CN113922691A - KVCS alternating current-direct current conversion energy storage converter - Google Patents
KVCS alternating current-direct current conversion energy storage converter Download PDFInfo
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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
- H02M7/53871—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 with automatic control of output voltage or current
- H02M7/53875—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 with automatic control of output voltage or current with analogue control of three-phase output
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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
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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
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
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Abstract
The invention discloses a KVCS alternating current-direct current conversion energy storage converter which comprises a bidirectional inverter circuit, wherein the direct current side of the bidirectional inverter circuit is electrically connected with a direct current bus of an energy storage system, and the alternating current side of the bidirectional inverter circuit is connected with an alternating current bus of the energy storage system; a control circuit comprising a microprocessor for data processing; the microprocessor is electrically connected with the bidirectional inverter circuit through the PWM driving control circuit; the input end of the signal acquisition circuit is electrically connected with the bidirectional inverter circuit; the output end of the signal acquisition circuit is connected to the microprocessor through the A/D conversion circuit; the KVCS AC/DC conversion energy storage converter disclosed by the invention has the advantages that the product becomes an AC/DC conversion energy storage converter in an energy storage system through technologies such as signal acquisition, signal processing, logic judgment, control algorithm and the like; the energy conversion and intelligent control of the energy storage system are met, and the power supply reliability and flexibility of the intelligent energy storage system are improved.
Description
Technical Field
The invention relates to a power electronic device with an alternating current-direct current conversion and conversion function, in particular to a KVCS alternating current-direct current conversion energy storage converter, and belongs to the technical field of energy storage control connection.
Background
The construction of a perfect intelligent energy storage system is a necessary choice for realizing carbon peak carbon neutralization and striving to construct a clean, low-carbon, safe and efficient energy system; the novel energy storage is the important component and the basic support that support the novel electric power system who uses the new forms of energy as the main part, and novel energy storage can show reinforcing electric power system's new forms of energy ability of consuming, promotes energy electric power system's stability, improves energy comprehensive utilization efficiency and safety guarantee ability, and green transformation, reply extreme incident, guarantee energy safety, promotion energy high quality development, support reply climate change target realization to the promotion energy have the significance.
The converter is applied to an energy conversion end of an alternating current bus and a direct current bus in the energy storage system; the conventional converter technology has the following defects: 1) energy of a traditional converter flows in a unidirectional mode, and only the mode that alternating current flows to direct current, or only the mode that direct current flows to alternating current, and bidirectional flow of the energy cannot be realized; 2) the traditional converter can only realize the setting of active power or reactive power; the P-Q decoupling function (four quadrant operation capability) cannot be realized; 3) the traditional converter can only be operated in a grid-connected mode or an off-grid mode, and one device cannot be operated in different states according to needs. Therefore, in order to solve the above problems, it is necessary to design a KVCS ac/dc conversion energy storage converter.
Disclosure of Invention
In order to solve the problems, the invention provides a KVCS alternating current-direct current conversion energy storage converter which can realize bidirectional alternating current-direct current energy conversion according to a set mode.
The invention relates to a KVCS alternating current-direct current conversion energy storage converter which is used for realizing bidirectional energy conversion between a direct current bus and an alternating current bus, can operate in an off-grid mode and a grid-connected mode and comprises
The direct current side of the bidirectional inverter circuit is electrically connected with a direct current bus of the energy storage system, and the alternating current side of the bidirectional inverter circuit is connected with an alternating current bus of the energy storage system; the bidirectional inverter circuit comprises a three-phase bridge inverter circuit; the filter circuit is used for converting the high-frequency voltage signal into a sine wave with harmonic wave meeting the requirement so as to meet the quality requirement of the national public power grid and is electrically connected with the three-phase bridge inverter circuit; the direct current main circuit is used for realizing switching on and off, protection and filtering of the direct current loop and is electrically connected with the three-phase bridge type inverter circuit; the alternating current main circuit is used for realizing switching on and off, protection and filtering of the alternating current loop and is electrically connected with the filter circuit; the direct current main circuit is connected with a direct current bus; the alternating current main circuit is connected with an alternating current bus; the bidirectional inverter circuit is an energy flow main channel of a KVCS alternating current-direct current conversion energy storage converter; the three-phase bridge type inverter circuit is a main core part of the bidirectional inverter circuit, the modulation ratio of the three-phase bridge type inverter circuit is the modulation ratio of the bidirectional inverter circuit, the three-phase bridge type inverter circuit is in an inverter state, the bidirectional inverter circuit is in a rectification state, and the bidirectional inverter circuit is in a rectification state; the three-phase bridge type inverter circuit adopts a forced air cooling heat dissipation mode, so that good heat dissipation can be ensured, and the three-phase bridge type inverter circuit can reliably, stably and efficiently work;
the control circuit is used for calculating the signals sent by the signal acquisition circuit to obtain processing result data of the target parameters, comparing the processing result data with the given values of the corresponding target parameters and outputting control signals for driving the PWM driving control circuit to work as required; the control circuit comprises a microprocessor for data processing; the microprocessor is electrically connected with the bidirectional inverter circuit through the PWM driving control circuit, is connected with the bidirectional inverter circuit through the PWM driving control circuit and outputs PWM driving control signals to the bidirectional inverter circuit so as to work in an active current transformation state, thereby realizing PWM control; the control circuit also comprises a communication interface circuit which is used for communicating with superior control equipment and receiving and transmitting signals with an HMI touch screen (human-computer interaction interface); and an input/output interface circuit for receiving digital signals and analog signals; the switching value interface circuit is used for receiving a hard contact signal of a BMS battery management system when a fault occurs, so that effective judgment is carried out and the operation of the system is protected; the communication interface circuit, the input/output interface circuit and the switching value interface circuit are respectively in communication connection with the microprocessor; the communication interface circuit is in bidirectional communication connection with the microprocessor;
the signal acquisition circuit is used for realizing high-precision detection, signal processing and fault signal detection of direct current end voltage, current, alternating current end voltage and current signals; the input end of the signal acquisition circuit is electrically connected with the bidirectional inverter circuit; the output end of the signal acquisition circuit is connected to the microprocessor through the A/D conversion circuit; the signal acquisition circuit comprises a signal acquisition module for acquiring digital signals and analog signals and a signal conditioning module for conditioning the acquired signals and electrically connected with the signal acquisition module;
the secondary auxiliary power supply is electrically connected with the control circuit and adopts alternating current and direct current hybrid power supply; the secondary auxiliary power supply can be a direct current power supply or an alternating current power supply, and has a wide range, wherein the direct current power supply is 200-264V/ac, and the alternating current power supply is 176-264V/ac; the alternating current-direct current double-circuit power supply effectively solves the problem of secondary power supply in communication debugging of equipment in the earlier stage.
The KVCS AC-DC conversion energy storage converter has the following operation mode:
when the energy storage control system is in an off-grid operation working state, the microprocessor executes a V-f control mode, provides a standard alternating current voltage source for an alternating current bus load by connecting a direct current bus of a bidirectional inverter circuit of the KVCS alternating current-direct current conversion energy storage converter, and provides power support according to the output of the alternating current bus and load change;
when V-f is controlled, the power frequency sine wave is discretized to obtain sine wave data of a plurality of discrete time points in a power frequency period, and a sine table array sin [ n ] composed of the sine wave data is formed]Forming corresponding rectangular pulse sequence according to the sine table array to replace power frequency sine wave required by V-f control as modulation wave, and obtaining the modulation wave through the relation between switching frequency and power frequencySwitch point number n corresponding to one power frequency cycle sine tablefThe total number n and n of array elements of the sine tablefSelecting rectangular pulses for modulation according to the moving step length of a pointer of the sine table when the power frequency sine wave is realized;
when the energy storage control system is in a grid-connected operation working state, the microprocessor quickly tracks power change, and controls the change of a direct current bus of the KVCS alternating current-direct current conversion energy storage converter to meet the load power shortage of the direct current bus; when the grid-connected operation is in a working state, the KVCS alternating current-direct current conversion energy storage converter executes a P-Q decoupling control mode, and the active power and the reactive power are controlled according to a scheduling instruction;
in P-Q decoupling control, power frequency sine waves are discretized to obtain sine wave data of a plurality of discrete time points in a power frequency period, and a sine table array sin [ m ] composed of the sine wave data is formed]Forming a corresponding rectangular pulse sequence according to the sine table array to replace a power frequency sine wave required by a voltage feedforward part in P-Q decoupling control as a modulation wave, and obtaining the number m of switching points corresponding to a power frequency period sine table through the relationship between the switching frequency and the power frequencyfThe total number of array elements m and m of the sine tablefThe multiple of (2) is that rectangular pulses used for modulation are selected for the step length of the movement of a sine table pointer when the power frequency sine wave is realized.
Furthermore, the microprocessor adopts an industrial grade DSP chip TMS320F28335 PGFA; the main functions which can be realized are as follows: the KVCS AC-DC conversion energy storage converter has the functions of supporting, controlling, calculating numerical values, judging logics, judging circuit faults, protecting and communicating bidirectionally; the communication function is mainly realized by means of a corresponding interface circuit connected with the DSP in bidirectional communication, and the control function of the KVCS alternating current-direct current conversion energy storage converter can be realized.
Further, the PWM driving control circuit is electrically connected with the three-phase bridge type inverter circuit; the multi-path PWM output is respectively connected to the control end of each IGBT module; the PWM driving control circuit sends out a PWM signal, frequency or duty ratio information carried by the PWM signal is calculated by the DSP, and then control signal amplification is carried out, so that the control signal output by the PWM driving control circuit can drive the IGBT module; the PWM driving control circuit adopts a special driving circuit, so that the IGBT tube switch can be in an optimal state, and meanwhile, the PWM driving control circuit also comprises a perfect protection function (the IGBT module detects abnormal states such as overcurrent, driving undervoltage, overtemperature, faults and the like), and when the abnormality is detected, a fault signal can effectively turn off the IGBT module.
Still further, the three-phase bridge inverter circuit is composed of a full-bridge circuit; each bridge arm of the full-bridge circuit is formed by reversely connecting an IGBT module and a diode in parallel; the reverse diode and the IGBT (British flying FF450R12ME4) are packaged together, and the reverse diode is used for preventing breakdown by high reverse voltage and playing a role in protection; the on and off of the IGBT tube realizes the alternating current-direct current conversion and the bidirectional flow of energy.
Further, the filter circuit is composed of an LCL filter.
Further, the direct current main circuit is composed of a direct current breaker, a direct current arrester, a direct current contactor, a direct current filter, a direct current fuse, a pre-charging circuit, a discharging circuit, a bus capacitor and an IGBT absorption capacitor.
Furthermore, the alternating current main circuit is composed of an alternating current breaker, an alternating current lightning arrester, an alternating current contactor, an alternating current filter, an alternating current fuse and a pre-charging circuit.
Compared with the prior art, the KVCS AC/DC conversion energy storage converter disclosed by the invention has the advantages that the product becomes the AC/DC conversion energy storage converter in an energy storage system through the technologies of signal acquisition, signal processing, logic judgment, control algorithm and the like; the energy conversion and intelligent control of the energy storage system are met, the power supply reliability and flexibility of the intelligent energy storage system are improved, and sustainable guarantee is provided for the development of a new energy power grid.
Drawings
Fig. 1 is a schematic view of the overall structure of the present invention.
Fig. 2 is a schematic diagram of a bidirectional inverter circuit topology according to the present invention.
Fig. 3 is a schematic diagram of the three-phase bridge inverter circuit of the present invention operating in an active inversion state.
Fig. 4 is a schematic diagram of the three-phase bridge inverter circuit of the present invention operating in an active rectification state.
Figure 5 is a four quadrant operating schematic of the present invention.
FIG. 6 is a schematic block diagram of the V-f control principle of the present invention.
FIG. 7 is a schematic block diagram of the P-Q decoupling control principle of the present invention.
The components in the drawings are labeled as: the intelligent control system comprises a 1-bidirectional inverter circuit, a 11-three-phase bridge inverter circuit, a 12-filter circuit, a 13-direct current main circuit, a 14-alternating current main circuit, a 2-direct current bus, a 3-alternating current bus, a 4-control circuit, a 5-signal acquisition circuit, a 6-secondary auxiliary power supply, a 7-man-machine interaction interface, a K1-direct current breaker, an M1-direct current arrester, an N1-direct current contactor, an H1-direct current filter, a K2-alternating current breaker, an M2-alternating current arrester, an N2-alternating current contactor and an H2-alternating current filter.
Detailed Description
The KVCS ac-dc conversion energy storage converter shown in fig. 1 and 2 is used for realizing bidirectional energy conversion between a dc bus and an ac bus, and can operate in an off-grid mode and a grid-connected mode, and includes
The energy storage system comprises a bidirectional inverter circuit 1, wherein the direct current side of the bidirectional inverter circuit 1 is electrically connected with a direct current bus 2 of the energy storage system, and the alternating current side of the bidirectional inverter circuit is connected with an alternating current bus 3 of the energy storage system; the bidirectional inverter circuit 1 comprises a three-phase bridge inverter circuit 11; the filter circuit 12 is used for converting a high-frequency voltage signal into a sine wave with harmonic wave meeting the requirement so as to meet the quality requirement of a national public power grid and is electrically connected with the three-phase bridge inverter circuit; the direct current main circuit 13 is used for realizing switching on and off, protection and filtering of the direct current loop and is electrically connected with the three-phase bridge type inverter circuit; the alternating current main circuit 14 is used for realizing switching on and off, protection and filtering of the alternating current loop and is electrically connected with the filter circuit; the direct current main circuit is connected with a direct current bus; the alternating current main circuit is connected with an alternating current bus; the bidirectional inverter circuit is an energy flow main channel of a KVCS alternating current-direct current conversion energy storage converter; the three-phase bridge type inverter circuit is a main core part of the bidirectional inverter circuit, the modulation ratio of the three-phase bridge type inverter circuit is the modulation ratio of the bidirectional inverter circuit, the three-phase bridge type inverter circuit is in an inverter state, the bidirectional inverter circuit is in a rectification state, and the bidirectional inverter circuit is in a rectification state; the three-phase bridge type inverter circuit adopts a forced air cooling heat dissipation mode, so that good heat dissipation can be ensured, and the three-phase bridge type inverter circuit can reliably, stably and efficiently work;
the control circuit 4 is used for calculating the signals sent by the signal acquisition circuit to obtain processing result data of the target parameters, comparing the processing result data with the given values of the corresponding target parameters and outputting control signals for driving the PWM driving control circuit to work as required; the control circuit 4 comprises a microprocessor for data processing; the microprocessor is electrically connected with the bidirectional inverter circuit through the PWM driving control circuit, is connected with the bidirectional inverter circuit through the PWM driving control circuit and outputs PWM driving control signals to the bidirectional inverter circuit so as to work in an active current transformation state, thereby realizing PWM control; the control circuit also comprises a communication interface circuit which is used for communicating with superior control equipment and receiving and transmitting signals with an HMI touch screen (a human-computer interaction interface 7); and an input/output interface circuit for receiving digital signals and analog signals; the switching value interface circuit is used for receiving a hard contact signal of a BMS battery management system when a fault occurs, so that effective judgment is carried out and the operation of the system is protected; the communication interface circuit, the input/output interface circuit and the switching value interface circuit are respectively in communication connection with the microprocessor; the communication interface circuit is in bidirectional communication connection with the microprocessor;
the signal acquisition circuit 5 is used for realizing high-precision detection of direct current end voltage, current, alternating current end voltage and current signals, signal processing and fault signal detection; the input end of the signal acquisition circuit 5 is electrically connected with the bidirectional inverter circuit 1; the output end of the signal acquisition circuit 5 is connected to the microprocessor through an A/D conversion circuit; the signal acquisition circuit 5 comprises a signal acquisition module for acquiring digital signals and analog signals, and a signal conditioning module for conditioning the acquired signals and electrically connected with the signal acquisition module;
the secondary auxiliary power supply 6 is electrically connected with the control circuit 4, and the secondary auxiliary power supply adopts alternating current and direct current hybrid power supply; the secondary auxiliary power supply can be a direct current power supply or an alternating current power supply, and has a wide range, wherein the direct current power supply is 200-264V/ac, and the alternating current power supply is 176-264V/ac; the alternating current-direct current double-circuit power supply effectively solves the problem of secondary power supply in communication debugging of equipment in the earlier stage.
The microprocessor adopts an industrial grade DSP chip TMS320F28335 PGFA; the main functions which can be realized are as follows: the KVCS AC-DC conversion energy storage converter has the functions of supporting, controlling, calculating numerical values, judging logics, judging circuit faults, protecting and communicating bidirectionally; the communication function is mainly realized by means of a corresponding interface circuit connected with the DSP in bidirectional communication, and the control function of the KVCS alternating current-direct current conversion energy storage converter can be realized.
The PWM driving control circuit is electrically connected with the three-phase bridge inverter circuit 11; the multi-path PWM output is respectively connected to the control end of each IGBT module; the PWM driving control circuit sends out a PWM signal, frequency or duty ratio information carried by the PWM signal is calculated by the DSP, and then control signal amplification is carried out, so that the control signal output by the PWM driving control circuit can drive the IGBT module; the PWM driving control circuit adopts a special driving circuit, so that the IGBT tube switch can be in an optimal state, and meanwhile, the PWM driving control circuit also comprises a perfect protection function (the IGBT module detects abnormal states such as overcurrent, driving undervoltage, overtemperature, faults and the like), and when the abnormality is detected, a fault signal can effectively turn off the IGBT module.
The three-phase bridge inverter circuit 11 is composed of a full-bridge circuit; each bridge arm of the full-bridge circuit is formed by reversely connecting an IGBT module and a diode in parallel; the reverse diode and the IGBT (British flying FF450R12ME4) are packaged together, and the reverse diode is used for preventing breakdown by high reverse voltage and playing a role in protection; the on and off of the IGBT tube realizes the alternating current-direct current conversion and the bidirectional flow of energy.
The filter circuit 12 is constituted by an LCL filter.
The direct current main circuit 13 is composed of a direct current breaker K1, a direct current arrester M1, a direct current contactor N1, a direct current filter H1, a direct current fuse, a pre-charging circuit, a discharging circuit, a bus capacitor and an IGBT absorption capacitor.
The alternating current main circuit 14 is composed of an alternating current breaker K2, an alternating current arrester M2, an alternating current contactor N2, an alternating current filter H2, an alternating current fuse and a pre-charging circuit.
The invention relates to a KVCS alternating current-direct current conversion energy storage converter, which has the following working principle of a three-phase bridge type inverter circuit:
as shown in fig. 3, when the three-phase bridge inverter circuit works in an active inversion state, the dc bus releases electric energy to the ac bus, and the three-phase bridge inverter circuit is controlled to convert the energy from dc to ac, thereby obtaining high-quality three-phase ac (UA/UB/UC); when the KVCS AC-DC conversion energy storage converter is in an off-grid operation working state, the part of electric energy can be supplied to a load of an AC bus; when the KVCS alternating current-direct current conversion energy storage converter is in a grid-connected operation working state and when the inversion power is larger than the load of the alternating current bus, the part of electric energy can not only supply the load of the alternating current bus, but also flow to a public power grid;
as shown in fig. 4, when the three-phase bridge inverter circuit works in an active rectification state, the ac bus releases electric energy to the dc bus, and the three-phase bridge inverter circuit is controlled to convert the electric energy from ac to dc, so as to obtain stable dc electric energy to supply to the dc bus electric equipment;
as shown in fig. 5, by adjusting the phase angle between the output voltage and the current of the three-phase bridge inverter circuit, the four-quadrant operation of the KVCS ac-dc conversion energy storage converter can be realized;
the KVCS AC-DC conversion energy storage converter has the following operation modes:
firstly, in an off-grid mode,
when the KVCS AC-DC conversion energy storage converter is in an off-grid operation working state, the microprocessor executes a V-f control mode, and the V-f control needs a power frequency sine wave as a modulation wave, wherein the modulation wave forming method comprises the following steps: discretizing power frequency sine wave (preferably power frequency sine wave with amplitude of 1) to obtain sine wave data of a plurality of (n) discrete time points in a power frequency period to form a positive sine wave composed of the sine wave dataSine array sin [ n ] of chord meter]Forming a rectangular pulse sequence corresponding to the power frequency sine wave data at each discrete time point under the discrete time point according to the sine table array instead of a power frequency sine wave required by V-f control as a modulation wave, and obtaining the number n of switching points corresponding to a power frequency cycle sine table through the relationship between the switching frequency and the power frequencyf(i.e., a value of switching frequency in a power frequency cycle), n and n in total number of array elements of the sine tablefThe multiples of the square pulse are that rectangular pulses for modulation are selected for the step length of the movement of a sine table pointer when the power frequency sine wave is realized, so that a plurality of matrix pulses (matrix pulse subsequences) corresponding to the time points of the switching signals are selected from the matrix pulse sequences, and the matrix pulses are used as modulation waves to be compared with the switching signals and to be modulated and output to enable the modulation waves to accord with the power frequency sine wave (including the same phase); the current array pointer sin _ pointer in the sine table array changes according to a certain step length to realize power frequency modulation waves, and the phase locking angle theta is updated by using the angle corresponding to the sin _ pointer;
as shown in FIG. 6, for the analysis of phase A, the period of the triangular carrier corresponds to the period count value CounprThe on-pulse time of phase A corresponds to the pulse count CouncmpAThe number of points of the phase A in the sine table array is nAHas CouncmpA＝0.5×Counpr(1+ma sin[nA]) The B-phase modulation wave and the C-phase modulation wave can also be obtained by carrying out corresponding point shifting operation from the sine table array;
secondly, in a grid-connected mode,
when the KVCS AC/DC conversion energy storage converter is in a grid-connected operation working state, the microprocessor quickly tracks power change, controls the change of a DC bus of the KVCS AC/DC conversion energy storage converter at the same time, and meets the shortage of the load power of the DC bus; during grid-connected work, the KVCS alternating current-direct current conversion energy storage converter can execute a P-Q decoupling control mode, the P-Q decoupling control needs to convert variables in a three-symmetric static coordinate system into variables in a synchronous rotating coordinate system with grid fundamental wave voltage as a reference (namely, the variables are converted into d-Q coordinates through park conversion), and after conversion, fundamental wave alternating current sine quantities are converted into direct current variables in the synchronous rotating coordinate system; wherein the q-axis current is equal toThe power is related, the d-axis current is related to the active component, and the conversion realizes the decoupling control of the active power and the reactive power; the voltage feedforward part in P-Q decoupling control also needs power frequency sine wave as modulation wave, the forming method of the modulation wave in the device of the invention is the same as the forming method of the modulation wave in V-f control: discretizing power frequency sine wave (preferably power frequency sine wave with amplitude of 1 for convenience of operation) to obtain sine wave data of a plurality of discrete time points in a power frequency period, and forming sine array sin [ m ] composed of a plurality of (m) sine wave data](according to the optimal resolution of system hardware and the response speed of a processor, the minimum resolution of the group of data is set to 0.5 degrees, namely, the data is decomposed into 720 points per period), a corresponding rectangular pulse sequence is formed according to the sine table array to replace a power frequency sine wave required by a voltage feedforward part in P-Q decoupling control to be used as a modulation wave, and the number m of switching points corresponding to a power frequency period sine table is obtained through the relationship between the switching frequency and the power frequencyfThe total number of array elements m and m of the sine tablefSelecting rectangular pulses for modulation for the moving step length of the pointer of the sine wave meter when the multiple of the switching frequency value (namely the switching frequency value taking one power frequency period as a unit) is used for realizing the power frequency sine wave; m and n are integers greater than 1; the phase locking angle theta is changed along with the phase of the power grid voltage, and the phase locking angle is used for corresponding to a pointer sin _ pointer in a sine table arrayPQThe current array pointer sin _ pointer and the corresponding angle realize a reference modulation wave, and the modulation wave obtained by the P-Q decoupling current loop is superposed on the reference modulation wave generated by the sine table, so that an output modulation wave controlled by P-Q decoupling can be obtained, and the power tracking of a grid-connected mode is realized;
as shown in FIG. 7, PrefFor a given active power, QrefFor a given reactive power, iidrefIs an active current, iiqrefIs a reactive current, ea、eb、ecFor the mains voltage, iia、iib、iicFor the inverter output current udcIs the DC side voltage of the inverter udcrefFor inverter DC voltage reference, k is the transformer transformation ratio, w0For synchronous rotation of angular frequency, maTo modulateRatio, uma、umb、umcIs a modulating wave of P-Q decoupling control, uiabcThree-phase voltage u of filter capacitor of bidirectional inverter circuitiabcrefThe reference is the three-phase voltage reference of the filter capacitor of the bidirectional inverter circuit.
The key calculation and control processes of the KVCS AC-DC conversion energy storage converter are as follows:
1) acquiring a grid-connected side alternating current frequency (fixed power frequency 50Hz in isolated network) by using a phase-locked loop with hardware error correction, and performing error correction by using equipment hardware correction parameters in phase locking; when the equipment leaves a factory for debugging, each machine uses a standard source to correct multi-level hardware errors (the error correction parameters can participate in a plurality of steps in the calculation process);
2) respectively carrying out error correction calculation on the currently output and input alternating current active power and reactive power, and storing the calculation results for use in the subsequent calculation process;
3) in a grid-connected operation state, PQ conversion is carried out according to specified target active power and reactive power, and PI regulation of voltage and current is carried out according to inherent errors of a system; in an isolated network (off-network) state, the power is not calculated, the V/F control is directly carried out, and the voltage and the current are subjected to PI regulation;
4) after a target value of PI regulation is obtained, amplitude limiting control is carried out according to the inherent capacity of a hardware system; finally, acquiring target voltage and current values needing to be controlled and output;
5) carrying out vector calculation on the voltage and current values to obtain an output target value of a vector field; then, the sine modulation wave is tried out, PWM calculation is carried out on the output target value, and basic parameters of PWM output are determined under the condition that the safety and the reliability of a hardware system are ensured (each different device has the same safety threshold value of the PWM output, and needs to be tested independently to ensure that the data deviation is within a specified range);
6) according to the PWM basic parameters, IGBT driving is carried out, multiple hardware checks are needed for IGBT driving, and the running safety of equipment is ensured;
7) and in the whole equipment operation process, under the condition of no abnormality, continuously repeating the calculation processes from 1) to 6).
The KVCS AC-DC conversion energy storage converter has the following characteristics:
1) the charging and discharging are integrally designed, so that the energy bidirectional flow of an alternating current system and a direct current system is realized;
2) the main power loop adopts a high-reliability intelligent power module, and the controller adopts a 32-bit high-performance CPU (central processing unit) with a bus not leading out of a chip;
3) the efficient vector control algorithm realizes active and reactive decoupling control;
4) the power factor can be adjusted at will, and the reactive power can be generated in a capacity range, so that reactive power compensation is realized;
5) the three-phase full-bridge bidirectional PWM conversion is adopted, so that bidirectional AC/DC energy conversion can be realized;
6) the primary converter is adopted, so that the topology is simple and the reliability is high;
7) the inverter has a perfect relay protection function, an alternating current circuit breaker and an alternating current fuse are arranged on the alternating current side, and a direct current circuit breaker and a direct current fuse are arranged on the direct current side, so that the abnormal damage of the inverter is effectively prevented;
8) pre-charging loops are arranged on the alternating current side and the direct current side, so that starting impact is small;
9) the HMI touch screen can check the running state, running data, equipment information, parameter setting and the like of the KVCS alternating current-direct current conversion energy storage converter and relevant running operation of equipment;
10) the communication interface is used for communication between the KVCS alternating current-direct current conversion energy storage converter and the background EMS management system;
11) the operation indicator lamp is used for indicating the operation state of the equipment, the charge and discharge indicator lamp is used for indicating the charge and discharge state of the equipment, and the fault indicator lamp is used for indicating the fault state of the equipment;
12) the device is arranged in a high-reliability cabinet, and meets the requirements of different operation areas.
The above-described embodiments are merely preferred embodiments of the present invention, and all equivalent changes or modifications of the structures, features and principles described in the claims of the present invention are included in the scope of the present invention.
Claims (7)
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| CN116505564A (en) * | 2023-04-03 | 2023-07-28 | 深圳市恩玖科技有限公司 | Control circuit of energy storage converter |
| CN116646966A (en) * | 2023-04-24 | 2023-08-25 | 深圳市恩玖科技有限公司 | A Modular Low Voltage Flexible DC Converter System |
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Application publication date: 20220111 |