CN112039063A - PET topological structure and coordination control method of PET topological structure and energy storage system - Google Patents
PET topological structure and coordination control method of PET topological structure and energy storage system Download PDFInfo
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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
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
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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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
- H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
- H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
- H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
- H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M5/4585—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only having a rectifier with controlled elements
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
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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
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
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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
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
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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 relates to a PET topological structure and a coordination control method of the PET topological structure and an energy storage system. The PET topological structure comprises an input stage structure, a middle isolation stage structure and an output stage structure which are sequentially connected, wherein the input stage structure comprises three input lines, each input line comprises two symmetrical sub-input lines, and the sub-input lines comprise an input module and an inductor which are mutually connected; the middle isolation level structure comprises three H-shaped bridge type circuits and capacitors, the capacitors are connected in parallel to the output ends of the three H-shaped bridge type circuits, and each H-shaped bridge type circuit comprises two isolation level modules and a coil; the output stage structure comprises three output lines, each output line comprises a first output module, a second output module and a diode, and the second output module and the diode are connected in parallel and then connected with the first output module. The invention can realize the functions of PET input stage unit power factor operation, constant output stage voltage, voltage depth drop coping and light storage complementation.
Description
Technical Field
The invention relates to the field of micro-grid control, in particular to a PET topological structure and a coordination control method of the PET topological structure and an energy storage system.
Background
With the rapid development of economy, society has raised higher and higher requirements on the power quality of a power supply system and the reliability of power supply. Conventional energy resources owned by China are limited, non-renewable energy resources such as petroleum and coal are gradually exhausted, and the environmental problems faced by the present are more and more severe, so that thermal power generation is gradually replaced by new energy power generation. In recent years, the field of new energy has been rapidly developed and applied, and new energy power generation has become a research hotspot, and the new energy power generation has volatility, intermittency and uncertainty, and the safety and the stability of a power grid can be reduced if the new energy power generation is connected to the power grid on a large scale. The micro-grid mainly comprises a new energy power generation device and an energy storage system, and can be separated from a large power grid to operate independently or be parallel to the large power grid. As the development of micro-grid technology continues, micro-grid structures with power electronic transformers as the core are proposed and paid much attention. The micro-grid can effectively improve the consumption capability of the power grid to distributed energy, and the power electronic transformer can play an increasingly important role in the micro-grid.
The power electronic transformer is a novel transformer which realizes power conversion and energy transfer through power electronic technology. The transformer is a novel transformer which combines a power electronic conversion technology with a high-frequency electric energy conversion technology based on the electromagnetic induction principle, and can convert one power characteristic into another power characteristic. The power characteristics refer to the frequency, assignment, phase and the like of the voltage or the current. In recent years, the national university of science and technology in China and the institute of electrician in the Chinese academy of sciences have proposed the topology of a novel power electronic transformer one after another, and the defects of large volume and weight, poor electric energy quality and the like of the traditional transformer are overcome, but the defects of low operation efficiency and poor reliability of PET still exist.
The traditional power grid is often in a dynamic balance state of power generation and load during operation, namely a state of immediate generation and immediate use, but with the development of economy and society, the control and management of the power grid are more and more difficult to achieve real-time balance of power generation and power utilization according to the power supply requirements of users. This results in a low overall system efficiency and a low utilization of the power resources.
Disclosure of Invention
The invention aims to provide a PET topological structure and a coordination control method of the PET topological structure and an energy storage system, which realize the functions of PET input stage unit power factor operation, constant output stage voltage, voltage depth drop coping and light storage complementation, and can flexibly control the voltage, the current, the power and the like of the primary side and the secondary side of a transformer.
In order to achieve the purpose, the invention provides the following scheme:
a PET topological structure comprises an input stage structure, a middle isolation stage structure and an output stage structure which are sequentially connected, wherein the input stage structure comprises three input lines, each input line comprises two symmetrical sub-input lines, and the sub-input lines comprise an input module and an inductor which are mutually connected; the middle isolation level structure comprises three H-shaped bridge circuits and capacitors, the capacitors are connected in parallel to the output ends of the three H-shaped bridge circuits, each H-shaped bridge circuit comprises two isolation level modules and a coil, and each isolation level module comprises four isolation level sub-modules; the output stage structure comprises three output lines, each output line comprises a first output module, a second output module and a diode, and the second output module and the diode are connected in parallel and then connected with the first output module.
Optionally, each of the input modules includes two power field effect transistors, two diodes, and a capacitor, wherein a source of a first one of the power field effect transistors is connected to a drain of a second one of the power field effect transistors, the diodes are connected in parallel between the source and the drain of the power field effect transistors, and the capacitor is connected in parallel between the drain of the first one of the power field effect transistors and the source of the second one of the power field effect transistors.
Optionally, each of the sub-modules includes a power field effect transistor and a diode, and the diode is connected in parallel between a source and a drain of the power field effect transistor.
Optionally, the first output module and the second output module have the same composition structure, and each of the first output module and the second output module includes an insulated gate bipolar transistor and a diode, and the diode is connected in parallel between an emitter and a collector of the insulated gate bipolar transistor.
Optionally, a capacitor is connected in parallel between the input stage structure and the intermediate isolation stage structure, and a capacitor is connected in parallel between the intermediate isolation stage structure and the output stage structure.
Optionally, the input stage structure is controlled by a hysteresis current control method, the intermediate isolation stage structure is controlled by a PWM modulation method, and the output stage structure is controlled by an SPWM modulation method.
A PET topological structure and energy storage system coordination control method comprises the following steps:
when the voltage of the power grid is normal, the PET topological structure provides voltage for a low-voltage direct-current bus of the energy storage system;
when the voltage of a power grid is disturbed, the alternating current bus of the PET topological structure loses voltage, the power grid and a load circuit connected with the PET topological structure are cut off, an energy storage converter in an energy storage system supplies voltage to the alternating current bus of the PET topological structure in a control mode of alternating current voltage, and the alternating current bus of the PET topological structure is regulated to a normal value and then is reconnected with the circuit of the PET topological structure, the power grid and the load circuit.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention designs a modularized multi-level power electronic transformer and provides a coordination control method of an energy storage system and the power electronic transformer, considering that the PET input stage unit power factor operation, the output stage voltage constant, the functions of coping with voltage deep drop and light storage complementation are realized, and the factors of improving the power conversion efficiency, the electric energy quality and the like are further improved. By using the method, the energy storage system can be reasonably adjusted, the state of charge is ensured to work in a normal range, and the fluctuation of the frequency of the microgrid can be inhibited by utilizing the rapid charge and discharge capacity of the energy storage system.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a diagram of the PET topology of the present invention;
FIG. 2 is a schematic diagram of sub-modules in an input stage architecture, an intermediate isolation stage architecture, and an output stage architecture;
FIG. 3 is a schematic structural diagram of the entire microgrid designed according to the present invention;
fig. 4 is a control flow chart of the entire microgrid.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. 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 invention.
The invention aims to provide a PET topological structure and a coordination control method of the PET topological structure and an energy storage system, which solve the problems of how to realize the operation of PET input stage unit power factors, constant output stage voltage, the functions of coping with voltage depth drop and light storage complementation, and flexibly control the voltage, the current and the power of a primary side and a secondary side of a transformer.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
FIG. 1 is a diagram of the PET topology of the present invention. As shown in fig. 1, a PET topology includes an input stage structure, an intermediate isolation stage structure, and an output stage structure, which are connected in sequence. The input stage structure of the PET topological structure adopts a three-phase modular multilevel converter, the intermediate isolation stage structure adopts an H-shaped bridge circuit, and the output stage structure adopts a midpoint clamping type three-level inverter.
Fig. 2 is a schematic diagram of sub-modules in an input stage structure, an intermediate isolation stage structure, and an output stage structure. As shown in fig. 1 and 2, the input stage structure includes three input lines, each of which includes two symmetrical sub-input lines, and the sub-input lines include an input module and an inductor connected to each other; each input module comprises two power field effect transistors, two diodes and a capacitor, wherein the source of the first power field effect transistor is connected with the drain of the second power field effect transistor, the diodes are connected between the source and the drain of the power field effect transistors in parallel, and the capacitor is connected between the drain of the first power field effect transistor and the source of the second power field effect transistor in parallel. And a capacitor is connected in parallel between the input stage structure and the intermediate isolation stage structure. The input end a of the three-phase modular multilevel converter is connected with an alternating current power grid, and the output b is connected to the input end d of the H-type bridge circuit. Capacitance c between input stage and intermediate isolation stage1The buffer function of stabilizing voltage is achieved, and the reliability of PET is improved. The operation efficiency of the three-phase modular multilevel converter is higher than that of a single-level or high-low level converter. The submodule of the PET input stage, i.e. the input module (denoted SM1 in the figure), consists of two power field effect transistors connected in series, the gates of whichThe electrode (G) is connected to the ASIC drive circuit, and the two wires led out from the other electrode are connected as shown in FIG. 2.
The middle isolation level structure comprises three H-shaped bridge circuits and capacitors, the capacitors are connected in parallel to the output ends of the three H-shaped bridge circuits, each H-shaped bridge circuit comprises two isolation level modules and a coil, and each isolation level module comprises four isolation level sub-modules; each isolation level submodule comprises a power field effect transistor and a diode, and the diode is connected between a source electrode and a drain electrode of the power field effect transistor in parallel. The input end d of the H-type bridge circuit is connected with the output end b of the three-phase modular multilevel converter, the output end e of the H-type bridge circuit is connected with the input end f of the neutral point embedded type three-level inverter, the effect of isolating the input side and the output side and buffering partial loss is achieved, and the capacitor c is achieved1And c2The voltage is equalized, the short circuit condition can not occur when the device is conducted, and the overcurrent protection function is achieved, so that the risk of short circuit of the PET is reduced, and the power supply reliability of the intermediate isolation level of the PET is improved; capacitance c in intermediate isolation stage2And a capacitor c between the intermediate isolation stage and the output stage3The sub-modules of the middle isolation stage, namely the sub-modules of the isolation stage (indicated by SM2 in figure 1), are formed by connecting a diode in parallel with a power field effect transistor, and the grid (G) of the power field effect transistor is connected with an application-specific integrated drive circuit.
The output stage structure comprises three output lines, each output line comprises a first output module, a second output module and a diode, and the second output module and the diode are connected in parallel and then connected with the first output module. The first output module and the second output module have the same composition structure, and both comprise an insulated gate bipolar transistor and a diode, and the diode is connected in parallel between an emitter and a collector of the insulated gate bipolar transistor. The output stage structure of the invention adopts a three-level inverter, the input end f of the three-level inverter is connected with the output end e of the H-type bridge circuit, the output end i of the three-level inverter is connected with a load, the three-level inverter is a power device with output phase voltages having three levels (high level v/2, zero level 0 and low level-v/2), the control precision is higher than that of a single level and high and low levels, 3 switching state conversions are provided, the problem of series connection of two power switching devices is solved, the output waveform is also obviously improved, meanwhile, the switching loss and frequency can be reduced, the harmonic wave of the output voltage is less, the withstand voltage of the power switching devices is increased, and the operation efficiency and reliability of the PET output side are improved. The first output module and the second output module (denoted by SM3 in fig. 1), which are the submodules of the output stage, are formed by connecting an Insulated Gate Bipolar Transistor (IGBT) with a diode in parallel, and the gate stage G of the IGBT is connected with an application specific integrated drive circuit.
The input stage structure is controlled by adopting a hysteresis current control method. Furthermore, the input stage structure of the invention adopts hysteresis current control in a direct current control mode, namely, a tracking type PWM control technology is adopted to carry out feedback control on current waveform, the current value is detected at the output end of the PET input stage and compared with the preset current value, if the detected current value is smaller than the preset current value, the power MOSFET of the upper bridge arm in the SM is closed, the power MOSFET of the lower bridge arm is opened, and the output current is improved; if the detected current value is larger than the preset current value, the power MOSFET of the upper bridge arm is opened (SM1), the power MOSFET of the lower bridge arm is closed, and the power MOSFET is controlled to be switched on and off by a discrete element driving circuit (such as a dual-power optical coupling isolation direct driving circuit). The hysteresis current control method can reduce output current, so that the actual current value can quickly follow a preset value, and the current can be directly regulated. The method has the advantages of high current response speed and good robustness to disturbance phenomena.
Compared with a high-low level topological structure, the three-level topological structure adopted by the invention has the most obvious advantage that the voltage value born by each power switch device is 1/2 of the original direct-current voltage, and the three-level topological structure is very suitable for high-voltage large-capacity occasions. The input stage structure, the intermediate isolation stage structure and the output stage structure are designed to improve the operating efficiency and reliability of the PET, and the characteristics of high voltage resistance, switching loss and frequency reduction of the PET, unit power factor operation of the input stage of the power electronic transformer and the like are realized.
The intermediate isolation level structure is controlled by a PWM (pulse-width modulation) method. Furthermore, the intermediate isolation stage structure of the invention needs the synchronous work of the power devices of the primary side and the secondary side of the high-frequency isolation transformer, the switching function of the power device is a square wave with the duty ratio of 50 percent (namely the proportion of the time of the pulse signal to the time of the periodic signal is 50 percent), and the high-frequency voltage and frequency can be controlled by the PWM modulation technology. Among them, the power MOSFET control method in (SM2) of the intermediate isolation stage is the same as (SM 1).
The output stage structure is controlled by adopting an SPWM modulation method. Further, the output stage structure adopts an SPWM modulation method, and aims to prevent harmonic wave increase, voltage waveform distortion and loss of a switching power device. The on-off of each power switch element of the PET output stage, namely the mid-point clamping type inverter circuit is controlled by a PWM waveform equivalent to a sine wave, the sine wave is used as a signal expected to be output, an actual output waveform is used as a carrier wave, and the waveform of the carrier wave is gradually close to the sine wave by modulating the carrier wave. The output voltage and amplitude of the midpoint clamping type inverter circuit can be changed by changing the frequency and amplitude of the desired output signal. Wherein, the IGBT in (SM3) is controlled by the integrated driving circuit (EXB841 driver) to turn on and off.
The invention provides a control method of input stage, intermediate isolation stage and output stage of PET in actual operation and a control strategy of coordination and cooperation of an energy storage system and the PET, so that the technical problems of light storage complementation and prevention of voltage deep drop can be realized under the micro-grid environment of the PET topological structure designed by the invention.
The invention also provides a PET topological structure and energy storage system coordination control method, which comprises the following steps:
step 101: when the voltage of the power grid is normal, the PET topological structure provides voltage for a low-voltage direct-current bus of the energy storage system.
Step 102: when the voltage of a power grid is disturbed, the alternating current bus of the PET topological structure loses voltage, the power grid and a load circuit connected with the PET topological structure are cut off, an energy storage converter in an energy storage system supplies voltage to the alternating current bus of the PET topological structure in a control mode of alternating current voltage, and the alternating current bus of the PET topological structure is regulated to a normal value and then is reconnected with the circuit of the PET topological structure, the power grid and the load circuit.
When the voltage of a power grid is normal, the voltage of a low-voltage direct-current bus of the energy storage system is supported by PET, the energy storage system adopts a control mode of self-adaptive charge and discharge power, actual charge and discharge power is used as a feedback signal to be compared with preset charge and discharge power, so that the power released and absorbed by the energy storage system can work on a maximum power point as much as possible, the working voltage value of the battery pack is periodically disturbed according to the p/v characteristic of the battery pack in the energy storage system, the change of the power before and after disturbance is compared, if the power value is increased, the disturbance direction is correct, if the power is reduced, the disturbance direction is wrong and the disturbance direction is converted, and the output power of the battery pack is close to. The periodic disturbance is controlled by a microprocessor C8051F 330; when the power grid side is disturbed to cause voltage depth drop, the PET alternating current bus is subjected to voltage loss, so that normal work of a load is influenced, at the moment, a circuit for connecting the PET with the power grid and the load needs to be cut off, an energy storage converter in an energy storage system supplies voltage to the PET alternating current bus voltage in an alternating voltage control mode (voltage droop control), and the circuit for connecting the PET with the power grid and the load is reconnected after the PET alternating current bus voltage is adjusted to a normal value. The two controls are switched smoothly, and the functions of light storage complementation and voltage deep drop response are realized through coordination control, so that the utilization rate of new energy and the power supply reliability are improved. Fig. 3 is a schematic structural diagram of the entire microgrid designed by the invention. Fig. 4 is a control flow chart of the entire microgrid.
According to the PET topological structure, the specific control method of the PET topological structure and the coordination control method of the PET topological structure and the energy storage system, a modeling method can be utilized to model the whole microgrid. Based on a microgrid model, the obtained model is simulated, and the light storage complementation and voltage drop prevention functions of the power electronic transformer are tested. In the light storage complementary performance experiment, comparing and analyzing the waveform when the energy storage system coordination control is not applied and the waveform when the energy storage system coordination control is applied; in the experiment of the performance of stabilizing the voltage drop, 3 parts of the PET are controlled to obtain a simulation waveform, and then the simulation waveform is analyzed, and finally the effectiveness of the method is verified.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to assist understanding of the system and its core concepts; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (7)
1. A PET topological structure is characterized by comprising an input stage structure, a middle isolation stage structure and an output stage structure which are sequentially connected, wherein the input stage structure comprises three input lines, each input line comprises two symmetrical sub-input lines, and the sub-input lines comprise an input module and an inductor which are mutually connected; the middle isolation level structure comprises three H-shaped bridge circuits and capacitors, the capacitors are connected in parallel to the output ends of the three H-shaped bridge circuits, each H-shaped bridge circuit comprises two isolation level modules and a coil, and each isolation level module comprises four isolation level sub-modules; the output stage structure comprises three output lines, each output line comprises a first output module, a second output module and a diode, and the second output module and the diode are connected in parallel and then connected with the first output module.
2. The PET topology of claim 1, wherein each of the input modules includes two power field effect transistors, two diodes, and a capacitor, a first of the power field effect transistors having a source connected to a drain of a second of the power field effect transistors, the diodes connected in parallel between the source and drain of the power field effect transistors, and the capacitor connected in parallel between the drain of the first of the power field effect transistors and the source of the second of the power field effect transistors.
3. The PET topology of claim 1, wherein each of the isolation stage submodules comprises a power field effect transistor and a diode, and one of the diodes is connected in parallel between a source and a drain of the power field effect transistor.
4. The PET topology of claim 1, wherein the first output module and the second output module are identical in composition, and each of the first output module and the second output module comprises an insulated gate bipolar transistor and a diode connected in parallel between an emitter and a collector of the insulated gate bipolar transistor.
5. The PET topology of claim 1, wherein a capacitance is connected in parallel between the input stage structure and the intermediate isolation stage structure, and a capacitance is connected in parallel between the intermediate isolation stage structure and the output stage structure.
6. The PET topology of claim 1, wherein the input stage structure is controlled using a hysteresis current control method, the intermediate isolation stage structure is controlled using a PWM modulation method, and the output stage structure is controlled using a SPWM modulation method.
7. The PET topological structure and energy storage system coordinated control method based on any one of claims 1-6, characterized by comprising the following steps:
when the voltage of the power grid is normal, the PET topological structure provides voltage for a low-voltage direct-current bus of the energy storage system;
when the voltage of a power grid is disturbed, the alternating current bus of the PET topological structure loses voltage, the power grid and a load circuit connected with the PET topological structure are cut off, an energy storage converter in an energy storage system supplies voltage to the alternating current bus of the PET topological structure in a control mode of alternating current voltage, and the alternating current bus of the PET topological structure is regulated to a normal value and then is reconnected with the circuit of the PET topological structure, the power grid and the load circuit.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000125553A (en) * | 1998-10-14 | 2000-04-28 | Sony Corp | Voltage resonance type switching power supply circuit |
| CN110868082A (en) * | 2019-11-29 | 2020-03-06 | 上海电力大学 | MMC-PET control method for supplying power to passive network based on power grid voltage fault |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000125553A (en) * | 1998-10-14 | 2000-04-28 | Sony Corp | Voltage resonance type switching power supply circuit |
| CN110868082A (en) * | 2019-11-29 | 2020-03-06 | 上海电力大学 | MMC-PET control method for supplying power to passive network based on power grid voltage fault |
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