CN115579926B - Energy storage system and control method thereof - Google Patents
Energy storage system and control method thereof Download PDFInfo
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- CN115579926B CN115579926B CN202211340874.2A CN202211340874A CN115579926B CN 115579926 B CN115579926 B CN 115579926B CN 202211340874 A CN202211340874 A CN 202211340874A CN 115579926 B CN115579926 B CN 115579926B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
- H02J7/35—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering with light sensitive cells
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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Abstract
The invention discloses an energy storage system and a control method thereof. The energy storage system comprises an inverter grid-connected control loop and an optical Fu Zhiliu converter control loop, wherein the inverter grid-connected control loop is provided with a first battery voltage upper limit limiting loop and a battery voltage lower limit limiting loop, and the optical Fu Zhiliu converter control loop is provided with a second battery voltage upper limit limiting loop and a bus voltage upper limit limiting loop; and through detecting the upper and lower limits of the battery voltage and the upper limit of the bus voltage, the first battery voltage upper limit limiting loop, the battery voltage lower limit limiting loop, the second battery voltage upper limit limiting loop and the bus voltage upper limit limiting loop are automatically switched according to the operation mode judgment and detection results of the energy storage system, and the output power of the inverter and the light Fu Zhiliu converter is adjusted according to the loop results. The present invention automatically adjusts the power control of the inverter and the optical Fu Zhiliu converter by adding additional control constraint loops.
Description
Technical Field
The invention relates to the technical field of electrochemical energy storage, in particular to an energy storage system and a control method thereof.
Background
Typically, the energy storage system topology is shown in fig. 1, and mainly comprises 0 or one or more photovoltaic dc converters 102,0 or one or more battery dc converters 103, and an inverter 104, wherein the front end input of the light Fu Zhiliu converter 102 is a photovoltaic cell 106, the front end input of the battery dc converter 103 is a battery 107, the outputs of the light Fu Zhiliu converter 102 and the battery dc converter 103 are connected to the input end of the inverter 104 together, and the output end of the inverter 104 is connected to the power grid 105 and the load 108. When the number of the light Fu Zhiliu converters 102 is 0, the system is not connected to the photovoltaic cell 106, and when the number of the battery direct current converters 103 is 0, the battery 107 is directly connected to the input end of the inverter 104. When the power grid voltage is normal, the system is switched to off-grid operation when the power grid voltage is abnormal. When the system works, the battery direct-current converter 103 controls the bus voltage at the output end to a constant value, the inverter 104 performs power control according to the power setting of the dispatching system, and the light Fu Zhiliu converter 102 performs power control according to the maximum power point of the photovoltaic cell 106. Depending on the power balance, there is a light Fu Zhiliu converter total output power 110+ battery dc converter total output power 111 = inverter output power 112.
In the existing energy storage system control method, as the inverter needs to respond to a power instruction of a dispatching system, a battery direct-current converter stabilizes the bus voltage, no special control link is needed for directly controlling the battery voltage and the battery power, and when the battery power exceeds a certain value, the photovoltaic power is subtracted from the battery power to obtain the given output power of the inverter for control through a power balance formula; when the battery voltage exceeds a certain value, the inverter power command value is linearly attenuated, and the given output power of the photovoltaic direct-current converter is controlled through a power balance formula. The method has certain hysteresis for controlling the battery voltage and the battery charge and discharge power, and can influence the safety performance of the battery when the power response and the power control precision of the inverter and the light Fu Zhiliu converter are insufficient.
Based on the shortcomings of the control method, it is necessary to develop an energy storage system and a control method thereof, starting from an inverter and an optical Fu Zhiliu converter control loop, by adding an additional control constraint loop, the power control of the inverter and the optical Fu Zhiliu converter is automatically adjusted, the problems of power distribution and safety constraint among power modules of the energy storage system are solved, and by replacing the system power balance calculation with the control constraint loop, the dynamic response speed of the system is improved and the complexity of the system control logic is reduced.
Disclosure of Invention
The invention aims to provide an energy storage system and a control method thereof, which overcome the defects in the prior art.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the energy storage system comprises an inverter grid-connected control loop and an optical Fu Zhiliu converter control loop, wherein the inverter grid-connected control loop is provided with a first battery voltage upper limit limiting loop and a battery voltage lower limit limiting loop, and the optical Fu Zhiliu converter control loop is provided with a second battery voltage upper limit limiting loop and a bus voltage upper limit limiting loop; and through detecting the upper and lower limits of the battery voltage and the upper limit of the bus voltage, the first battery voltage upper limit limiting loop, the battery voltage lower limit limiting loop, the second battery voltage upper limit limiting loop and the bus voltage upper limit limiting loop are automatically switched according to the operation mode judgment and detection results of the energy storage system, and the output power of the inverter and the light Fu Zhiliu converter is adjusted according to the loop results.
The invention also provides a control method of the energy storage system, which comprises the following steps,
step S301, judging an operation mode of an energy storage system;
step S302, if the operation mode of the energy storage system is grid-connected operation, step S303 is executed;
step S303, the energy storage system judges whether the battery voltage reaches the upper limit, if so, step S304 is executed, otherwise, step S309 is executed;
step S304, triggering the first battery voltage upper limit limiting loop to automatically take effect;
step S305, the first battery voltage upper limit limiting loop controls the battery voltage within the upper limit limiting by increasing the inverter discharging power or decreasing the inverter charging power;
step S306, the energy storage system judges that the trigger power limit value of the inverter is up to the upper limit;
step S307, triggering the second battery voltage upper limit limiting loop to automatically take effect;
step S308, the second battery voltage upper limit clipping loop controls the battery voltage within the upper limit clipping by reducing the output power of the light Fu Zhiliu converter;
step S309, the energy storage system judges that the battery voltage reaches the lower limit amplitude limit;
step S310, triggering a battery voltage lower limit limiting loop to take effect;
step S311, the battery voltage lower limit limiting loop controls the battery voltage above the lower limit limiting by reducing the inverter discharge power or increasing the inverter charge power;
step S312, if the operation mode of the energy storage system is off-grid operation, step S313 is executed;
step S313, the energy storage system judges whether the battery voltage reaches the upper limit, if yes, the step S314 is executed, otherwise, the step S316 is executed;
step S314, triggering the second battery voltage upper limit limiting loop to automatically take effect;
step S315, the second battery voltage upper limit clipping loop controls the battery voltage within the upper limit clipping by reducing the light Fu Zhiliu converter output power;
step S316, the energy storage system judges that the bus voltage exceeds a control value;
step S317, triggering a bus voltage upper limit limiting loop to automatically take effect;
in step S318, the bus voltage upper limit clipping loop controls the bus voltage within the upper limit clipping by reducing the optical Fu Zhiliu converter output power.
Further, the working process of the first battery voltage upper limit limiting loop is as follows: the upper limit of the battery voltage UbatUpLimit is differed from the corresponding battery voltage feedback value UbatFb and then sent to the PI controller, and the PI controller outputs the voltage and then passes through a limit loop and takes the voltage as the adjustment quantity delta PinvRef2 of the output power of the inverter.
Further, the working process of the battery voltage lower limit limiting loop is as follows: the lower limit amplitude limiting UbatDpLimit of the battery voltage is differed with the corresponding feedback value UbatFb of the battery voltage and then is sent to a PI controller, and the output of the PI controller is subjected to amplitude limiting loop and is inverted to be used as the adjustment quantity delta Pinv_ref1 of the output power of the inverter.
Further, the step S306 specifically includes: when the inverter detects that the total power of the inverter is equal to the upper limit limiting value of the power limiting value loop, the adjusting capacity of the inverter reaches the upper limit and the lower limit, a Flag bit is set at the moment, and when the light Fu Zhiliu converter detects the Flag of the inverter, the upper limit limiting loop of the second battery voltage is triggered to automatically take effect.
Further, the working process of the second battery voltage upper limit limiting loop is as follows: the upper limit UbatUpLimit of the battery voltage is differed from the corresponding feedback value UbatFb of the battery voltage and then sent to a PI controller, the PI controller outputs the voltage and takes the voltage as a voltage adjustment quantity delta UpvRef2 after passing through a limit loop and reversing the voltage, and the power of a photovoltaic maximum power tracking module MPPT output voltage reference value Upv0Ref is adjusted to an open-circuit voltage so as to automatically adjust the power of a photovoltaic battery, thereby realizing the adjustment of the charging power of the battery.
Further, the working process of the bus voltage upper limit limiting loop is as follows: the light Fu Zhiliu converter sets a bus voltage upper limit value UbusUpLimit, the photovoltaic direct current converter obtains a bus voltage Ubus, the bus voltage upper limit value UbusUpLimit and the bus voltage Ubus are input into the PI controller for operation, the output result of the PI controller is limited, and the output result of the PI controller is inverted and then assigned to the voltage adjustment quantity DeltaUpvRef.
Compared with the prior art, the invention has the advantages that: the invention starts from the control loop of the inverter and the light Fu Zhiliu converter, automatically adjusts the power control of the inverter and the light Fu Zhiliu converter by adding an additional control constraint loop, solves the problems of power distribution and safety constraint among power modules of the energy storage system, and improves the dynamic response speed of the system and reduces the complexity of the system control by replacing the power balance calculation of the system by the control constraint loop.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a topology of a prior art energy storage system.
Fig. 2 is a typical dual loop control block diagram.
Fig. 3 is a flow chart of an implementation of the present invention.
Fig. 4 is a logic diagram of an embodiment of the present invention.
Fig. 5 is a diagram of an inverter grid-tie control loop in the present invention.
Fig. 6 is a diagram of an optical Fu Zhiliu converter control loop in accordance with the present invention.
Detailed Description
The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making clear and defining the scope of the present invention.
A typical dual-loop control box of the energy storage system is shown in fig. 2, wherein the difference between an outer loop given Rref(s) 201 and an outer loop feedback RFb(s) 202 is sent to an outer loop PI controller 203, the output of the PI controller is given as an inner loop after passing through a limiting link 205, the difference between the inner loop given and the inner loop feedback IFb(s) 205 is sent to an inner loop PI controller 206, and the output of the inner loop PI controller is added with a feedforward value Forward(s) 207 and is used as a duty cycle PWM output 208 of the power device. The transfer function of the PI controller (203,206) is f(s) = (kp s+ki)/s.
The control loop of the battery direct-current converter is controlled by a bus voltage outer ring and a battery current inner ring double ring, the control aim is to control a bus voltage given UbusRef to be a constant value, therefore UbusRef is taken as an input of a voltage ring, the voltage ring is fed back to be a bus voltage UbusFb, the output of a voltage ring PI controller is divided by the number x of the online batteries to be given Ibattref of each path of battery current inner ring, the current inner ring is fed back to be a battery current IbatFb, and the feedforward value is given by the bus voltage. The upper limit of the limiting ring is the maximum allowable discharging current value of the battery, and the lower limit of the limiting ring is the maximum allowable charging current value of the battery.
The grid-connected control loop of the inverter is divided into grid-connected operation control and off-grid operation control, wherein the grid-connected operation control is controlled by an inner loop and an outer loop of inversion output power and inversion current, the control target is to accurately output an inversion output power given value Pinv0Ref, so that Pinv0Ref is used as input of a power loop, the feedback of the power loop is the inverter output power pinvFb, the feedback of the current inner loop is the inversion current iinvFb, and the feedforward value is the grid voltage Vgrid. The off-grid control is controlled by an inversion output voltage outer ring inversion current inner ring double loop, and the control aim is to accurately output an inversion voltage given VinvRef, so that VinvRef is taken as the input of a voltage outer ring, the voltage ring is fed back as an inverter output voltage VinvFb, the current inner ring is fed back as an inversion current IinvFb, and the feedforward value is the inversion voltage given VinvRef.
The light Fu Zhiliu converter control loop is controlled by a photovoltaic cell voltage outer loop and a photovoltaic cell current inner loop double loop, the control aim is to control the photovoltaic cell voltage given UpvRef at the maximum power point MPPT of the photovoltaic cell, so that UpvRef is used as the input of the voltage loop, the voltage loop is fed back to be photovoltaic cell voltage UpvFb, the current inner loop is fed back to be photovoltaic cell current IpvFb, and the feedforward value is the photovoltaic cell voltage given UpvRef.
Referring to fig. 3, 5 and 6, the invention discloses an energy storage system, which comprises an inverter grid-connected control loop and an optical Fu Zhiliu converter control loop, wherein a first battery voltage upper limit limiting loop 401 and a battery voltage lower limit limiting loop 402 are arranged on the inverter grid-connected control loop, and a second battery voltage upper limit limiting loop 501 and a bus voltage upper limit limiting loop 502 are arranged on the optical Fu Zhiliu converter control loop; by detecting the upper and lower limits of the battery voltage and the upper limit of the bus voltage, the first battery voltage upper limit limiting loop 401, the battery voltage lower limit limiting loop 402, the second battery voltage upper limit limiting loop 501 and the bus voltage upper limit limiting loop 502 are automatically switched according to the judging and detecting results of the operation mode of the energy storage system, and the output power of the inverter and the light Fu Zhiliu converter is adjusted according to the loop results, so that the safety of the charge and discharge power of the battery is ensured.
Referring to fig. 4, the present invention also provides a control method of the energy storage system according to the above description, the control method includes the following steps,
step S301, determining an operation mode of the energy storage system.
Step S302, if the operation mode of the energy storage system is grid-connected operation, step S303 is executed.
Step S303, the energy storage system judges whether the battery voltage reaches the upper limit, if yes, step S304 is executed, otherwise step S309 is executed.
Step S304, the first battery voltage upper limit limiter loop 401 is triggered to take effect automatically.
In step S305, the first battery voltage upper limit limiter loop 401 controls the battery voltage within the upper limit limiter by increasing the inverter discharge power or decreasing the inverter charge power.
Step S306, the energy storage system judges that the trigger power limit value of the inverter is up to the upper limit.
Step S307 triggers the second battery voltage upper limit clipping loop 501 to automatically take effect.
In step S308, the second battery voltage upper limit limiter loop 501 controls the battery voltage within the upper limit limiter by reducing the light Fu Zhiliu converter output power.
Step S309, the energy storage system judges that the battery voltage reaches the lower limit.
Step S310, the battery voltage lower limit clipping loop 402 is triggered to take effect.
In step S311, the battery voltage lower limit limiter loop 402 controls the battery voltage above the lower limit limiter by decreasing the inverter discharge power or increasing the inverter charge power.
Step S312, if the operation mode of the energy storage system is off-grid operation, step S313 is executed.
Step S313, the energy storage system determines whether the battery voltage reaches the upper limit, if yes, step S314 is executed, otherwise step S316 is executed.
In step S314, the second battery voltage upper limit limiter loop 501 is triggered to take effect automatically.
In step S315, the second battery voltage upper limit clipping loop 501 controls the battery voltage within the upper limit clipping by reducing the light Fu Zhiliu converter output power.
Step S316, the energy storage system judges that the bus voltage exceeds the control value.
In step S317, the bus voltage upper limit limiter loop 502 is triggered to take effect automatically.
In step S318, the bus voltage upper limit limiter loop 502 controls the bus voltage within the upper limit limiter by reducing the optical Fu Zhiliu converter output power.
According to the invention, a first battery voltage upper limit limiting loop 401 and a battery voltage lower limit limiting loop 402 are added on an inverter grid-connected control loop, a second battery voltage upper limit limiting loop 501 is added on an optical Fu Zhiliu converter control loop, and automatic switching-in and switching-out of the loops are performed, so that automatic control of battery voltage safety is realized. When the inverter runs off the network, the upper limit limiting loop 502 of the bus voltage is added on the control loop of the photovoltaic direct-current converter, and the automatic control of the safety of the battery charging and discharging power is realized by the automatic switching of the loop.
Referring to fig. 5, which is a diagram of an inverter grid-connected control loop, it can be seen that the working process of the first battery voltage upper limit clipping loop 401 is as follows: the battery voltage upper limit limiter UbatUpLimit (411) is differed from the corresponding battery voltage feedback value UbatFb (412) and then sent to the PI controller, and the output of the PI controller is processed by the limiter loop 414 and is inverted 415 to be used as the adjustment quantity delta PinvRef2 of the output power of the inverter (416). The analysis shows that when the battery voltage feedback value UbatFb is smaller than the battery voltage upper limit limiter UbatUpLimit, the battery is in a voltage safety range, the loop difference result is positive, the loop is output to be positive after passing through the PI controller, the limiter loop limits the forward limiter to 0, and the output power adjustment amount delta PinvRef2 is 0, so that the loop is not effective. When the battery voltage feedback value UbatFb is greater than the battery voltage upper limit amplitude limit UbatUpLimit, the battery is about to be overcharged, the loop difference result is negative, the output is negative after passing through the PI controller, the amplitude limiting loop negative amplitude limit is effective, and the output delta PinvRef2 is greater than 0 after the negation processing 415, so that the output power is increased or the charging power is reduced, and the battery is prevented from being overcharged.
The battery voltage lower limit clipping loop 402 operates as follows: the lower limit limiter UbatDpLimit (421) of the battery voltage is differed from the corresponding feedback value UbatFb (422) of the battery voltage and then is sent to a PI controller, and the output of the PI controller is processed by a limiter loop 424 and is inverted 425 to be used as the adjustment quantity DeltaPinv_ref1 (426) of the output power of the inverter. The analysis shows that when the battery voltage feedback value UbatFb is greater than the battery voltage lower limit limiter UbatDpLimit, the battery is in the voltage safety range, the loop difference result is negative, the output is negative after passing through the PI controller, the limiter loop limits the negative limiter to 0, and the output power adjustment amount Δpinvref1 is 0, so that the loop is not effective. When the battery voltage feedback value UbatFb is smaller than the battery voltage upper limit amplitude limit UbatDpLimit, the situation that the battery is over-discharged is indicated, the loop difference result is positive, the output is positive after passing through the PI controller, the forward amplitude limit of the amplitude limit loop is effective, and the output delta PinvRef1 is smaller than 0 after the inverse processing 425, so that the output power is reduced or the charging power is increased, and the battery is prevented from over-discharging.
In this embodiment, the step S306 specifically includes: when the inverter detects that the total power of the inverter is equal to the upper limit limiting value of the power limiting value loop, the inverter regulating capacity reaches the upper limit and the lower limit, the Flag bit Flag is set at the moment, and when the light Fu Zhiliu converter detects the inverter Flag, the second battery voltage upper limit limiting loop 501 is triggered to automatically take effect.
The working process of the second battery voltage upper limit limiting loop 501 is consistent with that of the inverter battery voltage upper limit limiting loop (401), namely, the difference between the battery voltage upper limit limiting UbatUpLimit and the corresponding battery voltage feedback value UbatFb is sent to a PI controller, the PI controller outputs the voltage and takes the voltage as a voltage adjustment quantity delta UpvRef2 (511), and the photovoltaic maximum power tracking module MPPT (512) outputs a voltage reference value Upv0Ref (513) to carry out open-circuit voltage adjustment to automatically adjust the power of the photovoltaic battery so as to realize the adjustment of the battery charging power.
Referring to fig. 6, the control loop of the optical Fu Zhiliu converter, in which the photovoltaic dc converter operates at the maximum power point of the photovoltaic, indicates that the power between the power modules of the energy storage system is out of balance when the bus voltage is detected to be higher than the bus voltage target value controlled by the battery dc converter, such as ubusref+20v, and then the upper limit limiter loop of the bus voltage needs to be put into to adjust the output power of the photovoltaic dc converter to maintain the system stable. The upper bus voltage limit loop is designed such that the optical Fu Zhiliu converter sets an upper bus voltage limit value UbusUpLimit, such as ubusuplimit=ubusref+20v. The photovoltaic direct current converter obtains the bus voltage Ubus, the upper limit value UbusUpLimit of the bus voltage is calculated with the input PI controller of the bus voltage Ubus, and the output result of the PI controller is limited, wherein the positive limit is 0, the negative limit is 700V, the PI output result is inverted and then is assigned to DeltaUpvRef, when the light Fu Zhiliu converter detects that the bus voltage is larger than the upper limit of the bus voltage, the photovoltaic power is overlarge, and at the moment, the PI output result DeltaUpvRef is larger than 0, namely the searching voltage of the light Fu Zhiliu converter is adjusted towards the direction of the photovoltaic open-circuit voltage so as to reduce the power output of the light Fu Zhiliu converter. When the bus voltage is smaller than the bus voltage upper limit amplitude limit, the photovoltaic power is in a normal range, and the PI output result DeltaUpvRef is smaller than 0 and limited to 0 by the amplitude limiting ring, namely the output power of the light Fu Zhiliu converter is not affected.
The invention starts from the control loop of the inverter and the light Fu Zhiliu converter, automatically adjusts the power control of the inverter and the light Fu Zhiliu converter by adding an additional control constraint loop, solves the problems of power distribution and safety constraint among power modules of the energy storage system, and improves the dynamic response speed of the system and reduces the complexity of the system control by replacing the power balance calculation of the system by the control constraint loop.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, the patentees may make various modifications or alterations within the scope of the appended claims, and are intended to be within the scope of the invention as described in the claims.
Claims (2)
1. The control method of the energy storage system is realized based on the energy storage system, and the energy storage system comprises an inverter grid-connected control loop and an optical Fu Zhiliu converter control loop, and is characterized in that a first battery voltage upper limit limiting loop and a battery voltage lower limit limiting loop are arranged on the inverter grid-connected control loop, and a second battery voltage upper limit limiting loop and a bus voltage upper limit limiting loop are arranged on the optical Fu Zhiliu converter control loop; the method comprises the steps of automatically switching a first battery voltage upper limit limiting loop, a battery voltage lower limit limiting loop, a second battery voltage upper limit limiting loop and a bus voltage upper limit limiting loop according to a battery voltage upper limit and lower limit detection and bus voltage upper limit detection result and judging and detecting according to an operation mode of an energy storage system, and adjusting output power of an inverter and an optical Fu Zhiliu converter according to a loop result;
the control method of the energy storage system comprises the following steps,
step S301, judging an operation mode of an energy storage system;
step S302, if the operation mode of the energy storage system is grid-connected operation, step S303 is executed;
step S303, the energy storage system judges whether the battery voltage reaches the upper limit, if so, step S304 is executed, otherwise, step S309 is executed;
step S304, triggering the first battery voltage upper limit limiting loop to automatically take effect;
step S305, the first battery voltage upper limit limiting loop controls the battery voltage within the upper limit limiting by increasing the inverter discharging power or decreasing the inverter charging power;
step S306, the energy storage system judges that the trigger power limit value of the inverter is up to the upper limit;
step S307, triggering the second battery voltage upper limit limiting loop to automatically take effect;
step S308, the second battery voltage upper limit clipping loop controls the battery voltage within the upper limit clipping by reducing the output power of the light Fu Zhiliu converter;
step S309, the energy storage system judges that the battery voltage reaches the lower limit amplitude limit;
step S310, triggering a battery voltage lower limit limiting loop to take effect;
step S311, the battery voltage lower limit limiting loop controls the battery voltage above the lower limit limiting by reducing the inverter discharge power or increasing the inverter charge power;
step S312, if the operation mode of the energy storage system is off-grid operation, step S313 is executed;
step S313, the energy storage system judges whether the battery voltage reaches the upper limit, if yes, the step S314 is executed, otherwise, the step S316 is executed;
step S314, triggering the second battery voltage upper limit limiting loop to automatically take effect;
step S315, the second battery voltage upper limit clipping loop controls the battery voltage within the upper limit clipping by reducing the light Fu Zhiliu converter output power;
step S316, the energy storage system judges that the bus voltage exceeds a control value;
step S317, triggering a bus voltage upper limit limiting loop to automatically take effect;
step S318, the bus voltage upper limit limiting loop controls the bus voltage within the upper limit limiting by reducing the output power of the light Fu Zhiliu converter;
the working process of the first battery voltage upper limit limiting loop is as follows: the upper limit of the battery voltage is subjected to amplitude limiting UbatUpLimit and a corresponding battery voltage feedback value UbatFb, and then the difference is sent to a PI controller, and the PI controller outputs the difference and then passes through an amplitude limiting loop and takes the difference as an adjustment quantity delta PinvRef2 of the output power of the inverter;
the working process of the battery voltage lower limit limiting loop is as follows: the lower limit amplitude limiting UbatDpLimit of the battery voltage is differed with the corresponding feedback value UbatFb of the battery voltage and then sent to a PI controller, and the output of the PI controller is subjected to an amplitude limiting loop and is inverted to be used as the adjustment quantity delta Pinv_ref1 of the output power of the inverter;
the working process of the second battery voltage upper limit limiting loop is as follows: the upper limit of the battery voltage is subjected to amplitude limiting UbatUpLimit and a corresponding battery voltage feedback value UbatFb, and then the difference is sent to a PI controller, the PI controller outputs the voltage and takes the voltage as a voltage adjustment quantity delta UpvRef2 after passing through an amplitude limiting loop and reversing the voltage, and the power of a photovoltaic maximum power tracking module MPPT output voltage reference value Upv0Ref is automatically adjusted to open-circuit voltage so as to realize the adjustment of battery charging power;
the working process of the bus voltage upper limit limiting loop is as follows: the light Fu Zhiliu converter sets a bus voltage upper limit value UbusUpLimit, the photovoltaic direct current converter obtains a bus voltage Ubus, the bus voltage upper limit value UbusUpLimit and the bus voltage Ubus are input into the PI controller for operation, the output result of the PI controller is limited, and the output result of the PI controller is inverted and then assigned to the voltage adjustment quantity DeltaUpvRef.
2. The control method according to claim 1, wherein the step S306 is specifically: when the inverter detects that the total power of the inverter is equal to the upper limit limiting value of the power limiting value loop, the inverter regulating capacity reaches the upper limit and the lower limit, the Flag bit Flag is set at the moment, and when the light Fu Zhiliu converter detects the inverter Flag, the second battery voltage upper limit limiting loop 501 is triggered to automatically take effect.
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| CN202211340874.2A CN115579926B (en) | 2022-10-30 | 2022-10-30 | Energy storage system and control method thereof |
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