CN106374529B - Distributed energy is grid-connected and reactive compensation composite control method - Google Patents

Distributed energy is grid-connected and reactive compensation composite control method Download PDF

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Publication number
CN106374529B
CN106374529B CN201610852578.9A CN201610852578A CN106374529B CN 106374529 B CN106374529 B CN 106374529B CN 201610852578 A CN201610852578 A CN 201610852578A CN 106374529 B CN106374529 B CN 106374529B
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grid
current
power
reactive
voltage
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CN106374529A (en
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冯文俊
胡海敏
徐刚
金琪
李佳文
杨振睿
冯璇
何正宇
施俊
尤智文
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State Grid Shanghai Electric Power Co Ltd
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State Grid Shanghai Electric Power Co Ltd
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/383
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/48Controlling the sharing of the in-phase component
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/50Controlling the sharing of the out-of-phase component
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/56Power conversion systems, e.g. maximum power point trackers

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

The present invention relates to a kind of distributed energy is grid-connected and reactive compensation composite control method, including following procedure:Real-time grid voltage V is obtained by acquisition moduleS, system power IS, DC bus-bar voltage VdcAfter send digital signal processor DSP to, by the reactive current and grid-connected current being calculated in load, reactive current and grid-connected current are determined into frequency pwm pulse by the generation of PI controller afterwards compared with the adjusting target value of setting and drive inverter power pipe IGBT turn-on and turn-off, the output of each phase grid-connected current of control system and compensation electric current, system is set to export maximum grid-connected power under active preferential mode, the first compensation system reactive current under the idle preferential mode in region, provides that system is active and reactive compensation under regional balance mode.The present invention allows distributed energy access device is more intelligent to be applied in regional power grid, has the characteristics that grid connection efficiency is high by control system output that is each mutually grid-connected and compensating electric current.

Description

Distributed energy is grid-connected and reactive compensation composite control method
Technical field
The present invention relates to a kind of distributed energy grid-connected control method, in particular to a kind of distributed energy is grid-connected and idle Composite control method is compensated, power grid cutting-in control field is belonged to.
Background technique
As world economy continues, the development of high speed, countries in the world are increasing to the demand of fossil energy, so that changing The consumption of the stone energy sharply in addition, the large-scale development of fossil energy and utilization affect global climate, and causes acid rain, temperature The a series of environmental problems such as room effect, depletion of the ozone layer.Research and practice have shown that, solar energy is inexhaustible, and It cleans harmless, is to solve that world energy sources crisis and environmental pollution be most reliable and effective green energy resource.It was predicted that as too The photovoltaic power generation technology of the positive energy main approach of the utilization of resources will rapidly develop within coming few decades, send out to end of this century photovoltaic Electric total amount will account for 60% or more of global power supply.Wherein, the installation of grid-connected photovoltaic system accounts for whole photovoltaic systems 90% or more of installation of uniting, the development trend as field of photovoltaic power generation free from controversy.But photovoltaic power generation power output is by day Gas variation influences have the characteristics that intermittent and uncertainty, so that the utilization rate of photovoltaic combining inverter is only 20% or so, And frequent switching can also be such that grid stability declines, and bring various disturbances to power distribution network, influence power quality.
Under traditional energy shortage and the increasingly serious situation of problem of environmental pollution, the research and development of new energy are obtained Extensive concern both domestic and external.Solar energy is inexhaustible with its, nexhaustible advantage become most potential new energy it One.It meanwhile using new energy such as photovoltaic power generations being the distributed generation resource of representative just gradually from autonomous system towards large-scale grid connection direction Development.
Since 1970s, power electronic technique is developed rapidly, various electronic electric equipment it is extensive Using increasing phenomena such as causing power grid to generate harmonic wave, voltage fluctuation, flickering and three-phase imbalance.These power quality problems The safe and stable and economical operation of electricity supply and use equipment is seriously affected.In addition, with the distributed generation technology of renewable energy Greatly develop, solar energy, wind energy, fuel cell distributed new energy it is grid-connected, lead to the further unstable of power grid.However Requirement of the precision equipment, household electrical appliance that user uses to power grid is higher and higher, serious electric pollution and high-quality electric energy matter The demand of amount increasingly contradiction.
With photovoltaic solar, the grid-connected application of large area of the various energy storage devices such as wind energy, conventional distributed energy is grid-connected Electricity generation system is provided only to electric network active electric energy under normal circumstances, and the reactive energy loaded is generally provided by power grid or by special Reactive-load compensation equipment provides.Current solar grid-connected, wind power grid, electric vehicle V2G are grid-connected only active power It is sent into power grid, and to power factor of reactive power, whole region power distribution network inside regional power grid etc. without any control, Reactive loss in this way on route still has, and is also consumed by capacity of trunk.
Photovoltaic power generation occupies an important position in the utilization of global new energy development, is also gradually increasing to the permeability of power grid Greatly.Grid-connected photovoltaic system is provided only to electric network active electric energy under normal circumstances, i.e., by the direct current of photovoltaic array Electric energy, which is converted to, is fed to power grid with the AC energy of phase with frequency with power grid, and guarantees its power factor with higher.And it bears The reactive energy of load is generally provided by power grid or is provided by dedicated reactive-load compensation equipment, although dedicated reactive-load compensation equipment has There are good compensation characteristic and effect, but this also will increase additional construction cost.
One kind that photovoltaic parallel in system generates electricity as micro-capacitance sensor, the direct current that solar battery group is generated is by grid-connected inverse Become device to be converted into after meeting the alternating current of grid requirements, is directly entered public electric wire net.A small amount of introducing photovoltaic generating module is to electricity Net will not have an impact, however large-scale application very likely destroys system stability and power quality is caused to deteriorate.Photovoltaic power generation by Environment influence is very big, and when weather changes, electricity generation system output power will appear quickly and acute variation, maximum variation Rate is more than 10% nominal output/second.The variation of generated output will lead to output voltage and larger fluctuation occurs, and areal because Environmental change unanimously will lead to power generation by bigger influence.
Traditional grid-connected photovoltaic system includes this several part of photovoltaic array, gird-connected inverter and power grid.Wherein, photovoltaic Array is solar energy collecting and converting means, and effect is to absorb the luminous energy of solar radiation and convert thereof into direct current, grid-connected Inverter is the interface arrangement of entire grid-connected photovoltaic system, and effect is by converting direct-current power into alternating-current power and to access electricity Net.Photovoltaic generating system can only provide active power to power grid, cannot provide reactive power, and active power is highly prone to the sun Light has jurisdiction over the influence of the external environments such as degree of penetrating, environment temperature, and power swing is big, is a kind of intermittent unstable energy, can be right Power grid generates impact.And reactive compensation system only provides idle compensation to power grid.Both it has the following disadvantages:Cost compared with Height has a single function, and utilization rate is low.
Current grid-connection device at full capacity or half rated load work time it is all considerably less, or even quite a few when Between do not work, but equipment is to design according to peak capacity, causes the service efficiency of equipment low.In addition, for distribution The access of the energy leads to area in active output of the access point to grid-connection device, idle none specific standard requirements of output Power quality in domain cannot reach the state of comparison optimization.
When grid-connected photovoltaic system DC side is fitted without energy-storage travelling wave tube, when intensity of illumination is very low or night without System will stop powering when illumination, and photovoltaic parallel in system must be disconnected with power grid in the meantime, be in idle state;Only work as light It could be again grid-connected when being reached a certain level according to intensity.Daily day alternates with night in the case where, photovoltaic parallel in system repeatedly with electricity Net is connected and disconnected from, this makes a big impact to photovoltaic system service life and reduces system availability.
With the rapid growth of China's economy, the capacity of power distribution network is sharply increased, each department lOkV distribution line below 50% or so of regional total power supply volume is provided, still, major part power distribution network in China's operates in natural power factor for a long time Below.Reactive capability is insufficient and response is slowly that the problem of presence for a long time in China's distribution, can all cause huge loss every year. Reactive compensation is most important for the safe and economic operation of power distribution network, and power distribution network is directly connected with load, distribution network line and Reactive power consumed by loading must be balanced, and otherwise will affect voltage operation level.
Summary of the invention
Distributed energy of the present invention is grid-connected and reactive compensation composite control method discloses new scheme, passes through real-time measurement System power situation passes through the adjusting target with setting by the component size that corresponding algorithm analysis system is active and idle Value compares, and controls the switch of IGBT, so that control system output that is each mutually grid-connected and compensating electric current, finally makes system active excellent Maximum grid-connected power is exported under first mode, the first compensation system reactive current under the idle preferential mode in region is flat in region The active and reactive compensation of system is provided under weighing apparatus mode, the control higher cost of existing scheme is solved, has a single function, equipment benefit With the low problem of rate.
Distributed energy of the present invention is grid-connected and reactive compensation composite control method includes following procedure:It is obtained by acquisition module Obtain real-time grid voltage VS, system power IS, DC bus-bar voltage VdcAfter send digital signal processor DSP, digital signal to Processor DSP is according to the network voltage V receivedS, system power IS, DC bus-bar voltage VdcBy the nothing being calculated in load Function electric current and grid-connected current generate reactive current and grid-connected current by PI controller afterwards compared with the adjusting target value of setting Determine frequency pwm pulse driving inverter power pipe IGBT turn-on and turn-off, each phase grid-connected current of control system is defeated with compensation electric current Out, system is made to export maximum grid-connected power under active preferential mode, the first compensation system under the idle preferential mode in region Reactive current, provides that system is active and reactive compensation under regional balance mode.
Further, the system of this programme includes that DSP module, AD signal processing module, data processing module, SPWM pulse are defeated Module, digital PI controller module out, under reactive compensation mode, controller acquires institute's electricity demand from power grid, passes through AD signal Processing module is converted to digital quantity, calculates the power for needing to compensate by data processing module, passes through digital PI controller mould Block, SPWM pulse output module are converted to IGBT bridge control signal, issue the pwm signal switched at high speed by controller to control The switch of IGBT bridge provides idle and harmonic power to load, and under grid-connect mode, controller acquires network voltage in real time, control Device measures inverter output current and power grid electricity according to whether collected network voltage detection network operation state is normal simultaneously Whether pressure synchronizes, voltage zero-crossing point of power grid, is closed and network relay realization is grid-connected.
Further, the system of this programme further includes protective module, and protective module is according to obtained SVG DC capacitor voltage mistake It is high or capacitor voltage difference is excessive up and down or network voltage exception or the excessively high information of power device temperature cut off PWM output signal, SVG is closed.
Further, the system of this programme further includes IGBT converter temperature detecting module, IGBT converter temperature detection mould Root tuber is sent out high temperature alarm signal by twin wire serial bus communication interfaces according to the high temperature signal of collected IGBT converter DSP module is given, DSP module closes SPWM pulse output module by protective module according to the high temperature alarm signal received.
Further, the system of this programme further includes communication module RS485, RS232 and with the read-only storage of electric erazable programmable Device, system are communicated by communication module RS485, RS232 with control centre, and system passes through band Electrically Erasable Programmable Read-Only Memory Realize data protection, store function.
Further, this programme also uses phase lock control output phase, frequency signal consistent with input signal, phaselocked loop The difference of the phase information of network voltage and the phase information of the lockin signal of output is output to loop filter by phase discriminator, poor Value signal after loop filter filters out noise enter voltage-controlled oscillator adjustment phase place information until output phase information with The phase information of network voltage is consistent, realizes locking phase.
Further, the DC bus-bar voltage V of this programmedcVoltage V is set with DC side* dcMore afterwards through PI1 controller, two Grid-connected current active component i is generated after secondary trapper processing* sd, network voltage VSThree-phase VSU、VSV、VSWAfter uvw/ α β transformation Obtain V、VMajor network voltage positive sequence fundamental wave is obtained through positive sequence fundamental extraction while calculating negative phase-sequence and harmonic component passes through feedforward Control is to inhibit influence of the grid disturbance to current control, system power ISThree-phase ISU、ISV、ISWAfter uvw/ α β transformation To I、I, system passes through V、VWith I、IDetection controls after relatively through secondary trapper, PI2 after obtaining reactive power Grid-connected current reactive component i is generated after device processing* sq, grid-connected current active component i* sd, grid-connected current reactive component i* sqThrough dq/ α β converts to obtain i* 、i* , i* 、i* With I、IMore afterwards through quasi- PR controller processing after through α β/uvw transformation after through SPWM Three phase inverter bridge is delivered to after modulation.
Further, this programme obtains the electric current other than the real part of forward-order current phasor by the vector of symmetrical component method Component, the real part of forward-order current phasor are active components, and the current component other than the real part of forward-order current phasor includes positive sequence electricity Flow the imaginary part and negative-sequence current phasor of phasor.
Distributed energy of the present invention is grid-connected and reactive compensation composite control method is each mutually grid-connected by control system and compensates The output of electric current allows distributed energy access device is more intelligent to be applied in regional power grid, has grid connection efficiency high The characteristics of.
Detailed description of the invention
Fig. 1 is the schematic illustration of this programme control method.
Fig. 2 is active power, the schematic illustration of reactive power control method under two rest frames.
Fig. 3 is the schematic illustration of phaselocked loop.
Fig. 4 is the vector block diagram of symmetrical component method.
Fig. 5 is the schematic diagram of system parallel connection access power grid.
Specific embodiment
Below in conjunction with attached drawing, the invention will be further described.
Voltage and current sample, the gird-connected inverter of photovoltaic battery array output are generally comprised in grid-connected photovoltaic system Export current sample, network voltage sampling, converters and control system etc..In three-phase photovoltaic grid-connected electricity generation system Gird-connected inverter, main circuit generally use voltage-type full bridge structure, the master of the structure and conventional active reactive power compensator Circuit is completely the same, and therefore, grid-connected and reactive compensation composite control apparatus can be effectively saved equipment investment, simplifies system knot Structure, and there is excellent reactive compensation fast response characteristic, play a significant role to raising power grid tip power supply capacity and quality. Grid-connected and reactive compensation composite control apparatus key technology is the detection and algorithm design to system power, in order to guarantee power grid Power supply quality, device allow for according to system power realize fast reaction.The compound control of grid-connected and reactive compensation of this programme Device processed mainly passes through real-time measurement system current conditions, big by the active and idle component of corresponding algorithm analysis system It is small, by the adjusting target value with setting compared with, the switch of IGBT is controlled, so that control system is each mutually grid-connected and compensates electric current Output finally makes system export maximum grid-connected power under active preferential mode, first mends under the idle preferential mode in region System Reactive Power electric current is repaid, the active and reactive compensation of system is provided under regional balance mode.
Photovoltaic combining inverter topological structure schematic diagram.This programme uses double -loop control mode.Outer ring controller is mainly used In the different control purpose of embodiment, while inner ring reference signal is generated, common dynamic response is slower.Inner loop control device is substantially carried out Fine adjusting, for improving the power quality of inverter output, common dynamic response is very fast.Gird-connected inverter is with power ring Outer ring directly controls the output power of distributed generation resource, it is ensured that system can be in voltage ripple of power network with permanent function Rate output.Using electric current loop as inner ring, in conjunction with voltage space vector modulation mode, solve to adopt caused by traditional switch frequency is not fixed The high defect of sample frequency finally realizes that High Power Factor, invariable power are grid-connected.Gird-connected inverter is the core of grid-connected photovoltaic system Heart equipment, this programme use voltage source inverter, in DC side parallel bulky capacitor, can preferably resist by power grid interference fringe Lai DC voltage fluctuation, be suitable for the biggish occasion of voltage ripple of power network.Grid-connected system utilizes inverter by direct current It can be converted to AC energy input power grid, this programme uses non-scheduling formula grid-connected photovoltaic system.
Reactive power needed for power distribution network usually requires to install reactive power compensator sending reactive power in a power distribution system To compensate the idle of power distribution network consumption.The essential condition that reactive compensation is power distribution network the safe and economic operation is carried out to power distribution network, is closed It is that whether can obtain safety, good electric energy to user.Distribution network var compensation can be effectively improved power quality, reduce line Path loss consumption can also effectively improve generator and transformation to improve the power transmission efficiency of route, improve the ability to transmit electricity of route The power output of device.The reactive compensation control system of this programme consists of two parts, and instruction current computing circuit and compensates electric current Circuit.Instruction current computing circuit detects the reactive current component in target compensation electric current, compensation current occuring circuit according to The command signal for the compensation electric current that instruction current computing circuit obtains, generates actual compensation electric current.This programme uses instantaneous nothing The detection method of function theory detects reactive current.The basic ideas of instantaneous reactive power theory are by abc three-phase system voltage, electricity Circulation changes the vector on α β ο coordinate system into, the dot product of voltage, current phasor is defined as instantaneous active power, by voltage, electric current The cross product of vector is defined as instantaneous reactive power, these power invertings are then compensated electric current for three-phase again.Instantaneous reactive power Theoretical breakthrough power definition of conventional power theory on the basis of " average value ", becoming the real-time detection of reactive current can Energy.This method has preferable real-time for the transient current detection of three-phase balanced system, is conducive to the quick control of system, Preferable compensation effect can be obtained.
Reactive compensation inverter topology and photovoltaic combining inverter topological structure are almost the same, from system structure, function It can be compared respectively analysis with three aspect of control method, both discoveries there are many something in common:(1) configuration aspects, SVG and light Photovoltaic grid-connected system is identical in the mode of inverter topology and connection power grid;(2) in terms of function, the function of SVG is compensation Idle to inject reactive energy to power grid, the function of grid-connected photovoltaic system is to generate electricity by way of merging two or more grid systems to inject active electricity to power grid Can, power grid is both injected in the form of electric current;(3) the exchange side of control method, the two belongs to current follow-up control, can In a manner of using identical current follow-up control.For such system, DC side is usually connected to capacitor, DC capacitor voltage It is to be maintained by the energy exchange of system itself and power grid, when capacitor DC side voltage is more than given value, capacitor passes through To inject active power to power grid reduce DC voltage, maintains its stabilization with this.Therefore, if photovoltaic generating system control Function occurs for setting compensation electric current during making, so that it may realize that photovoltaic parallel in system is injecting the same of active power to power grid When, realize the reactive compensation to power grid.
Grid-connected photovoltaic system can inject active power or reactive power to power grid.When photovoltaic system is with unity power factor control When making grid-connected, if the variation of △ u occurs for grid entry point voltage u, △ i variation occurs for corresponding electric current i.When photovoltaic active power is contributed When greater than certain value, necessarily cause grid entry point voltage out-of-limit, photovoltaic plant preferably makes full use of the reactive power tune of inverter at this time Energy saving power carries out reactive power and voltage is adjusted.Inverter reactive power fan-out capability is not only by self-capacity and transmission line of electricity Limitation, in the case where inverter capacity is sufficiently large, is limited by DC voltage.With photovoltaic system active power, idle The increase of power output, inverter output voltage increase.Inverter ac output voltage exceed its restriction range, at this time with IGBT Antiparallel freewheeling diode conducting, causes commutation failure, and DC side voltage of converter increases, and output electric current is distorted, and has Function power, reactive power fluctuate, and therefore, when power grid needs photovoltaic system to provide the support of larger reactive power, should reduce Active power output operation.
As shown in Fig. 2, active power, Reactive Power Control strategy under two-phase stationary coordinate system, mainly include active power Control ring, reactive power independent control ring, current regulator.For for the foundation of single photovoltaic grid-connected inversion unit shown in figure Reactive power independent control.Under the static α β coordinate system of two-phase, current control amount is sinusoidal quantity, can be real using quasi- PR controller Existing zero steady-state error tracking, and active and reactive electric current is without coupling, it can independent control.Active and reactive control ring output is available simultaneously The active and reactive component given value of net electric currentIt is transformed to current inner loop instruction value under rest frame through dq/ α β, it is inverse Become device and generally phaselocked loop is used to realize with synchronized.And when network voltage distortion and imbalance, especially there are multiple mistakes in voltage When zero point, phaselocked loop meeting losing lock influences inverter normal work.This programme obtains major network voltage using positive sequence fundamental extraction principle Positive sequence fundamental wave, while negative phase-sequence and harmonic component are calculated, by feedforward control to inhibit influence of the grid disturbance to current control, It eliminates because power grid distortion and imbalance cause the negative phase-sequence contained in electric current and harmonic component.
In order to realize the optimization design of recombination current, grid-connected watt current and the System Reactive Power for compensation are required first Electric current can be respectively controlled, i.e., electric current has diversity.For the recombination current of optimization design, although each phase all may Comprising active component, but the active component is not consumption in inverter bridge, but is transferred to power grid by inverter.It realizes The balance of system reactive power compensation and region active power needs to know reactive component and have that every phase load respectively needs Function component.By the vector of symmetrical component method, other than the real part (i.e. active component) of available forward-order current phasor Current component (imaginary part and negative-sequence current phasor including forward-order current phasor).As shown in figure 4, setting threephase load line current size RespectivelyABC three-phase system is converted into α β binary system, because α β transformation has ready-made phasor recognizer component, Positive sequence and negative sequence component are transformed into after phasor identifies, then by α and β component.The real part for extracting forward-order current phasor can obtain three Phase load respectively required for compensation rate, be set to:Wherein:Ia, Ib, IcPoint Not Wei the compensation magnitude of current needed for three-phase amplitude, and α, beta, gamma are then corresponding phase angle.As shown in Figure 1, device detection power grid electricity Reactive compensation electric current and load watt current is obtained by calculation in pressure and system power.By PI controller, according to dead beat control Principle processed generates the turn-on and turn-off for determining frequency pwm pulse driving inverter power pipe IGBT.The available stabilization of the control program Quick current control effect, while system power factor can also be correspondingly improved.
The control of electric current loop is the key component of system control, and power device switching frequency is very high, reaches 10kHz, needs Very quick control method, so current loop control must account in terms of dynamic responding speed, compensation precision two first, It is also contemplated that the DC terminal voltage or the factors such as current utilization rate and power device switching frequency of device itself.This programme uses three Carrier wave linear control methods in angle are a kind of a kind of linear control methods derived by Instantaneous Comparison Method, it passes through electric current reality Compared with the corresponding control signal that deviation between value and reference value generates carries out in real time with the delta modulation wave of high frequency, it is obtained The foundation that is acted as inverter switching device of intersection point.The great advantage of this method is that switching frequency is fixed, and simple and easy, Fast response time has preferable control characteristic to the system of high switching frequency.Electric current loop mainly includes following part:Grid-connected electricity Detection unit, control unit and the pwm pulse allocation unit of stream and load reactive current.Control unit generates modulated signal, this A signal only changes in sampling instant, and remains unchanged before next sampling instant, it is sent into pulse distribution unit and generates IGBT Switching signal, realize control action.As shown in figure 3, device uses phaselocked loop phase tracking system, it is ensured that the phase of output Position is consistent with frequency signal with input signal, its working principle is that phase discriminator is by the locking phase of the phase information of network voltage and output The difference of the phase information of signal is output to loop filter, filters out the noise in difference signal, and then enters voltage control vibration Dynamic device adjustment phase place information simultaneously exports, until last output phase information is consistent with the phase information of network voltage, realizes locking phase.
The major function of the control system of this programme is conditioning real-time monitoring signal, is quickly calculated according to preset algorithm and most Control signal is exported to power circuit eventually.In experimental prototype, master control digital signal processor chooses the DSP core of TI company TMS320F28335, according to the control mode of setting, to obtained by sensor and pass through analog circuit conditioning main circuit direct current, Exchange the pressure of side, current signal is calculated, judged and exported, realization preset strategy.Control system also needs CPLD to realize PWM Signal logic combination realizes that peripheral communications and EEPROM realize the functions such as data protection storage by RS485 and RS232.Electricity Net output end Ua、Ub、UcFor ac grid voltage, loads as three-phase nonlinear load, can consume idle.Multiplex control system by Two large divisions's composition, i.e. idle current detecting circuit and compensation current occuring circuit.Main circuit uses insulated gate bipolar crystal The PWM converter that (IGBT) is constituted is managed, when generating compensation electric current, is worked mainly as inverter.System basic functional principle It is exactly by the electric current in the detection load of sample detecting circuit, by being calculated in load for digital signal processor (DSP) Reactive current and grid-connected power, the operating mode then set by control strategy control active power and reactive power Output.The hardware design of SVG mainly includes main circuit design and control circuit design, and control circuit is the important composition portion of SVG Point, it is mainly made of following components:DSP control circuit, voltage and current detection circuit, PWM output circuit, protection electricity Road, IGBT temperature detection etc..
(1) DSP control circuit
Entire control circuit using 32 floating-point microprocessor TMS320F28335 of TI company as main control chip, TMS320F28335 is under the jurisdiction of Delfino MCU series of products member, and running frequency may be up to 150MHZ, is stringent for requiring Control highly integrated, the high performance solution of application.Control system is aided with the EPM570T100 CPLD core of altera corp Piece, CPLD is substantially carried out the logical process of some digital signals, and dsp chip completes sampled signal processing, control calculates, protection And the major functions such as pwm signal output.
(2) AD signal detection and conditioning unit
AD signal detection includes three-phase power grid voltage signal detection, the detection of threephase load current signal, three-phase SVG output altogether Current detecting, the detection of two-way DC capacitor voltage, are detected through mutual inductor, after operational amplifier circuit conditioning, by external AD sampling A/D chip AD7657 sample conversion, output digit signals to DSP are handled.IGBT temperature is detected by an individual A/D chip AD7995 It completes, is exported by twin wire universal serial bus (I2C) communication interface to DSP.
(3) circuit is protected
The effect of protection circuit is protection SVG failure-free operation, when SVG DC capacitor voltage is excessively high, or capacitor electricity up and down Pressure difference is excessive, and network voltage is abnormal, and when the temperature is excessively high, protection circuit sells of one's property raw protection signal, cutting PWM output letter to power device Number, close SVG.
(4) PWM drives
DSP generates pwm signal after calculation process, by external amplifying circuit amplified signal, using isolated drive circuit Form the IGBT for having the PWM drive signal of driving capability to drive main power circuit.
(5) communicate
Serial communication interface (SCI), Serial Peripheral Interface (SPI) communication interface of DSP control system are whole It is reserved, it is communicated after convenient with control centre.
When reactive compensation mode, controller acquires institute's electricity demand from power grid, is digital quantity by AD conversion, calculates needs The power of compensation is then converted into IGBT bridge control signal, issues the pwm signal switched at high speed by controller to control IGBT bridge Switch, to provide idle and harmonic power for load, transformer no longer needs to idle required for providing load.Grid-connect mode When, controller acquires network voltage in real time, and whether detection network operation state is normal, and measures inverter output current and power grid Whether voltage synchronizes, and after reaching grid-connected requirement, in voltage zero-crossing point of power grid closure, simultaneously network relay realization is grid-connected.Between mode Conversion, can be configured on the LCD liquid crystal display that device provides according to power grid demand.As shown in figure 5, device uses and couples Line mode accesses power grid, and sets there are three types of operating mode:It is grid-connected it is preferential, reactive compensation is preferential, area power balance is preferential, and set There is RS485/RS232 communication interface for the transmission of data and checks.
Electric appliance involved in above scheme, circuit, module and electronic component are in addition to special instruction, according to its realization Concrete function can choose design and scheme generally in the art, can also select according to actual needs other design and side Case.
In grid-connected photovoltaic system, idle detection and compensation control are combined with control of generating electricity by way of merging two or more grid systems, realized simultaneously Net power generation is uniformly controlled with reactive compensation, is feasible in theory and practice.Its work generated electricity by way of merging two or more grid systems operation not only may be used Effectively to provide electric network active electric energy, and the reactive current in transmission power grid can be compensated, be conducive to power grid power supply capacity Positive effect is had especially for the power supply of power grid tip with further increasing for quality.System use based on instantaneous reactive The Detecting Reactive Current mode of Power Theory has obtained successful reality under the digital control support of high-speed dsp in an experiment It is existing.
This programme is closed by the gird-connected inverter control, idle detection and compensation etc. for analysing in depth grid-connected photovoltaic system Key technology simulates parallel network power generation, will generate electricity by way of merging two or more grid systems and carries out comprehensively control with reactive compensation.The photovoltaic parallel in system is integrated with The function of control and reactive compensation of generating electricity by way of merging two or more grid systems is realized in the more stable area of operation of power networks with PV Grid Connected Generation Based on, supplemented by no-power compensation function, and the area more severe in grid power quality, realize the no-power compensation function to power grid Based on, generate electricity by way of merging two or more grid systems supplemented by function.The research of this programme meets that China's geographical conditions difference is big, economic development is uneven, right Energy demand requires different reality, and the harmonious development of development and utilization and green network for new energy has wide application Prospect and important realistic meaning.This programme is disclosed by the structure of comparison grid-connected photovoltaic system and reactive compensation system There are similitudes in structure for the two.Grid-connected photovoltaic system provides active power, and idle system to power grid by current transformer System passes through current transformer and provides reactive compensation to power grid, so in grid-connected system, by idle detection and compensation control and simultaneously Net Generation Control combines, and it is necessary that realization, which is generated electricity by way of merging two or more grid systems with being uniformly controlled for reactive compensation,.The work generated electricity by way of merging two or more grid systems Operation not only can effectively provide electric network active electric energy, but also can compensate the reactive current in transmission power grid, be conducive to electricity Net power supply capacity and quality further increase.
As the world plans that China is to photovoltaic and other renewable energy to the craving of generation of electricity by new energy and " 12th Five-Year Plan " Industry is vigorously supported, and the grid-connected photovoltaic system of this programme not only can effectively realize photovoltaic power generation, improves electric energy matter Amount and reduction power loss, and to corresponding equipment investment is saved, it improves system availability and is also of great significance.
The distributed energy of this programme is grid-connected and reactive compensation composite control method is not limited to public affairs in specific embodiment The content opened, the technical solution occurred in embodiment can also mutually can include with individualism, those skilled in the art according to The simple replacement scheme that this programme combination common knowledge is made also belongs to the range of this programme.

Claims (7)

1. distributed energy is grid-connected and reactive compensation composite control method, it is characterized in that including following procedure:
Real-time grid voltage V is obtained by acquisition moduleS, system power IS, DC bus-bar voltage VdcAfter send at digital signal Device DSP is managed, digital signal processor DSP is according to the network voltage V receivedS, system power IS, DC bus-bar voltage VdcBy meter Calculate loaded in reactive current and grid-connected current, by reactive current and grid-connected current compared with the adjusting target value of setting after Frequency pwm pulse, which is determined, by the generation of PI controller drives inverter power pipe IGBT turn-on and turn-off, each mutually grid-connected electricity of control system The output of stream and compensation electric current makes system export maximum grid-connected power under active preferential mode, idle preferentially in region First compensation system reactive current under mode, provides that system is active and reactive compensation under regional balance mode,
System includes DSP module, AD signal processing module, data processing module, SPWM pulse output module, digital PI controller Module, under reactive compensation mode, controller acquires institute's electricity demand from power grid, is converted to number by AD signal processing module Amount calculates the power for needing to compensate by data processing module, passes through digital PI controller module, SPWM pulse output module IGBT bridge control signal is converted to, the pwm signal switched at high speed is issued by controller and is mentioned to control the switch of IGBT bridge to load For idle and harmonic power, under grid-connect mode, controller acquires network voltage in real time, and controller is according to collected power grid electricity Whether the whether normal inverter output current that measures simultaneously of pressure detection network operation state is synchronous with network voltage, network voltage mistake Zero point, is closed and network relay realization is grid-connected.
2. distributed energy according to claim 1 is grid-connected and reactive compensation composite control method, which is characterized in that system It further include protective module, protective module is excessively high according to obtained SVG DC capacitor voltage or upper and lower capacitor voltage difference is excessive or electric Net electric voltage exception or the excessively high information of power device temperature cut off PWM output signal, and SVG is closed.
3. distributed energy according to claim 2 is grid-connected and reactive compensation composite control method, which is characterized in that system It further include IGBT converter temperature detecting module, IGBT converter temperature detecting module is according to the height of collected IGBT converter High temperature alarm signal is sent to DSP module by twin wire serial bus communication interfaces by warm signal, and DSP module is according to receiving High temperature alarm signal closes SPWM pulse output module by protective module.
4. distributed energy according to claim 1 is grid-connected and reactive compensation composite control method, which is characterized in that system Further include communication module RS485, RS232 and with Electrically Erasable Programmable Read-Only Memory, system by communication module RS485, RS232 is communicated with control centre, and system passes through band Electrically Erasable Programmable Read-Only Memory and realizes data protection, store function.
5. distributed energy according to claim 1 is grid-connected and reactive compensation composite control method, which is characterized in that use Phase lock control output phase, frequency signal are consistent with input signal, and the phase discriminator of phaselocked loop is by the phase information of network voltage It is output to loop filter with the difference of the phase information of the lockin signal of output, difference signal filters out noise through loop filter Afterwards enter voltage-controlled oscillator adjustment phase place information until output phase information it is consistent with the phase information of network voltage, realize Locking phase.
6. distributed energy according to claim 1 is grid-connected and reactive compensation composite control method, which is characterized in that direct current Busbar voltage VdcVoltage V is set with DC side* dcGenerating grid-connected current after PI1 controller, the processing of secondary trapper more afterwards has Function component i* sd, network voltage VSThree-phase VSU、VSV、VSWV is obtained after uvw/ α β transformation、VIt is obtained through positive sequence fundamental extraction Major network voltage positive sequence fundamental wave calculates negative phase-sequence and harmonic component by feedforward control to inhibit grid disturbance to current control simultaneously Influence, system power ISThree-phase ISU、ISV、ISWI is obtained after uvw/ α β transformation、I, system passes through V、VWith I、 IDetection generates grid-connected current reactive component after secondary trapper, the processing of PI2 controller after relatively after obtaining reactive power i* sq, grid-connected current active component i* sd, grid-connected current reactive component i* sqIt converts to obtain i through dq/ α β* 、i* , i* 、i* With I、IThree phase inverter bridge is delivered to after SPWM is modulated after α β/uvw transformation after the processing of quasi- PR controller more afterwards.
7. distributed energy according to claim 1 is grid-connected and reactive compensation composite control method, which is characterized in that pass through The vector of symmetrical component method obtains the current component other than the real part of forward-order current phasor, and the real part of forward-order current phasor is Active component, the current component other than the real part of forward-order current phasor include the imaginary part and negative-sequence current phase of forward-order current phasor Amount.
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