CN114268155A - Battery energy storage system power distribution method considering battery inconsistency - Google Patents
Battery energy storage system power distribution method considering battery inconsistency Download PDFInfo
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- 238000004146 energy storage Methods 0.000 title claims abstract description 156
- 238000000034 method Methods 0.000 title claims abstract description 27
- 238000009826 distribution Methods 0.000 title claims abstract description 8
- 238000004364 calculation method Methods 0.000 claims description 5
- 238000007599 discharging Methods 0.000 claims description 4
- 210000000352 storage cell Anatomy 0.000 claims description 3
- 239000000178 monomer Substances 0.000 claims description 2
- 230000015556 catabolic process Effects 0.000 abstract description 2
- 230000001939 inductive effect Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
- 230000032683 aging Effects 0.000 description 1
- 210000004027 cell Anatomy 0.000 description 1
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Abstract
The invention discloses a battery energy storage system power distribution method considering battery inconsistency, which considers the maximum releasable power and charging power of a battery, can prevent overcharge and overdischarge of certain batteries by providing the currently releasable maximum power of the battery for an energy storage converter, particularly when the temperature difference is large, the releasable power of the battery has great change, the power is evenly distributed when the SOC of the battery is consistent at a certain moment, but the power released by a certain battery exceeds the self limit, the battery is damaged, and the system health is seriously damaged. The invention realizes the SOP balance control among the multi-battery energy storage systems and can ensure that the battery energy storage systems simultaneously exit the microgrid. The method can prevent the SOP of a certain battery energy storage system from reaching the limit and exiting the microgrid in advance, and can cause the system breakdown when the capacity of the remaining battery energy storage systems is not enough to support the whole system.
Description
Technical Field
The invention relates to a battery power distribution method, in particular to a battery energy storage system power distribution method considering battery inconsistency
Background
In recent years, with the gradual depletion of traditional fossil energy and the increasing of environmental crisis, a micro-grid system composed of renewable clean energy and an energy storage system receives more and more attention. The storage battery is used as an energy storage unit medium, the configuration capacity is high, the quantity is large, the lithium ion battery is restricted by a lithium ion battery preparation process, inconsistency exists among single lithium batteries, the difference is amplified due to factors such as working environment temperature, discharge efficiency and the influence of a protection circuit on a battery pack in the using process, and particularly, echelon batteries are mostly used in energy storage power station application, and the inconsistency is particularly obvious. This inconsistency causes circulating current losses and short plate effects, which can lead to a battery exiting the system in advance, especially compromising the safety and reliability of the system.
The problem of inconsistency of the lithium battery pack is solved, and besides control in a production process, an effective method is to perform balanced management on the battery pack. Currently, Battery balancing technologies are mainly classified into a Battery Management System (BMS) and a Power Converter System (PCS). In the balancing control scheme based on the BMS, the balancing control among all the series-connected battery units in one battery cluster can be realized, but the balancing control among multiple parallel-connected battery clusters cannot be realized, and the scheme based on the PCS can realize the balancing control among the clusters.
Patent CN 106450528B proposes an energy storage system, a power balance control method and a control device thereof, which calculate the given power of the corresponding energy storage converter module according to the rated power ratio of each battery cluster and the total given power, so as to perform balance control. However, the maximum power which can be output by the battery along with the operation of the energy storage system is constantly changed, the power distribution cannot be accurately realized only by using rated power, and meanwhile, the patent only gives out power balance in an inversion state and does not consider a rectification state.
Disclosure of Invention
In order to overcome the defects, the invention provides a power distribution method of a battery energy storage system, which considers the inconsistency of batteries.
In order to achieve the purpose, the invention is implemented according to the following steps:
the method comprises the following steps: constructing an alternating current micro-grid system with a plurality of energy storage converters connected in parallel;
selecting a plurality of energy storage converters, connecting the AC sides of the energy storage converters in parallel, connecting the energy storage converters with a power grid and a load, and respectively connecting the DC sides with energy storage units;
step two: acquiring the voltage and current of each energy storage unit, and calculating the peak power SOP of each battery cluster according to the BMS;
step three: when the energy storage converter works in an inversion state, calculating the ratio of the peak power SOP of the energy storage unit corresponding to each energy storage converter module to the sum of the peak power SOP of all the energy storage units;
when the energy storage converters work in a rectification state, setting balance factors of the energy storage converters according to the sequence of the SOP values, wherein the balance factors specifically comprise the following contents;
sorting the SOP values of the batteries according to the magnitude, and assuming that n energy storage converters are connected in parallel and correspond to n energy storage units, the peak power SOP of the ith energy storage unitiArranged at the x-th position, then SOPi_jIndicating the SOP value, SOP, of the energy storage cells arranged in the n-x positioniAnd SOPi_jOne-to-one correspondence is realized; calculating the ratio of the SOP value of the energy storage units corresponding to each energy storage converter module, which are in the same position as the original sequence after the energy storage units SOP are sorted in the reverse direction according to the size, to the sum of all the energy storage units SOP; when the energy storage unit fails, the corresponding energy storage converter is blocked, and the corresponding SOP value does not enter the sorting;
step four: multiplying the SOP ratio of the energy storage unit obtained in the step three by the active power target value to obtain the given active power of the corresponding energy storage converter;
step five: obtaining a current loop reference current through PI modulation after the difference is made between the output power of the energy storage converter and the given power obtained through calculation; finally, obtaining the modulation wave of the energy storage converter through a current loop; the corresponding energy storage converter with the high SOP of the energy storage unit is high in output power, the corresponding energy storage converter with the low SOP is low in output power, power is evenly divided through modulation for a period of time, and the consistency difference of the batteries is eliminated.
Preferably, the energy storage unit is formed by connecting a plurality of battery cells in series and in parallel.
Preferably, the step five specifically comprises the following steps:
step S1, acquiring three-phase output current and three-phase output voltage of each energy storage converter, and converting the three-phase current and voltage to obtain d-axis three-phase current voltage components and q-axis three-phase current voltage components;
and step S2, calculating the output active power and reactive power of each energy storage converter according to the d-axis voltage component, the q-axis voltage component, the d-axis current component and the q-axis current component.
Step S3: according to the difference between the active power and the reactive power and the given power obtained in the third step, a current loop reference current is obtained through the adjustment of a PI controller;
step S4: obtaining an energy storage converter modulation wave through a current loop according to the current reference value;
preferably, the control principle expression of the step five is specifically as follows:
in the formula GPIIs a proportional integral coefficient;
idrefand iqrefCurrent d-axis and q-axis reference values, respectively;
pi and Qi are active power and reactive power output by each energy storage converter;
Prefand QrefActive and reactive power target values;
alpha is an SOP balance factor and is used for realizing SOP balance control in the charging and discharging process of the energy storage converter;
SOPithe peak power state of an energy storage unit connected with the ith energy storage converter is represented;
SOPi_jrepresenting SOPiAnd sorting the SOP values in the same positions as the original sequence in a reverse order, namely if the SOP value of a certain module is the maximum, calculating the minimum SOP value in all the modules when the active power in the rectification state is given, and so on.
Preferably, in order to ensure the normal operation and service life of the energy storage device, the energy storage units should be prevented from operating in a deep discharge state. For this purpose, the detected peak power SOP of each energy storage unit is compared with the rated power; if the power ratio of the energy storage unit is lower than 20%, the pulse width modulation of the energy storage interface converter should be blocked to wait for charging.
The invention has the advantages that: the problem that the aging degree and the temperature of the battery are different due to different SOC change rates, the SOC is inconsistent again is solved, the maximum releasable power and the charging power of the battery are considered, the maximum releasable maximum power of the battery is provided for the energy storage converter, the overcharge and over-discharge of some batteries can be prevented, particularly, when the temperature difference is large, the releasable power of the battery is changed greatly, the power is evenly divided when the SOC of the battery is consistent at a certain moment, but the power released by a certain battery exceeds the self limit, the battery is damaged, and the system health is seriously damaged. The invention realizes the SOP balance control among the multi-battery energy storage systems and can ensure that the battery energy storage systems simultaneously exit the microgrid. The method can prevent the SOP of a certain battery energy storage system from reaching the limit and exiting the microgrid in advance, and can cause the system breakdown when the capacity of the remaining battery energy storage systems is not enough to support the whole system.
Drawings
FIG. 1 is a schematic diagram of a prior art energy storage system;
FIG. 2 is a block diagram of a method for controlling equalization according to the present invention;
FIG. 3 is a control flow diagram of the present invention;
Detailed Description
The present invention will be described in detail below by way of specific examples in conjunction with the accompanying drawings.
Taking a parallel energy storage converter as an example, as shown in fig. 1, the energy storage system includes n energy storage converters, the ac sides of the energy storage converters are arranged in parallel and connected to an ac power grid, and the dc sides of the energy storage converters are connected to an energy storage unit; the energy storage unit is formed by connecting a plurality of battery monomers in series and parallel.
A battery energy storage system power allocation method considering battery inconsistency, the control method is shown in fig. 2; the method comprises the following steps: acquiring output voltage and output current of each energy storage unit, and processing the output voltage and the output current through a BMS (battery management system) to obtain an SOP (state of charge) value of each energy storage unit;
step two: when the energy storage converter works in an inversion state, calculating the ratio of the peak power SOP of the energy storage unit corresponding to each energy storage converter module to the sum of the peak power SOP of all the energy storage units;
when the energy storage converters work in a rectification state, setting balance factors of the energy storage converters according to the sequence of the SOP values, wherein the balance factors specifically comprise the following contents;
sorting the SOP values of the batteries according to the magnitude, and assuming that n energy storage converters are connected in parallel and correspond to n energy storage units, the peak power SOP of the ith energy storage unitiArranged at the x-th position, then SOPi_jIndicating the SOP value, SOP, of the energy storage cells arranged in the n-x positioniAnd SOPi_jOne-to-one correspondence is realized; calculating the ratio of the SOP value of the energy storage units corresponding to each energy storage converter module, which are in the same position as the original sequence after the energy storage units SOP are sorted in the reverse direction according to the size, to the sum of all the energy storage units SOP;
particularly, when the energy storage unit has a fault, the corresponding energy storage converter is blocked, and the corresponding SOP value does not enter the sequence;
step three: multiplying the SOP ratio of the energy storage unit obtained in the step two by the active power target value to obtain the given active power of the corresponding energy storage converter;
step four: obtaining a current loop reference current through PI modulation after the difference is made between the output power of the energy storage converter and the given power obtained through calculation; finally, the modulation wave of the energy storage converter is obtained through a current loop. The corresponding energy storage converter with the high SOP of the energy storage unit is high in output power, the corresponding energy storage converter with the low SOP is low in output power, power is evenly divided through modulation for a period of time, and the consistency difference of the batteries is eliminated.
Preferably, the fourth step of the method specifically comprises the following steps:
step S1: acquiring three-phase output current and three-phase output voltage of each energy storage converter, and converting the three-phase current and voltage to obtain d-axis three-phase current voltage components and q-axis three-phase current voltage components;
and step S2, calculating the output active power and reactive power of each energy storage converter according to the d-axis voltage component, the q-axis voltage component, the d-axis current component and the q-axis current component.
Step S3, obtaining a current loop reference current value by PI modulation after the difference between the output power of the energy storage converter and the given power obtained by calculation is made according to the following formula;
step S4: acquiring three-phase inductive current of each energy storage converter, and converting the inductive current to obtain d-axis three-phase inductive current components and q-axis three-phase inductive current components;
and step S5, performing PI closed loop regulation control on the current loop reference value obtained by calculation and the inductive current component to obtain the final duty ratio of the switching tube of the energy storage converter.
As shown in fig. 3, which is a schematic control flow diagram of the present invention, first, an SOP value of an energy storage battery is obtained; further, detecting whether the energy storage converter works in an inversion state or a rectification state, and discharging and charging corresponding to the energy storage battery;
when the energy storage converter works in an inversion state, judging whether the ratio of the current peak power SOP of the energy storage battery to the rated power of the energy storage battery is greater than 20%, when the ratio is greater than 20%, the energy storage converter works normally, and the control system distributes power; when the power ratio is less than 20%, the corresponding energy storage converter is blocked to prevent the battery from deeply discharging;
when the energy storage converters work in a rectification state, the SOP values of the energy storage batteries are sequenced, the active power given by the energy storage converters is set according to the sequence of the SOP values, and the system is controlled to operate stably.
Claims (5)
1. A battery energy storage system power distribution method considering battery inconsistency is characterized by comprising the following specific steps:
the method comprises the following steps: constructing an alternating current micro-grid system with a plurality of energy storage converters connected in parallel;
selecting a plurality of energy storage converters, connecting the AC sides of the energy storage converters in parallel, connecting the energy storage converters with a power grid and a load, and respectively connecting the DC sides with energy storage units;
step two: acquiring the voltage and current of each energy storage unit, and calculating the peak power SOP of each battery cluster according to the BMS;
step three: when the energy storage converter works in an inversion state, calculating the ratio of the peak power SOP of the energy storage unit corresponding to each energy storage converter module to the sum of the peak power SOP of all the energy storage units;
when the energy storage converters work in a rectification state, setting balance factors of the energy storage converters according to the sequence of the SOP values, wherein the balance factors specifically comprise the following contents;
sorting the SOP values of the batteries according to the magnitude, and assuming that n energy storage converters are connected in parallel and correspond to n energy storage units, the peak power SOP of the ith energy storage unitiArranged at the x-th position, then SOPi_jIndicating the SOP value, SOP, of the energy storage cells arranged in the n-x positioniAnd SOPi_jOne-to-one correspondence is realized; calculating the ratio of the SOP value of the energy storage units corresponding to each energy storage converter module, which are in the same position as the original sequence after the energy storage units SOP are sorted in the reverse direction according to the size, to the sum of all the energy storage units SOP; when the energy storage unit fails, the corresponding energy storage converter is blocked, and the corresponding SOP value does not enter the sorting;
step four: multiplying the SOP ratio of the energy storage unit obtained in the step three by the active power target value to obtain the given active power of the corresponding energy storage converter;
step five: obtaining a current loop reference current through PI modulation after the difference is made between the output power of the energy storage converter and the given power obtained through calculation; finally, obtaining the modulation wave of the energy storage converter through a current loop; the corresponding energy storage converter with the high SOP of the energy storage unit is high in output power, the corresponding energy storage converter with the low SOP is low in output power, power is evenly divided through modulation for a period of time, and the consistency difference of the batteries is eliminated.
2. The method of claim 1, wherein the method comprises: the energy storage unit is formed by connecting a plurality of battery monomers in series and parallel.
3. The method for allocating power to a battery energy storage system considering the inconsistency of the battery according to claim 1, wherein the step five specifically comprises the steps of:
step S1, acquiring three-phase output current and three-phase output voltage of each energy storage converter, and converting the three-phase current and voltage to obtain d-axis three-phase current voltage components and q-axis three-phase current voltage components;
step S2, calculating the output active power and reactive power of each energy storage converter according to the d-axis voltage component, the q-axis voltage component, the d-axis current component and the q-axis current component;
step S3: according to the difference between the active power and the reactive power and the given power obtained in the third step, a current loop reference current is obtained through the adjustment of a PI controller;
step S4: and obtaining the modulation wave of the energy storage converter through a current loop according to the current reference value.
4. The method for distributing power of a battery energy storage system considering the inconsistency of the battery according to claim 1, wherein the control principle expression of the step five is specifically as follows:
in the formula GPIIs a proportional integral coefficient;
idrefand iqrefCurrent d-axis and q-axis reference values, respectively;
pi and Qi are active power and reactive power output by each energy storage converter;
Prefand QrefActive and reactive power target values;
alpha is an SOP balance factor and is used for realizing SOP balance control in the charging and discharging process of the energy storage converter;
SOPithe peak power state of an energy storage unit connected with the ith energy storage converter is represented;
SOPi_jrepresenting SOPiAnd sorting the SOP values in the same positions as the original sequence in a reverse order, namely if the SOP value of a certain module is the maximum, calculating the minimum SOP value in all the modules when the active power in the rectification state is given, and so on.
5. The method of claim 1, wherein the method comprises: comparing the peak power SOP of each energy storage unit with the rated power; if the power ratio of the energy storage unit is lower than 20%, the pulse width modulation of the energy storage interface converter is blocked to wait for charging.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116760155A (en) * | 2023-08-18 | 2023-09-15 | 合肥国轩高科动力能源有限公司 | Charge and discharge control method and device, storage medium and electronic equipment |
| WO2023240454A1 (en) * | 2022-06-14 | 2023-12-21 | 宁德时代新能源科技股份有限公司 | Control method and control apparatus of energy storage system, and energy storage system |
| CN117590242A (en) * | 2024-01-18 | 2024-02-23 | 未势能源科技有限公司 | Method and device for detecting consistency of galvanic pile, storage medium and electronic device |
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| CN106450528A (en) * | 2016-11-23 | 2017-02-22 | 许继电源有限公司 | Energy storage system and method and device for controlling power balance of energy storage system |
| CN109849737A (en) * | 2019-02-28 | 2019-06-07 | 北京机械设备研究所 | A kind of balance control method of power battery multi-parameter consistency |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106450528A (en) * | 2016-11-23 | 2017-02-22 | 许继电源有限公司 | Energy storage system and method and device for controlling power balance of energy storage system |
| CN109849737A (en) * | 2019-02-28 | 2019-06-07 | 北京机械设备研究所 | A kind of balance control method of power battery multi-parameter consistency |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023240454A1 (en) * | 2022-06-14 | 2023-12-21 | 宁德时代新能源科技股份有限公司 | Control method and control apparatus of energy storage system, and energy storage system |
| CN116760155A (en) * | 2023-08-18 | 2023-09-15 | 合肥国轩高科动力能源有限公司 | Charge and discharge control method and device, storage medium and electronic equipment |
| CN116760155B (en) * | 2023-08-18 | 2023-11-10 | 合肥国轩高科动力能源有限公司 | Charge and discharge control method and device, storage medium and electronic equipment |
| CN117590242A (en) * | 2024-01-18 | 2024-02-23 | 未势能源科技有限公司 | Method and device for detecting consistency of galvanic pile, storage medium and electronic device |
| CN117590242B (en) * | 2024-01-18 | 2024-04-26 | 未势能源科技有限公司 | Method and device for detecting consistency of galvanic pile, storage medium and electronic device |
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