CN104377723B - A kind of transient process control method for state type intermediate frequency power supply group network system - Google Patents

Abstract

The invention discloses a kind of pattern for state type intermediate frequency power supply group network system and switch transient process control method, when based on networking, mode switch first closes, on the basis of the optimized switching order of static switch elder generation disjunction during off-grid, CAN is utilized to transmit digital quantity, and pass through mean allocation and peak value, the smooth adjustment of phase place of networking cell current peak value, realize the smooth transition of state type intermediate frequency power supply group network system pattern switching transient process, it is ensured that networking unit and electrical network safe and reliable, be switched fast and stable operation.The present invention uses current peak mean allocation and peak value, the smooth adjustment control algolithm of phase place of closed loop mode, on the one hand, need not additional special energy storage device or logical operation circuit, it is ensured that the integrity of state type intermediate frequency power supply group network system structure, be easily achieved and capacity of resisting disturbance is strong；On the other hand, solve current amplitude and SPA sudden phase anomalies in pattern switching transient process, and ring current shock causes greatly the problem that networking is failed.

Description

A kind of transient process control method for state type intermediate frequency power supply group network system

Technical field

The invention belongs to inverter networking and control technical field, be specifically related to a kind of for state type intermediate frequency The pattern switching transient process control method of power supply group network system.

Background technology

State type intermediate frequency power supply uses the converters of electrically-based electronic switching device to produce 400Hz alternating current needed for life, has volume, weight little, and transformation of electrical energy efficiency is high, power supply layer Level is less, noise is little, dynamic response is fast, high reliability, and is easily achieved modularity, collection Cheng Hua.At present, state type intermediate frequency power supply is used for aviation and military field, along with military and economical Development, above-mentioned field is increasing for the capacity requirement of Intermediate frequency power supply system system, and in state type The group net operation of frequency power can expand power system capacity neatly, forms redundant system easily, mutually For backup, improve power supply reliability and the seriality of nucleus equipment.

But, for state type intermediate frequency power supply group network system, pattern switching transient process controls Quality has vital work to the stability of group network system and the life-span of networking each unit equipment With.Seamless switching between networking unit and intermediate frequency electrical network, it is ensured that important negative in networking unit The power supply continuity of lotus, also has important effect, conduct to the safe and stable operation of electrical network The important technology feature of group network system causes to be paid attention to widely.

Fig. 1 shows in detail state type intermediate frequency power supply networking, independent operation mode switching principle figure.Group Net unit uses voltage, the current double closed-loop i.e. voltage of ratio resonance (PR) control when stand-alone mode Source output mode, uses single electric current loop PR control i.e. current source output mode, group when networking model Net unit outfan connects through static switch control with electrical network, and static switch Guan Bi is networking list Unit's outfan accesses electrical network, and static switch is broken as networking unit and departs from electrical network.Host computer passes through mould Formula switching logic controls networking unit in two close cycles PR control model and single electric current loop PR control model Between switching.

Pattern at state type intermediate frequency power supply networking or off-grid switches in transient process, in fact it could happen that relatively Big voltage or rush of current, this is all unfavorable for intermediate frequency electrical network, load and intermediate frequency power supply itself 's.From the point of view of in theory, when mode switch and static switch synchronism switching, impact minimum, but actual During, due to factor, mode switch and static switches such as system and switch motion time delays hardly May realize synchronizing, therefore, during networking or off-grid, it is necessary to carry out effectively and reasonably Transient process controls.

The power frequency field that concentrates on that research is more is controlled, mainly currently for pattern switching transient process When showing as separate unit power frequency inverter or the load of micro-capacitance sensor band this locality, and the de-/networking between bulk power grid Handoff procedure.

Tang Xisheng et al. in 2011 in paper " micro-grid connection based on energy storage/off-network seamless switching skill Art " (electrotechnics journal, 2011,26 (1): 279-284) propose a kind of based on energy storage micro- Netting grid-connected/off-network seamless switching technique, this technology utilizes the energy storage can be at voltage mode control and electric current Flexible rapid translating between control model, completes the role transforming of power supply networking and off-grid, but the method State type intermediate frequency power supply for height underdamping can not directly be suitable for, and adds energy-storage units, System structure changes, reliability and economy reduce, cannot ensure appendent computer system without impact Grid-connected.

Chen Xiao et al. in 2012 in paper " design of independence/grid-connected dual-mode photovoltaic inverting system " (Power Electronic Technique, 2012,46 (1): 56-60) proposes a kind of logic-based chip UTC4053 Hardware circuit changing method realize the switching of the grid-connected and independent two kinds of mode of operations of inversion system. The method is as two input channels using be incorporated into the power networks control method and independent operating control method, Then given mode select signal by single-chip microcomputer and realize the selection of passage through UTC4053, the most also/ Off-grid state, this is preferable for small-power, simple power frequency inverter effect, and Large Copacity is static Formula intermediate frequency power supply system output current is relatively big, and the time delay that passage switching produces is for Phase synchronization control System impact strengthens, and not only adds extra chip, and cannot meet the flat of system power peak value All distribution and peak value, smooth adjustment of phase place.

The studies above is all based on power frequency system, but, for state type intermediate frequency power supply group network system Speech, output voltage frequency is the octuple of power frequency, when switching frequency is 10kHz, for power frequency system System, the phase contrast between twice action of switching device is 1.8 °, and middle state type intermediate frequency power supply networking Between twice action of system switching device, phase contrast is 14.4 °, and group network system pattern switching transient state controls Difficulty be greatly increased, existing pattern switching transient process control for state type intermediate frequency power supply group By helpless for net system.

Summary of the invention

It is an object of the invention to overcome the deficiency of above-mentioned technology, propose one for state type medium frequency electric The pattern switching transient process control method of source group network system, this control method can solve pattern and cut Change current amplitude and SPA sudden phase anomalies in transient process, and ring current shock cause greatly the problem that networking is failed, Ensure networking unit putting down with less rush of current implementation pattern switching during networking and off-grid Steady transition.

For achieving the above object, the mould of the state type intermediate frequency power supply group network system that the present invention provides Formula switching transient process control method, its step includes:

Mode A, state type intermediate frequency power supply networking unit independent operating is switched to group net operation method, Follow the steps below,

(1) state type intermediate frequency power supply group network system host computer monitoring intermediate frequency electrical network output voltage U_grid, And calculate intermediate frequency line voltage U in real time by logic and digital operation module UC&CG_{grid_pk}In, Frequently electrical network output total current I_{grid_pk}, intermediate frequency current on line side virtual value I_{grid_RMS}, pass through CAN Transmit information to each state type intermediate frequency power supply networking unit；

(2) state type intermediate frequency power supply networking unit is internal follows the tracks of intermediate frequency by discretization digital phase-locked loop The phase place of line voltage；

(3) host computer judges intermediate frequency electrical network output voltage U_gridWhether meet networking condition and static Formula intermediate frequency power supply networking unit output voltage in amplitude, phase place with intermediate frequency electrical network output voltage U_grid Whether mate, if meeting above-mentioned condition, entering step (4), otherwise proceeding to step (1)；

Wherein, the Rule of judgment of described step (3) is preferably:

Intermediate frequency electrical network output voltage U_gridScope: 113V～118V；

Difference in magnitude scope :-1V～+1V；

Phase range: ± π/360；

(4) state type intermediate frequency power supply group network system host computer sends networking instruction by CAN UpCmd_1, networking appendent computer system once confirms that networking instructs, first closed mode switch, by defeated Go out control model to control to be converted to networking model list electric current loop PR control from stand-alone mode two close cycles PR System, networking appendent computer system output given value of current initial value I_{refn_pk}, then, at voltage zero-crossing point of power grid Guan Bi static switch；

In said process, mode switch must close prior to static switch；

(5) by relationship below synchronization control state type intermediate frequency power supply networking appendent computer system output electricity The given initial value I of stream_{refn_pk}With initial phase I_{refn_θ}, it is ensured that networking cell pairs frequency electrical network synchronization with Track, until group network system stable operation；

First, the output given value of current initial value I of state type intermediate frequency power supply networking appendent computer system_{refn_pk}By electricity Net output total current I_{grid_pk}, networking main computer unit output current peak I_{1_pk}And networking appendent computer system is defeated Go out current peak I_{n_pk}By current peak actuator I_adTogether deciding on, concrete regulative mode is as follows:

$\begin{array}{cc}\begin{array}{c}{I}_{refn\_pk}=\frac{1}{n}{I}_{grid\_pk}+I_{pk\_offset}\\ I_{pk\_offset}=I_{1\_pk}-I_{n\_pk}\end{array}& \left\{\begin{array}{cc}{I}_{pk\_offset}=I_{pk\_offset},& |I_{1\_pk}-I_{n\_pk}|<{\mathrm{\&Delta;I}}_{pk}\\ I_{pk\_offset}=I_{pk\_offset}+I_{pk\_step},& |I_{1\_pk}-I_{n\_pk}|>{\mathrm{\&Delta;I}}_{pk}\end{array}\right.\end{array}$

In above-mentioned formula: n is state type intermediate frequency power supply networking element number, I_{pk_offset}For in state type Peak point current between frequency power networking unit is poor, Δ I_pkFor peak point current difference restriction range, its value can Need to be set according to real system, I_{pk_step}Step-length is regulated for peak value.

Secondly, the initial phase I of state type intermediate frequency power supply networking appendent computer system_{refn_θ}By discretization numeral Phaselocked loop output phase place I_{pll_θ}With from machine output voltage phase place U_{n_θ}Together decide on, concrete regulative mode As follows:

$\begin{array}{cc}\begin{array}{c}{I}_{refn\_\mathrm{\&theta;}}=I_{pll\_\mathrm{\&theta;}}+I_{\mathrm{\&theta;}\_offset}\\ I_{\mathrm{\&theta;}\_offset}=U_{n\_\mathrm{\&theta;}}-I_{pll\_\mathrm{\&theta;}}\end{array}& \left\{\begin{array}{cc}{I}_{\mathrm{\&theta;}\_offset}=I_{\mathrm{\&theta;}\_offset},& |U_{n\_\mathrm{\&theta;}}-I_{pll\_\mathrm{\&theta;}}|<{\mathrm{\&Delta;I}}_{\mathrm{\&theta;}}\\ I_{\mathrm{\&theta;}\_offset}=I_{\mathrm{\&theta;}\_offset}+I_{\mathrm{\&theta;}\_step},& |U_{n\_\mathrm{\&theta;}}-I_{pll\_\mathrm{\&theta;}}|>{\mathrm{\&Delta;I}}_{\mathrm{\&theta;}}\end{array}\right.\end{array}$

In above-mentioned formula: I_{θ_offset}For state type intermediate frequency power supply networking appendent computer system phase-locked output phase place with Actual output voltage phase contrast, Δ I_θFor phase contrast restriction range, its value can be according to real system needs It is set, I_{θ_step}For phase adjusted step-length.

State type intermediate frequency power supply networking unit group net operation is switched to independent operating:

(1) state type intermediate frequency power supply group network system host computer monitors intermediate frequency electrical network output voltage in real time U_gridThe most stable, if stable, then enter step (2), otherwise, continue monitoring, until intermediate frequency Electrical network output voltage U_gridStable；

(2) state type intermediate frequency power supply group network system host computer sends off-grid instruction by CAN UpCmd_0, networking appendent computer system once confirms that off-grid instructs, and networking appendent computer system immediately will output Given value of current initial value I_{refn_pk}Reducing to local load current, then at voltage zero-crossing point of power grid, disjunction is quiet State switchs；

(3) host computer judges static switch whether disjunction, if disjunction, then enters step (4), no Then enter step (2)；

(4) mode switch disconnects, and networking appendent computer system is converted to from single electric current loop PR control model Two close cycles PR control model, gives this locality load uninterrupted power supply, and pattern switching transient process terminates.

In said process, static switch must disconnect prior to mode switch；

Control method of the present invention need not additional special energy storage device or logical operation circuit, only profit Transmit digital quantity by CAN, and by the mean allocation of networking cell current peak value and peak value, The smooth adjustment of phase place, can realize state type intermediate frequency power supply group network system pattern switching transient process Smooth transition, solve current amplitude, SPA sudden phase anomalies, the problem that ring current shock is big, and output Voltage waveform and input current waveform are unaffected.Specifically, the present invention is relative to prior art Have the advantage that

(1) owing to using host computer to be responsible for the monitoring of whole intermediate frequency electrical network, networking appendent computer system electric current Distribution and the appointment of main frame operational mode, both alleviated group network system main frame and appendent computer system Computational burden, improves reliability and the redundancy of state type intermediate frequency power supply group network system simultaneously.

(2) redundancy and stronger anti-interference that CAN node configures are utilized, it is achieved static The data exchange of formula intermediate frequency power supply group network system host computer and slave.Owing to CAN is mainly born Duty transmission main frame designated order, voltage on line side, current peak and from machine reference current peak value equiband Less digital quantity, efficiency of transmission is higher and transmission range is greatly improved.

(3) current peak that have employed closed loop mode due to pattern switching transient process in controlling is average Distribution and peak value, the smooth adjustment of phase place, on the one hand, need not additionally increase logical operation circuit, Utilize logical AND digital operation module and the rheonome of internal system.On the other hand, Electrical network, main frame and share each other from the electric current of machine in group network system, it is ensured that current peak and phase place Quick regulation.Thus, it is ensured that the integrity of state type intermediate frequency power supply group network system structure, easily Strong in realization and capacity of resisting disturbance.

(4) owing to switching in transient process in the pattern of off-grid, networking appendent computer system first will output Current reference value reduces to local load current, networking appendent computer system feedback when reducing static switch disjunction Enter the impact of power network current, thus, the output voltage waveforms of state type intermediate frequency power supply group network system is relatively Good.

(5) due to mode switch elder generation when networking is followed in the switching of state type intermediate frequency power supply group network system pattern Guan Bi, the principle that during off-grid, static switch first disconnects, although load voltage sudden change number of times is more, but Because the amplitude of networking unit DC voltage limits the sudden change of output voltage, it is suppressed that system circulation, The safety of networking unit will not be threatened, and power work is the most stable in transient process.

Accompanying drawing explanation

Fig. 1 is state type intermediate frequency power supply networking, independent operation mode switching principle figure.

Fig. 2 is state type intermediate frequency power supply group network system block diagram.

Fig. 3 is that state type intermediate frequency power supply networking model switches transient process control flow chart.

Fig. 4 is that state type intermediate frequency power supply talk-around mode switches transient process control flow chart.

Fig. 5 is state type intermediate frequency power supply group network system control block diagram.

Detailed description of the invention

Below in conjunction with the accompanying drawings the present invention is described in further detail.

It is illustrated in figure 2 state type intermediate frequency power supply group network system block diagram.

It is first powered on by a certain state type intermediate frequency power supply, constitutes an Intermediate frequency power supply system net, work as intermediate frequency After electrical network is set up, by voltage, the electric current of upper computer detection electrical network, and judge whether it can permit Permitted from machine networking.If allowing, then mode switch first closes, and then static switch closes a floodgate, networking system All of in system operate in monocycle (networking model list electric current loop PR control model, be called for short monocycle) from machine I.e. electric current loop pattern, provides intermediate frequency electric energy and exchanges with intermediate frequency electrical network to local intermediate frequency load simultaneously Energy；Main frame operates in two close cycles (stand-alone mode two close cycles PR control model is called for short two close cycles) I.e. voltage, electric current loop pattern, provides fixed phase and current on line side amplitude to networking from machine；Upper Machine is responsible for detecting current electric grid voltage, current value, carries out reference current value from machine give grid-connected, Meanwhile, host computer is responsible for detecting Host Status, when main frame breaks down off-grid, specifies it immediately Certain networking unit remaining operates to host mode, it is achieved the seamless switching of slave power supply.Work as separate unit When machine needs off-grid, static switch disconnects, and off-grid needs to select to shut down according to this locality load from machine Or operate in two close cycles state.

It is illustrated in figure 3 state type intermediate frequency power supply networking model switching transient process control flow chart.

As a example by state type intermediate frequency power supply networking unit 2, when it is switched to networking fortune by independent operating During row, pattern switching transient process controls to comprise the following steps:

(1) state type intermediate frequency power supply group network system host computer monitoring intermediate frequency electrical network output voltage U_grid With output electric current I_grid。

Fig. 5 is state type intermediate frequency power supply group network system control block diagram.Shown in figure, host computer will inspection The intermediate frequency electrical network output voltage U measured_gridWith output electric current I_gridIncreased by line voltage feedback respectively Benefit module K_U, current feedback gain module K_I, zero-order holder and low pass filter G_f, finally Send into logic and digital operation module UC&CG is calculated intermediate frequency line voltage U in real time_{grid_pk}、 Intermediate frequency electrical network output total current I_{grid_pk}, phase place and intermediate frequency electrical network current on line side virtual value I_{grid_RMS}, U_{grid_pk}、I_{grid_pk}、I_{grid_RMS}It is transferred to networking unit 1 and networking unit 2 by CAN, Now networking unit 3 has neither part nor lot in networking.

(2) networking unit 2 is internal follows the tracks of line voltage by discretization digital phase-locked loop D-DPLL Phase place, not only alleviates the transmission pressure of CAN, and ensures that output voltage is in amplitude, phase With intermediate frequency electrical network output voltage U on position and frequency_gridMatch；

(3) host computer judges intermediate frequency electrical network output voltage U_gridWhether meet networking condition and static Formula intermediate frequency power supply networking networking unit output voltage in amplitude, phase place with intermediate frequency electrical network output voltage U_gridWhether mate, if meeting above-mentioned condition, entering step (4), otherwise proceeding to step (1)；

Described Rule of judgment is particularly as follows: intermediate frequency electrical network output voltage U_gridScope: 113V～118V；

Difference in magnitude scope :-1V～+1V；

Phase range: ± π/360；

(4) networking unit 2 performs the networking instruction that host computer is sent by CAN UpCmd_1。

As it is shown in figure 5, networking unit 2 once confirms that networking instructs, first closed mode switch, Control to be converted to networking model list electric current loop PR from stand-alone mode two close cycles PR by output control model Control, export given value of current initial value I_{ref2_pk}, then, at voltage zero-crossing point of power grid, close static state open Close, now, though load terminal voltage there will be amplitude and crosses punching, but limited by DC voltage amplitude, It is crossed punching and also can be restricted, and local load current and net side export current distortion limitation. Networking unit 1 is still operated in two close cycles PR control model, wherein G in above process_PRV、 G_PRIIt is respectively outer voltage and current inner loop controller.

(5) by relationship below synchronization control state type intermediate frequency power supply networking appendent computer system output electricity The given initial value I of stream_{ref2_pk}With initial phase I_{ref2_θ}, it is ensured that networking cell pairs frequency electrical network synchronization with Track, networking unit 1 will output current peak I by CAN_{1_pk}Real-time Transmission is given from machine networking Unit 2；

First, the output given value of current initial value I of state type intermediate frequency power supply networking appendent computer system_{ref2_pk}By electricity Net output total current I_{grid_pk}, host groups net unit output current peak I_{1_pk}And networking appendent computer system is defeated Go out current peak I_{2_pk}By current peak actuator I_adTogether deciding on, concrete regulative mode is as follows:

In above-mentioned formula: I_{pk_offset}It is poor for the peak point current between state type intermediate frequency power supply networking unit, ΔI_pkFor peak point current difference restriction range, its value can need to be set according to real system, I_{pk_step}

$\begin{array}{cc}\begin{array}{c}{I}_{ref2\_pk}=\frac{1}{n}{I}_{grid\_pk}+I_{pk\_offset}\\ I_{pk\_offset}=I_{1\_pk}-I_{2\_pk}\end{array}& \left\{\begin{array}{cc}{I}_{pk\_offset}=I_{pk\_offset},& |I_{1\_pk}-I_{2\_pk}|<{\mathrm{\&Delta;I}}_{pk}\\ I_{pk\_offset}=I_{pk\_offset}+I_{pk\_step},& |I_{1\_pk}-I_{2\_pk}|>{\mathrm{\&Delta;I}}_{pk}\end{array}\right.\end{array}$

Regulate step-length for peak value, be equivalent in actual DSP operation in peak point current difference more than restriction range Time, to I_{pk_offset}Carrying out PI regulation, main purpose is to ensure that the smooth adjustment of current amplitude.Above-mentioned Process is the idle amplitude modulation process during networking.

Secondly, the initial phase I of networking unit 2_{ref2_θ}Defeated by discretization digital phase-locked loop D-DPLL Go out phase place I_{pll_θ}With from machine output voltage phase place U_{2_θ}Together deciding on, concrete regulative mode is as follows:

$\begin{array}{cc}\begin{array}{c}{I}_{ref2\_\mathrm{\&theta;}}=I_{pll\_\mathrm{\&theta;}}+I_{\mathrm{\&theta;}\_offset}\\ I_{\mathrm{\&theta;}\_offset}=U_{2\_\mathrm{\&theta;}}-I_{pll\_\mathrm{\&theta;}}\end{array}& \left\{\begin{array}{cc}{I}_{\mathrm{\&theta;}\_offset}=I_{\mathrm{\&theta;}\_offset},& |U_{2\_\mathrm{\&theta;}}-I_{pll\_\mathrm{\&theta;}}|<{\mathrm{\&Delta;I}}_{\mathrm{\&theta;}}\\ I_{\mathrm{\&theta;}\_offset}=I_{\mathrm{\&theta;}\_offset}+I_{\mathrm{\&theta;}\_step},& |U_{2\_\mathrm{\&theta;}}-I_{pll\_\mathrm{\&theta;}}|>{\mathrm{\&Delta;I}}_{\mathrm{\&theta;}}\end{array}\right.\end{array}$

In above-mentioned formula: I_{θ_offset}For state type intermediate frequency power supply networking appendent computer system phase-locked output phase place with Actual output voltage phase contrast, Δ I_θFor phase contrast restriction range, its value can be according to real system needs It is set, I_{θ_step}For phase adjusted step-length, be equivalent at phase contrast big in actual DSP operation When restriction range, to I_{θ_offset}Carrying out PI regulation, main purpose is to ensure that the smooth adjustment of phase place. Said process is the meritorious phase modulation process in networking model switching transient process.

It is illustrated in figure 4 state type intermediate frequency power supply talk-around mode switching transient process control flow chart.

As a example by networking unit 2, when it is switched to independent operating by group net operation, pattern switches Transient process controls to comprise the following steps:

(1) state type intermediate frequency power supply group network system host computer monitors intermediate frequency electrical network output voltage in real time U_gridThe most stable, if stable, then enter step (2), otherwise, continue monitoring, until intermediate frequency Electrical network output voltage U_gridStable.

(2) state type intermediate frequency power supply group network system host computer sends off-grid instruction by CAN UpCmd_0, networking unit 2 once confirms that off-grid instructs, and networking unit 2 will export electric current immediately Given initial value I_{ref2_pk}Reducing to local load current, then at voltage zero-crossing point of power grid, disjunction static state is opened Close.

In said process, networking unit 2 continues to work under current source control model, and its output electric current is complete Portion pours into local load, though load terminal voltage there will be amplitude and crosses punching, but by DC voltage amplitude Restriction, it crosses punching and also can be restricted, and local load current and net side output current distortion journey Spend limited.

(3) host computer judges static switch whether disjunction, if disjunction, then enters step (4), no Then enter step (2)；

(4) mode switch disconnects, and networking unit 2 is converted to double from single electric current loop PR control model Closed loop PR control model, independent to this locality load uninterrupted power supply, pattern switching transient process terminates.

Obviously, the above is only for clearly demonstrating example, and not to embodiment Restriction.For those of ordinary skill in the field, the most also may be used Make other changes in different forms with the difference according to group network system capacity and quantity.This In without also cannot all of embodiment be given exhaustive.

Claims (4)

1. the pattern switching transient process control method for state type intermediate frequency power supply group network system, described control method includes that state type intermediate frequency power supply networking unit is switched to group net operation method by independent operating and is switched to independent operating method by group net operation, wherein

A: state type intermediate frequency power supply networking unit is switched to group net operation method by independent operating to be carried out as steps described below,

(1) state type intermediate frequency power supply group network system host computer monitoring intermediate frequency electrical network output voltage U_grid, and calculate intermediate frequency line voltage U in real time by logic and digital operation module_{grid_pk}, intermediate frequency electrical network output total current I_{grid_pk}, intermediate frequency current on line side virtual value I_{grid_RMS}, transmit information to each state type intermediate frequency power supply networking unit by CAN；

(2) the internal phase place being followed the tracks of intermediate frequency line voltage by discretization digital phase-locked loop of state type intermediate frequency power supply networking unit；

(3) host computer judges intermediate frequency electrical network output voltage U_gridWhether meet networking condition and state type intermediate frequency power supply networking unit output voltage in amplitude, phase place with intermediate frequency electrical network output voltage U_gridWhether mate, if meeting above-mentioned condition, entering step (4), if being unsatisfactory for described condition, then returning step (1)；

(4) state type intermediate frequency power supply group network system host computer sends networking instruction UpCmd_1 by CAN, networking unit once confirms that networking instructs, first, closed mode switchs, from stand-alone mode two close cycles PR, output control model is controlled be converted to networking model list electric current loop PR control, networking appendent computer system output given value of current initial value I_{refn_pk}, then, close static switch；

(5) synchronization control state type intermediate frequency power supply networking appendent computer system output given value of current initial value I_{refn_pk}With initial phase I_{refn_ θ}, it is ensured that the synchronized tracking of networking cell pairs frequency electrical network, until state type intermediate frequency power supply group network system stable operation；

B: state type intermediate frequency power supply networking unit is switched to independent operating by group net operation to be carried out as steps described below,

(1) state type intermediate frequency power supply group network system host computer monitors intermediate frequency electrical network output voltage U in real time_gridThe most stable, if stable, then enter step (2), otherwise, continue monitoring, until intermediate frequency electrical network output voltage U_gridStable；

(2) state type intermediate frequency power supply group network system host computer sends off-grid instruction UpCmd_0 by CAN, and networking appendent computer system once confirms that off-grid instructs, and networking appendent computer system immediately will output given value of current initial value I_{refn_pk}Reduce to local load current, then disjunction static switch；

(3) host computer judges static switch whether disjunction, if disjunction, then enters step (4), if non-disjunction, returns step (2)；

(4) mode switch disconnects, and networking unit controls to be converted to stand-alone mode two close cycles PR from networking model list electric current loop PR and controls, and gives this locality load uninterrupted power supply, and pattern switching transient process terminates.

The pattern switching transient process control method of state type intermediate frequency power supply group network system the most according to claim 1, it is characterised in that: under described mode A, the Rule of judgment of step (3) is:

Intermediate frequency electrical network output voltage U_gridScope: 113V～118V；

Difference in magnitude scope :-1V～+1V；

Phase range: ± π/360.

The pattern switching transient process control method of state type intermediate frequency power supply group network system the most according to claim 1, it is characterised in that: described static switch Guan Bi and disjunction are required at output voltage zero crossing.

The pattern switching transient process control method of state type intermediate frequency power supply group network system the most according to claim 1, it is characterised in that: under described mode A, networking appendent computer system output given value of current initial value I in step (5)_{refn_pk}With initial phase I_{refn_ θ}Should follow relationship below:

First, the output given value of current initial value I of state type intermediate frequency power supply networking appendent computer system_{refn_pk}Total current I is exported by electrical network_{grid_pk}, networking main computer unit output current peak I_{1_pk}And networking appendent computer system output current peak I_{n_pk}By current peak actuator I_adTogether deciding on, concrete regulative mode is as follows:

In above-mentioned formula: n is state type intermediate frequency power supply networking element number, I_{pk_offset}Poor for the peak point current between state type intermediate frequency power supply networking unit, Δ I_pkFor peak point current difference restriction range, I_{pk_step}Step-length is regulated for peak value；

Secondly, the initial phase I of state type intermediate frequency power supply networking appendent computer system_{refn_ θ}Phase place I is exported by discretization digital phase-locked loop_{pll_ θ}With from machine output voltage phase place U_{n_ θ}Together deciding on, concrete regulative mode is as follows:

In above-mentioned formula: I_{θ _offset}For state type intermediate frequency power supply networking appendent computer system phase-locked output phase place and actual output voltage phase contrast, Δ I_θFor phase contrast restriction range, I_{θ _step}For phase adjusted step-length.