CN203278263U - A bidirectional grid-connected inverter apparatus of a distributed new energy power generation system - Google Patents

Abstract

Provided is a bidirectional grid-connected inverter apparatus of a distributed new energy power generation system. The bidirectional grid-connected inverter apparatus comprises a signal acquiring unit, a master control unit, a rectification inverter unit, and an electricity storing unit. The signal acquiring unit comprises a first signal acquiring unit and a second signal acquiring unit. The input end of the first signal acquiring unit is connected with the DC input end of the rectification inverter unit. The input end of the second signal acquiring unit is connected with the power grid end of the rectification inverter unit. The rectification inverter unit comprises a bridge-type rectification circuit, a bridge-type inverter circuit, a Boost boost circuit, and a Cuk voltage reduction circuit. A storage battery of the electricity storing unit is connected with the distributed new energy power generation system through a storage battery controller. Firstly, the bidirectional grid-connected inverter apparatus performs fast determination and cut off the distributed new energy power generation system from the power grid if the distributed new energy power generation system is in an island state. Then the bidirectional grid-connected inverter apparatus calls an active detecting function to detect the result of a passive detecting function. The bidirectional grid-connected inverter apparatus fully functions an advantage of high detecting accuracy of the active detecting function and overcomes defects of a long detecting time and large harmonic pollution of the power grid.

Description

A kind of two-way parallel network reverse device of distributed new electricity generation system

Technical field

The utility model belongs to distributed new generating and technical field of electricity, is specifically related to a kind of two-way parallel network reverse device of distributed new electricity generation system.

Background technology

The energy is the source of human economy and cultural activity.Electric energy relies on its status of waiting many advantages to be sure to occupy energy currency convenient for cleaning.Along with the fossil energy of all parts of the world is day by day exhausted, new forms of energy (as wind energy, solar energy etc.) distributed power generation has more and more received people's concern with its exclusive characteristics.But island effect becomes the principal element of restriction distributed generation technology development.Its reason is mainly the distribution technique that supplies that distributed generation technology is different from the generating of traditional high-power station, large grid power transmission, the characteristics such as, scattered distribution little due to himself generate output, traditional scheduling mode can not control effectively, and will make the distributed generation system that is incorporated into the power networks be absorbed in island state when the access electrical network breaks down like this.The reliability, the controllability that are incorporated into the power networks in order to improve the distributed generation system that is incorporated into the power networks are given full play to the advantage of distributed generation system, and various countries all require to have the island effect measuring ability for the distributed generation system that is incorporated into the power networks.

The method of isolated island detection at present is existing a variety of, mainly is divided into active detecting, passive detection and detects based on the isolated island of communicating by letter.But the shortcomings such as these methods respectively have deficiency, and for example active detecting can produce disturbance to electrical network, and the passive detection threshold value is chosen difficulty, and the blind area is larger.

Simultaneously, due to the deficiency of distributed new interconnection technology, for avoiding distributed new, electrical network is impacted, the relevant laws and regulations that cause user side to be incorporated into the power networks are comparatively strict, and this has seriously limited the development of distributed new.

Summary of the invention

For the deficiency that prior art exists, the utility model provides a kind of two-way parallel network reverse device of distributed new electricity generation system.

The technical solution of the utility model is:

A kind of two-way parallel network reverse device of distributed new electricity generation system comprises signal gathering unit, main control unit, commutation inversion unit and electricity accumulating unit.

Described signal gathering unit comprises first signal collecting unit and secondary signal collecting unit, first signal collecting unit loader is connected to the direct-flow input end of commutation inversion unit, secondary signal collecting unit input is connected to the electrical network end of commutation inversion unit, and the output of first signal collecting unit is connected output and is all connected main control unit with the secondary signal collecting unit.

described commutation inversion unit comprises bridge rectifier, bridge inverter main circuit, Boost booster circuit and Cuk reduction voltage circuit, the input of Cuk reduction voltage circuit is connected input and is all connected the distributed new electricity generation system with the Boost booster circuit, the output of Cuk reduction voltage circuit connects the input of bridge rectifier, the output of Boost booster circuit connects the input of bridge inverter main circuit, the input of bridge rectifier, the input of bridge inverter main circuit also connects respectively main control unit, the output of bridge rectifier and the output of bridge inverter main circuit are connected to electrical network through circuit breaker.

Described electricity accumulating unit comprises storage battery and battery controller, and storage battery is connected to the distributed new electricity generation system through battery controller.

A side that is connected with the distributed new system of described commutation inversion unit is connected with ultracapacitor.

Described first signal collecting unit and secondary signal collecting unit include voltage sensor, current sensor, Frequency tester, bandwidth-limited circuit, three-phase voltage sampled signal modulation circuit, three-phase current sampled signal modulation circuit and frequency sampling signal modulation circuit.

The output of voltage sensor, the output of current sensor are connected output and all are connected with the input of bandwidth-limited circuit with Frequency tester, the output of bandwidth-limited circuit connects respectively the input of three-phase voltage sampled signal modulation circuit, the input of three-phase current sampled signal modulation circuit and the input of frequency sampling signal modulation circuit, and the output of the output of three-phase voltage sampled signal modulation circuit, three-phase current sampled signal modulation circuit and the output of frequency sampling signal modulation circuit all are connected to the input of main control unit.

Described main control unit is connected with power module, communication module, memory module and display module.

The mode of operation of described commutation inversion unit comprises inverter mode and rectification pattern; when the generating of distributed new electricity generation system is sufficient; the commutation inversion cell operation is at inverter mode; when distributed new electricity generation system abnormal electrical power supply or when needing electrical network to be charge in batteries, the commutation inversion cell operation is in the rectification pattern.

Described storage battery adopts lead acid accumulator, in parallel between each storage battery: battery controller comprises voltage stabilizing chip, power supply control chip and output pressure regulation chip, storage battery connects voltage stabilizing chip input, the output of voltage stabilizing chip connects the input of power supply control chip, output pressure regulation chip input is connected to the output of power supply control chip, and output pressure regulation chip output connects the distributed new electricity generation system.

The course of work of the two-way parallel network reverse device of described distributed new electricity generation system is as follows:

Step 1: voltage, electric current, the frequency of the DC side of the voltage of the common coupling node PCC of Real-time Collection electrical network, electric current, frequency and commutation inversion unit, and carry out filtering, noise reduction and transformation and process:

Step 2: the data of voltage, electric current and frequency after filtering, noise reduction and transformation are processed are carried out normalized, and the memory module that transfers to main control unit is preserved:

Step 3: initialization distributed new electricity generation system parameter comprises resistance value R, inductance value L and capacitance C;

Step 4: according to the data after the normalization of memory module preservation, active-power P and the reactive power Q of calculatingization distributed new electricity generation system also deposits memory module in and preserves;

Step 5: the data in memory module are sent into main control unit, utilize overvoltage/undervoltage/mistake under-frequency detection method to carry out passive isolated island and detect;

Step 5.1: the degree of unbalance of calculating active power and the degree of unbalance of reactive power also are stored to memory module:

Step 5.2: the voltage signal V that utilizes the method detection of grid point of common coupling of wavelet analysis _PCCSingular point:

Step 5.3: if V detected _PCCThere is singular point, and the degree of unbalance of active power and the imbalance of reactive power surpass threshold value, the distributed new electricity generation system has been in island state, main control unit sent the PWM ripple distributed new electricity generation system was carried out inversion control this moment, to drive circuit breaker, the distributed new electricity generation system is excised from electrical network, otherwise execution in step 6;

Step 6: utilize the active frequency shift method to carry out the active isolated island and detect;

Step 6.1: according to voltage, the current value at the electrical network point of common coupling place that gathers, the angular frequency of the PCC Nodes after the phase angle of the voltage after calculation perturbation, the phase angle of electric current and disturbance _Pcc

Step 6.2: the impedance angle of Computation distribution formula grid-connected power generation system;

Step 6.3: calculating frequency shift maximum ω _maxWith frequency displacement minimum value ω _min

Step 6.4: judgement ω _min＜ω _pcc＜ω _maxWhether set up, be, passive isolated island testing result is accurate, otherwise passive isolated island testing result is inaccurate, main control unit sent the PWM ripple distributed new electricity generation system was carried out inversion control this moment, drives circuit breaker the distributed new electricity generation system is excised from electrical network;

Step 7: the data of storing in memory module show in real time by display module, provide the maintenance foundation to the maintainer.

Beneficial effect:

The two-way parallel network reverse device of distributed new electricity generation system of the present utility model has the characteristics such as the blind area of detection is little, accuracy in detection is high, applicability is strong than traditional isolated island detecting device.The utility model adopts the mode of Schema-based identification wavelet analysis to carry out isolated island and detects, and effectively eliminates the blind area that Threshold brings.Than traditional employing tradition passive detection and the isolated island detecting device of active detecting, the rapidity of passive detection, the advantage little to harmonic pollution in electric power net have been given full play to, realized that at first checkout gear judges fast to system, if distributed generation system is in island state, rapidly system is excised from electrical network, then calling active detecting detects the result of passive detection, given full play to the high advantage of active detecting accuracy in detection, overcome detection time long, the deficiency large to the harmonic pollution in electric power net degree.Generally speaking, the utility model detects than traditional isolated island, detect the blind area and reduced by 24%, shortened 38% detection time, accuracy in detection has promoted 92%, and harmonic pollution in electric power net has been reduced by 93%, than traditional also net mode, the utility model can intelligence switch between the pattern of being incorporated into the power networks and island mode, for user side generate electricity by way of merging two or more grid systems arbitrarily provide may.

Description of drawings

Fig. 1 is the work system schematic diagram of two-way parallel network reverse device in electrical network of the distributed new electricity generation system of the utility model embodiment;

Fig. 2 is the two-way parallel network reverse apparatus structure schematic diagram of the distributed new electricity generation system of the utility model embodiment;

Fig. 3 is the circuit theory diagrams of the bandwidth-limited circuit of the utility model embodiment;

Fig. 4 is the circuit theory diagrams of the three-phase voltage sampled signal modulation circuit of the utility model embodiment;

Fig. 5 is the circuit theory diagrams of the three-phase current sampled signal modulation circuit of the utility model embodiment;

Fig. 6 is the circuit theory diagrams of the frequency sampling signal modulation circuit of the utility model embodiment;

Fig. 7 is the DSP of the utility model embodiment and the circuit theory diagrams of power module thereof;

Fig. 8 is the circuit theory diagrams of the memory module of the utility model embodiment;

Fig. 9 is the circuit theory diagrams of the communication module of the utility model embodiment;

Figure 10 is the circuit theory diagrams of the display module of the utility model embodiment;

Figure 11 is the commutation inversion element circuit schematic diagram of the utility model embodiment;

Figure 12 is the SPWM control flow chart of the utility model embodiment;

Figure 13 is the two-way parallel network reverse device course of work flow chart of the distributed new electricity generation system of the utility model embodiment;

Embodiment

Below in conjunction with accompanying drawing, embodiment of the present utility model is elaborated.

As shown in Figure 2, the two-way parallel network reverse device of distributed new electricity generation system comprises signal gathering unit, main control unit, commutation inversion unit and electricity accumulating unit.

Signal gathering unit comprises first signal collecting unit and secondary signal collecting unit, first signal collecting unit loader is connected to the direct-flow input end of commutation inversion unit, secondary signal collecting unit input is connected to the electrical network end of commutation inversion unit, and the output of first signal collecting unit is connected output and is all connected main control unit with the secondary signal collecting unit.

First signal collecting unit and secondary signal collecting unit include voltage sensor VT, current sensor CT, Frequency tester, bandwidth-limited circuit, three-phase voltage sampled signal modulation circuit, three-phase current sampled signal modulation circuit and frequency sampling signal modulation circuit.the model of voltage sensor is HNV500T, the model of current sensor is ACS712ELCTR-05A5A SOP-8, voltage sensor be used for to gather the voltage that distributed new electricity generation system and grid nodes (being the PCC node) are located, current sensor be used for to gather the electric current of the voltage distributed new output DC that distributed new electricity generation system and grid nodes (being the PCC node) locate, adopting model is the Frequency tester of BT3C, gather respectively frequency that distributed new electricity generation system and grid nodes (PCC node) locate and the frequency of distributed new electricity generation system dc output end.

The output of voltage sensor, the output of current sensor are connected output and all are connected with the input of bandwidth-limited circuit with Frequency tester, the output of bandwidth-limited circuit connects respectively the input of three-phase voltage sampled signal modulation circuit, the input of three-phase current sampled signal modulation circuit and the input of frequency sampling signal modulation circuit, and the output of the output of three-phase voltage sampled signal modulation circuit, three-phase current sampled signal modulation circuit and the output of frequency sampling signal modulation circuit all are connected to the input of main control unit.

The bandwidth-limited circuit of present embodiment as shown in Figure 3, the output pin u of bandwidth-limited circuit _oExport 7 road signals, wherein, voltage signal is connected to the u of three-phase voltage sampled signal modulation circuit _aInterface, as shown in Figure 4, the output OUT of three-phase voltage sampled signal modulation circuit _aThe signal input part (as ADCINA0, the ADCINA2 end of DSP) that connects respectively main control unit: 3 road current signals of bandwidth-limited circuit output are connected to the i of three-phase current sampled signal modulation circuit _aInterface, as shown in Figure 5, the output OUT of three-phase current sampled signal modulation circuit _a1The signal input part (as ADCINA3, the ADCINA5 end of DSP) that connects respectively main control unit; Frequency signal is connected to the input f of frequency sampling signal modulation circuit _g, as shown in Figure 6, the output OUT of frequency sampling signal modulation circuit _fEnd connects the signal input part (as the ADCINA6 end of DSP) of main control unit.

the commutation inversion unit as shown in figure 11, comprise bridge rectifier 2, bridge inverter main circuit 4, Boost booster circuit 3 and Cuk reduction voltage circuit 1, the input that the input of Cuk reduction voltage circuit 1 is connected with the Boost booster circuit all connects the distributed new electricity generation system, the output of Cuk reduction voltage circuit 1 connects the input of bridge rectifier 2, the output of Boost booster circuit 3 connects the input of bridge inverter main circuit 4, the input of bridge rectifier 2, the input of bridge inverter main circuit 4 also connects respectively main control unit, the output of the output of bridge rectifier 2 and bridge inverter main circuit 4 is connected to electrical network through circuit breaker.Wherein, the Boost booster circuit is without isolated connection bridge inverter main circuit, more isolated to be connected bridge rectifier in parallel with the Cuk reduction voltage circuit.

The two-way parallel network reverse device of distributed new electricity generation system produces PWM control wave signal by the I/O mouth of DSP, after this control signal is amplified through signal amplification circuit, be docked at the on off operating mode of the relay (model that adopts in present embodiment is the DW15 broken-circuit controller) that PCC orders and each thyristor in the commutation inversion unit and control, realize the excision operation of islet operation state of distributed new electricity generation system and the distributed generation system reclosing operation of island state.

The side that the commutation inversion unit is connected with the distributed new system is connected with ultracapacitor.

The mode of operation of commutation inversion unit comprises inverter mode and rectification pattern; when the generating of distributed new electricity generation system is sufficient; the commutation inversion cell operation is at inverter mode; when distributed new electricity generation system abnormal electrical power supply or when needing electrical network to be charge in batteries, the commutation inversion cell operation is in the rectification pattern.

In present embodiment, adopting model is that the DSP of TMS320F2812 is as main control unit, be used for phase voltage, phase current and frequency that the PCC that signal gathering unit collects is ordered are carried out the A/D conversion, and the signal after the A/D conversion is carried out isolated island detect, according to the corresponding Trig control signal of detection triggers, the actuator's (circuit breaker) that drives PCC point place moves accordingly.

As shown in Figure 7, the model of present embodiment is that the DSP of TMS320F2812 is connected with power module, communication module, memory module and display module, and this power module provides the 3.3V that satisfies job requirement voltage to DSP.

The output signal of DSP is sent memory module, communication module, display module and circuit breaker, memory module, display module are realized respectively storage and the demonstration to the critical data of distributed new operation of electric power system state, so that operating personnel understand the running status of system, and make correct processing operation according to the critical data of record.

In present embodiment, the model of memory module is CY7C1041BV33, and the XD0 of its data input pin DO～D15 pin and DSP～XD15 pin is connected, and the XA0 of A0～A17 pin and dsp chip～XA17 pin is connected, as shown in Figure 8.

Communication module is used for realizing the network communication of this device and host computer, is convenient to the dispatcher distributed new electricity generation system is made rational arrangement, realizes the greatest benefit operation of distributed new electricity generation system.Adopt RS485 communications protocol and MAX232 to drive chip in present embodiment and realize communication module, its circuit theory as shown in Figure 9, its R2OUT, T2IN, R1OUT, T1IN pin are connected with SCIRXDA, SCITXDA, SCIRXDB, the SCITXDB pin of DSP respectively.

Display module adopts liquid crystal display to realize, model is LCM12864ZK, as shown in figure 10, the RS pin of liquid crystal display is connected with the IOPF4 pin of TMS320LF2812 chip, the R/W pin of liquid crystal display is connected with the IOPF5 pin of DSP, the E pin of liquid crystal display is connected with the IOPF6 pin of DSP, and the IOPB1 of D0～D7 pin and DSP～IDPB7 pin is connected, liquid crystal display /the RST pin is connected with the IOPC1 pin of DSP.

Electricity accumulating unit comprises storage battery and battery controller, and storage battery is connected to the distributed new electricity generation system through battery controller.

Storage battery adopts lead acid accumulator, and is in parallel between each storage battery; Battery controller comprises voltage stabilizing chip, power supply control chip and output pressure regulation chip, storage battery connects voltage stabilizing chip input, the output of voltage stabilizing chip connects the input of power supply control chip, output pressure regulation chip input is connected to the output of power supply control chip, and output pressure regulation chip output connects the distributed new electricity generation system.

As shown in Figure 1, in the work system of two-way parallel network reverse device in electrical network of distributed new electricity generation system, the direct current of distributed new electricity generation system output through two-way parallel network reverse device output and line voltage frequency, amplitude and phase place all identical alternating current be local load supplying, namely island mode moves.The electric energy that provides when the distributed new electricity generation system meets the breaker closing when requiring that is incorporated into the power networks, and the distributed new electricity generation system mode operation that is incorporated into the power networks is the power supply of electrical network common load.When distributed new electricity generation system abnormal (for example sudden change of light condition in photovoltaic generation), circuit breaker excises the distributed new electricity generation system fast from electrical network.Ultracapacitor is used for providing or the required electric energy of access to electrical network in the time at breaker operator, and is consistent with electrical network to adjust distributed new electricity generation system electric voltage frequency, amplitude and phase place, thereby reduces the impact to electrical network.When restarting after the long-term dead electricity of distributed new electricity generation system or storage battery need to be from grid charging the time, two-way parallel network reverse device reverse operation is at rectification state, for electricity accumulating unit provides electric energy.

The two-way parallel network reverse device course of work of above-mentioned distributed new electricity generation system as shown in figure 13, comprises the following steps:

Step 1: voltage u, current i, the frequency of the DC side of the voltage of the common coupling node PCC of Real-time Collection electrical network, electric current, frequency and commutation inversion unit, and carry out filtering, noise reduction and transformation and process;

Step 2: the data of voltage, electric current and frequency after filtering, noise reduction and transformation are processed are carried out normalized, and the memory module that transfers to main control unit is preserved;

Step 3: initialization distributed new electricity generation system parameter comprises resistance value R, inductance value L and capacitance C;

Step 4: according to the data after the normalization of memory module preservation, active-power P and the reactive power Q of calculatingization distributed new electricity generation system also deposits memory module in and preserves;

Wherein,

Be power-factor angle, Z is the total load of network system;

Step 5: the data in memory module are sent into main control unit, utilize overvoltage/undervoltage/mistake under-frequency detection method to carry out passive isolated island and detect;

Step 5.1: the degree of unbalance of calculating active power

Degree of unbalance with reactive power

And be stored to memory module;

Calculate the active power degree of unbalance

With reactive power

The formula of degree of unbalance is as follows;

$\frac{\mathrm{\&Delta;P}}{P}=1-\frac{u_p^2}{{\mathrm{<figure-callout\; id="2"\; label="u\; g"\; filenames="HDA00003169615500033.png,HDA00003169615500061.png"\; state="\{\{state\}\}">u</figure-callout>}}_g^{}},$

$\frac{\mathrm{\&Delta;Q}}{Q}=\frac{{\mathrm{\&omega;}}_g}{{\mathrm{\&omega;}}_P}\frac{\mathrm{\&Delta;P}}{P}-(\frac{{\mathrm{\&omega;}}_g}{{\mathrm{\&omega;}}_P}-1)\frac{Q_Z}{Q}-\frac{{\mathrm{\&omega;}}_g}{{\mathrm{\&omega;}}_P}+1,$

Wherein, ω _gBe the electrical network angular frequency, and ω is arranged _g=2 π f _g, f _gBe mains frequency; u _gBe line voltage; Q _ZIdle on resonant capacitance, and have

Step 5.2: the voltage signal V of method detection of grid point of common coupling that utilizes the wavelet analysis of Schema-based identification _PCC, the voltage signal V of point of common coupling _PCCIt is the voltage signal that circuit breaker is incorporated into the power networks and locates;

Step 5.2.1: with V _PCCBe designated as u (t);

Step 5.2.2: the voltage signal of judgement point of common coupling is at the isolated island Sudden Changing Rate △ V of moment _PCCOr the frequency signal of point of common coupling is at the isolated island Sudden Changing Rate △ f of moment _PCCWhether surpass threshold value, if exceed threshold value, detect current distributed new electricity generation system and be in island state, otherwise execution in step 5.2.3;

Step 5.2.3: carry out singular point and detect;

Concrete grammar is as follows: definition u (t) ∈-L ²(R), θ (t) ∈-L ²(R) be the Gaussian smoothing function ,-L ²(R) expression real number two-dimensional space, the first derivative of getting respectively the Gaussian smoothing function

, second dervative

As the wavelet transformation generating function,

, θ _s(t) stretching under expression θ (t) scale factor s, u (t) is carried out wavelet transformation:

${\mathrm{WT}}_X^{\left(1\right)}(s,t)=u{\left(t\right)*\mathrm{\&psi;}}_s^{\left(1\right)}\left(t\right)=u\left(t\right)*\left[s^2\frac{d}{\mathrm{dt}}{\mathrm{\&theta;}}_s\left(t\right)\right]={\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="HDA00003169615500033.png,HDA00003169615500061.png"\; state="\{\{state\}\}">s</figure-callout>}}^2*\frac{d}{\mathrm{dt}}\left[u\left(t\right){\mathrm{\&theta;}}_s\left(t\right)\right]$

${\mathrm{WT}}_X^{\left(2\right)}(s,t)=u{\left(t\right)*\mathrm{\&psi;}}_s^{\left(2\right)}\left(t\right)=u\left(t\right)*\left[s^2\frac{{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HDA00003169615500033.png,HDA00003169615500061.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}{{\mathrm{<figure-callout\; id="2"\; label="dt"\; filenames="HDA00003169615500033.png,HDA00003169615500061.png"\; state="\{\{state\}\}">dt</figure-callout>}}^2}{\mathrm{\&theta;}}_s\left(t\right)\right]={\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="HDA00003169615500033.png,HDA00003169615500061.png"\; state="\{\{state\}\}">s</figure-callout>}}^2*\frac{{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HDA00003169615500033.png,HDA00003169615500061.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}{{\mathrm{dt}}^2}\left[u\left(t\right){\mathrm{\&theta;}}_s\left(t\right)\right]$

Wherein,

,

Be the WAVELET TRANSFORM MODULUS of signal u (t);

Known the WAVELET TRANSFORM MODULUS of signal u (t) by following formula

Local modulus maxima reaction signal u (t) have singular point (or catastrophe point); The WAVELET TRANSFORM MODULUS of signal u (t)

Local zero crossing, there is singular point (or catastrophe point) in reaction signal u (t).Therefore, for the primary signal that singular point is arranged, based on wavelet modulus maxima is exactly the singular point of primary signal;

Step 5.2.4: if V detected _PCCThere is singular point, postpones 50ms, treat V _PCCSignal is steady, and signal u (t) is carried out Fourier transform and calculates V _PCCFrequency spectrum, in this frequency spectrum, the amplitude of front 18 odd harmonics is as characteristic parameter, each characteristic parameter consists of the sample characteristics storehouse;

Step 5.2.5 utilizes the neural network classification algorithm to carry out pattern recognition to current demand signal u (t), namely carry out the characteristic parameter screening for the characteristic parameter of the frequency spectrum of current demand signal u (t) in the sample characteristics storehouse, whether be in the islet operation state with recognition system: if the characteristic parameter of the frequency spectrum of current demand signal u (t) is present in the sample characteristics storehouse, identifying the distributed new electricity generation system current is the islet operation state, and execution in step 5.3, be otherwise the distributed new electricity generation system is current the state of being incorporated into the power networks;

Present embodiment adopts the BP neural net of 18-36-1 to classify, and whether is in the islet operation state with recognition system;

Step 5.3: if neural network recognization distributed new electricity generation system is the islet operation state, and the degree of unbalance of active power and the imbalance of reactive power surpass threshold value, the distributed new electricity generation system has been in the islet operation state, main control unit sent the PWM ripple distributed new electricity generation system was carried out inversion control this moment, drive circuit breaker the distributed new electricity generation system is excised from electrical network, otherwise execution in step 6;

The process that the distributed new electricity generation system has been carried out inversion control is as shown in figure 12, and is specific as follows:

Interior circular current open-loop transfer function can be represented by the formula:

$G_I\left(S\right)=(G_P\left(S\right)*G_{\mathrm{INV}}\left(S\right)-U_{\mathrm{net}})*G_L\left(S\right)*e^{-\mathrm{\&omega;t}}$

In formula, G _P(S) be the PI adjustment function, G _INV(S) be inversion link transfer function, G _L(S) be filtering link transfer function.

The adjustment process that current inner loop is controlled can be described as: with respect to given reference current I _ref ^*, as inversion output grid-connected current I _outDuring less than reference current, both difference signals are regulated through PI for just, after adding the voltage feed-forward control value, have increased the amplitude of sinusoidal modulation signal, have therefore increased the duty ratio of inverter bridge, thereby the output grid-connected current is increased; As inverter output current I _outDuring greater than reference current, both difference signals are for negative, and the voltage feed-forward control value deducts the error signal of regulating through PI, thereby reduces the Using Sinusoidal Pulse Width Modulation signal amplitude, has reduced the duty ratio of inverter bridge, and then reduce inversion output grid-connected current.

Outer voltage is controlled, and is that the control DC bus-bar voltage is constant, and detailed process is: as bus voltage measurement value V _DclinkGreater than given reference value V _DcrefThe time, the capacitance stores energy, can regulate by PI and strengthen the reference current I that is incorporated into the power networks this moment _ref ^*, current inner loop is regulated and is controlled the increase of inverter bridge duty ratio, and the increase of output power that is incorporated into the power networks reduces capacitance voltage: as bus bar side voltage measuring value V _DclinkLess than given reference value V _DcrefThe time, electric capacity releases energy, and can reduce reference current I _ref ^*, reduce the power that is incorporated into the power networks, thereby increased capacitance voltage.

It is according to inversion output grid-connected current I that PI regulates _outWith reference current I _ref ^*Difference, make a response rapidly, to reach I _outFollow the tracks of fast I _ref ^*Change: to the DC bus-bar voltage V that adopts _DclinkWith given V _DcrefCompare the error signal (V that obtains _DclinkWith V _DcrefDifference) output after regulate processing through PI is as interior ring reference current amplitude I _ref, this amplitude multiply by line voltage with the unit sine wave of homophase frequently after as the given signal I of interior circular current _ref ^*, given electric current and output grid-connected current instantaneous value I _outCompare, after error signal process PI regulated and processes, as the sine pulse modulation signal, signal pulse was controlled inverter bridge power switch pipe break-make, and output obtains and the same sinusoidal current feed-in electrical network of homophase frequently of line voltage after filter circuit.

Step 6: utilize the active frequency shift method to carry out the active isolated island and detect;

Step 6.1: the output current that changes the commutation inversion unit by the PWM wave frequency that changes upper control unit output;

Step 6.2: the angular frequency that changes inverter output current PWM ripple is added disturbance;

Step 6.2: according to voltage, the current value of the PCC Nodes that gathers, the phase angle of the voltage after calculation perturbation

, electric current the phase angle Angular frequency with PCC Nodes after disturbance _Pcc, ω _pcc=2 π f _pcc

Step 6.3: the impedance angle of Computation distribution formula grid-connected power generation system, formula is as follows:

If the distributed new electricity generation system is in island state, the phase angle of the voltage of PCC Nodes

, electric current the phase angle

Difference equal load impedance angle

, namely have:

Step 6.4: calculating frequency shift maximum ω _maxWith frequency displacement minimum value ω _min

Calculating frequency shift maximum ω _maxWith frequency displacement minimum value ω _min, formula is as follows:

In formula,

Be voltage phase angle: Be current phase angle;

Step 6.4: judgement ω _min＜ω _pcc＜ω _maxWhether set up, be, passive isolated island testing result is accurate, otherwise passive isolated island testing result is inaccurate, main control unit sent the PWM ripple distributed new electricity generation system was carried out inversion control this moment, drives circuit breaker the distributed new electricity generation system is excised from electrical network;

Step 7: the data of storing in memory module show in real time by display module, provide the maintenance foundation to the maintainer.

Claims (6)

1. the two-way parallel network reverse device of a distributed new electricity generation system, is characterized in that: comprise signal gathering unit, main control unit, commutation inversion unit and electricity accumulating unit;

Described signal gathering unit comprises first signal collecting unit and secondary signal collecting unit, first signal collecting unit loader is connected to the direct-flow input end of commutation inversion unit, secondary signal collecting unit input is connected to the electrical network end of commutation inversion unit, and the output of first signal collecting unit is connected output and is all connected main control unit with the secondary signal collecting unit;

described commutation inversion unit comprises bridge rectifier, bridge inverter main circuit, Boost booster circuit and Cuk reduction voltage circuit, the input of Cuk reduction voltage circuit is connected input and is all connected the distributed new electricity generation system with the Boost booster circuit, the output of Cuk reduction voltage circuit connects the input of bridge rectifier, the output of Boost booster circuit connects the input of bridge inverter main circuit, the input of bridge rectifier, the input of bridge inverter main circuit also connects respectively main control unit, the output of bridge rectifier and the output of bridge inverter main circuit are connected to electrical network through circuit breaker,

Described electricity accumulating unit comprises storage battery and battery controller, and storage battery is connected to the distributed new electricity generation system through battery controller.

2. the two-way parallel network reverse device of distributed new electricity generation system according to claim 1 is characterized in that: a side that is connected with the distributed new electricity generation system of described commutation inversion unit is connected with ultracapacitor.

3. the two-way parallel network reverse device of distributed new electricity generation system according to claim 1, it is characterized in that: described first signal collecting unit and secondary signal collecting unit include voltage sensor, current sensor, Frequency tester, bandwidth-limited circuit, three-phase voltage sampled signal modulation circuit, three-phase current sampled signal modulation circuit and frequency sampling signal modulation circuit;

The output of voltage sensor, the output of current sensor are connected output and all are connected with the input of bandwidth-limited circuit with Frequency tester, the output of bandwidth-limited circuit connects respectively the input of three-phase voltage sampled signal modulation circuit, the input of three-phase current sampled signal modulation circuit and the input of frequency sampling signal modulation circuit, and the output of the output of three-phase voltage sampled signal modulation circuit, three-phase current sampled signal modulation circuit and the output of frequency sampling signal modulation circuit all are connected to the input of main control unit.

4. the two-way parallel network reverse device of distributed new electricity generation system according to claim 1, it is characterized in that: described main control unit is connected with power module, communication module, memory module and display module.

5. the two-way parallel network reverse device of distributed new electricity generation system according to claim 1; it is characterized in that: the mode of operation of described commutation inversion unit comprises inverter mode and rectification pattern; when the generating of distributed new electricity generation system is sufficient; the commutation inversion cell operation is at inverter mode; when distributed new electricity generation system abnormal electrical power supply or when needing electrical network to be charge in batteries, the commutation inversion cell operation is in the rectification pattern.

6. the two-way parallel network reverse device of distributed new electricity generation system according to claim 1, is characterized in that: described storage battery employing lead acid accumulator, parallel connection between each storage battery; Battery controller comprises voltage stabilizing chip, power supply control chip and output pressure regulation chip, storage battery connects voltage stabilizing chip input, the output of voltage stabilizing chip connects the input of power supply control chip, output pressure regulation chip input is connected to the output of power supply control chip, and output pressure regulation chip output connects the distributed new electricity generation system.

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