CN102222964B - Equalizing system and method for energy storage system - Google Patents

Abstract

The invention discloses an equalization system of an energy storage system, which includes a power generation device, an electric energy combining system, a DC bus, a charging module, a battery pack, a grid-connected inverter, a user module, a constant current source, and an input end of an equalized power supply. The power generation device is connected to the power combination system, and the power combination system is connected to the charging module through the DC bus, and the charging module is connected to the battery pack; the grid-connected inverter and the user module are connected to the DC bus in turn, and the constant current source is connected to On the user module, the AC power after passing through the inverter is converted into DC power, and connected to the battery pack through the balanced bus connected to the input end of the balanced power supply, and the constant current source converts the AC output after passing through the grid-connected inverter into The DC output is used as a balancing source to balance the battery cells in the battery pack. Adopting the present invention can realize effective dynamic equalization, in addition, a large amount of heat will not be generated during the equalization process, and the charging and discharging efficiency is improved.

Description

A balance system of energy storage system

technical field

The invention relates to a large-scale electric storage system, in particular to an equalization system and an equalization method of the energy storage system. the

Background technique

In the field of new energy power generation, the use of large-scale power storage technology can make the output power of unstable new energy power smoothly adjustable, change unstable power input into continuous, safe and reliable power output, and reduce the impact of fluctuating power on the grid. impact, thus solving the problem of grid-connected new energy power. For off-grid new energy power generation in islands and remote areas, large-scale power storage systems can achieve power smoothing and storage to meet the needs of off-grid power generation in islands and remote areas and the normal supply of power without new energy output. the

Safety and energy storage efficiency are two important parameters for examining energy storage systems. Temperature is an important external factor that affects the charge and discharge capacity of a battery cell and the safety of an energy storage battery system; the internal resistance of the battery and the consistency of batteries within and between modules are important internal factors that affect the performance of the energy storage system. Large-scale energy storage requires a large number of single batteries connected in series and parallel to obtain larger energy storage capacity and higher power output. In consideration of safety, the energy storage size of the battery pack depends on the worst battery. Charge and discharge characteristics. Because the batteries may not be manufactured in the same batch and the manufacturing process itself has certain differences, and as the battery usage time increases, the mutual difference in battery performance will be more significant, and the more single batteries connected in series, the more inconsistency protrude. If there is no balanced management of the battery, as the charging and discharging cycle progresses, the inconsistency between the single cells will cause undercharging, overcharging and overdischarging, which will seriously affect the performance and life of the battery pack, and will cause serious safety hazards. the

Among the existing equalization technologies, the most widely used one is to use resistors to perform dissipative equalization on the battery pack during the charging process. The principle of resistance equalization is shown in Figure 1. The biggest problem with this equalization method is that the resistors will generate a lot of heat during the equalization process, which reduces the charge and discharge efficiency and causes a huge waste of effective energy storage; at the same time, a large amount of heat is generated, which also increases the burden on thermal management. Existing non-dissipative equalization methods mainly include switched capacitor equalization methods, etc., but often have problems such as complex circuits and slow equalization speed. the

Therefore, the prior art still needs to be improved and developed. the

Contents of the invention

The purpose of the present invention is to provide an equalization scheme for an energy storage system, aiming at solving the problem that the existing resistance dissipation equalization method generates a large amount of heat during the equalization process, resulting in a huge waste of effective stored energy; at the same time, a large amount of heat is generated, Increase the burden of thermal management and other issues. At the same time, it solves the problem of slow equalization speed in a large-capacity energy storage system by a single equalization. the

Technical scheme of the present invention is as follows:

A balancing system of an energy storage system, including a power generating device, a power combining system, a DC bus, a charging module, a storage battery pack, a grid-connected inverter, a user module, a constant current source, and an input terminal of a balanced power supply, the power generating device Connected to the power combination system, the power combination system is connected to the charging module through the DC bus, and the charging module is connected to the battery pack; the grid-connected inverter and the user module are connected to the DC bus in turn, and the constant current source is connected to the user On the module, the AC power after the inverter is converted into DC power, and connected to the battery pack through the balanced bus connected to the input end of the balanced power supply, and the constant current source converts the AC output after passing through the grid-connected inverter into a DC output , as a balancing source to balance the battery cells in the battery pack. the

The balancing system of the energy storage system, wherein the battery pack includes an energy storage module and an energy storage control unit, the charging terminals of the energy storage modules are all cascaded to the input terminals of the balanced power supply, and the output terminals of the energy storage modules connected in series, the energy storage control unit is connected to the energy storage module through a can bus. the

The balanced system of the energy storage system, wherein the energy storage module includes a unit control module, a balanced power supply input module and a monomer package, and the balanced power supply input modules of the energy storage module are all connected in parallel to the positive and negative terminals of the balanced power supply input terminal. On the top; the unit control module in the energy storage module is connected to the energy storage control module through the can bus, the unit control module is connected to the monomer package through the lin bus, and the balanced bus of the monomer package is connected to the balanced power input module. the

In the equalization system of the energy storage system, the battery pack includes a plurality of energy storage modules, and the charging terminals of each energy storage module are cascaded to the input terminal of the equalization power supply. the

In the balance system of the energy storage system, each energy storage module includes two or more monomer packages connected in series. the

The balance system of the energy storage system, wherein, each single battery pack includes a single battery, a microprocessor, an isolation module, a positive pole, a negative pole, a lin bus and a balance bus, and the single battery The two poles are respectively connected to the positive pole, the negative pole and the microprocessor, the balanced bus is connected to the microprocessor, the lin bus is connected to the microprocessor through an isolation module, and the lin bus is connected to the control terminal above; the balanced bus is connected to the balanced power input; the positive and negative points are connected to the power output. the

In the balanced system of the energy storage system, an energy transfer module is connected in parallel to the electrode of each cell package, and each energy transfer module is distributed and installed in parallel on the balanced power supply input module. the

A method for equalizing an energy storage system, wherein the microprocessor collects the voltage of each single battery in an energy storage module and sends it to an energy storage control unit, and the energy storage control unit calculates the voltage of each single battery in each energy storage module. When the voltage of a single battery in a certain energy storage module is lower than the average voltage of the single battery in the energy storage module, the microcontroller in the single battery will control the balance between the single battery and the battery. When the battery is connected to the bus, the single battery absorbs the current on the equalization bus, and starts to balance the single battery; when the voltage of the single battery reaches the average voltage of the single battery in the energy storage module, the single battery is disconnected from the equalization bus, End the equalization of this single cell, and then perform equalization on another low-voltage single cell. the

In the equalization method of the energy storage system, the energy of the single battery with a voltage higher than the average voltage is transferred to the equalization bus through the energy transfer module in an energy transfer manner, and is absorbed by the battery cells with a voltage lower than the average voltage. the

The balancing method of the energy storage system, wherein, if the voltages of all the single cells in a certain energy storage module have been balanced, but lower than the average voltage among the energy storage modules in the energy storage system, the energy storage All the single cells of the module are connected to the balance bus to absorb the current on the balance bus, and each single battery in the energy storage module is charged until the voltage of the energy storage module reaches the average voltage of the energy storage unit module, and the storage is completed. energy system balance. the

Beneficial effects of the present invention: the present invention balances the storage battery system by simultaneously applying the non-dissipative energy transfer module and the supplementary power mode in which the user load in the system is input as a constant current source, and can balance a single battery at any time, as long as there is The voltage of the single battery is low, which satisfies the balance condition. Regardless of whether the energy storage unit or module is in the charging, discharging or placing state, it can be balanced immediately to achieve effective dynamic balance. In addition, a lot of heat will not be generated during the balance process, which improves the charging efficiency discharge efficiency. the

Description of drawings

Figure 1 is a schematic diagram of the existing resistance equalization;

Fig. 2 is the schematic diagram of the load-type power supply equalization system in the present invention;

Fig. 3 is a schematic diagram of the simultaneous application of supplementary power formula and energy transfer formula in the present invention;

Fig. 4 is a schematic diagram of monomer bag in the present invention;

Fig. 5 is a schematic structural diagram of the energy storage module in the power supplementary equalization system of the present invention. the

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear and definite, the present invention will be further described in detail below with reference to the accompanying drawings and examples. the

The load-type supplementary power balance system includes a power generation device, a power combination system, a DC bus, a charging module, a battery pack, a grid-connected inverter, a user module, a constant current source, and a balanced power input terminal. In the system provided by the present invention, there are multiple generating devices, generating device 1, generating device 2, ..., generating device n (wherein n is greater than or equal to 2), and are all connected to the electric energy integration system, the electric energy integration system The charging module is connected through the DC bus, and the charging module is connected to the battery pack; the grid-connected inverter and the user module are connected to the DC bus in turn, and the constant current source is connected to the user module to convert the AC power after passing through the inverter. for direct current. And connected to the storage battery pack through the balance bus connected to the balance power input terminal. the

The equalization system and equalization method of the energy storage system provided by the present invention transfer the electric energy of the high-voltage battery cells to the equalization bus by means of energy transfer, and are absorbed by the low-voltage battery cells for dynamic equalization. However, when the energy transferred by the high-voltage battery cell is not enough to supplement the low-voltage cell, as a supplement, the present invention also adopts a supplementary power method: the AC output after passing through the inverter is converted into a DC output through a constant current source , as an equalization source, flows into the equalization bus to equalize the monomers and units in the power storage system, and improve the speed and effect of equalization. the

The battery system is balanced using non-dissipative energy transfer modules. The idea of energy transfer balance is to use switching power supply technology, with voltage as the standard, to transfer the electric energy of high-voltage battery cells to the balance line by means of energy transfer, and to be absorbed by low-voltage battery cells for dynamic balance. the

In this energy transfer supplementary balance, an energy transfer module is connected in parallel to the electrode of each cell package, and each energy transfer module is dispersed and installed in parallel on each battery cell, as shown in Figure 3. The energy transfer module mainly uses DC/DC switching power supply technology to transfer the power of the high-voltage single battery to the low-voltage single battery by means of energy transfer, that is, the voltage is used as the measurement standard, and the energy transfer method will be higher than the average Energy from cells with a higher voltage is transferred to the equalization bus and absorbed by cells with a lower than average voltage. The power transfer is bidirectional and parallel, that is, the power of any high-voltage battery can be transferred to any low-voltage battery in parallel at the same time, so as to achieve the balance of battery voltage. the

The microprocessor in the cell pack collects the voltage of each cell in the energy storage unit, and the voltage data of the cell pack is uploaded to the energy storage control unit through the serial peripheral interface (SPI) transmission mode, and the energy storage control unit The processor calculates the average voltage of the single cells in the energy storage unit, and the calculation formula is: average voltage _Uaverage = total voltage of the energy storage module/total number of single cells in the energy storage module, as the basis for whether each single cell needs to be balanced, That is, the basis for balancing enabling work.

After the cell pack and the energy transfer module are connected, they start equalizing work. While the energy transfer module detects the voltage of the connected cell pack battery, it also detects the voltage of other cell pack batteries through the balance bus to obtain the average voltage of the battery pack. Comparing the battery voltage with the average voltage of the battery pack, if the battery voltage is higher than the average voltage, the circuit in the module will flow the higher energy into the balance bus through the DC/DC converter; if the voltage of the battery is lower than the average voltage, the circuit in the module will absorb the balance The power on the bus charges the battery. the

Continuing to refer to FIG. 3 , in the present invention, since the energy transfer balance mode is a two-way energy flow, infinite cascading of monomers can be performed. However, in a large-scale battery energy storage system, there are a large number of batteries. In order to simplify the battery management system, reduce the complexity of management, and ensure the balance speed and efficiency, the battery energy storage system is divided into multiple units, and the balance system is based on units. Energy transfer equalization has the characteristics of low power consumption, but the equalization speed is relatively slow. In order to improve the equalization speed, on the basis of the above equalization method, the present invention proposes to apply external power equalization as a supplement. Mainly based on energy transfer balance, supplemented by power supply balance. the

The basic principle of supplementary power balance is as follows: Refer to Figure 2. The principle of load-type power supplement balance provided by Embodiment 1 of the present invention is: the supplementary power supply is regarded as a load in the user, an external AC/DC constant current source is connected, and the balanced bus , to balance the monomer package of the energy storage module in the energy storage system. the

As a load in the user, the constant current source converts the AC output after the inverter into a DC output. As a balanced source, it balances the monomers in the module through the lin bus, and the can bus balances the modules to complete the storage. Balance the battery cells and modules of the battery pack in the electrical system. the

Due to the limited supplementary power of the constant current source, the entire energy storage system cannot be balanced at the same time. In this balance management method, the battery group in the energy storage system is divided into multiple energy storage modules, as shown in Figure 5. The storage battery pack includes a first energy storage module, a second energy storage module, ..., an nth energy storage module and an energy storage control unit, and the first energy storage module, the second energy storage module, ..., the nth energy storage module The charging ends of the energy storage modules are cascaded to the input end of the balanced power supply, and the output ends of the energy storage modules are connected in series. The energy storage control unit is connected to each energy storage module through a can bus. the

Referring to Fig. 3 and Fig. 5, the energy storage module includes a unit control module, a balanced power input module and a plurality of monomer packages, and the balanced power input modules of each energy storage module are connected in parallel to the positive and negative terminals of the balanced power input Above; the unit control modules in each energy storage module are connected to the energy storage control module through the can bus, the unit control modules are connected to each monomer package through the lin bus, and the balanced bus of each monomer package is connected to the balanced power supply input module. the

In this case, the constant current source corresponds to one energy storage module at a time, and the constant current source supplies power to the corresponding energy storage modules in a balanced manner. Each energy storage module includes two or more cell packages connected in series, see Figure 4 for a schematic diagram of the internal structure of the cell package, each cell package includes a single battery, a microprocessor (MPU) And an isolation module and positive pole, negative pole, lin bus and balanced bus. The two poles of the single battery are respectively connected to the positive pole, the negative pole and the microprocessor, the balance bus is connected to the microprocessor, the lin bus is connected to the microprocessor through an isolation module, and the The lin bus is connected to the control terminal; the balanced bus is connected to the balanced power supply input; the positive pole and negative pole are connected to the power output terminal. the

In the load balancing mode of the present invention, the voltage is used as the measurement standard, and the voltage of the battery with a low voltage is supplemented to make it equal to the voltage of other batteries to achieve balance. The order of equalization is to firstly balance each single battery in the module, and then to balance the modules and between modules. the

The microprocessor in the cell pack collects the voltage of each cell in the energy storage module, and the equalization is enabled to be input to the microprocessor (MPU) after passing through the Lin bus and the isolation module, and the MPU then controls the single cell and the equalization bus The connection relationship, connected to enter the equilibrium state. The voltage data of the cell pack is uploaded to the energy storage control unit through the serial peripheral interface (SPI), and the processor of the energy storage control unit calculates the average voltage of the cell in the energy storage module. The calculation formula is: average voltage U _Average = energy storage module voltage/total number of single cells in the energy storage module, which is used as the basis for balance between modules.

The equalization method of the above system is: when the voltage U _n of a single battery in a certain energy storage module is lower than the average voltage of the single battery in the module, such as U _n < _Uaverage , then start to carry out the adjustment on the single battery n balanced. At this time, the microprocessor MPU in the cell pack controls the internal electronic switch, the switch is closed, and the current on the equalization line flows into the single battery through the electronic switch. If the voltage U m of the single battery _m and the voltage U _n of the single battery n are both lower than the average voltage _Uaverage , the MPUs in the single battery m and the single battery n both control the internal electronic switch, the switch is closed, and the equalization line The current can flow into single cell m and single cell n at the same time. When the voltages of the single cells in the module are equalized, the electronic switch is turned off. In this way, the voltage balance of the single cells in the energy storage module is realized.

Although the voltages between the single cells in the energy storage modules are balanced, there may be an imbalance between the overall voltage _U'n of each energy storage module and the overall voltage of other energy storage modules.

Therefore, if the voltages of all the single cells in an energy storage module have been balanced, but the overall voltage _U'n of the energy storage module is lower than _the average voltage U'average of the overall voltages of the energy storage modules in the energy storage system, Then the balanced power supply (that is, the constant current source) of the energy storage system supplies power to all the single batteries in the energy storage module until the overall voltage of the energy storage module reaches the average voltage of the overall voltage of the energy storage module, Then the energy storage system ends the balance among the energy storage modules.

The equalization solution in the present invention is applicable to power storage systems for new energy power generation, and is also applicable to large-scale battery power storage systems such as power plants and smart grids. the

The present invention balances the battery system by simultaneously applying the non-dissipative energy transfer module and the supplementary power mode with the user load in the system as the constant current source input, and can balance a single battery at any time. As long as there is a single battery with low voltage, Satisfying the equilibrium conditions, no matter the energy storage unit or module is in the state of charging, discharging or placing, it can be immediately balanced to achieve effective dynamic equilibrium. In addition, a large amount of heat will not be generated during the equalization process, which improves the charging and discharging efficiency. the

It should be understood that the application of the present invention is not limited to the above examples, and those skilled in the art can make improvements or transformations according to the above descriptions, and all these improvements and transformations should belong to the protection scope of the appended claims of the present invention. the

Claims (7)

1. the equalizing system of an energy-storage system, it is characterized in that, comprise Blast Furnace Top Gas Recovery Turbine Unit (TRT), electric energy combination system, dc bus, charging module, batteries, combining inverter, line module, constant-current source, balanced power input, described Blast Furnace Top Gas Recovery Turbine Unit (TRT) is connected on the electric energy combination system, described electric energy combination system connects charging module by dc bus, and described charging module connects batteries; Be connected with combining inverter and line module on described dc bus in turn, constant-current source is connected on line module, to change direct current into through the alternating current after inverter, and be connected to batteries by the equalizing bus bar that is connected on balanced power input, constant-current source carries out equilibrium as balanced source to the battery cell in batteries being transformed into direct current output through the output of the interchange after combining inverter.

2. the equalizing system of energy-storage system according to claim 1, it is characterized in that, batteries comprises energy-storage module and energy storage control unit, the charging end of described energy-storage module all level is associated on balanced power input, be connected in series between the output of energy-storage module, described energy storage control unit is connected to energy-storage module by the can bus.

3. the equalizing system of energy-storage system according to claim 2, it is characterized in that, described energy-storage module comprises unit controls module, balanced Power Entry Module and monomer bag, and the balanced Power Entry Module of described energy-storage module all is connected in parallel on the both positive and negative polarity of balanced power input; Unit controls module in described energy-storage module is connected to the energy storage control unit by the can bus, and described unit controls module is connected to the monomer bag by the lin bus, and the equalizing bus bar of monomer bag is connected to balanced Power Entry Module.

4. the equalizing system of energy-storage system according to claim 3, is characterized in that, described batteries comprises a plurality of energy-storage modules, and the charging end of each energy-storage module all level is associated on balanced power input.

5. the equalizing system of energy-storage system according to claim 3, is characterized in that, each energy-storage module comprises two or more monomer bags that are connected in series.

6. the equalizing system of energy-storage system according to claim 3, it is characterized in that, each monomer bag comprises a cell, microprocessor and isolation module and positive limit, negative pole point, lin bus and equalizing bus bar, the two poles of the earth of described cell are connected respectively on positive limit and negative pole point and on microprocessor, described equalizing bus bar is connected on microprocessor, described lin bus is connected on microprocessor by isolation module, and described lin bus is connected on the unit controls module; Described equalizing bus bar is connected on balanced power input; Described positive limit is connected with negative pole and is connected electric energy output end.

7. the equalizing system of according to claim 3-6 described energy-storage systems of any one, is characterized in that, energy transfer module in parallel on the electrode of each monomer bag, and each energy transfer module disperses to be installed in parallel on balanced Power Entry Module.

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