CN104953620B - Single-phase grid-connected and off-grid inverter system and control method thereof - Google Patents

Single-phase grid-connected and off-grid inverter system and control method thereof Download PDF

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Publication number
CN104953620B
CN104953620B CN201510394020.6A CN201510394020A CN104953620B CN 104953620 B CN104953620 B CN 104953620B CN 201510394020 A CN201510394020 A CN 201510394020A CN 104953620 B CN104953620 B CN 104953620B
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China
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output voltage
external power
circuit
voltage
power grid
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CN201510394020.6A
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CN104953620A (en
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李练兵
马欲晓
姚春明
王泽伟
张佳
唐会莉
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河北工业大学
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Abstract

The invention relates to a single-phase grid-connected and off-grid inverter system and a control method thereof. The inverter system comprises a single-phase grid-connected and off-grid inverter, a switch circuit, a switch circuit control module and a signal acquisition module, wherein the signal acquisition module comprises an external direct current voltage acquisition circuit, an inversion output voltage acquisition circuit, an external power grid current acquisition circuit and an external power grid output voltage acquisition circuit; the input end of the single-phase grid-connected and off-grid inverter is connected with the output end of an external direct current voltage supply device, the output end of the single-phase grid-connected and off-grid inverter is connected with the input end of the switch circuit, the output end of the switch circuit control module is connected with the switch circuit, and the output end of the switch circuit is bidirectionally connected with an external power grid; the external direct current voltage acquisition circuit is connected with the external direct current voltage supply device, the inversion output voltage acquisition circuit is connected with the output end of the single-phase grid-connected and off-grid inverter, the external power grid current acquisition circuit is connected with the output end of the switch circuit, and the external power grid output voltage acquisition circuit is connected with the external power grid.

Description

A kind of single-phase and off-network inverter system and its control method

Technical field

Technical scheme is related to a kind of and off-network inverter system and its control method, specifically a kind of single Phase off-network inverter system and its control method.

Background technology

And one of the key technology of off-network inverter is the mutual switching of island mode and grid-connect mode.In normal work mould Under formula, micro-capacitance sensor and bulk power grid parallel running, when bulk power grid breaks down or the quality of power supply is not reached when requiring, inverter dress Put and islet operation is isolated with electrical network by isolating device.After electric network fault is eliminated, DC-to-AC converter is again same with external power grid Step, realizes being incorporated into the power networks.

At present, there are three kinds of control models for the control structure of distributed generation system operational mode switching:Voltage mode Control, indirect current Schema control and mixed-voltage Controlled in Current Mode and Based.Voltage mode control, i.e., either for island mode Or for grid-connect mode, inverter is treated as a voltage source all the time, therefore electricity is loaded in the handoff procedure of operational mode Preferably, but there is active power outer shroud in pressure quality, so the dynamic property of system can be deteriorated.Indirect current Schema control, be Finger is controlled to load voltage always, and carries out feedback control to power network current peak value, and the control method causes load electricity Pressure quality is preferable, but dynamic property is poor, and realizes also more complicated.Mixed-voltage Controlled in Current Mode and Based is referred to, in isolated island During pattern, inverter is treated as a voltage source, and using voltage mode control structure, under grid-connect mode, inverter is treated as One current source, adopts Controlled in Current Mode and Based, because the method is directly controlled to voltage or current instantaneous value, has Good dynamic property, but in handoff procedure, load voltage is second-rate.

In addition, grid-connected switching device generally adopts bidirectional thyristor, due to the control signal and switch electricity of bidirectional thyristor The time delay on road, certainly exists switching transient process.And when driving load is perception, RC absorption circuits to be added to control spike Voltage, but as RC absorption circuits itself can be to load electric leakage so that IGCT can not be complete switched off, if load is very light, very To the possibility for being likely to occur load on-line operation so as to not by bidirectional thyristor control.

The content of the invention

For the deficiencies in the prior art, the technical problem that the present invention is intended to solve is to provide a kind of single-phase and off-network inverter System and its control method.The mode selector switch device solid-state relay of the inverter system instead of bidirectional thyristor, Isolating for control end and load end is realized, input can just directly drive large current load with small control signal, and Mechanical is got an electric shock, life-span length, noiselessness, anti-vibration, disconnects in zero crossing, and arcing interference is little, and conducting speed is fast, handover operation side Just it is quick, depending on the fixed position of solid-state relay can be with being actually needed, realize island mode/grid-connect mode switching.Should , using the Dual-loop feedback control control program based on mixed-voltage current control mode, the control method can be accurately fast for control method Speed realizes the synchronization of the amplitude and phase place of inverter output voltage and external power grid output voltage, can realize island mode and grid-connected mould In formula handoff procedure, load voltage and load current are seamlessly transitted, and overcome existing voltage mode control technology in handoff procedure The dynamic property of middle system can be deteriorated the defect second-rate with load voltage.

The present invention solves the technical scheme adopted by the inverter system technical problem:A kind of single-phase and off-network is provided Inverter system, it is characterised in that the inverter system includes single-phase and off-network inverter, on-off circuit, on-off circuit control mould Block and signal acquisition module, the signal acquisition module include external dc voltage Acquisition Circuit, inverter output voltage collection electricity Road, external power grid current collection circuit and external power grid output voltage Acquisition Circuit;The described single-phase and input of off-network inverter with External dc connects for the outfan of pressure device, and the single-phase and outfan of off-network inverter is connected with the input of on-off circuit, The outfan of on-off circuit control module is connected with on-off circuit, and outfan and the external power grid of on-off circuit are bi-directionally connected;It is described External dc voltage Acquisition Circuit is connected for pressure device with external dc, inverter output voltage Acquisition Circuit with it is single-phase and off-network is inverse Become the outfan connection of device, external power grid current collection circuit is connected with the outfan of on-off circuit, the collection of external power grid output voltage Circuit is connected with external power grid, has island mode and grid-connect mode changeover program, isolated island inspection in the on-off circuit control module Ranging sequence, electric voltage feed forward program, phase synchronizing program and Dual-loop feedback control control program, wherein on-off circuit adopt solid-state relay Device is constituted.

Above-mentioned single-phase and off-network inverter system, the circuit of the on-off circuit constitute and are:Including two terminals be J1 and J2, current sensor M1, four Chip-Rs are R1, R2, R3 and R4, and varistor R5, two electrochemical capacitors are E1 and E2, patch Chip capacitor C1, two solid-state relay U1 and U2 and protective tube F1;The resistance of R1 and R3 in four Chip-Rs is 100 Ω, the resistance of R2 and R4 in four Chip-Rs is 500 Ω, varistors of the R5 for model MYG14K681, terminal J1 is inverter output voltage outfan, and the H1 pins of J1 are connected with S1, S2, S3 pin of current sensor M1, current sensor The S8 pins of M1 are connected with SGND, and the S9 pins of current sensor M1 are connected with one end of patch capacitor C1 and+5V simultaneously, paster The other end of electric capacity C1 is connected with SGND, and the S7 pins out of current sensor M1 is exported for external power grid electric current, current sensor M1 S4, S5, S6 pin be simultaneously connected with the A3 pins of solid-state relay U1, the A1 pins and Chip-R R2 of solid-state relay U1 One end, the positive pole of electrochemical capacitor E1 be connected, the other end of Chip-R R2, the negative pole of electrochemical capacitor E1 are simultaneously and Chip-R One end of R1 is connected, and the other end of Chip-R R1 is connected with on-off circuit control signal relay, and the A2 of solid-state relay U1 draws Foot connects 24V DC voltages, is connected with the K1 pins of terminal J2 after the A4 pins of solid-state relay U1 and protective tube F1 series connection, and J2 is External power grid output voltage outfan, while varistor R5 one end is connected with the A4 pins of solid-state relay U1, the other end and end The K2 pins of sub- J2, the B4 pins of solid-state relay U2 are connected;The B1 pins of solid-state relay U2 are connected with Chip-R R4 one end Connect, the other end of Chip-R R4 is connected with one end of Chip-R R3, the other end and the on-off circuit of Chip-R R3 are controlled Signal relay is connected, and the negative pole of electrochemical capacitor E2 is connected with the B1 pins of solid-state relay U2, positive pole and the patch of electrochemical capacitor E2 The other end connection of sheet resistance R4, the B2 pins of solid-state relay U2 connect 24V DC voltages, the B3 pins of solid-state relay U2 with The H2 pins of terminal J1 are connected;Wherein, control while on-off circuit control signal relay is given for on-off circuit control module The control signal of the on off state of two solid-state relays U1 and U2 in on-off circuit.

Above-mentioned single-phase and off-network inverter system, has island mode and grid-connect mode in the on-off circuit control module Changeover program is:Start → define and initialize whether each control parameter → original state is set as island mode → external power grid NormallyExternal power grid is returned whether normal;Solid-state relay adhesive in on-off circuit is switched to grid-connect mode → external power grid It is whether normalWhether solid-state relay adhesive in on-off circuit is switched to the external power grid of grid-connect mode → return previous step Normally;Whether just solid-state relay disconnection in on-off circuit is switched to the external power grid of island mode → return previous step Often.

Above-mentioned single-phase and off-network inverter system, the on-off circuit control module adopt TMS320F2808 chips.

The control method of a kind of single-phase and off-network inverter system, the control method application is above-mentioned single-phase and off-network inverter System, it is characterised in that the control method is comprised the concrete steps that:

The amplitude and phase place of the first step, Synchronization Control inverter output voltage and external power grid output voltage:

When being switched to grid-connect mode from island mode, it is to be ensured that inverter output voltage and external power grid output voltage are same with width Phase;

(1) amplitude of Synchronization Control inverter output voltage and external power grid output voltage:

In a voltage cycle 20ms, the collection step number of inverter output voltage is 400 steps, is adopted by inverter output voltage Collector collection inversion output from the 90th step to the voltage magnitude the 110th step and is sued for peace, and then takes its meansigma methods as adopting The inverter output voltage peak value for collecting;The external power grid voltage theoretical peak that external power grid voltage collection circuit is collected is 314V, such as In range of error of the inverter output voltage peak value that fruit inverter output voltage Acquisition Circuit is collected between 312V to 316V, i.e., Can determine whether that inverter output voltage amplitude and external power grid output voltage amplitude are equal, i.e. inverter output voltage and external power grid output voltage Amplitude synchronization;If the inverter output voltage peak value that inverter output voltage Acquisition Circuit is collected is less than 312V or is more than 316V, you can judge that inverter output voltage amplitude and external power grid output voltage amplitude are unequal, i.e. inverter output voltage and dispatch from foreign news agency Net output voltage amplitude is not reaching to synchronization, then in the electric voltage feed forward program in on-off circuit control module in units of 2 Electric voltage feed forward coefficient is increasedd or decreased gradually, so that the inverter output voltage that external power grid voltage collection circuit is collected accordingly increases Or reduce, until error model of the inverter output voltage peak value that collects of external power grid voltage collection circuit between 312V to 316V In enclosing;

(2) phase place of Synchronization Control inverter output voltage and external power grid output voltage:

The external power grid output voltage Acquisition Circuit moment detects external power grid output voltage, when capturing external power grid output voltage During rising edge, inverter output voltage and external power grid output voltage in the phase synchronizing program in on-off circuit control module, are calculated Phase contrast, i.e. the step number of inverter output voltage and external power grid output voltage is poor, if step number difference is more than 1, in on-off circuit Real-time step number is subtracted 2 in phase synchronizing program in control module;If step number difference is less than 1, in on-off circuit control module In phase synchronizing program in real-time step number is added 2, then capture the next of external power grid in outer line voltage Acquisition Circuit again At the moment of individual rising edge, in the phase synchronizing program in on-off circuit control module, recalculate inverter output voltage and dispatch from foreign news agency The step number of net output voltage is poor, until the step number difference of inverter output voltage and external power grid output voltage is 0 or 1, can now sentence The Phase synchronization of the phase place and external power grid output voltage of disconnected inverter output voltage;

Second step, by mix island detection method carry out isolated island detection:

After the amplitude of first step Synchronization Control inverter output voltage and external power grid output voltage, switched by grid-connect mode To before island mode, isolated island detection is carried out using method for quick first, i.e., in a voltage cycle 20ms, voltage is adopted Collection step number is 400 steps, when inverter output voltage Acquisition Circuit detects the corresponding moment of 4 continuous instantaneous voltage magnitudes and setting Reference voltage amplitude difference be more than 10V or less than -10V when, you can judge electric network power-fail, after judging electric network power-fail, directly Determine whether to make single-phase and off-network inverter is switched to island mode from grid-connect mode;If do not sentenced using method for quick Break and electric network power-fail, reapplied/under-voltage detection and mistake/under-frequency detected as island detection method, judge it is single-phase and from Whether net inverter enters isolated island, determines whether to make single-phase and off-network inverter is switched to island mode from grid-connect mode;

3rd step, taking over seamlessly for load voltage and load current is realized based on Dual-loop feedback control control program:

When island mode is switched to grid-connect mode, need to guarantee inverter output voltage and external power grid output through the first step Voltage is with carrying out taking over seamlessly for load voltage and load current after width homophase;The needs when grid-connect mode is switched to island mode After second step carries out isolated island detection, then carry out taking over seamlessly for load voltage and load current;

Employ outside comprising load current internal ring and load voltage on the basis of mixed-voltage Controlled in Current Mode and Based structure The Dual-loop feedback control control program of ring, realizes taking over seamlessly for load voltage and load current, in isolated island/grid-connect mode switching During, it is using mixed-voltage Controlled in Current Mode and Based structure, i.e., in island mode, single-phase and off-network inverter is treated as one Voltage source, using voltage mode control structure;Under grid-connect mode, single-phase and off-network inverter is treated as a current source, adopts Use current-mode control structure;

The mutual switching of the 4th step, island mode and grid-connect mode:

(1) realization of the island mode to the switching of grid-connect mode:

After the 3rd step realizes the taking over seamlessly of load voltage and load current, exported by on-off circuit control module Low level, i.e. on-off circuit control signal relay are low level, so as to the solid-state relay U1's and U2 in controlling switch circuit Closure, completes island mode to the switching of grid-connect mode;

(2) realization of the grid-connect mode to the switching of island mode:

Isolated island detection is carried out by the mixing island detection method of second step, when single-phase and off-network inverter system meet into When entering the condition of island mode, i.e., after method for quick judges electric network power-fail, single-phase and off-network inverter is made from grid-connected Pattern switching is to island mode, or again by mistake/under-voltage detection and mistake/under-frequency detection as island detection method, judges single Mutually and off-network inverter enters isolated island, it is determined that making single-phase and off-network inverter is switched to island mode from grid-connect mode;Pass through again After 3rd step realizes the taking over seamlessly of load voltage and load current, on-off circuit control module output high level switchs electricity Road control signal relay is high level, so as to the disconnection of solid-state relay U1 and U2 in controlling switch circuit, completes grid-connected mould Switching of the formula to island mode.

Single-phase and off-network inverter system and its control method of the invention have the advantages that:

(1) invention increases the on-off circuit of interior electrical network and external power grid, can quickly complete island mode and grid-connected mould The switching action of formula, the problem for overcoming bidirectional thyristor complete switch off as pattern switching status switch IGCT.Solid-state Relay isolating device realizes isolating for control end and load end, and input reaches directly drive with small control signal Dynamic large current load.Mechanical is got an electric shock, life-span length, noiselessness, anti-vibration, disconnects in zero crossing, and arcing interference is little, turns on speed Hurry up.Fixed position can with the need depending on.When overcoming bidirectional thyristor driving inductive load, RC absorption circuits to be added to control Peak voltage, RC absorption circuits itself can be to load electric leakages so that the problem that IGCT can not be complete switched off.

(2) present invention accurately can quickly realize the same of the amplitude and phase place of inverter output voltage and external power grid output voltage Step.The present invention realizes inverter output voltage amplitude and external power grid output voltage by adjusting and judging inverter output voltage peak value The synchronization of amplitude, realizes inverter output voltage phase place and external power grid by real-time step number is stepped up or reduced in units of 2 The synchronization of output voltage phase place.

(3) present invention applied/under-voltage detection and mistake/under-frequency detected as island detection method, and in the isolated island Before detection method, method for quick is added, improve detection speed.

(4) present invention can realize taking over seamlessly for load voltage and load current simultaneously, and overcoming traditional method can only The shortcoming that proof load voltage takes over seamlessly.The present invention is controlled using the Dual-loop feedback control based on mixed-voltage current control mode Pattern.When island mode is switched to from grid-connect mode, before isolated island occurs, outer voltage does not have the effect of regulation, works as orphan After island occurs, outer voltage automatically engages operation, and load voltage is adjusted so that load voltage quality is in handoff procedure Improved.When grid-connect mode is switched to from island mode, outer voltage loses adjustment effect, and current inner loop starts to put into work It is adjusted so that load current quality is improved in handoff procedure.

(5) present invention is simple and practical, it is easy to popularization and popularization.

Description of the drawings

The structural schematic block diagram of Fig. 1 single-phase and off-network inverter systems of the present invention;

The circuit diagram of Fig. 2 single-phase and on-off circuits of off-network inverter system of the present invention;

The island mode that has and grid-connected in Fig. 3 single-phase and off-network inverter system breaker in middle circuit control modules of the present invention The schematic flow sheet of mode switching program.

In figure, 1. external dc supplies pressure device, 2. single-phase and off-network inverter, 3. on-off circuit, 4. on-off circuit control Module, 5. signal acquisition module, 51. external dc voltage Acquisition Circuit, 52. inverter output voltage Acquisition Circuit, 53. external power grids Current collection circuit, 54. external power grid output voltage Acquisition Circuit.

Specific embodiment

Below in conjunction with the accompanying drawings and embodiment is described in further detail the present invention, but not in this, as will to right of the present invention Ask the restriction of protection domain.

Embodiment illustrated in fig. 1 shows, dotted line inframe of the invention single-phase off-network inverter system includes single-phase and off-network Inverter 2, on-off circuit 3, on-off circuit control module 4 and signal acquisition module 5, the signal acquisition module include outside straight Stream voltage collection circuit 51, inverter output voltage Acquisition Circuit 52, external power grid current collection circuit 53 and external power grid output voltage Acquisition Circuit 54;Outfan of the input of described single-phase and off-network inverter 2 with external dc for pressure device 1 is connected, single-phase And the outfan of off-network inverter 2 is connected with the input of on-off circuit 3, outfan and the switch of on-off circuit control module 4 Circuit 3 connects, and outfan and the external power grid of on-off circuit 3 are bi-directionally connected;The external dc voltage Acquisition Circuit 51 and outside Direct current connects for pressure device 1, and inverter output voltage Acquisition Circuit 52 is connected with single-phase and off-network inverter 2 outfan, dispatch from foreign news agency Net current collection circuit 53 is connected with the outfan of on-off circuit 3, and external power grid output voltage Acquisition Circuit 54 is connected with external power grid, There are isolated island/grid-connect mode changeover program, isolated island detection program, electric voltage feed forward program, phase in the on-off circuit control module 4 Bit synchronization program and Dual-loop feedback control control program, wherein on-off circuit are constituted using solid-state relay.

Embodiment illustrated in fig. 2 shows that the circuit of the on-off circuit 3 of single-phase and off-network inverter system of the invention constitutes and is: It is J1 and J2, current sensor M1 including two terminals, four Chip-Rs are R1, R2, R3 and R4, varistor R5, two Electrochemical capacitor is E1 and E2, patch capacitor C1, two solid-state relay U1 and U2 and protective tube F1;In four Chip-Rs R1 and the resistance of R3 be 100 Ω, the resistance of R2 and R4 in four Chip-Rs is 500 Ω, and R5 is model The varistor of MYG14K681, terminal J1 is inverter output voltage outfan, the H1 pins of J1 and the S1 of current sensor M1, S2, S3 pin is connected, and the S8 pins of current sensor M1 are connected with SGND, and the S9 pins of current sensor M1 are simultaneously electric with paster The one end for holding C1 is connected with+5V, and the other end of patch capacitor C1 is connected with SGND, and the S7 pin out of current sensor M1 are outer Power network current is exported, and S4, S5, S6 pin of current sensor M1 is connected with the A3 pins of solid-state relay U1 simultaneously, solid-state after The A1 pins of electrical equipment U1 are connected with the positive pole of one end of Chip-R R2, electrochemical capacitor E1, the other end of Chip-R R2, electrolysis The negative pole of electric capacity E1 is connected with one end of Chip-R R1 simultaneously, the other end and the on-off circuit control signal of Chip-R R1 Relay is connected, and the A2 pins of solid-state relay U1 connect 24V DC voltages, the A4 pins of solid-state relay U1 and protective tube F1 strings Be connected with the K1 pins of terminal J2 after connection, J2 is external power grid output voltage outfan, at the same varistor R5 one end and solid-state after The A4 pins connection of electrical equipment U1, the other end are connected with the K2 pins of terminal J2, the B4 pins of solid-state relay U2;Solid-state relay The B1 pins of U2 are connected with Chip-R R4 one end, and the other end of Chip-R R4 is connected with one end of Chip-R R3, paster The other end of resistance R3 is connected with on-off circuit control signal relay, the negative pole of electrochemical capacitor E2 and the B1 of solid-state relay U2 Pin connects, and the positive pole of electrochemical capacitor E2 is connected with the other end of Chip-R R4, and it is straight that the B2 pins of solid-state relay U2 meet 24V Stream voltage, the B3 pins of solid-state relay U2 are connected with the H2 pins of terminal J1;Wherein, on-off circuit control signal relay is The on off state of two solid-state relays U1 and U2 while on-off circuit control module 4 is given in controlling switch circuit 3 Control signal.

The operation principle of on-off circuit shown in Fig. 2 is:Solid-state relay U2 and U1 are direct current 24V control relays, when When on-off circuit control signal relay is low level, while solid-state relay U2 and U1 adhesive is controlled, when on-off circuit control is believed When number relay is high level, while control solid-state relay U2 and U1 disconnecting.In this and off-network inverter system, J1 is inverse Become output voltage terminal, J2 is external power grid output voltage lead-out terminal, and on-off circuit control module 4 is using TMS320F2808 cores Piece, exports low level relay, controls solid-state relay U2 and U1 in closure switch circuit, completes island mode to grid-connected mould The switching of formula;On-off circuit control module output high level arrive relay, control disconnect on-off circuit in solid-state relay U2 with U1, completes grid-connect mode to the switching of off-network pattern.

Embodiment illustrated in fig. 3 shows have in the on-off circuit control module 4 of single-phase and off-network inverter system of the invention Island mode and the flow process of grid-connect mode changeover program be:Start → define and initialize each control parameter → original state It is set as whether island mode → external power grid is normalExternal power grid is returned whether normal;Solid-state relay in on-off circuit Whether adhesive is switched to grid-connect mode → external power grid normalSolid-state relay adhesive in on-off circuit is switched to grid-connect mode Whether the external power grid of → return previous step is normal;Solid-state relay in on-off circuit disconnect be switched to island mode → Whether the external power grid for returning previous step is normal.

Embodiment

The single-phase and off-network inverter system of the present embodiment includes single-phase and off-network inverter 2, on-off circuit 3, switch electricity Road control module 4 and signal acquisition module 5, the signal acquisition module include that external dc voltage Acquisition Circuit 51, inversion is defeated Go out voltage collection circuit 52, external power grid current collection circuit 53 and external power grid output voltage Acquisition Circuit 54;It is described single-phase and from The input of net inverter 2 and external dc be connecteds for the outfan of pressure device 1, the single-phase and outfan of off-network inverter 2 and The input connection of on-off circuit 3, the outfan of on-off circuit control module 4 is connected with on-off circuit 3, on-off circuit 3 it is defeated Go out end to be bi-directionally connected with external power grid;The external dc voltage Acquisition Circuit 51 is connected for pressure device 1 with external dc, and inversion is defeated Go out voltage collection circuit 52 to be connected with single-phase and off-network inverter 2 outfan, external power grid current collection circuit 53 is electric with switch The outfan connection on road 3, external power grid output voltage Acquisition Circuit 54 is connected with external power grid, in the on-off circuit control module 4 There are island mode and grid-connect mode changeover program, isolated island detection program, electric voltage feed forward program, phase synchronizing program and two close cycles Feedback control procedures, wherein on-off circuit are constituted using solid-state relay.

The single-phase and control method of off-network inverter system of the present embodiment is comprised the concrete steps that:

The amplitude and phase place of the first step, Synchronization Control inverter output voltage and external power grid output voltage:

When being switched to grid-connect mode from island mode, it is to be ensured that inverter output voltage and external power grid output voltage are same with width Phase;

(1) amplitude of Synchronization Control inverter output voltage and external power grid output voltage:

In a voltage cycle 20ms, the collection step number of inverter output voltage is 400 steps, and the 100th step is inverse in theory Become output voltage peak value, inversion output is gathered from the 90th step (include the 90th step) to the by inverter output voltage Acquisition Circuit 52 Voltage magnitude between 110 steps (include the 110th step) is simultaneously sued for peace, and then takes its meansigma methods as the inverter output voltage for collecting Peak value;Because China's civil power single-phase voltage theoretical peak is 314V, i.e., the external power grid that external power grid voltage collection circuit 54 is collected Voltage theoretical peak is 314V, if the inverter output voltage peak value that inverter output voltage Acquisition Circuit 52 is collected is in 312V (including 312V) is in the range of error between 316V (including 316V), you can judge that inverter output voltage amplitude and external power grid are defeated Go out voltage magnitude equal, i.e. inverter output voltage and external power grid output voltage amplitude synchronization;If inverter output voltage collection electricity The inverter output voltage peak value that road 52 collects is less than 312V (not including 312V) or is more than 316V (not including 316V), you can Judge that inverter output voltage amplitude and external power grid output voltage amplitude are unequal, i.e. inverter output voltage and external power grid output voltage Amplitude is not reaching to synchronization, then in the electric voltage feed forward program in on-off circuit control module in units of 2 gradually increase or Reduce electric voltage feed forward coefficient, so that inverter output voltage accordingly increase or the reduction that external power grid voltage collection circuit 54 is collected, Until the inverter output voltage peak value that external power grid voltage collection circuit 54 is collected (includes to 316V in 312V (including 312V) In range of error between 316V).

(2) phase place of Synchronization Control inverter output voltage and external power grid output voltage:

54 moment of external power grid output voltage Acquisition Circuit detects external power grid output voltage, when capturing external power grid output voltage Rising edge when, in the phase synchronizing program in on-off circuit control module calculate inverter output voltage and external power grid output electricity The step number of the phase contrast of pressure, i.e. inverter output voltage and external power grid output voltage is poor, if step number difference is more than 1, in switch electricity Real-time step number is subtracted 2 in phase synchronizing program in the control module of road;If step number difference is less than 1, mould is controlled in on-off circuit Real-time step number is added 2 in phase synchronizing program in block, then external power grid is captured in outer line voltage Acquisition Circuit 54 again During the moment of next rising edge, in the phase synchronizing program in on-off circuit control module, inverter output voltage is recalculated It is poor with the step number of external power grid output voltage, until the step number difference of inverter output voltage and external power grid output voltage is 0 or 1, now The Phase synchronization of the phase place and external power grid output voltage of inverter output voltage is can determine whether.

Second step, by mix island detection method carry out isolated island detection:

After the amplitude of first step Synchronization Control inverter output voltage and external power grid output voltage, switched by grid-connect mode To before island mode, isolated island detection is carried out using method for quick first, i.e., in a voltage cycle 20ms, voltage is adopted Collection step number be 400 steps, when inverter output voltage Acquisition Circuit 52 detect 4 continuous instantaneous voltage magnitudes with set it is corresponding when When the difference of the reference voltage amplitude at quarter is more than 10V or is less than -10V, you can judge electric network power-fail, after judging electric network power-fail, directly Connect and determine whether to make single-phase and off-network inverter 2 is switched to island mode from grid-connect mode;If do not had using method for quick Have and judge electric network power-fail, reapplied/under-voltage detection (i.e. over-pressed or under-voltage detection) and mistake/under-frequency detects (i.e. overfrequency Or under-frequency detection) as island detection method, judge single-phase and whether off-network inverter 2 enters isolated island, determine whether to make It is single-phase and off-network inverter 2 is switched to island mode from grid-connect mode.The mixed method can be in conventional island detection method It is used for quickly detecting before detection first, improves rapidity.

3rd step, taking over seamlessly for load voltage and load current is realized based on Dual-loop feedback control control program:

When island mode is switched to grid-connect mode, need to guarantee inverter output voltage and external power grid output through the first step Voltage is with carrying out taking over seamlessly for load voltage and load current after width homophase;The needs when grid-connect mode is switched to island mode After second step carries out isolated island detection, then carry out taking over seamlessly for load voltage and load current;

During island mode and grid-connect mode switch, using mixed-voltage Controlled in Current Mode and Based structure, i.e., in orphan During the pattern of island, single-phase and off-network inverter 2 is treated as a voltage source, using voltage mode control structure;Under grid-connect mode, Single-phase and off-network inverter 2 is treated as a current source, using Controlled in Current Mode and Based structure because the method directly to voltage or Current instantaneous value is controlled, so with good dynamic property.The present invention is in mixed-voltage Controlled in Current Mode and Based structure On the basis of employ the Dual-loop feedback control control program comprising load current internal ring and load voltage outer shroud, realize load voltage and Load current takes over seamlessly.Wherein, load current is the external power grid electric current of the collection of external power grid current collection circuit 53, i.e. electric current The S7 pin out of sensor M1, load voltage are the inverter output voltage of the collection of inverter output voltage Acquisition Circuit 52, will load Realize in the Dual-loop feedback control control program of electric current and load voltage as feedback quantity in on-off circuit control module 4.

The two close cycles based on mixed-voltage current control mode of the present embodiment are introduced with reference to different switch modes Feedback control procedures:

When island mode is switched to from grid-connect mode, before isolated island occurs, outer voltage does not have the effect of regulation, when After isolated island occurs, outer voltage automatically engages operation, and load voltage is adjusted;When being switched to grid-connect mode from island mode When, outer voltage loses adjustment effect, and current inner loop starts to devote oneself to work and is adjusted.

Can being played based on the Dual-loop feedback control control model of mixed-voltage current control mode for the present embodiment is imitated as follows Really:When being switched to island mode from grid-connect mode, load voltage quality can change to improvement;Grid-connected mould is switched to from island mode During formula, load current quality can be improved.

The mutual switching of the 4th step, island mode and grid-connect mode:

(1) realization of the island mode to the switching of grid-connect mode

It is after the 3rd step realizes the taking over seamlessly of load voltage and load current, defeated by on-off circuit control module 4 The relay gone out in low level, i.e. Fig. 2 is low level, so as to the closure of solid-state relay U1 and U2 in controlling switch circuit 3, Island mode is completed to the switching of grid-connect mode.

(2) realization of the grid-connect mode to the switching of island mode

Isolated island detection is carried out by the mixing island detection method of second step, when single-phase and off-network inverter system meet into When entering the condition of island mode, i.e., after method for quick judges electric network power-fail, single-phase and off-network inverter 2 is made from grid-connected Pattern switching is to island mode, or again by mistake/under-voltage detection and mistake/under-frequency detection as island detection method, judges single Mutually and off-network inverter 2 enters isolated island, it is determined that making single-phase and off-network inverter 2 is switched to island mode from grid-connect mode;Jing again Cross after the 3rd step realizes the taking over seamlessly of load voltage and load current, on-off circuit control module 4 output high level, i.e. Fig. 2 In relay be high level, so as to the disconnection of solid-state relay U1 and U2 in controlling switch circuit, complete grid-connect mode to orphan The switching of island pattern.

Embodiment adds the on-off circuit of interior electrical network and external power grid, before grid-connect mode is switched to from island mode, The synchronization of the amplitude and phase place of inverter output voltage and external power grid output voltage is realized by the first step, is being switched from grid-connect mode Isolated island detection is carried out by second step to before island mode, then the solid-state in 4 controlling switch circuit 3 of on-off circuit control module The closed and disconnected of relay U1 and U2, so as to realize the mutual switching of island mode and grid-connect mode.

Isolated island detection program, electric voltage feed forward program and the Phase synchronization having in breaker in middle circuit control module of the present invention 4 Program is known technology.

Claims (4)

1. a kind of single-phase and off-network inverter system, it is characterised in that:The inverter system includes single-phase and off-network inverter, opens Powered-down road, on-off circuit control module and signal acquisition module, the signal acquisition module include external dc voltage collection electricity Road, inverter output voltage Acquisition Circuit, external power grid current collection circuit and external power grid output voltage Acquisition Circuit;It is described it is single-phase simultaneously The input of off-network inverter and external dc are connected for the outfan of pressure device, the single-phase and outfan of off-network inverter with open The input connection on powered-down road, the outfan of on-off circuit control module is connected with on-off circuit, the outfan of on-off circuit and External power grid is bi-directionally connected;The external dc voltage Acquisition Circuit is connected for pressure device with external dc, and inverter output voltage is adopted Collector is connected with single-phase and off-network inverter outfan, and external power grid current collection circuit is connected with the outfan of on-off circuit Connect, external power grid output voltage Acquisition Circuit is connected with external power grid, in the on-off circuit control module, have island mode and simultaneously Net mode switching program, isolated island detection program, electric voltage feed forward program, phase synchronizing program and Dual-loop feedback control control program, its Breaker in middle circuit is constituted using solid-state relay;
The circuit of the on-off circuit is constituted:It is J1 and J2, current sensor M1 including two terminals, four Chip-Rs are R1, R2, R3 and R4, varistor R5, two electrochemical capacitors are E1 and E2, patch capacitor C1, two solid-state relays U1 and U2 And protective tube F1;The resistance of R1 and R3 in four Chip-Rs is 100 Ω, the R2 and R4 in four Chip-Rs Resistance be 500 Ω, R5 for model MYG14K681 varistor, terminal J1 be inverter output voltage outfan, the H1 of J1 Pin is connected with S1, S2, S3 pin of current sensor M1, and the S8 pins of current sensor M1 are connected with SGND, current sense The S9 pins of device M1 are connected with one end of patch capacitor C1 and+5V simultaneously, and the other end of patch capacitor C1 is connected with SGND, electric current The S7 pins out of sensor M1 is the output of external power grid electric current, S4, S5, S6 pin of current sensor M1 simultaneously with solid-state relay The A3 pins of device U1 are connected, and the A1 pins of solid-state relay U1 are connected with the positive pole of one end of Chip-R R2, electrochemical capacitor E1, The other end of Chip-R R2, the negative pole of electrochemical capacitor E1 are connected with one end of Chip-R R1 simultaneously, and Chip-R R1's is another One end is connected with on-off circuit control signal relay, and the A2 pins of solid-state relay U1 connect 24V DC voltages, solid-state relay It is connected with the K1 pins of terminal J2 after the A4 pins of U1 and protective tube F1 series connection, J2 is external power grid output voltage outfan, while Varistor R5 one end is connected with the A4 pins of solid-state relay U1, the K2 pins of the other end and terminal J2, solid-state relay U2 B4 pins be connected;The B1 pins of solid-state relay U2 are connected with Chip-R R4 one end, the other end and the patch of Chip-R R4 One end of sheet resistance R3 is connected, and the other end of Chip-R R3 is connected with on-off circuit control signal relay, electrochemical capacitor E2's Negative pole is connected with the B1 pins of solid-state relay U2, and the positive pole of electrochemical capacitor E2 is connected with the other end of Chip-R R4, solid-state The B2 pins of relay U2 connect 24V DC voltages, and the B3 pins of solid-state relay U2 are connected with the H2 pins of terminal J1;Wherein, On-off circuit control signal relay is two solid-state relays while on-off circuit control module is given in controlling switch circuit The control signal of the on off state of device U1 and U2.
2. according to claim 1 single-phase and off-network inverter system, it is characterised in that:The on-off circuit control module In have island mode and grid-connect mode changeover program and be:First, each control parameter is defined and initializes, then original state It is set as island mode, then judges whether external power grid is normal, if abnormal, continuation judges whether external power grid is normal;Such as Fruit is normal, then the solid-state relay adhesive in on-off circuit is switched to grid-connect mode, then proceedes to judge whether external power grid is normal, If normal, the solid-state relay adhesive in on-off circuit is switched to grid-connect mode, is then back to outside the judgement of previous step Whether electrical network is normal, if abnormal, the solid-state relay in on-off circuit disconnects and is switched to island mode, is then back to One step judges whether external power grid is normal.
3. according to claim 1 single-phase and off-network inverter system, it is characterised in that:The on-off circuit control module Using TMS320F2808 chips.
4. the control method of a kind of single-phase and off-network inverter system described in claim 1, it is characterised in that the control method Comprise the concrete steps that:
The amplitude and phase place of the first step, Synchronization Control inverter output voltage and external power grid output voltage:
When being switched to grid-connect mode from island mode, it is to be ensured that inverter output voltage and external power grid output voltage are with width homophase;
(1) amplitude of Synchronization Control inverter output voltage and external power grid output voltage:
In a voltage cycle 20ms, the collection step number of inverter output voltage is 400 steps, by inverter output voltage collection electricity Inverter output voltage is from the 90th step to the voltage magnitude the 110th step and sues for peace for road collection, then takes its meansigma methods as adopting The inverter output voltage peak value for collecting;The external power grid voltage theoretical peak that external power grid voltage collection circuit is collected is 314V, such as In range of error of the inverter output voltage peak value that fruit inverter output voltage Acquisition Circuit is collected between 312V to 316V, i.e., Can determine whether that inverter output voltage amplitude and external power grid output voltage amplitude are equal, i.e. inverter output voltage and external power grid output voltage Amplitude synchronization;If the inverter output voltage peak value that inverter output voltage Acquisition Circuit is collected is less than 312V or is more than 316V, you can judge that inverter output voltage amplitude and external power grid output voltage amplitude are unequal, i.e. inverter output voltage and dispatch from foreign news agency Net output voltage amplitude is not reaching to synchronization, then in the electric voltage feed forward program in on-off circuit control module in units of 2 Electric voltage feed forward coefficient is increasedd or decreased gradually, so that the inverter output voltage that external power grid voltage collection circuit is collected accordingly increases Or reduce, until error model of the inverter output voltage peak value that collects of external power grid voltage collection circuit between 312V to 316V In enclosing;
(2) phase place of Synchronization Control inverter output voltage and external power grid output voltage:
The external power grid output voltage Acquisition Circuit moment detects external power grid output voltage, when the rising for capturing external power grid output voltage Along when, the phase of inverter output voltage and external power grid output voltage is calculated in the phase synchronizing program in on-off circuit control module The step number of potential difference, i.e. inverter output voltage and external power grid output voltage is poor, if step number difference is more than 1, in on-off circuit control Real-time step number is subtracted 2 in phase synchronizing program in module;If step number difference is less than 1, in on-off circuit control module Real-time step number is added 2 in phase synchronizing program, then again on the next one that outer line voltage Acquisition Circuit captures external power grid When rising the moment on edge, inverter output voltage and external power grid in the phase synchronizing program in on-off circuit control module, are recalculated The step number of output voltage is poor, until the step number difference of inverter output voltage and external power grid output voltage is 0 or 1, now can determine whether The Phase synchronization of the phase place and external power grid output voltage of inverter output voltage;
Second step, by mix island detection method carry out isolated island detection:
After the amplitude of first step Synchronization Control inverter output voltage and external power grid output voltage, orphan is switched to by grid-connect mode Before the pattern of island, isolated island detection is carried out using method for quick first, i.e., in a voltage cycle 20ms, the collection step of voltage Number is 400 steps, when inverter output voltage Acquisition Circuit detects the ginseng of 4 continuous instantaneous voltage magnitudes and the corresponding moment of setting When examining the difference of voltage magnitude more than 10V or being less than -10V, you can judge electric network power-fail, after judging electric network power-fail, directly determine Whether make single-phase and off-network inverter is switched to island mode from grid-connect mode;If do not judged using method for quick Electric network power-fail, reapplied/under-voltage is detected and mistake/under-frequency is detected as island detection method, judge single-phase and off-network is inverse Become whether device enters isolated island, determine whether to make single-phase and off-network inverter is switched to island mode from grid-connect mode;
3rd step, taking over seamlessly for load voltage and load current is realized based on Dual-loop feedback control control program:
When island mode is switched to grid-connect mode, need to guarantee inverter output voltage and external power grid output voltage through the first step With taking over seamlessly for load voltage and load current is carried out after width homophase;Need to pass through when grid-connect mode is switched to island mode After second step carries out isolated island detection, then carry out taking over seamlessly for load voltage and load current;
Employ on the basis of mixed-voltage Controlled in Current Mode and Based structure comprising load current internal ring and load voltage outer shroud Dual-loop feedback control control program, realizes taking over seamlessly for load voltage and load current, switches in island mode and grid-connect mode During, using mixed-voltage Controlled in Current Mode and Based, i.e., in island mode, single-phase and off-network inverter be treated as one it is electric Potential source, using voltage mode control structure;Under grid-connect mode, single-phase and off-network inverter is treated as a current source, adopts Controlled in Current Mode and Based structure;
The mutual switching of the 4th step, island mode and grid-connect mode:
(1) realization of the island mode to the switching of grid-connect mode:
Realize that inverter output voltage and the amplitude of external power grid output voltage are realized with the synchronous of phase place and the 3rd step through the first step After the taking over seamlessly of load voltage and load current, low level, i.e. on-off circuit control are exported by on-off circuit control module Signal relay is low level, so as to the closure of solid-state relay U1 and U2 in controlling switch circuit, completes island mode to simultaneously The switching of net pattern;
(2) realization of the grid-connect mode to the switching of island mode:
Isolated island detection is carried out by the mixing island detection method of second step, enters lonely when single-phase and off-network inverter system meets During the condition of island pattern, i.e., after method for quick judges electric network power-fail, single-phase and off-network inverter is made from grid-connect mode Be switched to island mode, or detected as island detection method by mistake/under-voltage detection and mistake/under-frequency again, judge it is single-phase simultaneously Off-network inverter enters isolated island, it is determined that making single-phase and off-network inverter is switched to island mode from grid-connect mode;Again through the 3rd After step realizes the taking over seamlessly of load voltage and load current, on-off circuit control module output high level, i.e. on-off circuit control Signal relay processed is high level, so as to the disconnection of solid-state relay U1 and U2 in controlling switch circuit, completes grid-connect mode and arrives The switching of island mode.
CN201510394020.6A 2015-07-07 2015-07-07 Single-phase grid-connected and off-grid inverter system and control method thereof CN104953620B (en)

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