and carrying out electrified hot plugging on the battery pack and the single battery of the energy storage power station so as to carry out charging and discharging protection on the battery pack and the single battery of the energy storage power station. The electromagnetic compatibility of the electromagnetic sensitive circuit in the energy storage power station is improved, and the service life of the battery pack of the energy storage power station is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of battery charging and discharging protection, and in particular to a charging and discharging protection system for a battery pack of an energy storage power station. Background Art

[0002] With the proposal of the dual carbon goals, the scale of renewable energy continues to expand. Energy storage power stations currently generally use lithium iron phosphate batteries, mainly because lithium iron phosphate batteries perform well in high temperature environments. From the perspective of theory and practical applications (such as widespread use in the automotive industry), lithium iron phosphate batteries can be charged and discharged normally in a temperature range of -20°C to +60°C without special insulation measures. However, under low temperature conditions, such as -20°C, its capacity will decrease compared to +25°C, and conservatively estimated to be only 60% to 70% of the latter, which means that the energy storage capacity of the battery in low temperature environments will be reduced. Although the battery supports a charge and discharge current of up to 2C, under such conditions, its charge and discharge life is usually officially calibrated to about 2,000 times, that is, excessive charging or discharging will significantly shorten the battery's service life, and extreme overcharging or over-discharging will greatly reduce the number of charge and discharge times the battery can withstand. In addition, since lithium iron phosphate batteries have no obvious memory effect, full charging and discharging will not extend the battery's service life.

[0003] Therefore, the high lifespan target of more than 5,000 charge and discharge cycles cannot be achieved by fast charging or high-intensity discharging. In order to maximize the lifespan of the battery pack, measures are needed to avoid rapid charging and discharging and extend the battery life.

[0004] In addition, in high humidity environments, using switching power supplies to achieve high voltage insulation is a challenge for small power supplies (mainly used for power collection units). These power supplies are usually small in size, and it is not only difficult to manufacture high-voltage insulation products, but also difficult to adapt to future voltage increases. As the insulation layer thickens, the voltage resistance of small power supplies may increase, but their efficiency and reliability tend to decrease. At the same time, since this type of power supply is usually produced in small batches, it is unlikely to become a mass-produced product, so the cost is relatively high. Summary of the invention

[0005] The purpose of the present invention is to provide a charge and discharge protection system for a battery pack of an energy storage power station, which can improve the electromagnetic compatibility of electromagnetic sensitive circuits in the energy storage power station and extend the life of the battery pack of the energy storage power station.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A charging and discharging protection system for a battery pack of an energy storage power station, comprising:

[0008] An electromagnetic pulse protection device is provided on the electromagnetic sensitive circuit of the energy storage power station to shield the interference of the electromagnetic pulse on the electromagnetic sensitive circuit;

[0009] The charge and discharge protection device is connected to the battery pack and battery cell of the energy storage power station, and is used to collect the real-time temperature, real-time voltage and real-time current of the battery pack and battery cell of the energy storage power station, and based on the real-time temperature, real-time voltage and real-time current of the battery pack and battery cell of the energy storage power station, perform live hot swapping of the battery pack and battery cell of the energy storage power station to perform charge and discharge protection on the battery pack and battery cell of the energy storage power station.

[0010] Optionally, the electromagnetic sensitive circuit of the energy storage power station includes a converter, a switching power supply, a signal acquisition circuit and a central processing unit.

[0011] Optionally, the electromagnetic pulse protection device comprises:

[0012] An input protection device is arranged at the entrance of the electromagnetic sensitive circuit of the energy storage power station and is used to isolate and protect the electromagnetic pulses entering the entrance of the electromagnetic sensitive circuit;

[0013] Gas protection equipment, which is installed between the converter and the power grid of the energy storage power station to prevent electromagnetic pulses from entering the converter in reverse;

[0014] A shielding device, arranged on the electromagnetic sensitive circuit of the energy storage power station, for shielding the induction pulse of the electromagnetic sensitive circuit;

[0015] The external communication protection device is arranged at the external communication port of the energy storage power station to prevent the induced electromagnetic pulse of the external communication port from entering the electromagnetic sensitive circuit of the energy storage power station.

[0016] Optionally, the input protection device comprises:

[0017] A power factor compensation device, connected to the converter of the energy storage power station, for performing power factor compensation on the converter;

[0018] A gas discharge tube is arranged at the inlet of the switching power supply of the energy storage power station, and is used to discharge the lightning instantaneous overcurrent at the inlet of the switching power supply and limit the overvoltage;

[0019] Common-mode and differential-mode neutralization filters are provided at the inlet of the switching power supply of the energy storage power station and are used to filter the electromagnetic pulses at the inlet of the switching power supply;

[0020] The shielding layer is arranged between the primary winding and the secondary winding of the switching power supply transformer of the energy storage power station, and is used to isolate the electromagnetic pulses coupled by the capacitive coupling of the primary winding and the secondary winding.

[0021] Optionally, the power factor compensation device is an active power factor compensation device.

[0022] Optionally, the common-mode and differential-mode neutralization filter comprises a first common-mode inductor, a second common-mode inductor, a first capacitor, a second capacitor, a third capacitor and a fourth capacitor;

[0023] The first common-mode inductor is connected to the positive input of the switching power supply, and the second common-mode inductor is connected to the negative input of the switching power supply;

[0024] One end of the first capacitor is connected between the first common-mode inductor and the alternating current, one end of the second capacitor is connected between the first common-mode inductor and the positive input of the switching power supply, the third capacitor is connected between the second common-mode inductor and the alternating current, the fourth capacitor is connected between the second common-mode inductor and the negative input of the switching power supply, and the other ends of the first capacitor, the second capacitor, the third capacitor and the fourth capacitor are all grounded;

[0025] One end of the gas discharge tube is connected between the first common mode inductor and the alternating current, and the other end of the gas discharge tube is connected between the second common mode inductor and the alternating current.

[0026] Optionally, the gas protection device is a gas discharge tube.

[0027] Optionally, the shielding device is a shielding cover.

[0028] Optionally, the external communication protection device includes:

[0029] A TVS diode is arranged at the outlet of the switching power supply of the energy storage power station and is used to absorb electromagnetic pulses at the outlet of the switching power supply;

[0030] The optical fiber is arranged between the upper end collection unit and the lower end collection unit of the energy storage power station, and is used to isolate the voltage between the upper end collection unit and the lower end collection unit.

[0031] Optionally, the charge and discharge protection device includes:

[0032] A temperature sensor is provided on the battery pack and battery cell of the energy storage power station and is connected to the battery management system of the energy storage power station to collect the real-time temperature of the battery pack and battery cell of the energy storage power station and send it to the battery management system;

[0033] A voltage sensor connected to the battery pack and battery cells of the energy storage power station, used to collect the real-time voltage of the battery pack and battery cells of the energy storage power station and send it to the battery management system;

[0034] A current sensor connected to the battery pack and battery cell of the energy storage power station, used to collect the real-time current of the battery pack and battery cell of the energy storage power station and send it to the battery management system;

[0035] The battery management system determines the working state of each battery pack and each battery cell according to the real-time temperature, real-time voltage and real-time current of the battery pack and battery cell of the energy storage power station, and generates an alarm signal when the working state of any battery pack or any battery cell is abnormal;

[0036] The flame and combustible gas alarm device is arranged in the battery module box of the energy storage power station, and is used to detect whether there is flame and combustible gas in the battery module box, and if so, generates an alarm signal;

[0037] The live hot swap device is arranged between the battery groups and between the battery cells of the energy storage power station, and is respectively connected to the battery management system and the flame and combustible gas alarm device, and is used to disconnect the connection between the corresponding battery groups or the connection between the corresponding battery cells when the battery management system or the flame and combustible gas alarm device generates an alarm signal.

[0038] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: by arranging an electromagnetic pulse protection device on the electromagnetic sensitive circuit of the energy storage power station, the interference caused by the electromagnetic pulse to the electromagnetic sensitive circuit is shielded, and the electromagnetic compatibility of the electromagnetic sensitive circuit in the energy storage power station is improved; the real-time temperature, real-time voltage and real-time current of the battery pack and the battery cell are collected through the charge and discharge protection device, and the battery pack and the battery cell are hot-swapped under power on, so as to perform charge and discharge protection on the battery pack and the battery cell, thereby maximizing the life of the battery pack and the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be 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 labor.

[0040] Figure 1 It is a schematic diagram of the connection between the power factor compensation device and the gas discharge tube and the converter;

[0041] Figure 2 is a schematic diagram of common mode and differential mode neutralization filters;

[0042] Figure 3 is a schematic diagram of the shielding layer;

[0043] Figure 4It is a waveform diagram of the relationship between time and voltage of lightning electromagnetic pulse on the power line;

[0044] Figure 5 It is a waveform diagram of the relationship between the frequency and normalized spectrum of the lightning electromagnetic pulse on the power line;

[0045] Figure 6 This is a waveform diagram of the electromagnetic pulse produced by an unprotected electromagnetic pulse impacting a conductor in a laboratory test;

[0046] Figure 7 This is a diagram of the induction waveform of an unprotected electromagnetic pulse impacting a nearby conductor in a laboratory test;

[0047] Figure 8 is a schematic diagram of a shielding cover;

[0048] Fig. 9 Schematic diagram of electromagnetic field shielding principle;

[0049] Fig.10 This is a schematic diagram of the location of the TVS diode;

[0050] Fig.11 Schematic diagram of a DC / DC switching power supply.

[0051] Fig.12 It is a schematic diagram of the CAN bus isolator and protection circuit;

[0052] Fig.13 This is a schematic diagram of the internal structure of the CAN bus isolator.

[0053] Explanation of symbols:

[0054] 1-converter, 2-isolating switch, 3-external power line, 4-power factor compensation device, 5-gas discharge tube, 6-shielding layer, 7-shielding cover, 8-electromagnetic sensitive circuit, 9-TVS diode, 10-CAN bus isolator, 11-electromagnetic pulse absorption circuit. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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 this field without creative work are within the scope of protection of the present invention.

[0056] The purpose of the present invention is to provide a charging and discharging protection system for battery packs in energy storage power stations, which can avoid rapid charging and discharging and ensure that the charging and discharging current is lower than 1C. For electrical components susceptible to electromagnetic interference, under the condition of strong external interference, significant pulse electromagnetic interference may enter through the load end and damage the equipment. Therefore, for electromagnetic sensitive circuits, special electromagnetic pulse protection measures are taken to improve their electromagnetic compatibility, thereby maximizing the life of the battery pack.

[0057] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0058] The charging and discharging protection system for a battery pack of an energy storage power station provided by the present invention comprises an electromagnetic pulse protection device and a charging and discharging protection device.

[0059] (1) The electromagnetic pulse protection device is installed on the electromagnetic sensitive circuit of the energy storage power station, and the electromagnetic pulse protection device is used to shield the interference caused by the electromagnetic pulse to the electromagnetic sensitive circuit.

[0060] The electromagnetic sensitive circuit of the energy storage power station includes a converter, a switching power supply, a signal acquisition circuit and a central processing unit.

[0061] For electromagnetically sensitive circuits in energy storage power stations, special attention should be paid to their vulnerability. The damage voltage threshold of these circuits is very low. For example, operational amplifiers and AD converters may only withstand overvoltage pulses of tens of volts. The sensitive components of the central processing unit (CPU) are even more fragile, and a voltage pulse of a few volts is enough to interfere with its normal operation. Therefore, in order to ensure the safety of these critical circuits, not only special protection circuits need to be installed, but also appropriate shielding measures should be taken. Such preventive measures are essential to maintaining the stability and reliability of the entire energy storage system.

[0062] Specifically, electromagnetic compatibility proposes relevant protection measures for each part. The electromagnetic pulse protection device includes: input protection equipment, gas protection equipment, shielding equipment and external communication protection equipment.

[0063] (1) The input protection device is arranged at the entrance of the electromagnetic sensitive circuit of the energy storage power station, and is used to isolate and protect the electromagnetic pulses entering the entrance of the electromagnetic sensitive circuit.

[0064] Specifically, Figure 1As shown, the input protection device includes: a power factor compensation device 4, a gas discharge tube 5, a common mode and a differential mode neutralization filter and a shielding layer. When the energy storage power station adopts AC input, a power factor compensation device 4 and a lightning protection gas discharge tube 5 need to be installed. This measure is not only to meet the electromagnetic compatibility requirements of the power grid or the environment, but also plays an important role in preventing electromagnetic pulses from interfering with the internal circuit. In this way, the overall stability and reliability of the energy storage power station can be effectively improved.

[0065] 1) The power factor compensation device 4 is connected to the converter 1 of the energy storage power station, and the power factor compensation device 4 is used to perform power factor compensation on the converter 1. In this embodiment, the power factor compensation device 4 is an active power factor compensation device.

[0066] Since the AC current output by the converter 1 is pulse-width modulated, it is not actually a sine wave, but the effective value is a sine wave within one wave cycle, so a large number of high-order harmonic components will be generated, which will cause great interference to the electronic equipment in the power grid and the energy storage power station. At present, high-order harmonic emissions are generally regarded as reactive emissions with low power factor. It is almost impossible to achieve complete or high-order harmonics below 1%. There are many solutions, among which the multi-level method can achieve relatively low harmonics, but the circuit is proportionally complicated and the cost is very high. In particular, the converter 1 in the energy storage power station requires light weight, small size, low cost, high reliability, and small high-order harmonics. In addition, the power grid also has strict requirements on the high-order harmonic emissions connected to the energy storage power station.

[0067] At the same time, the energy storage power station also requires that the converter 1 should operate in four quadrants, and it is hoped that it has the function of charging the energy storage battery. Some of these requirements are contradictory, and the circuits are very complicated to implement and difficult to work reliably. Therefore, it is necessary to set up a power factor compensation circuit separately. Since the emission of high-order harmonics is also considered as reactive emission, but in principle, the emission of high-order harmonics and the inductive reactive power caused by inductive loads to the power supply are essentially different. The method of parallel capacitance cannot be used to compensate for the reactive emission caused by high-order harmonics. Instead, electronic devices should be used to generate high-order harmonics to offset the high-order harmonics generated by the converter 1. This device is called active power factor compensation.

[0068] At present, there are many manufacturers of active power factor compensation devices, and the models are not uniform, but it must be emphasized that paid power factor compensation can generally achieve active dynamic compensation. It is itself an active dynamic CPU-controlled device that can work actively without the intervention of external control signals.

[0069] 2) The gas discharge tube 5 is arranged at the inlet of the switching power supply of the energy storage power station. The gas discharge tube 5 is used to discharge the lightning instantaneous overcurrent at the inlet of the switching power supply and limit the overvoltage.

[0070] Figure 1 In the embodiment, the converter 1 is connected to the external power line 3 through the isolating switch 2, and the power factor compensation device 4 and the gas discharge tube 5 are connected between the converter 1 and the isolating switch 2.

[0071] 3) The common-mode and differential-mode neutralization filters are arranged at the inlet of the switching power supply of the energy storage power station, and the common-mode and differential-mode neutralization filters are used to filter the electromagnetic pulses at the inlet of the switching power supply.

[0072] In this embodiment, Figure 2 As shown, the common-mode and differential-mode neutralization filter includes a first common-mode inductor L1, a second common-mode inductor L2, a first capacitor C1, a second capacitor C2, a third capacitor C3 and a fourth capacitor C4.

[0073] The first common-mode inductor L1 is connected to the positive input of the switching power supply, and the second common-mode inductor L2 is connected to the negative input of the switching power supply.

[0074] One end of the first capacitor C1 is connected between the first common-mode inductor L1 and the alternating current, one end of the second capacitor C2 is connected between the first common-mode inductor L1 and the positive electrode input of the switching power supply, the third capacitor C3 is connected between the second common-mode inductor L2 and the alternating current, the fourth capacitor C4 is connected between the second common-mode inductor L2 and the negative electrode input of the switching power supply, and the other ends of the first capacitor C1, the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 are all grounded.

[0075] One end of the gas discharge tube 5 is connected between the first common mode inductor L1 and the alternating current, and the other end of the gas discharge tube 5 is connected between the second common mode inductor L2 and the alternating current.

[0076] The electromagnetic pulse entering the inlet of the switching power supply can be bypassed by the gas discharge tube 5. The gas discharge tube 5 has a high voltage protection value and a large current flow, which can well protect the inlet of the switching power supply from the impact of the electromagnetic pulse.

[0077] 4) If Figure 3 As shown, the shielding layer 6 is arranged between the primary winding and the secondary winding of the switching power supply transformer of the energy storage power station, and the shielding layer 6 is used to isolate the electromagnetic pulses coupled by the capacitive coupling of the primary winding and the secondary winding.

[0078] The present invention adds a thin copper sheet (the two ends can overlap but not communicate) between the primary winding and the secondary winding of the switching power supply transformer, isolates the two sides, and connects the copper sheet to the ground. It can ensure the normal electromagnetic induction of the switching power supply transformer when it is working, but has a good isolation effect on the electromagnetic pulse coupled through the capacitor of the primary winding and the secondary winding, and is connected to the ground, which can effectively prevent the primary electromagnetic pulse from inducing the secondary winding.

[0079] (2) The gas protection device is arranged between the converter 1 of the energy storage power station and the power grid, and the gas protection device is used to prevent the electromagnetic pulse from reversely entering the converter 1. In this embodiment, the gas protection device is a gas discharge tube 5. The present invention installs a gas discharge tube 5 at the connection between the converter 1 and the power grid to prevent the high-voltage electromagnetic pulse from reversely entering the converter 1 and damaging the IGBT transistor in the converter 1.

[0080] The present invention adds a filter and a gas discharger to prevent strong electromagnetic pulses such as lightning from being mixed into the power line. The waveform of the induced signal on the power line caused by the lightning pulse is as follows: Figure 4 and Figure 5 As shown in the figure, the electromagnetic pulse induction signal without protection in a laboratory test is as follows Figure 6 and Figure 7 As shown, if not handled, it will pose a threat to the safety of the control circuit and battery.

[0081] (3) The shielding device is arranged on the electromagnetic sensitive circuit of the energy storage power station, and is used to shield the induction pulse of the electromagnetic sensitive circuit. In this embodiment, the shielding device is a shielding cover.

[0082] like Figure 8 As shown, the present invention adds a shielding cover 7 to the electromagnetic sensitive circuit 8, and the shielding cover 7 can effectively prevent the harm of the induction pulse. The circuit board of the electromagnetic sensitive circuit 8 adopts a multi-layer circuit board, and the circuit leads of the interface and other circuits sensitive to electromagnetic pulses are sandwiched in the middle of the multi-layer circuit board after being led out of the shielding layer 6. The upper and lower layers of the circuit board are grounded at the same layer, which also acts as a shield.

[0083] The present invention adds shielding measures to the electromagnetic sensitive circuit 8. Shielding measures are particularly effective for radiated electromagnetic interference. For example, the shells of various switches, power isolation modules, etc. are all made of conductive materials and are grounded. In addition, cables and the like also have a shielding layer 6, which also needs to be grounded. The shielding effect is bidirectional. Adding shielding measures to devices or cables with electromagnetic pulse radiation can confine the electromagnetic pulse radiation within the shielding range. Similarly, for parts that are sensitive to electromagnetic pulses, such as the CPU, a shielding cover 7 is also required and grounded to prevent external electromagnetic pulses from entering the circuit and interfering with the normal operation of the circuit. Since electromagnetic pulse interference will leak into the gap, the gap of the shielding cover 7 needs to be minimized during installation.

[0084] The shielding cover 7 needs to be grounded. If there is a high potential between the ground potential and the shielded electronic device, insulation treatment needs to be done. Improving battery compatibility is a systematic project. It is necessary to use TVS diode 9 inductive absorption circuit for prevention (such as CAN bus isolation circuit), and to add isolation measures. For sensitive circuits such as CPU, shielding circuits need to be installed. For the problem of the converter 1 emitting a large amount of reactive power of electromagnetic pulse nature, active power factor compensation measures should be adopted. For the strong electromagnetic pulses such as lightning that enter the converter 1 through external overhead power lines, gas discharge tubes 5 (or gas discharge protectors) must be used for protection. For problems such as electromagnetic compatibility, especially battery energy storage systems that have both outdoor working requirements and connections to the power grid, the converter 1 itself must radiate high-power high-order harmonics, and there are also communication ports such as CAN bus and network cables. These circuits are sensitive to electromagnetic radiation and conductive interference, and multiple comprehensive measures are needed to solve the problem.

[0085] The shielding principle of electromagnetic field is as follows Fig. 9 As shown, E1 represents the intensity of the incident electromagnetic wave, R1 represents the amplitude of the reflection field of the electromagnetic wave on the A surface, R2 represents the amplitude of the reflection field of the electromagnetic wave on the B surface, T represents the transmission amplitude of the electromagnetic wave in the shielding cover 7, A represents the front side of the shielding cover 7, B represents the back side of the shielding cover 7, and E0 represents the amplitude of the electromagnetic wave penetrating out of the shielding cover 7.

[0086] (4) The external communication protection device is arranged at the external communication port of the energy storage power station. The external communication protection device is used to prevent the induced electromagnetic pulse of the external communication port from entering the electromagnetic sensitive circuit of the energy storage power station.

[0087] The external communication port can use a shielded network cable or optical fiber interface. Optical fiber usually has an advantage in anti-interference ability. Considering the operating voltage of energy storage power stations, the current products on the market can reach up to 2kV. Since the voltage of a single lithium iron phosphate battery is only 3.7V, more than 500 batteries or battery modules need to be connected in series to achieve the required operating voltage, which causes a potential difference of up to several thousand volts between the upper and lower acquisition units.

[0088] In this embodiment, the external communication protection device includes: a TVS diode 9 and an optical fiber.

[0089] The TVS diode 9 is arranged at the outlet of the switching power supply of the energy storage power station, and is used to absorb the electromagnetic pulse at the outlet of the switching power supply. The TVS diode 9 can further absorb a small amount of electromagnetic pulses leaked by the switching power supply. The present invention adds a TVS diode 9 to the external communication port to absorb the pulse interference signal to prevent the external induced electromagnetic pulse of the port from entering the internal circuit.

[0090] Furthermore, for interfaces such as RS 485CAN bus, TVS diode arrays and isolators are used for protection to prevent the circuit from being impacted by electromagnetic pulses. For important parts such as the CPU in the BMS, TVS diodes 9 are used to ensure that the potential in the circuit is at a safe value under electromagnetic impact. Fig.10 As shown, a TVS diode 9 is installed at the external communication port to absorb pulse interference signals to prevent the external induced electromagnetic pulse of the port from entering the internal circuit.

[0091] The optical fiber is arranged between the upper end collection unit and the lower end collection unit of the energy storage power station, and the optical fiber is used to isolate the voltage between the upper end collection unit and the lower end collection unit.

[0092] There are many ways to isolate the voltage between the upper and lower acquisition units, such as on-board photoelectric isolation, installing isolators, using optical fiber, etc. These methods have their own advantages and disadvantages. However, from the perspective of large-scale production, using battery modules to power the ports is a solution, which can reduce the dependence on the power switch power supply. In terms of communication, using optical fiber is usually the most economical and safe method without hidden dangers. This method saves costs and effectively avoids safety risks.

[0093] In order to improve the electromagnetic compatibility of the energy storage power station and the protection performance of the circuit, the communication port power supply external connection port must be equipped with a protection circuit to filter out and absorb electromagnetic pulses.

[0094] In addition, considering the working voltage of the energy storage power station, more than 500 batteries or battery modules need to be connected in series to achieve the required working voltage, which causes a potential difference of up to several thousand volts between the upper and lower acquisition units. In order to isolate this part of the voltage, the battery module can be used to supply power to reduce the dependence on the power supply switch. In terms of communication, the use of optical fiber is usually the most economical and safe method without hidden dangers.

[0095] Considering that the energy storage power station has a relatively large energy storage working power and a relatively high output voltage, a step-up transformer is generally not added after the converter 1, so the current and voltage are relatively high. Generally, hundreds of batteries are connected in series, and the integrated circuit on the battery protection circuit BMS board is generally 6 to 16 batteries connected in series. The communication between the battery protection board and the control unit generally adopts the CAN bus. At this time, a CAN driver with an isolation function must be used. Such products are sold on the market, but a CAN driver with a high enough isolation voltage and a suitable operating temperature range must be selected.

[0096] To maintain the working BMS board, a power supply is required. The CAN bus isolator also needs a power supply when it is working. Since the battery pack is composed of hundreds of cells connected in series, the upper BMS protection board and the CAN bus isolator need a 24VDC power supply. Moreover, due to the adoption of hot-swap technology, when the battery is disconnected from the BMS board due to plugging and unplugging, if the battery pack protected by this BMS is used for power supply, the battery will be disconnected from the BMS after being unplugged, and the power supply will be interrupted. Therefore, an isolation voltage of 300V (with a margin to ensure safety) and multiple power supply measures should be adopted.

[0097] like Fig.11 As shown, the multiple DC / DC switching power supplies to the BMS battery protection board are high isolation voltage DC / DC switching power supplies, which supply power to each BMS protection board and CAN isolator.

[0098] In addition, in order to prevent external electromagnetic pulse interference and high-order harmonic interference generated by the converter 1, such as Fig.12 As shown, an electromagnetic pulse absorption circuit 11 is installed at the outlet of the CAN bus isolator 10. Fig.13 The internal structure of the CAN bus isolator 10 is shown.

[0099] (ii) a charge and discharge protection device is connected to the battery pack and battery cells of the energy storage power station, and is used to collect the real-time temperature, real-time voltage and real-time current of the battery pack and battery cells of the energy storage power station, and based on the real-time temperature, real-time voltage and real-time current of the battery pack and battery cells of the energy storage power station, perform live hot swapping of the battery pack and battery cells of the energy storage power station to perform charge and discharge protection on the battery pack and battery cells of the energy storage power station.

[0100] Specifically, the charging and discharging protection device includes: a temperature sensor, a voltage sensor, a current sensor, a flame and combustible gas alarm device and a live hot plug device.

[0101] (1) The temperature sensor is installed on the battery pack and battery cell of the energy storage power station and connected to the battery management system (BMS) of the energy storage power station. The temperature sensor is used to collect the real-time temperature of the battery pack and battery cell of the energy storage power station and send it to the battery management system.

[0102] The temperature sensor is connected to the BMS and should be installed in a position that ensures that the dynamic temperature of the battery when it is working can be collected. Then, by uploading it to the BMS, the health status of the battery pack and battery cells and the temperature under working conditions can be grasped. The working status of the battery pack and battery cells can be judged together with the current collected by the current sensor and the voltage collected by the voltage sensor. It is an important sensor for judging the health and safety status of the battery.

[0103] The present invention ensures that there are no blind spots when placing the temperature sensor in the battery pack, ensuring that a danger alarm can be issued when the temperature rises too high, that is, ensuring that the BMS can respond correctly.

[0104] When the battery capacity is large, each battery pack or each battery cell is provided with a temperature sensor to ensure that the detection covers each battery cell.

[0105] (2) The voltage sensor is connected to the battery pack and battery cells of the energy storage power station. The voltage sensor is used to collect the real-time voltage of the battery pack and battery cells of the energy storage power station and send it to the battery management system.

[0106] Voltage is a key parameter for controlling the battery charging state. In the present invention, the voltage sensor includes an operational amplifier and an A / D converter. Each battery pack and each battery cell is connected to a voltage sensor.

[0107] (3) The current sensor is connected to the battery pack and battery cell of the energy storage power station. The current sensor is used to collect the real-time current of the battery pack and battery cell of the energy storage power station and send it to the battery management system.

[0108] When the detected current is small, the current sensor includes a resistor (milliohm high-precision resistor), an operational amplifier and an A / D converter. The current value is read by the A / D converter and sent to the BMS to grasp the battery charging current, and combined with the voltage signal to accumulate the number of charge and discharge times, the degree of battery degradation, and determine the battery aging and degradation status.

[0109] In addition, the current sensor can also be transmitted to the operational amplifier through the Hall sensor, and then the current value is read through the A / D converter.

[0110] Compared with Hall sensors, resistors have lower costs and are easier to judge in quality. When working, there is voltage drop, power loss, and heat generation, so reliability is easier to ensure. Hall sensors are a type of sensor similar to semiconductors. If they are well made, they can work safely and for a long time, and they have almost no voltage drop and do not generate heat.

[0111] The battery management system determines the working status of each battery pack and each battery cell according to the real-time temperature, real-time voltage and real-time current of the battery pack and battery cell of the energy storage power station, and generates an alarm signal when the working status of any battery pack or any battery cell is abnormal.

[0112] (4) The flame and combustible gas alarm device is installed in the battery module box of the energy storage power station. The flame and combustible gas alarm device is used to detect whether there is flame and combustible gas in the battery module box. If so, an alarm signal is generated.

[0113] In the present invention, the flame and combustible gas alarm device includes a probe and an upper alarm circuit. The flame and combustible gas alarm device is produced by a specialized factory and must be approved by a specialized department. At least one probe should be set in a battery module box to be linked to the BMS and the charging control circuit to ensure the safe operation of the energy storage power station to avoid accidents.

[0114] (6) The powered hot-swap device is arranged between the battery groups and between the battery cells of the energy storage power station, and is respectively connected to the battery management system and the flame and combustible gas alarm device. The powered hot-swap device is used to disconnect the connection between the corresponding battery groups or the connection between the corresponding battery cells when the battery management system or the flame and combustible gas alarm device generates an alarm signal.

[0115] The maintenance time can be greatly shortened by combining the hot-swap method with the structure. When a battery cell or battery pack is damaged, the alarm light comes on, and the battery cell or battery pack is automatically cut off under the drive of the hot-swap device, waiting for replacement. When replacing, only a new battery cell or battery pack is needed, and the whole process does not require power outage.

[0116] Hot swapping requires that each battery pack must be equipped with a disconnectable switch component, which generally uses a MOS transistor to work under the drive of the BMS, light up the fault indicator light, and disconnect the faulty battery pack. Disconnect one of the multiple battery cells through the switch, light up the fault indicator light, and replace it with a new battery cell. The condition is that when the old battery cell is unplugged and the new battery cell has not been inserted, the other battery cells need to share the load current.

[0117] For the battery pack, each battery pack must at least include the following functions:

[0118] 1) Pluggable component structure.

[0119] 2) The battery assembly must be equipped with complete sensors when plugging and unplugging.

[0120] 3) The battery assembly is connected to the entire chassis with electrical pins, and the physical structure and insulation structure are made of high-performance materials. Since the amount used is very small, it will not affect the cost.

[0121] In the present invention, the front-end battery protection board of the plug-in battery is made into an integrated component with the chassis and connected to the battery component with a pin, so that only the battery needs to be replaced without replacing the protection board, which is more conducive to reducing maintenance costs, making full use of fixed assets, and extending the technical life of the product.

[0122] Furthermore, for small-capacity battery packs, the battery series-parallel combination can appropriately simplify the structure of the battery protection circuit board. For a single battery pack, it is not limited to single parallel use, but multiple batteries are connected in series, and several groups of batteries are connected in parallel to form a series-parallel battery pack, which can simplify the battery protection circuit. When hot plugging is used, three groups of series-parallel battery packs should be connected in parallel to ensure that when one group of batteries is pulled out, the other two groups can still ensure the circuit operation.

[0123] Based on the above-mentioned charge and discharge protection system for battery packs in energy storage power stations, the present invention further provides the following five embodiments.

[0124] Example 1: A parallel battery pack consisting of ten batteries, pull out a battery unit of a group of two batteries, and when replacing, the other eight batteries bear all the load current. Therefore, when replacing the battery, the load current of the other batteries must match the rated current of the battery and should not exceed the rated discharge current of the battery cell, otherwise it will affect the battery life. By improving the electromagnetic compatibility and power factor of the energy storage power station, the quality of the electric energy provided by the energy storage power station is higher and closer to a sine wave. In a complex electromagnetic environment, the energy storage power station is more reliable and less prone to damage, reducing the maintenance workload caused by damage to the energy storage power station due to electromagnetic pulses.

[0125] Example 2: The factory specification of large-capacity batteries produced by a certain factory clearly states that no more than four batteries can be connected in parallel. It is believed that large-capacity batteries are prone to different internal resistance due to individual differences in battery manufacturing after being connected in parallel. The internal resistance of large-capacity batteries is very low, which can easily cause uneven distribution of charging current. Even if they are carefully selected, it is difficult to maintain consistency under long-term use. If they must be connected in parallel, each battery unit should have a separate voltage, current detection and shutdown circuit to ensure the safety of the battery cell.

[0126] Example 3: There are many examples of small-capacity battery packs being used in parallel. Multiple batteries connected in parallel can simplify the circuit protection board, but the heat dissipation conditions of the batteries in the middle are worse than those of the surrounding batteries close to the radiator, which is not conducive to heat dissipation. Moreover, if one battery in a group of batteries fails, the entire group of batteries will stop working. Once an individual battery explodes, it will cause damage to other surrounding batteries. Therefore, when using AC input, a power factor compensation device 4 needs to be installed to improve the overall stability and reliability of the energy storage power station.

[0127] Example 4: Variable speed drives and inverters in wind power generation systems may cause power quality problems such as harmonics and power factor degradation. Therefore, installing a power factor compensation device 4 in a wind energy storage power station helps stabilize the grid connection and ensure power transmission efficiency and grid stability.

[0128] It is worth noting that the electromagnetic pulse intensity generated by external indirect lightning strikes can reach 20kV / m to 40kV / m, which is comparable to the electromagnetic pulse intensity generated by a nuclear explosion (about 40kV / m). Therefore, a lightning-proof gas discharge tube 5 is installed at the input part of the device to prevent external electromagnetic pulses from invading and damaging the device, and the cost of the gas discharge tube 5 is relatively low.

[0129] Example 5: In communication equipment, such as routers and switches, the core processing units are very sensitive. In order to protect these core components, linear regulators, low-pass filters, and physical shielding are used to reduce external electromagnetic interference.

[0130] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0131] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A charging and discharging protection system for a battery pack of an energy storage power station, characterized in that: The charging and discharging protection system for the battery pack of the energy storage power station includes: An electromagnetic pulse protection device is provided on the electromagnetic sensitive circuit of the energy storage power station to shield the interference of the electromagnetic pulse on the electromagnetic sensitive circuit; The charge and discharge protection device is connected to the battery pack and battery cell of the energy storage power station, and is used to collect the real-time temperature, real-time voltage and real-time current of the battery pack and battery cell of the energy storage power station, and based on the real-time temperature, real-time voltage and real-time current of the battery pack and battery cell of the energy storage power station, perform live hot swapping of the battery pack and battery cell of the energy storage power station to perform charge and discharge protection on the battery pack and battery cell of the energy storage power station.

2. The charge and discharge protection system for energy storage power station battery pack according to claim 1 is characterized in that: The electromagnetic sensitive circuit of the energy storage power station includes a converter, a switching power supply, a signal acquisition circuit and a central processing unit.

3. The charge and discharge protection system for energy storage power station battery pack according to claim 1 is characterized in that: The electromagnetic pulse protection device includes: An input protection device is arranged at the entrance of the electromagnetic sensitive circuit of the energy storage power station and is used to isolate and protect the electromagnetic pulses entering the entrance of the electromagnetic sensitive circuit; Gas protection equipment, which is installed between the converter and the power grid of the energy storage power station to prevent electromagnetic pulses from entering the converter in reverse; A shielding device, arranged on the electromagnetic sensitive circuit of the energy storage power station, for shielding the induction pulse of the electromagnetic sensitive circuit; The external communication protection device is arranged at the external communication port of the energy storage power station to prevent the induced electromagnetic pulse of the external communication port from entering the electromagnetic sensitive circuit of the energy storage power station.

4. The charge and discharge protection system for energy storage power station battery pack according to claim 3 is characterized in that: The input protection device comprises: A power factor compensation device, connected to the converter of the energy storage power station, for performing power factor compensation on the converter; A gas discharge tube is arranged at the inlet of the switching power supply of the energy storage power station, and is used to discharge the lightning instantaneous overcurrent at the inlet of the switching power supply and limit the overvoltage; Common-mode and differential-mode neutralization filters are provided at the inlet of the switching power supply of the energy storage power station and are used to filter the electromagnetic pulses at the inlet of the switching power supply; The shielding layer is arranged between the primary winding and the secondary winding of the switching power supply transformer of the energy storage power station, and is used to isolate the electromagnetic pulses coupled by the capacitive coupling of the primary winding and the secondary winding.

5. The charge and discharge protection system for energy storage power station battery pack according to claim 4 is characterized in that: The power factor compensation device is an active power factor compensation device.

6. The charge and discharge protection system for battery packs of energy storage power stations according to claim 4, characterized in that: The common-mode and differential-mode neutralization filter comprises a first common-mode inductor, a second common-mode inductor, a first capacitor, a second capacitor, a third capacitor and a fourth capacitor; The first common-mode inductor is connected to the positive input of the switching power supply, and the second common-mode inductor is connected to the negative input of the switching power supply; One end of the first capacitor is connected between the first common-mode inductor and the alternating current, one end of the second capacitor is connected between the first common-mode inductor and the positive input of the switching power supply, the third capacitor is connected between the second common-mode inductor and the alternating current, the fourth capacitor is connected between the second common-mode inductor and the negative input of the switching power supply, and the other ends of the first capacitor, the second capacitor, the third capacitor and the fourth capacitor are all grounded; One end of the gas discharge tube is connected between the first common mode inductor and the alternating current, and the other end of the gas discharge tube is connected between the second common mode inductor and the alternating current.

7. The charge and discharge protection system for energy storage power station battery pack according to claim 3 is characterized in that: The gas protection device is a gas discharge tube.

8. The charge and discharge protection system for energy storage power station battery pack according to claim 3 is characterized in that: The shielding device is a shielding cover.

9. The charge and discharge protection system for energy storage power station battery pack according to claim 3, characterized in that: The external communication protection device comprises: A TVS diode is arranged at the outlet of the switching power supply of the energy storage power station and is used to absorb electromagnetic pulses at the outlet of the switching power supply; The optical fiber is arranged between the upper end collection unit and the lower end collection unit of the energy storage power station, and is used to isolate the voltage between the upper end collection unit and the lower end collection unit.

10. The charge and discharge protection system for battery packs of energy storage power stations according to claim 1, characterized in that: The charge and discharge protection device comprises: A temperature sensor is provided on the battery pack and battery cell of the energy storage power station and is connected to the battery management system of the energy storage power station to collect the real-time temperature of the battery pack and battery cell of the energy storage power station and send it to the battery management system; A voltage sensor connected to the battery pack and battery cells of the energy storage power station, used to collect the real-time voltage of the battery pack and battery cells of the energy storage power station and send it to the battery management system; A current sensor connected to the battery pack and battery cell of the energy storage power station, used to collect the real-time current of the battery pack and battery cell of the energy storage power station and send it to the battery management system; The battery management system determines the working state of each battery pack and each battery cell according to the real-time temperature, real-time voltage and real-time current of the battery pack and battery cell of the energy storage power station, and generates an alarm signal when the working state of any battery pack or any battery cell is abnormal; The flame and combustible gas alarm device is arranged in the battery module box of the energy storage power station, and is used to detect whether there is flame and combustible gas in the battery module box, and if so, generates an alarm signal; The live hot swap device is arranged between the battery groups and between the battery cells of the energy storage power station, and is respectively connected to the battery management system and the flame and combustible gas alarm device, and is used to disconnect the connection between the corresponding battery groups or the connection between the corresponding battery cells when the battery management system or the flame and combustible gas alarm device generates an alarm signal.

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