CN112186792A - Method, system and device for controlling switching of operation modes of energy storage converter - Google Patents
Method, system and device for controlling switching of operation modes of energy storage converter Download PDFInfo
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- CN112186792A CN112186792A CN202011092115.XA CN202011092115A CN112186792A CN 112186792 A CN112186792 A CN 112186792A CN 202011092115 A CN202011092115 A CN 202011092115A CN 112186792 A CN112186792 A CN 112186792A
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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
- H02J7/0068—Battery or charger load switching, e.g. concurrent charging and load supply
Abstract
The application provides a method, a system and a device for controlling operation mode switching of an energy storage converter and electronic equipment, and relates to the field of battery energy storage and current conversion control. The control method comprises the following steps: the DC/AC converter controls the voltage of the direct current bus to keep constant; generating a control reference value of the battery current sharing inner ring through the corresponding outer ring according to the operation mode; controlling the DC/DC converter with the battery current inner loop; acquiring and latching a control reference value of a current battery current inner ring; and executing operation mode switching, wherein a threshold input mechanism is adopted to dynamically superpose the closed-loop output value of the alternating current power on the constant direct current power, so that a control reference value of the battery current sharing inner loop is generated. According to the technical scheme of the embodiment of the application, the voltage fluctuation of the direct-current bus in the switching process can be reduced; and (4) suppressing sudden change of the control variable at the moment of mode switching.
Description
Technical Field
The application relates to the field of battery energy storage and current transformation control, in particular to a method, a system, a device and electronic equipment for controlling operation mode switching of an energy storage current transformer.
Background
In recent years, electrochemical energy storage systems have played an increasing role in promoting the sustainable development of clean energy. In an electrochemical energy storage system, an all-vanadium redox flow battery is taken as a typical redox flow battery energy storage system, and the all-vanadium redox flow battery becomes a research hotspot gradually due to the advantages of flexible capacity configuration, high safety, long service life, no pollution and the like; because the battery is open-circuited and the voltage generates larger fluctuation along with different charging and discharging states, and the voltage matching is not facilitated, in practical application, most energy storage converters (PCS) are introduced into a direct current converter, namely a two-stage PCS structure of a DC/DC converter and a DC/AC converter is formed, the direct current side adaptive capacity can be improved, and the system flexibility is increased.
The two-stage PCS control mode is more complex than the single-stage PCS control mode, and the coordination problem between two stages needs to be considered. When the actual energy storage system is operated in a grid-connected mode, the power of an alternating current side needs to be controlled to respond to a power instruction requirement, namely a grid-connected PQ operation mode, a DC/AC converter controls the voltage of a direct current bus to be constant, and the DC/AC converter performs grid-connected PQ control; in the last stage of battery charging and discharging, in order to prevent the battery from being overcharged and overdischarged, the PCS needs to be operated in an automatic constant battery voltage conversion control mode, namely a DC/DC converter controls the voltage of the battery, and the DC/AC converter is used for controlling the voltage of a direct current bus; in addition, there is also the problem of initial charging for flow batteries, i.e. constant battery current charging is required to establish the battery voltage in the initial phase, i.e. the DC/DC converter controls the battery current and the DC/AC converter controls the DC bus voltage. In order to meet the functional requirements, a conventional control method is adopted, the problem of mode switching of the front-stage converter and the rear-stage converter in the operation process of the two-stage PCS is solved, communication delay and mode switching control delay between the front-stage converter and the rear-stage converter are considered, and the direct-current bus voltage at the moment of switching cannot be effectively controlled, so that the direct-current bus voltage is excessively fluctuated, a switching device is damaged, and even the energy storage converter is unstable.
Therefore, the research on the two-stage PCS coordination control method realizes smooth switching among different control modes on the basis of meeting the system function requirements, ensures that the voltage fluctuation of the direct-current bus in the switching process is within a reasonable range, and has important significance.
Disclosure of Invention
The application provides a method, a system, a device and electronic equipment for controlling operation mode switching of an energy storage converter, which ensure that the control mode of a DC/DC converter is smoothly switched in different operation modes, the DC/AC converter controls the voltage of a direct current bus to keep stable, the reference value of battery current is latched and released in the switching process, and the voltage fluctuation of the direct current bus in the switching process is ensured to be within a reasonable range.
The features and advantages of the control method of the present application will become apparent from the detailed description, which follows, or may be learned, in part, by practice of the present application.
According to an aspect of the present application, a method for mode smooth switching control of an energy storage converter comprising a DC/DC converter, a DC/AC converter and a PWM pulse modulated regulator, said operation modes comprising a constant battery current operation mode, a constant alternating current power operation mode, a constant battery voltage operation mode, said method comprising: the DC/AC converter controls the voltage of the direct current bus to keep constant; generating a control reference value of a common battery current inner ring through a corresponding outer ring according to the operation mode; controlling the DC/DC converter with the battery current inner loop; acquiring and latching a control reference value of a current battery current inner ring, and taking the control reference value as an initial value of a maximum amplitude limit and a minimum amplitude limit of a PI controller of a corresponding outer ring to be switched; and executing operation mode switching, and switching the amplitude limiting value of the PI controller of the corresponding outer ring after switching to a preset value, wherein in the constant alternating current power operation mode, a threshold input mechanism is adopted to dynamically superpose an alternating current power closed-loop output value on constant direct current power, so that a control reference value of the battery current sharing inner ring is generated.
According to some embodiments, the initial charging phase of the constant battery current operation mode controls the energy storage converter to start at zero voltage, and charges the battery in the constant current operation mode.
According to some embodiments, in the constant AC power operation mode, dynamically superposing the AC power closed-loop output value on the constant DC power by adopting a threshold input mechanism to generate the control reference value of the battery current sharing inner loop, wherein the control reference value comprises the following steps of according to the AC power given value PrefReal-time power P to AC sideacDetermining the closed-loop output value P of the alternating current powercl(ii) a Setting the AC power to a given value PrefAnd said closed loop output value P of AC powerclThe superposition value of the direct current power outer loop is used as a total direct current power reference value of the direct current power outer loop in the constant alternating current power operation mode; and regulating the difference value between the total direct current power reference value and the actual direct current power through a PI controller to generate the control reference value of the battery current inner loop.
According to some embodiments, the given value of ac power P is determined by the ac powerrefReal-time power P to AC sideacDetermining the closed-loop output value P of the AC powerclThe method comprises the following steps: detecting the real-time power P of the AC sideac(ii) a Calculating the real-time power P of the AC sideacAnd the given value P of the alternating current powerrefThe ratio λ of (a); the closed loop output value P of the alternating current powerclIs determined according to the following relation：
Wherein λ is0A coefficient of input for a threshold, 0 < lambda0＜1；kps、kisThe proportional coefficient and the integral coefficient of the alternating current power closed-loop controller are respectively.
According to some embodiments, the obtaining and latching a control reference value for a present battery current inner loop comprises: judging the current operation mode, if the current operation mode is a constant battery voltage operation mode or a constant battery current operation mode, controlling the limiting value of a first outer ring PI regulator corresponding to the constant alternating current power operation mode to be Im1＝Im2＝Idcref(ii) a Wherein, Im1And Im2Respectively a maximum limit amplitude and a minimum limit amplitude, I, of the first outer ring PI regulatordcrefAnd the reference value is the inner loop reference value of the battery current in the current control mode.
According to some embodiments, the obtaining and latching a control reference value for a present battery current inner loop further comprises: judging the current operation mode, if the current operation mode is a constant alternating current power operation mode or a constant battery current operation mode, controlling the amplitude limit value of a second outer ring PI regulator corresponding to the constant battery voltage operation mode to be Im3＝Im4＝IdcrefWherein, Im3And Im4Respectively a maximum limit amplitude and a minimum limit amplitude, I, of the second outer ring PI regulatordcrefAnd the reference value is the inner loop reference value of the battery current in the current control mode.
According to some embodiments, controlling the DC/DC converter with the battery current inner loop comprises: inner loop final command I of the battery currentdcrefAnd the battery current idcThe difference value is regulated by a PI regulator to generate a control signal; and controlling a PWM (pulse-width modulation) regulator by using the control signal to drive a switching tube.
According to some embodiments, the predetermined value is the rated battery current of the energy storage converter.
According to an aspect of the application, an apparatus for energy storage converter operating mode switching control, said smooth switching comprising smooth switching from a constant battery current operating mode through a constant ac power operating mode to a constant battery voltage operating mode, said apparatus comprising: the DC/AC control module is used for controlling the voltage of the direct-current bus to keep constant; the outer ring control module is used for generating a control reference value of a shared battery current inner ring; the threshold input mechanism module is used for generating an output signal as an alternating current power closed loop output value; the battery current inner loop control module is used for controlling the DC/DC converter; the latching module is used for acquiring and latching a control reference value of a current battery current inner ring, and taking the control reference value as an initial value of a maximum amplitude limit and a minimum amplitude limit of a PI controller of a corresponding outer ring to be switched; and the execution switching processing module is used for switching the amplitude limiting value of the PI controller of the corresponding outer ring after switching to a preset value.
In accordance with another aspect of the present application, a system for control of operating mode switching of an energy storage converter having a DC/DC converter, a DC/AC converter and a PWM pulse modulated regulator, said smooth switching being from a constant battery current operating mode, through a constant AC power operating mode to a constant battery voltage operating mode, said system comprising: a first adder receiving the power signal PrefAnd PacA signal, calculating; a divider for dividing the power signal PrefAnd PacThe ratio is taken as an output signal lambda; comparator for comparing signals lambda and lambda0The output signal is the regulator S1 logic signal. The first switch is switched on according to the output signal logic of the comparator; a first PI regulator for regulating output signal P via proportional coefficient and integral coefficientcl(ii) a A second adder receiving the power signal Pcl、PdcAnd PrefForming a second PI regulator input signal; a second PI regulator for regulating the output signal I via a proportionality coefficient and an integral coefficientdcref1And sets the clipping value Im1、Im2(ii) a A third adder receiving the voltage signal VdcrefAnd VdcForming a third PI regulator input signal. A third PI regulator for regulating output signal via proportional coefficient and integral coefficientIdcref2And sets the clipping value Im3、Im4(ii) a A second switch that is turned on according to the logic signal; a fourth adder for receiving the current signal IdcrefAnd idcForming a fourth regulator input signal; and the PWM regulator controls the analog circuit to output a stable signal waveform.
According to an aspect of the present application, an electronic device is provided, the electronic device including: one or more processors; storage means for storing one or more programs; when executed by one or more processors, cause the one or more processors to implement a method as above.
According to the embodiment, the control mode of the DC/DC converter is switched to meet the requirement of double-stage PCS multi-mode operation, the DC/AC converter does not need to be switched to the mode, the voltage of a direct-current bus is guaranteed to be constant, the voltage fluctuation of the direct-current bus in the switching process is reduced, and the stability of a system is improved.
According to some embodiments, the constant alternating current power control adopts a threshold input mechanism, dynamically superposes the alternating current power closed-loop output value, realizes the no-difference tracking of the alternating current power, and reduces the power jump at the tracking moment.
According to some embodiments, the outer-loop output instruction latch release mechanism realizes smooth switching of three operation modes of constant alternating current power, constant battery current and constant battery voltage of the two-stage PCS.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
Drawings
In order to more clearly explain the technical solutions in the embodiments of the present application, the drawings that are needed to be used in the description of the embodiments will be briefly described below. Other features, objects and advantages of the present application will become more apparent in the following detailed description of non-limiting embodiments thereof, with reference to the accompanying drawings.
Fig. 1 shows a schematic diagram of an energy storage converter application according to an exemplary embodiment;
fig. 2a shows a flow chart of energy storage converter switching according to an exemplary embodiment;
FIG. 2b shows a schematic diagram of a DC/DC converter control architecture according to an exemplary embodiment;
FIG. 3 shows a flow chart of an energy storage converter switching control according to another exemplary embodiment;
FIG. 4 illustrates an electronic block diagram of energy storage converter operation switching in accordance with an exemplary embodiment;
fig. 5 shows a block diagram of an energy storage converter switching system according to an exemplary embodiment.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Fig. 1 shows a schematic diagram of an energy storage converter application according to an exemplary embodiment.
As shown in fig. 1, the energy storage converter includes: a DC/DC converter 100, a DC/AC converter 101, a DC bus capacitor 102, a battery 103 and a power grid 104.
According to an exemplary embodiment, switching between the different operation modes is performed in the DC/DC converter 100.
According to an exemplary embodiment, in the DC/DC converter 100, the clip value of the PI regulator of the corresponding outer loop after switching is switched to a predetermined value.
According to an example embodiment, the energy storage converter is operated in a grid-connected manner, and charging and discharging of the battery 103 are controlled.
According to an example embodiment, the battery 103 is a flow battery. The flow battery has a zero-voltage working condition and needs zero-voltage initial charging; and in the last stage of charging and discharging of the flow battery, the flow battery needs to be switched to a constant battery voltage control mode to operate. In addition, when the grid-connected operation is carried out, the flow battery needs to be operated in a constant alternating current power control mode.
In the prior art, generally, because a battery is open-circuited, and voltage fluctuates greatly along with different charging and discharging states, which is not favorable for voltage matching, in practical applications, most energy storage converters (PCS) are introduced into a direct current converter, that is, a two-stage PCS structure of a DC/DC converter 100 and a DC/AC converter 101 is formed, so that system flexibility is increased. However, the applicant finds that in practical use, the two-stage PCS control mode is more complicated than the single-stage PCS control mode, and in order to achieve the above functional requirements, the conventional control method causes the problem of mode switching of the front-stage and rear-stage converters during the two-stage PCS operation. The communication delay and the mode switching control delay between the front-stage converter and the rear-stage converter are considered, the direct-current bus voltage at the moment of switching cannot be effectively controlled, the direct-current bus voltage fluctuation is too large, the switching device is damaged, and even the energy storage converter is unstable.
To this end, the present application proposes a method for controlling the switching of the operating modes of an energy storage converter.
According to an exemplary embodiment, in fig. 1, the DC bus voltage is controlled to be kept constant by the DC/AC converter 101, and the DC/DC converter 100 performs smooth switching between different operation modes, so that at the moment of switching, the DC bus voltage fluctuates within a reasonable range, and the bipolar PCS control mode is simplified.
The technical solution of the present application is described in detail below with reference to example embodiments.
Fig. 2a shows a flow chart of energy storage converter switching according to an exemplary embodiment. Fig. 2b shows a schematic diagram of a DC/DC converter control structure according to an exemplary embodiment.
The smooth switching of the storage converter is explained below with reference to fig. 2a and 2 b. It is easy to understand that the method of smooth switching of the energy storage converter can be applied not only to the control structure shown in fig. 2b, but also to other similar control structures.
At S200, the DC/AC converter 101 controls the DC bus voltage to be constant.
According to an example embodiment, the DC/AC converter 101 controls the DC bus voltage vbusThe constant is kept to reduce the voltage fluctuation of the direct current bus in the switching process and realize the smooth switching of different control modes.
For example, inIn the existing constant alternating current power operation mode, the DC/AC converter needs to control the alternating current side power PacD.c. bus voltage vbusThe control is performed by the DC/DC converter, which causes that when the constant AC power operation is switched to the constant battery voltage operation or the constant battery current operation, the control modes of the DC/DC converter and the DC/AC converter need to be switched simultaneously (the DC/AC converter controls the AC side power to be converted into the control DC bus voltage, and the DC/DC converter controls the DC bus voltage to be converted into the control battery voltage or the battery current), which causes the DC bus voltage to fluctuate greatly, and even causes the system to be unstable. According to the embodiment of the application, the constant alternating current power control function is realized through the DC/DC converter, and the mode of the DC/AC converter is always kept unchanged in the mode switching process, so that smooth switching is realized.
At S201, a control reference value of a common battery current inner loop is generated through a corresponding outer loop according to an operation mode.
According to example embodiments, the operating modes may include a constant battery current operating mode, a constant ac power operating mode, and a constant battery voltage operating mode.
According to an example embodiment, during an initial charging phase of the constant battery current operation mode, the energy storage device converter is controlled to start at zero voltage, and the battery is charged in the constant current operation mode.
In a constant ac power mode of operation, according to an example embodiment, in the constant ac power mode of operation, the DC/DC converter operates in a constant DC power control mode, and a threshold input mechanism is employed to dynamically superimpose the closed loop output value of the ac power on the constant DC power.
Referring to FIG. 2b, the DC/DC converter has a control mode structure of DC power PdcOuter loop, battery current idcDouble closed loop control of inner loop, control of direct power reference command superposition value P through mode switch K1clThe size of (2). Power instruction PrefDivided by AC real-time power PacObtaining power ratio coefficient lambda, lambda and threshold input coefficient lambda0The comparison result is the value of the selector S1 of the mode switch K1, see formula (1). The value of S1 determines the output value of the mode switch K1, the output value of the mode switch K1Adjusting by a PI regulator to generate an AC power closed-loop output value Pcl，PclSee formula (2). PclAs a reference command, superimposed on the power reference value of the dc power outer loop, i.e. the total dc power reference value is Pref+PclThe value of which is related to the actual DC power PdcThe difference value is regulated by a PI regulator to generate a reference value I of the inner loop of the battery currentdcref1。
Wherein λ is0A coefficient of input for a threshold, 0 < lambda0＜1；kps、kisThe proportional coefficient and the integral coefficient of the alternating current power closed-loop controller are respectively.
By the threshold input mechanism, the output value P of the closed-loop control of the dynamically input alternating current power is realizedclIn general, λ0Close to 1, i.e. the energy storage converter is commanded to power PrefConstant DC power control is carried out until the AC real-time power PacProximity power instruction PrefThe closed-loop control of the alternating current power is put into operation, the problem of system power oscillation caused by too early input is avoided, and the function of controlling the constant alternating current power is realized.
Referring to FIG. 2b, according to an exemplary embodiment, the constant AC power mode of operation, the constant battery current mode of operation, and the constant battery voltage mode of operation correspond to a battery current inner loop reference value of I, respectivelydcref1，Idcref0And Idcref2. The outputs of the three reference values are selectively controlled by a mode switch K2, and the value of the selector S2 determines the reference value I output by the mode switch K2dcref1，Idcref0Or Idcref2See formula (3).
The output value of the mode switch K2 is a final command I of the battery current inner loopdcref。IdcrefAnd the battery current idcThe difference value is regulated by a PI regulator, and the generated modulation wave finally drives a switch tube through PWM pulse modulation. The direct-current power outer loop PI regulator and the battery voltage outer loop PI regulator have amplitude limiting functions. The energy storage converter judges the current operation mode, and if the current operation mode is a constant alternating current power operation mode or a constant battery current operation mode, the limiting amplitude value of the battery voltage outer ring PI regulator is controlled to be Im3＝Im4＝Idcref(ii) a If the operation mode is a constant battery voltage operation mode or a constant battery current operation mode, controlling the limiting value of the direct current power outer loop PI regulator to be Im1＝Im2＝Idcref。Im1And Im2Respectively a maximum limit amplitude and a minimum limit amplitude, I, of the direct current power outer loop PI regulatorm3And Im4The maximum amplitude and the minimum amplitude of the battery voltage outer ring PI regulator are respectively.
At S203, the DC/DC converter is controlled with the battery current inner loop.
According to an exemplary embodiment, the battery current inner loop final command IdcrefAnd the battery current idcThe difference value of (d) is regulated by a PI regulator to generate a control signal. Then, the PWM pulse modulation regulator is controlled by the control signal to drive the switching tube.
According to an example embodiment, referring to fig. 2b, the battery current inner loop final command I calculated by the fourth adder 2011dcrefAnd the battery current idcThe difference of (d) is adjusted by the fourth PI adjuster 2012 to generate a modulation wave. The modulation wave generated by the fourth PI regulator 2012 passes through the PWM pulse modulation regulator 2013 to drive the switching tube.
In S205, a control reference value of the current battery current inner loop is obtained and latched, and the control reference value is used as an initial value of the maximum amplitude limit and the minimum amplitude limit of the PI controller of the corresponding outer loop after switching.
According to an exemplary embodiment, the current operating mode is determined, if it is a constant battery voltage operating mode or a constant powerIn the pool current operation mode, controlling the limiting amplitude value of a first outer ring PI regulator corresponding to the constant alternating current power operation mode to be Im1＝Im2＝Idcref。
If the operation mode is a constant alternating current power operation mode or a constant battery current operation mode, controlling the amplitude limit value of a second outer ring PI regulator corresponding to the constant battery voltage operation mode to be Im3＝Im4＝Idcref。
Im1And Im2Respectively a maximum limit amplitude and a minimum limit amplitude, I, of the first outer ring PI regulatorm3And Im4Respectively a maximum limit amplitude and a minimum limit amplitude, I, of the second outer ring PI regulatordcrefAnd the reference value is the inner loop reference value of the battery current in the current control mode.
Referring to fig. 2b, when the DC/DC converter 100 initially operates in the constant battery current operation mode and the control signal of the second control switch 2010 is 0, the second PI regulator 2007 and the third PI regulator 2009 clip satisfy Im1＝Im2＝Im3＝Im4＝Idcref＝Idcref0。Im1And Im2A dc power outer loop PI regulator, second PI regulator 2007, maximum amplitude limit and minimum amplitude limit, Im3And Im4An outer loop PI regulator for the battery voltage, i.e. a third PI regulator 2009, maximum and minimum amplitude limits, IdcrefReference value of inner loop of battery current, Idcref0The reference value of the inner loop of the battery current in the constant battery current operation mode is obtained.
In S207, the operation mode switching is performed, and the amplitude limit value of the PI controller of the corresponding outer loop after the switching is switched to a predetermined value.
During the operation of the system, the system can be switched between different operation modes according to the operation condition or the operation stage. For example, in the initial charging stage of the battery, the energy storage converter is started in a zero voltage mode and slowly charges the battery in a constant current mode; after the direct-current voltage is established by the battery, the system can be switched to a constant alternating-current power operation mode; at the end of the battery charge and discharge, the system can switch to constant battery voltage mode. Furthermore, according to some embodiments, grid-tied operation requires operation in a constant ac power mode of operation.
According to some embodiments, referring to fig. 2b, the state of charge of the battery is detected to set the value of the selector S2. For example, in the initial charging stage of the battery, the value of the selector S2 is set to 0; after the battery establishes the dc voltage, the value of the selector S2 is set to 1; at the end of battery charge and discharge, the value of the selector S2 is set to 2. The value of selector S2 determines the value of mode switch K2 output corresponding outer loop.
Based on the outer loop output instruction latch mechanism in S206, when the operation mode is switched, since the control reference value of the battery current inner loop in the operation mode before switching is latched in advance, and the corresponding outer loop PI regulator after switching adjusts with the latched control reference value as an initial value, the change of the control intermediate variable in the switching process is small, and the sudden change of the control variable at the moment of switching the mode can be suppressed.
After switching, the amplitude limit value of the PI controller of the corresponding outer loop may be switched to a predetermined value, for example, the rated battery current of the energy storage converter.
According to an exemplary embodiment, the DC/DC converter 100 is controlled by sharing the battery current inner loop in different operating modes. By acquiring and latching the control reference value of the battery current inner ring before switching and taking the control reference value as the initial value of the maximum amplitude limit and the minimum amplitude limit of the PI regulator of the corresponding outer ring after switching, the effective control of the direct current bus voltage at the moment of switching is ensured, the overlarge voltage fluctuation of the direct current bus is avoided, and the switching device is protected.
Fig. 3 shows a flow chart of an energy storage converter switching control according to another example embodiment.
Referring to fig. 3, in S301, in the initial charging stage of the constant battery current operation mode, when the selector S2 is equal to 0, the DC/DC converter controls the battery current idcDC/AC converter controlling DC bus voltage vbusThe energy storage converter is started at zero voltage, the battery is charged in a constant current running mode, and the limiting amplitude values of the direct current power outer ring and the battery voltage outer ring meet Im1＝Im2＝Im3＝Im4＝Idcref。
When the battery builds the dc voltage, that is, the control signal is detected to make the selector S2 equal to 1, the operation mode is switched to the constant ac power operation mode.
At S302a, the amplitude latched in advance is clipped from I by the second PI regulator 2007m1＝Im2＝Idcref＝Idcref0Release of Im1＝-Im2＝Irate(ii) a Wherein, IrateThe battery current is rated for the energy storage converter. Switching to constant AC power mode of operationdcref＝Idcref1: due to Idcref1Is latched in advance, Idcref1Through the second PI regulator 2007 in the outer loop of DC power as the initial value IdcrefAnd (5) adjustment is carried out, and the change of the intermediate variable in the switching process is small.
In the constant AC power mode of operation, according to an exemplary embodiment, see FIG. 2b, a given value P is given according to AC powerrefReal-time power P to AC sideacVia divider 2002 and comparator 2003 as selection signals for first switch 2004 to determine a closed loop output value P for the flow powercl。
When the control signal of the first switch 2004 is 0, the AC power closed loop output value PclIs 0; when the control signal of the first switch 2004 is 1, the flow power closed loop output value PclCalculating a given value of AC power P for the first adder 2001refAnd real-time power P at AC sideacIs at the ac power closed loop output value P output through the first PI regulator 2005cl。
According to an exemplary embodiment, the alternating current power is given a value PrefAnd said closed loop output value P of AC powerclThe superimposed value passing through the second adder 2006 is used as a total dc power reference value of the dc power outer loop in the constant ac power operation mode; the difference between the total dc power reference and the actual dc power is regulated 2007 by a second PI regulator to generate the control reference for the battery current inner loop.
In addition, λ and λ can be compared in time0The magnitude relation of (1) as a control signal of the switch K1, thereby determining P in S302bclThe size of (2).
At S302c, clipping of the third PI regulator 2009, i.e., latching of I, continues to be maintained for the battery voltage outer loopm3＝Im4＝Idcref＝Idcre1f。
When the battery enters the end stage of charging and discharging, the second selector 2010 is switched to S2 being 2, and the energy storage converter is switched to the constant battery voltage operation mode.
See fig. 2b, vdcrefAnd vdcVia a third adder 2008 as an input value, I, for a third PI regulator 2009m3、Im4An outer-loop PI regulator for the battery voltage, i.e. a third PI regulator 2009 maximum and minimum amplitude limits, Idcref2The reference value of the inner loop of the battery current in the constant battery voltage operation mode is obtained.
At S303, the third PI regulator 2009 clips, advancing the latched amplitude Im3＝Im4＝Idcref＝Idcref1Release of Im3＝-Im4＝IrateSwitching to constant battery voltage mode to enable Idcref＝Idcref2. Due to Idcref2Is latched in advance, Idcref2Through battery voltage outer ring PI controller with initial value IdcrefAnd (5) adjustment is carried out, and the change of the intermediate variable in the switching process is small. In addition, the amplitude limit, I, of the DC power outer loop PI controller can be changedm1＝Im2＝Idcref＝Idcref2And (4) until the charging and discharging of the battery are finished.
Through the description of the exemplary embodiments, those skilled in the art can easily understand that the method for smooth switching control of the energy storage converter according to the embodiments of the present application has at least one or more of the following advantages.
According to some embodiments, the above threshold input mechanism can avoid system power oscillation problem caused by too early input.
According to other embodiments, the DC bus voltage is controlled to be kept constant through the DC/AC converter, and the DC/DC converter is controlled in a mode of different outer rings and a common battery current inner ring under different operation modes, so that the condition that the DC bus voltage is fluctuated greatly in the switching process and even the system is unstable is avoided.
According to the technical scheme, the engineering problem can be solved practically, and the smooth switching of the energy storage converter can be realized.
Fig. 4 shows a block diagram of an electronic device for switching the operation of an energy storage converter according to an exemplary embodiment. The electronic device according to fig. 4 may perform the aforementioned method according to an embodiment of the present application.
An electronic device 400 according to this embodiment of the present application is described below with reference to fig. 4. The electronic device 400 shown in fig. 4 is only an example, and should not bring any limitation to the functions and the scope of use of the embodiments of the present application.
As shown in fig. 4, electronic device 400 is embodied in the form of a general purpose computing device. The components of electronic device 400 may include, but are not limited to: at least one processing unit 410, at least one memory unit 420, a bus 430 that connects the various system components (including the memory unit 420 and the processing unit 410), a display unit 440, and the like.
Wherein the storage unit stores program code, which can be executed by the processing unit 410, to cause the processing unit 410 to perform the methods according to various exemplary embodiments of the present application described herein.
The electronic device 400 may also communicate with one or more external devices 500 (e.g., keyboard, pointing device, bluetooth device, etc.), with one or more devices that enable a user to interact with the electronic device 400, and/or with any devices (e.g., router, modem, etc.) that enable the electronic device 400 to communicate with one or more other computing devices. Such communication may occur via input/output (I/O) interfaces 450. Also, the electronic device 400 may communicate with one or more networks (e.g., a Local Area Network (LAN), a Wide Area Network (WAN), and/or a public network, such as the internet) via the network adapter 460. The network adapter 460 may communicate with other modules of the electronic device 400 via the bus 430. It should be appreciated that although not shown in the figures, other hardware and/or software modules may be used in conjunction with electronic device 400, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems, among others.
Fig. 5 shows a block diagram of an energy storage converter switching system according to an exemplary embodiment.
As shown in fig. 5, the energy storage converter mode smooth switching control system according to an example embodiment includes: a DC/AC control module 501, an outer loop control module 502, a battery current inner loop control module 503, a latch module 504, and an execution switching processing module 505. The system modules shown in fig. 5 are only an example, and should not bring any limitation to the functions and the scope of use of the embodiments of the present application.
The DC/AC control module 501 is used to control the DC bus voltage to remain constant.
The outer loop control module 502 is used to generate a control reference for the common battery current inner loop.
The battery current inner loop control module 503 is used to control the DC/DC converter.
The latch module 504 is configured to obtain and latch a control reference value of the current inner loop of the battery current, and use the control reference value as an initial value of a maximum amplitude limit and a minimum amplitude limit of the PI controller of the corresponding outer loop to be switched.
The execution switching processing module 505 is configured to switch the amplitude limiting value of the PI controller of the corresponding outer loop to a predetermined value after switching.
The threshold input mechanism module 506 is configured to dynamically superimpose the closed-loop output value of the ac power in the constant ac power operation mode, so as to generate a control reference value of the battery current sharing inner loop.
The foregoing detailed description of the embodiments of the present application has been presented to illustrate the principles and implementations of the present application, and the description of the embodiments is only intended to facilitate the understanding of the methods and their core concepts of the present application. Meanwhile, a person skilled in the art should, according to the idea of the present application, change or modify the embodiments and applications of the present application based on the scope of the present application. In view of the above, the description should not be taken as limiting the application.
Claims (11)
1. A method for switching control of operating modes of an energy storage converter, the energy storage converter comprising a DC/DC converter, a DC/AC converter and a PWM pulse modulation controller, the operating modes including a constant battery current operating mode, a constant AC power operating mode and a constant battery voltage operating mode, the method comprising:
the DC/AC converter controls the voltage of the direct current bus to keep constant;
generating a control reference value of the battery current sharing inner ring through the corresponding outer ring according to the operation mode;
controlling the DC/DC converter with the battery current inner loop;
acquiring and latching a control reference value of a current battery current inner ring, and taking the control reference value as an initial value of a maximum amplitude limit and a minimum amplitude limit of a PI controller of a corresponding outer ring to be switched;
executing operation mode switching, switching the amplitude limiting value of the PI controller of the corresponding outer ring after switching to a preset value,
and in the constant alternating current power operation mode, a threshold input mechanism is adopted to dynamically superpose the alternating current power closed-loop output value on the constant direct current power, so that a control reference value of the battery current sharing inner loop is generated.
2. The method according to claim 1, characterized in that the energy storage converter is controlled to start at zero voltage to charge the battery in the constant current operation mode during the initial charging phase of the constant current operation mode.
3. The method of claim 1, wherein dynamically superimposing an ac power closed loop output value on a constant dc power using a threshold input mechanism to generate a control reference value for a common inner loop of battery current in the constant ac power mode of operation comprises:
according to given value P of AC powerrefReal-time power P to AC sideacDetermining the closed-loop output value P of the alternating current powercl；
Setting the AC power to a given value PrefAnd said closed loop output value P of AC powerclThe superposition value of the direct current power outer loop is used as a total direct current power reference value of the direct current power outer loop in the constant alternating current power operation mode;
and regulating the difference value between the total direct current power reference value and the actual direct current power through a PI controller to generate the control reference value of the battery current inner loop.
4. The method of claim 3,
according to the given value P of the alternating current powerrefReal-time power P to AC sideacDetermining the closed-loop output value P of the AC powerclThe method comprises the following steps:
detecting the real-time power P of the AC sideac；
Calculating the real-time power P of the AC sideacAnd the given value P of the alternating current powerrefThe ratio λ of (a);
the closed loop output value P of the alternating current powerclDetermined according to the following relationship:
wherein λ is0A coefficient of input for a threshold, 0 < lambda0＜1；kps、kisThe proportional coefficient and the integral coefficient of the alternating current power closed-loop controller are respectively.
5. The method of claim 1, wherein the obtaining and latching the control reference value for the current battery current inner loop comprises:
judging the current operation mode, if it is a constant battery voltage operation mode or a constant battery current operation mode, controlling the operation modeThe amplitude limit value of a first outer ring PI regulator corresponding to the constant alternating current power operation mode is Im1＝Im2＝Idcref；
Wherein, Im1And Im2Respectively a maximum limit amplitude and a minimum limit amplitude, I, of the first outer ring PI regulatordcrefAnd the reference value is the inner loop reference value of the battery current in the current control mode.
6. The method of claim 1, wherein the obtaining and latching the control reference value for the current battery current inner loop comprises:
judging the current operation mode, if the current operation mode is a constant alternating current power operation mode or a constant battery current operation mode, controlling the amplitude limit value of a second outer ring PI regulator corresponding to the constant battery voltage operation mode to be Im3＝Im4＝Idcref；
Wherein, Im3And Im4Respectively a maximum limit amplitude and a minimum limit amplitude, I, of the second outer ring PI regulatordcrefAnd the reference value is the inner loop reference value of the battery current in the current control mode.
7. The method of claim 1, wherein controlling the DC/DC converter with the battery current inner loop comprises:
inner loop final command I of the battery currentdcrefAnd the battery current idcThe difference value is regulated by a PI regulator to generate a control signal;
and controlling a PWM (pulse-width modulation) regulator by using the control signal to drive a switching tube.
8. The method of claim 1, wherein the predetermined value is a rated battery current of the energy storage converter.
9. An apparatus for energy storage converter operating mode switching control, said smooth switching comprising smooth switching from a constant battery current operating mode through a constant ac power operating mode to a constant battery voltage operating mode, said apparatus comprising:
the DC/AC control module is used for controlling the voltage of the direct-current bus to keep constant;
the outer ring control module is used for generating a control reference value of the battery current sharing inner ring;
the threshold input mechanism module is used for dynamically superposing an alternating current power closed-loop output value under the constant alternating current power operation mode so as to generate a control reference value of a battery current sharing inner ring;
generating an output signal as an alternating current power closed loop output value;
the battery current inner loop control module is used for controlling the DC/DC converter;
the latching module is used for acquiring and latching a control reference value of a current battery current inner ring, and taking the control reference value as an initial value of a maximum amplitude limit and a minimum amplitude limit of a PI controller of a corresponding outer ring to be switched;
and the execution switching processing module is used for switching the amplitude limiting value of the PI controller of the corresponding outer ring after switching to a preset value.
10. A system for control of switching of operating modes of an energy storage converter having a DC/DC converter, a DC/AC converter and a PWM pulse modulated regulator, said smooth switching being from a constant battery current operating mode, through a constant AC power operating mode to a constant battery voltage operating mode, said system comprising:
a first adder receiving the power signal PrefAnd PacA signal, calculating;
a divider for dividing the power signal PrefAnd PacThe ratio is taken as an output signal lambda;
comparator for comparing signals lambda and lambda0The output signal is a regulator S1 logic signal;
the first switch is switched on according to the output signal logic of the comparator;
a first PI regulator for regulating output signal P via proportional coefficient and integral coefficientcl；
A second adder receiving the power signal Pcl、PdcAnd PrefForming a second PI regulator input signal;
a second PI regulator for regulating the output signal I via a proportionality coefficient and an integral coefficientdcref1And sets the clipping value Im1、Im2；
A third adder receiving the voltage signal VdcrefAnd VdcForming a third PI regulator input signal;
a third PI regulator for regulating output signal I via proportional coefficient and integral coefficientdcref2And sets the clipping value Im3、Im4；
A second switch that is turned on according to the logic signal;
a fourth adder for receiving the current signal IdcrefAnd idcForming a fourth regulator input signal;
and the PWM regulator controls the analog circuit to output a stable signal waveform.
11. An electronic device, comprising:
one or more processors;
storage means for storing one or more programs;
when executed by the one or more processors, cause the one or more processors to implement the method of any one of claims 1-8.
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