CN115864470A - Battery energy storage system - Google Patents
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Abstract
The utility model relates to a battery energy storage system, which comprises a plurality of energy storage modules connected in parallel and a controller connected with the energy storage modules, wherein the energy storage modules comprise a battery pack and a DCDC converter, the battery pack is connected with the high-voltage side of the DCDC converter, the output end of the energy storage modules consists of the negative pole of the low-voltage side of the DCDC converter and the positive pole of the battery pack, and is used for connecting electric equipment and determining the shunt proportion of each target energy storage module according to the output voltage of all target energy storage modules in the energy storage system; the target compensation voltage to be provided by the DCDC converter in the target energy storage module is determined according to the shunt proportion and the output current of each target energy storage module, and the target compensation voltage can be provided by controlling the DCDC converter to enable the battery energy storage system to provide constant voltage for the electric equipment, so that constant voltage current sharing control according to the SOC can be avoided, and the accuracy of constant voltage control of the battery energy storage system can be improved.
Description
Technical Field
The disclosure relates to the technical field of battery energy storage, in particular to a battery energy storage system.
Background
The battery energy storage system can realize energy storage and power bidirectional flow, is beneficial to improving the comprehensive utilization rate of power grid equipment, the peak-load modulation and reactive power supporting capacity of the system and the like, and is beneficial to improving the stability, economy and flexibility of power grid operation.
At present, a battery energy storage system generally adopts a Boost type converter and a battery string to be connected in series to form a minimum energy storage unit, then a plurality of minimum energy storage units are connected in parallel to form the battery energy storage system, the output end of the Boost type converter in each minimum energy storage unit in the battery energy storage system is directly connected to a direct current bus, namely, the output voltage of a Boost circuit is the voltage of a parallel bus, and because the output voltage of the Boost type converter is greater than the input voltage, the output voltage of the battery string connected in series with the Boost type converter can be limited, so that the terminal voltage of the battery string is lower, and the energy transmission efficiency and the power transmission efficiency are limited, thereby being not beneficial to improving the economy of the whole energy storage system. In addition, the current battery energy storage system usually adopts an SOC (state of charge) shunt method to perform current-sharing constant-voltage control on the battery energy storage system, and since a main parameter SOC used in the SOC shunt method usually has about 3% of acquisition error, the accuracy of current-sharing constant-voltage control performed by the SOC shunt method is poor.
Disclosure of Invention
The battery energy storage system comprises a plurality of energy storage modules connected in parallel and a controller connected with the energy storage modules, wherein each energy storage module comprises a battery pack and a DCDC converter, the battery pack is connected with the high-voltage side of the DCDC converter, and the output end of each energy storage module consists of the negative electrode of the low-voltage side of the DCDC converter and the positive electrode of the battery pack and is used for connecting electric equipment;
the controller is used for acquiring the battery voltage of a battery pack in each energy storage module, determining one or more target energy storage modules from the plurality of energy storage modules according to the battery voltage, and acquiring the output voltage and the output current of each target energy storage module; determining the shunt proportion of each target energy storage module according to the output voltages of all target energy storage modules in the energy storage system; determining a target compensation voltage to be provided by the DCDC converter in each target energy storage module according to the shunt proportion and the output current of each target energy storage module; and controlling the DCDC converter to provide a target compensation voltage according to the target compensation voltage so that the target energy storage module outputs constant voltage to the electric equipment.
Optionally, the controller is configured to:
acquiring the dispersion of the output voltage of each target energy storage module;
determining the average value of the voltage difference of each target energy storage module according to the dispersion of the output voltage of each target energy storage module;
and determining the corresponding shunt proportion of each target energy storage module according to the output voltage of each target energy storage module and the average value of the voltage difference.
Optionally, the controller is configured to:
under the condition that the output voltage of the target energy storage module is smaller than the average value of the voltage difference, the shunt ratio is calculated according to a first preset formula; and under the condition that the output voltage of the target energy storage module is greater than or equal to the average voltage difference value, the shunt ratio is calculated according to a second preset formula, the first preset formula and the second preset formula are both related to the number of the target energy storage modules in the battery energy storage system, and the average voltage difference value of the target energy storage modules is related to the variance of the output voltage.
Optionally, the first preset formula is:
the second preset formula is as follows:
the number of the target energy storage modules in the battery energy storage system is represented by the number of the target energy storage modules in the battery energy storage system, and the differential ratio of the average value of the voltage difference to the variance of the output voltage is represented by the number of the target energy storage modules in the battery energy storage system.
Optionally, the controller is configured to:
calculating the dispersion of the output voltage of the target energy storage module by the following formula:
Ubatt dispersion[i] ＝Ubattsreal[i]-MeanVolt；
Ubatt dispersion[i] for the dispersion of the output voltage of the ith target energy storage module, ubattsreal [ i]The voltage is output by the ith target energy storage module, and MeanVolt is the average value of the output voltages of all target energy storage modules in the battery energy storage system.
Optionally, the controller is configured to:
determining a first correction voltage according to the output current of each target energy storage module and the shunt ratio; acquiring a first sum of the maximum output voltage and the first correction voltage in all target energy storage modules in the battery energy storage system; acquiring a second difference value between the first sum value and the output voltage of each target energy storage module; and controlling the DCDC converter to provide a target compensation voltage according to the second difference.
Optionally, the controller is configured to:
acquiring a second sum of output currents of all target energy storage modules in the battery energy storage system; determining a target current of each target energy storage module according to the shunt proportion and the second sum of each target energy storage module; acquiring a second difference value between the target current of the target energy storage module and the output current of the target energy storage module; and taking the second difference value and the target current of the target energy storage module as the input of a preset PI regulator, so that the preset PI regulator outputs the first correction voltage.
Optionally, the controller is configured to:
the output voltage of each target energy storage module and the second difference value are used as the input of a preset phase shifting controller to output and obtain the DCDC driving signal; adjusting the DCDC converter according to the DCDC driving signal to enable the DCDC converter to provide the target compensation voltage.
Optionally, the controller is configured to:
determining a maximum battery voltage of the battery packs in the plurality of energy storage modules; acquiring a first difference value between the battery voltage of a battery pack in each energy storage module and the maximum battery voltage; and taking the energy storage module where the battery pack is located as the target energy storage module when the first difference is smaller than or equal to the voltage difference threshold.
Optionally, a filter inductor is connected to a low-voltage side of the DCDC converter, and the voltage difference threshold is related to a maximum battery voltage of a battery pack in a plurality of energy storage modules of the battery energy storage system, a transformation ratio of the DCDC converter, and a voltage of the filter inductor.
According to the technical scheme, the battery energy storage system comprises a plurality of energy storage modules connected in parallel and a controller connected with the energy storage modules, wherein each energy storage module comprises a battery pack and a DCDC converter, the battery pack is connected with the high-voltage side of the DCDC converter, the output end of each energy storage module consists of the negative electrode of the low-voltage side of the DCDC converter and the positive electrode of the battery pack and is used for connecting electric equipment, so that the negative electrode of the low-voltage side of the DCDC converter and the positive electrode of the battery pack form the output end of the energy storage module, the output voltage of the battery pack can be ensured to be the maximum voltage which can be currently output by the battery pack, the output power of the battery pack can be effectively improved, and the economical efficiency of the battery energy storage system can be improved; the battery energy storage system can determine the shunt proportion of each target energy storage module according to the output voltage of all the target energy storage modules in the energy storage system; the target compensation voltage to be provided by the DCDC converter in the target energy storage module is determined according to the shunt proportion and the output current of each target energy storage module, and the DCDC converter is controlled to provide the target compensation voltage so that the battery energy storage system can provide constant voltage for the electric equipment, so that constant voltage current sharing control according to the SOC can be avoided, and the accuracy of constant voltage control of the battery energy storage system can be improved.
Additional features and advantages of the disclosure will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure, but do not constitute a limitation of the disclosure. In the drawings:
fig. 1 is a block diagram of a battery energy storage system shown in an exemplary embodiment of the present disclosure;
fig. 2 is a topology diagram of a DCDC converter according to an exemplary embodiment of the present disclosure.
Detailed Description
The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.
Before the detailed description of the specific embodiments of the present disclosure, the following description is first made on an application scenario of the present disclosure, and the present disclosure may be applied to a scenario in which power is supplied through an energy storage device, a current battery energy storage system generally adopts a Boost type converter and a battery string to form a minimum energy storage unit from a topological structure, and then a plurality of the minimum energy storage units are connected in parallel to form the battery energy storage system, an output end of the Boost type converter in each minimum energy storage unit in the battery energy storage system is directly connected to a dc bus, that is, an output voltage of a Boost circuit is a parallel bus voltage, and since the output voltage of the Boost type converter is greater than an input voltage, an output voltage of the battery string connected in series with the Boost type converter is limited, which results in that a terminal voltage of the battery string is low, and energy transmission efficiency and power transmission efficiency are limited. From the aspect of voltage regulation control strategies, in the related art, a current-sharing constant-voltage control is usually performed on a battery energy storage system by using an SOC (state of charge) shunt method, that is, when the system is in a discharge mode, the SOC of each battery string is collected, and the sum of the product of the SOC of each battery string in the battery energy storage system and the corresponding maximum continuous discharge current is divided by the product of the SOC of each battery string in the battery energy storage system and the corresponding maximum continuous discharge current to obtain a discharge proportion; and then multiplying the discharge proportion of each battery string by the total discharge current of the battery energy storage system to obtain the discharge current target of each battery string. When the battery energy storage system is in a charging mode, collecting the SOC of each battery string, and dividing the product of the consumption capacity (namely 100-SOC) of each battery string and the maximum continuous discharging current by the sum of the products of the consumption capacity of each battery string in the battery energy storage system and the corresponding maximum continuous charging current to obtain a charging proportion; then the charging proportion of each battery string is multiplied by the total charging current of the battery energy storage system to obtain a charging current target of each battery string, then the PI regulator is used for controlling the actual charging current or discharging current of each battery string to obtain a corrected voltage target, and further a constant voltage target of the battery energy storage system is obtained. In addition, in the topology of the battery pack and the DCDC converter in the related art, since the DCDC converter is full-power output, when the battery unit connected in series with the DCDC converter needs to output more power in the discharging state, the DCDC converter also needs to output more power, and meanwhile, the output end of the DCDC converter needs to meet the voltage and power requirements of the battery unit. Therefore, the performance requirements of the DCDC converter are high, especially in those high-power energy storage devices, the cost of the DCDC converter to be invested is particularly high, and the energy loss caused by the switching loss in the DCDC converter is also large, which is not favorable for improving the electric energy transmission efficiency.
In order to solve the above technical problems, the present disclosure provides a battery energy storage system, which includes a plurality of energy storage modules connected in parallel, and a controller connected to the energy storage modules, where the energy storage modules include a battery pack and a dc (Direct Current converter) converter, the battery pack is connected to a high-voltage side of the dc-dc converter, and an output end of the energy storage module is formed by a negative electrode on a low-voltage side of the dc-dc converter and a positive electrode of the battery pack and is used for connecting an electric device, so that by making the negative electrode on the low-voltage side of the dc-dc converter and the positive electrode of the battery pack form the output end of the energy storage module, it is possible to ensure that an output voltage of the battery pack used is a maximum voltage that the battery pack can currently output, and thus it is possible to effectively increase an output power of the battery pack, which is advantageous for increasing economy of the battery energy storage system, and because the dc-dc converter is not fully powered, its output voltage is only used as a correction voltage when the battery pack is subjected to parallel equalization control, and thus its output power is relatively small, energy loss caused by switching loss in the dc-dc converter, and the energy storage system can also relatively reduce a shunt ratio of all energy storage modules in the energy storage system; the target compensation voltage to be provided by the DCDC converter in the target energy storage module is determined according to the shunt proportion and the output current of each target energy storage module, the target compensation voltage can be provided by controlling the DCDC converter, so that the battery energy storage system provides constant voltage for the electric equipment, constant voltage current sharing control according to SOC can be avoided, and the accuracy of constant voltage control of the battery energy storage system can be effectively improved.
The present disclosure is described below with reference to specific examples.
Fig. 1 is a block diagram of a battery energy storage system shown in an exemplary embodiment of the present disclosure; as shown in fig. 1, the battery energy storage system includes a plurality of energy storage modules 101 connected in parallel, and a controller 102 connected to the energy storage modules, where the energy storage modules 101 include a battery pack 1011 and a DCDC converter 1012, the battery pack 1011 is connected to a high-voltage side of the DCDC converter 1012, and an output end of the energy storage module 101 is formed by a negative electrode of a low-voltage side of the DCDC converter 1012 and a positive electrode of the battery pack 1011, and is used for connecting to an electric device.
The battery energy storage system may include 8 energy storage modules, and output ends of the 8 energy storage modules are connected to a power supply end of the electric device. The DCDC converter 1012 may adopt a bidirectional full-bridge LC resonance type topology, as shown in fig. 2, fig. 2 is a topology diagram of a DCDC converter shown in an exemplary embodiment of the present disclosure, the DCDC converter 1012 may include a high-frequency transformer T1, a high-voltage side of the high-frequency transformer T1 is connected to a first full-bridge switching circuit, a low-voltage side of the high-frequency transformer T1 is connected to a second full-bridge switching circuit, the first full-bridge switching circuit is composed of two bridge arms formed by switching tubes Q1 to Q4, the second full-bridge switching circuit is composed of two bridge arms formed by switching tubes Q5 to Q8, an LC series resonance network (i.e., a branch where L1 and C1 are located) is added to the high-voltage side of the high-frequency transformer T1, a current flowing through the high-frequency transformer T1 may approach a sine wave through a resonance manner, so that a current harmonic may be reduced, a magnetic core loss of the transformer may be reduced, a current of the switching tubes may be reduced at a switching moment, and an effect of reducing a switching loss may be achieved; the low-voltage side of the transformer T1 is added with a filter inductor L2, so that the output current ripple of the low-voltage side can be reduced; because the high-voltage side of the DCDC converter 1012 is connected to the output end of the battery pack 1011, the negative electrode of the low-voltage side of the DCDC converter 1012 and the positive electrode of the battery pack 1011 form the output end of the energy storage module, when the DCDC converter 1012 is used as a compensation voltage regulator of the battery energy storage system, the voltage range matched with the battery energy storage system can be larger, and the robustness of the battery energy storage system can be effectively improved. And because the DCDC converter 1012 adopts the high-frequency transformer for isolation, the voltage and current stress of the switching tube in the DCDC converter 1012 are relatively small, so that the transmission efficiency can be effectively improved. The negative pole through making this DCDC converter 1012 low pressure side constitutes this energy storage module's output like this and the positive pole of this battery package 1011, can guarantee that the output voltage of used battery package 1011 is the maximum voltage that this battery package can be exported at present, can effectively improve the output of battery package 1011, thereby there is the economic nature that is favorable to promoting battery energy storage system, and can provide target compensation voltage through controlling this DCDC converter 1012 and make this battery energy storage system provide constant voltage electricity to this consumer, be favorable to improving the accuracy of this battery energy storage system constant voltage control.
In addition, the controller 102 is configured to obtain a battery voltage of a battery pack 1011 in each energy storage module 101, determine one or more target energy storage modules from the plurality of energy storage modules 101 according to the battery voltage, and obtain an output voltage and an output current of each target energy storage module; determining the shunt ratio of each target energy storage module according to the output voltages of all target energy storage modules in the energy storage system; determining a target compensation voltage to be provided by the DCDC converter 1012 in each target energy storage module according to the shunt proportion and the output current of the target energy storage module; and controlling the DCDC converter 1012 to provide a target compensation voltage according to the target compensation voltage, so that the target energy storage module outputs a constant voltage to the electric equipment.
According to the technical scheme, the battery energy storage system can determine the shunt proportion of each target energy storage module according to the output voltages of all the target energy storage modules in the energy storage system; determining a target compensation voltage to be provided by the DCDC converter in each target energy storage module according to the shunt proportion and the output current of each target energy storage module; and the DCDC converter is controlled to provide target compensation voltage so that the target energy storage module outputs constant voltage to the electric equipment, constant voltage current sharing control according to SOC can be avoided, and the accuracy of constant voltage control of the battery energy storage system can be effectively improved.
Further, when determining one or more target energy storage modules from the plurality of energy storage modules according to the battery voltage, the controller 102 may:
determining a maximum battery voltage of the battery pack 1011 in the plurality of energy storage modules;
acquiring a first difference value between the battery voltage and the maximum battery voltage of the battery pack 1011 in each energy storage module;
and when the first difference is smaller than or equal to the voltage difference threshold, taking the energy storage module where the battery pack 1011 is located as the target energy storage module.
It should be noted that the voltage difference threshold may be a value preset empirically, or may be a value calculated by the following formula:
where maxvult is a maximum battery voltage of the battery pack 1011 in the energy storage modules forming the battery energy storage system, n is a transformation ratio of a high-frequency transformer forming the DCDC converter 1012, and VL is a filter inductance voltage at a low-voltage side in the DCDC converter 1012. Therefore, a plurality of energy storage modules forming the battery energy storage system are screened by the battery voltage of the battery pack 1011, the energy storage modules with lower battery voltage can be effectively removed, and the reliability and the stability of the battery energy storage system are favorably improved.
In addition, when the controller 102 determines the shunt ratio of each target energy storage module according to the output voltages of all target energy storage modules in the energy storage system, the implementation manner used may be:
the dispersion of the output voltage of each target energy storage module can be obtained firstly; then determining the average value of the voltage difference of each target energy storage module according to the dispersion of the output voltage of each target energy storage module; and determining the corresponding shunt proportion of each target energy storage module according to the output voltage of each target energy storage module and the average value of the voltage difference.
The formula for calculating the dispersion of the output voltage of the ith target energy storage module may be:
Ubatt dispersion[i] ＝Ubattsreal[i]-MeanVolt；
Ubattsreal[i]the output voltage of the ith target energy storage module can be directly acquired by voltage acquisition equipment such as a voltmeter and the like, the mean volt is the average value of the output voltages of the plurality of target energy storage modules, and the average value of the output voltages can be obtained through a formula
And (4) calculating.
The controller 102, when determining the average value of the voltage difference of each target energy storage module according to the dispersion of the output voltage of each target energy storage module, may be implemented as follows:
and acquiring the absolute value of the dispersion of the output voltage of each target energy storage module, then calculating the mean value of the dispersion corresponding to the absolute value of the output voltage of all the target energy storage modules in the battery energy storage system, and taking the mean value of the dispersion corresponding to the absolute value as the pressure difference mean value.
Further, when the controller 102 determines the shunt ratio corresponding to each target energy storage module according to the output voltage of the target energy storage module and the average value of the voltage difference, the implementation manner may be:
under the condition that the output voltage of the target energy storage module is smaller than the average value of the voltage difference, the shunt ratio is calculated according to a first preset formula; and under the condition that the output voltage of the target energy storage module is greater than or equal to the average voltage difference value, the shunt ratio is calculated according to a second preset formula, and the first preset formula and the second preset formula are both related to the average voltage difference value and the variance of the output voltage of the target energy storage module.
Further, the first preset formula is:
the second preset formula is as follows:
the number of the target energy storage modules in the battery energy storage system is represented by the number of the target energy storage modules in the battery energy storage system, and the differential ratio of the average value of the voltage difference to the variance of the output voltage is represented by the number of the target energy storage modules in the battery energy storage system.
It should be noted that t can be calculated by the following formula:
in the above formula, packNum is the number of target energy storage modules in the battery energy storage system, ubatt _ dispersion [ i [ ]]For the dispersion of the output voltage of the ith energy storage module,
is a mean value of the pressure difference>
Is the variance of the output voltage.
Illustratively, taking the above fig. 1 as an example, when the number of target energy storage modules in the battery energy storage system is 8, the first preset formula may be divedrates [ i ] =0.125 (1-t), and the second preset formula may be divedrates [ i ] =0.125 (1 +t).
Further, when determining the target compensation voltage to be provided by the DCDC converter 1012 in each target energy storage module according to the shunt ratio and the output current of the target energy storage module, the following embodiments may be used:
determining a first correction voltage according to the output current of the target energy storage module and the shunt ratio;
acquiring a first sum of the maximum output voltage and the first correction voltage in all target energy storage modules in the battery energy storage system;
acquiring a second difference value between the first sum value and the output voltage of each target energy storage module;
the target compensation voltage provided by the DCDC converter 1012 is adjusted according to the second difference.
Optionally, when the controller determines the first correction voltage according to the output current of the target energy storage module and the shunt ratio, the adopted embodiment may be that:
acquiring second sum values of output currents of all target energy storage modules in the battery energy storage system; determining the target current of each target energy storage module according to the shunt proportion of each target energy storage module and the second sum; acquiring a second difference value between the target current of the target energy storage module and the output current of the target energy storage module; and taking the second difference value and the target current of the target energy storage module as the input of a preset PI regulator, so that the preset PI regulator outputs the first correction voltage.
It should be noted that, if the output current of the ith target energy storage module is Ibatts [ i [ ]]The calculation formula of the second Sum Sum _ Ibatts can be
The PackNum is the number of target energy storage modules in the battery energy storage system, and the target current of each target energy storage module can be calculated by the following formula:
wherein Ibattsobj [ i ] is the target current of the ith target energy storage module, and DivideRates [ i ] is the shunt ratio of the ith target energy storage module. A second difference delta _ Ibatts [ i ] between the target current of the ith target energy storage module and the output current of the target energy storage module can be calculated by a formula delta _ Ibatts [ i ] = Ibattsobj [ i ] -Ibatts [ i ]. The Delta _ Ibatts [ i ] can be used as the input of the preset PI regulator, so that the PI regulator outputs the first correction voltage Delta _ Ubatts [ i ] of the ith target energy storage module.
In addition, it should be noted that the PI regulator needs to set a clipping value to ensure that the compensation voltage in each target energy storage module that is started is within the adjustable range of the DCDC converter 1012, where the calculation formula of the clipping value may be the same as the calculation formula of the above voltage difference threshold, that is:
where maxvult is a maximum battery voltage of the battery pack 1011 in the energy storage modules forming the battery energy storage system, n is a transformation ratio of a high-frequency transformer forming the DCDC converter 1012, and VL is a filter inductance voltage at a low-voltage side in the DCDC converter 1012. The PI regulator may be any proportional-integral regulator in the prior art, which is not limited in this disclosure.
Optionally, when the controller adjusts the target compensation voltage provided by the DCDC converter 1012 according to the second difference, the controller may use an embodiment including:
taking the output voltage of each target energy storage module and the second difference value as the input of a preset phase shifting controller to output and obtain the DCDC driving signal; the DCDC converter 1012 is adjusted according to the DCDC driving signal such that the DCDC converter 1012 provides the target compensation voltage.
It should be noted that the calculation formula of the second difference value LUDCs [ i ] corresponding to the ith target energy storage module may be:
LUDCs[i]＝UbattsRef[i]-Ubatts[i]；
the UbattsRef [ i ] is a first sum value, and UbattsRef [ i ] = Ubatts _ max + Delta _ Ubatts [ i ], wherein the Ubatts _ max is the maximum output voltage of all target energy storage modules in the battery energy storage system, and the Delta _ Ubatts [ i ] is a first correction voltage. The output voltage Ubattsreal [ i ] of the ith energy storage module and the second difference value LUDCs [ i ] corresponding to the ith target energy storage module are used as inputs of the preset phase shift controller, so that the preset phase shift controller outputs to obtain the DCDC driving signal, where the DCDC driving signal may be a switching signal for controlling on or off of the switching tubes Q1 to Q8 in the DCDC converter 1012, and the phase shift controller may be any phase shift controller in the prior art, which is not limited by the disclosure.
In the above technical solution, the DCDC converter 1012 is controlled to provide a target compensation voltage, so that the battery energy storage system provides a constant voltage to the electrical equipment, and thus, effective current-sharing constant-voltage control can be performed on each target energy storage module in the battery energy storage system, the robustness of the battery energy storage system can also be effectively improved, and the shunt ratio of each target energy storage module can be determined according to the output voltages of all target energy storage modules in the energy storage system; determining a target compensation voltage to be provided by the DCDC converter in each target energy storage module according to the shunt proportion and the output current of each target energy storage module; the DCDC converter can be controlled to provide target compensation voltage so that the target energy storage module outputs constant voltage to the electric equipment, constant voltage current sharing control according to SOC can be avoided, and the accuracy of constant voltage control of the battery energy storage system is improved.
The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.
It should be noted that, in the foregoing embodiments, various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various combinations that are possible in the present disclosure are not described again.
In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.
Claims (10)
1. The battery energy storage system is characterized by comprising a plurality of energy storage modules connected in parallel and a controller connected with the energy storage modules, wherein each energy storage module comprises a battery pack and a DCDC converter, the battery pack is connected with the high-voltage side of the DCDC converter, and the output end of each energy storage module consists of the negative electrode of the low-voltage side of the DCDC converter and the positive electrode of the battery pack and is used for connecting electric equipment;
the controller is used for acquiring the battery voltage of a battery pack in each energy storage module, determining one or more target energy storage modules from the plurality of energy storage modules according to the battery voltage, and acquiring the output voltage and the output current of each target energy storage module; determining the shunt proportion of each target energy storage module according to the output voltages of all target energy storage modules in the energy storage system; determining a target compensation voltage to be provided by the DCDC converter in each target energy storage module according to the shunt proportion and the output current of each target energy storage module; and controlling the DCDC converter to provide a target compensation voltage according to the target compensation voltage so that the target energy storage module outputs constant voltage to the electric equipment.
2. The system of claim 1, wherein the controller is configured to:
acquiring dispersion of output voltage of each target energy storage module;
determining the average value of the voltage difference of each target energy storage module according to the dispersion of the output voltage of each target energy storage module;
and determining the corresponding shunt ratio of each target energy storage module according to the output voltage of each target energy storage module and the average value of the voltage difference.
3. The system of claim 2, wherein the controller is configured to:
under the condition that the output voltage of the target energy storage module is smaller than the average value of the voltage difference, the shunt ratio is calculated according to a first preset formula; and under the condition that the output voltage of the target energy storage module is greater than or equal to the average voltage difference value, the shunt ratio is calculated according to a second preset formula, the first preset formula and the second preset formula are both related to the number of the target energy storage modules in the battery energy storage system, and the average voltage difference value of the target energy storage modules is related to the variance of the output voltage.
4. The system of claim 3,
the first preset formula is as follows:
the second preset formula is as follows:
the number of the target energy storage modules in the battery energy storage system is t, and t is the ratio of the average value of the voltage difference to the variance of the output voltage.
5. The system of claim 2, wherein the controller is configured to:
calculating the dispersion of the output voltage of the target energy storage module by the following formula:
Ubatt dispersion[i] ＝Ubattsreal[i]-MeanVolt；
Ubatt dispersion[i] for the dispersion of the output voltage of the ith target energy storage module, ubattsreal [ i]The voltage is output by the ith target energy storage module, and MeanVolt is the average value of the output voltages of all target energy storage modules in the battery energy storage system.
6. The system of claim 1, wherein the controller is configured to:
determining a first correction voltage according to the output current of each target energy storage module and the shunt ratio; acquiring a first sum of the maximum output voltage and the first correction voltage in all target energy storage modules in the battery energy storage system; acquiring a second difference value between the first sum value and the output voltage of each target energy storage module; and controlling the DCDC converter to provide a target compensation voltage according to the second difference.
7. The system of claim 6, wherein the controller is to:
acquiring a second sum of output currents of all target energy storage modules in the battery energy storage system; determining a target current of each target energy storage module according to the shunt proportion and the second sum of each target energy storage module; acquiring a second difference value between the target current of the target energy storage module and the output current of the target energy storage module; and taking the second difference value and the target current of the target energy storage module as the input of a preset PI regulator, so that the preset PI regulator outputs the first correction voltage.
8. The system of claim 6, wherein the controller is to:
the output voltage of each target energy storage module and the second difference value are used as the input of a preset phase shifting controller to output and obtain the DCDC driving signal; adjusting the DCDC converter according to the DCDC driving signal so that the DCDC converter provides the target compensation voltage.
9. The system of claim 1, wherein the controller is configured to:
determining a maximum battery voltage of the battery packs in the plurality of energy storage modules; acquiring a first difference value between the battery voltage of a battery pack in each energy storage module and the maximum battery voltage; and taking the energy storage module where the battery pack is located as the target energy storage module when the first difference is smaller than or equal to a voltage difference threshold.
10. The system of claim 9, wherein a filter inductor is connected to the low voltage side of the DCDC converter, and wherein the voltage difference threshold is related to a maximum battery voltage of a battery pack in a plurality of energy storage modules of the battery energy storage system, a transformation ratio of the DCDC converter, and the filter inductor voltage.
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