CN102624027B - Multiprocess island effect detection device and method - Google Patents

Abstract

The invention relates to a multiprocess island effect detection device and method and belongs to the field of fault detection of distributed power generation systems. Compared with the traditional island detection device, the multiprocess island effect detection device provided by the invention has the characteristics of small non-detection zone, high detection accuracy, strong applicability and the like; and island detection is carried out on a system by adopting a passive detection mode in which detection variables are mutually independent, and the island detection can be carried out on the system more comprehensively. Compared with the traditional island detection device which adopts single passive detection and active detection, the detection device provided by the invention has the characteristics that the advantages of less pollution to harmonic wave of a power grid and rapidity of passive detection are fully played, rapid judgement on the system is firstly realized, if the distributed power generation system is in an island state, the system is rapidly removed from the power grid. Besides, active detection is called to recheck the result of the passive detection, the advantage of high detection accuracy of the passive detection is fully played, and the defects that the detection time is long and the pollution level to the harmonic wave of the power grid is high can be overcome.

Description

A kind of island effect checkout gear and method of multi-process

Technical field

The invention belongs to distributed generation system fault detect field, be specifically related to a kind of island effect checkout gear and method of multi-process.

Background technology

Since twentieth century, along with economical and social fast development, energy resource consumption grows with each passing day, electricity needs increase the development that makes people more and more pay attention to regenerative resource rapidly, distributed generation technology causes that with its exclusive feature people more and more pay close attention to.Along with the grid-connected quantity increasing year by year of distributed generation system, island effect becomes the principal element of restriction distributed generation technology, 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, due to features such as himself generate output is little, scattered distributions, traditional scheduling mode can not control effectively, and will make grid-connected distributed generation system be absorbed in island state like this when access electrical network breaks down.In order to improve grid-connected distributed power generation, be grid-connected reliability, controllability, give full play to the advantage of distributed generation system, various countries are all to require to have island effect measuring ability for grid-connected distributed power generation, for example: in Japan, require to have at least a kind of passive detection method and a kind of active detecting method; In North America, require manufacturer to adopt the active alone island detection mode based on frequency, phase place or variation; In China, during requiring, GB/T19939-2005 photovoltaic system interconnection technology requires at least each a kind of active and passive isolated island detecting device.Therefore, for the research of island effect detection technique and the research of relevant apparatus thereof, become domestic and international electric power researcher's study hotspot.

Now, about distributed generation system island effect detection method, there have been many kinds, have mainly been divided into active detecting and the large class of passive detection two.For now, it is simple, easy to implement that passive detection possesses skills, and do not need to inject disturbance to system, reduced the advantages such as harmonic effects.But passive detection can only be that electricity generation system detects to the distribution after island effect, and makes corresponding processing, it can not find isolated island phenomenon in advance, and the detection blind area of passive detection is large in addition.Advantages such as it is high that although the detection of active detecting method has accuracy of detection, and detection blind area is little, it is more complicated that the method is controlled, and because testing process need to be injected disturbing signal, reduced the quality of inverter output electric energy.No matter because be the merits and demerits that passive type detection method or active detection method all exist self, so combining with passive detection, active detecting becomes the new direction that nowadays becomes the research of isolated island detection technique.The isolated island detection technique that present active detecting is combined with passive detection is of a great variety, as overvoltage/undervoltage/mistake under-frequency detection method is combined with frequency offset detection method, voltage harmonic detection method frequently floats detection method with sliding formwork and is combined ... the defect but these methods all possess skills, for example implement that technical difficulty greatly, also exists larger detection blind area, control device is complicated, detection time is long etc.

Summary of the invention

The deficiency existing for existing method, the present invention proposes a kind of island effect checkout gear and method of multi-process, to reach the object of more comprehensively system being carried out to isolated island detection.

Technical scheme of the present invention is achieved in that a kind of island effect detection method of multi-process, comprises the following steps:

Step 1: the three-phase voltage collecting, electric current and frequency are carried out to filtering, noise reduction, transformation processing and analog-to-digital conversion, and the digital signal after conversion is normalized, deliver to data memory unit and preserve;

Step 2: initialization system parameter, described system parameters comprises the resistance value R of system, inductance value L and capacitance C;

Step 3: utilize the data of step 1 storage, the active-power P of computing system and reactive power Q, and deposit active power value and reactive power value in data memory unit preservation;

Step 4: the data in data storage are sent into the CPU of DSP, carried out passive isolated island detection, judge whether isolated island occurs, and method is: (1) utilizes overvoltage/undervoltage/mistake under-frequency detection method to calculate the degree of unbalance of active power and reactive power; (2) utilize Phase jump detection method calculating voltage current phase declinate; (3) utilize power/frequency rate of change detection method to calculate the interconversion rate of active power interconversion rate, reactive power interconversion rate and frequency; Utilize the result of above-mentioned (1) (2) (3), calculate passive detection comprehensive evaluation index value, if this value is not more than 10, illustrate that distributed generation system is for the state that is normally incorporated into the power networks, utilize the result that initiatively isolated island testing process detects passive isolated island to check, perform step 5; This value is greater than 10, illustrates that distributed generation system is in island state, and now system DSP sends PWM ripple and drives broken-circuit controller, and distributed generation system is excised from electrical network;

Step 5: initiatively isolated island detects, and method is: the maximum ω that utilizes Active frequency drift method calculating frequency shift _maxwith minimum value ω _min, the angular frequency at Computation distribution formula electricity generation system and grid nodes place _pif do not meet ω _min< ω _p< ω _max, illustrate that the result of passive detection is incorrect, now DSP sends PWM ripple and drives broken-circuit controller, and distributed generation system is excised from electrical network; Otherwise the result that passive detection is described is correct, performs step 6;

Step 6: distributed generation system, in islet operation state, utilizes communication unit and host computer to carry out telecommunication, excises from electrical network to operating personnel's prompt system;

Step 7: be stored in the state that the data of data storage element carry out distributed generation system by display unit and show, provide maintenance foundation to system overhaul personnel;

Step 8: for the distributed generation system having excised from electrical network, isolated island detecting device can be detected distributed generation system is carried out to active detecting by active isolated island, judge whether distributed generation system meets the requirement of being again incorporated into the power networks, if met, DSP sends PWM ripple and drives broken-circuit controller that distributed generation system is incorporated into the power networks again.

The device of realizing the island effect detection method of multi-process, comprising:

Signal gathering unit: for gathering three-phase voltage, electric current and the frequency at distributed generation system and grid nodes place and the signal collecting being carried out to filtering, noise reduction, transformation processing;

Main control unit: further process for the signal that signal gathering unit is collected, carry out passive isolated island and detect and initiatively isolated island detection, and according to testing result, control distributed generation system is connected and shutoff with electrical network;

Data memory unit: for storing the interconversion rate of degree of unbalance, electric current and voltage phase angle, active power interconversion rate, reactive power interconversion rate and the frequency of active power and reactive power;

Communication unit: for realizing the network communication of island effect checkout gear and host computer.

Advantage of the present invention: the island effect checkout gear of multi-process proposed by the invention, than traditional isolated island detecting device, has the features such as the blind area of detection is little, accuracy in detection is high, applicability is strong.This isolated island detecting device adopts the separate passive detection mode of multiple detection variable to carry out isolated island detection to system, more comprehensively system is carried out to isolated island detection.Isolated island detecting device than the single passive detection of traditional employing and active detecting, the rapidity of passive detection, the advantage little to harmonic pollution in electric power net have been given full play to, having realized checkout gear first judges fast to system, if distributed generation system, in island state, excises system rapidly from electrical network.Next calls active detecting the result of passive detection is checked, and has given full play to the high advantage of active detecting accuracy in detection, has overcome detection time long, the deficiency large to harmonic pollution in electric power net degree.Generally speaking, the island effect checkout gear of the multi-process that the present invention proposes, than traditional isolated island detecting device, detects blind area and has reduced by 25%, has shortened 40% detection time, and accuracy in detection has promoted 90%, to the reduction of harmonic pollution in electric power net 92%.

Accompanying drawing explanation

Fig. 1 is the structured flowchart of the island effect checkout gear of one embodiment of the present invention multi-process;

Fig. 2 is the circuit theory diagrams of one embodiment of the present invention bandwidth-limited circuit;

Fig. 3 is the circuit theory diagrams of one embodiment of the present invention three-phase voltage sampled signal modulation circuit;

Fig. 4 is the circuit theory diagrams of one embodiment of the present invention three-phase current sampled signal modulation circuit;

Fig. 5 is the circuit theory diagrams of one embodiment of the present invention frequency sampling signal modulation circuit;

Fig. 6 is the circuit theory diagrams of one embodiment of the present invention DSP and power module thereof;

Fig. 7 is the circuit theory diagrams of one embodiment of the present invention data storage cell;

Fig. 8 is the circuit theory diagrams of one embodiment of the present invention communication module;

Fig. 9 is the circuit theory diagrams of one embodiment of the present invention LCD MODULE;

Figure 10 is the island effect overhaul flow chart of one embodiment of the present invention multi-process;

Figure 11 is the passive isolated island overhaul flow charts of one embodiment of the present invention;

Figure 12 is one embodiment of the present invention overvoltage/undervoltage/mistake under-frequency detection method flow chart;

Figure 13 is one embodiment of the present invention Phase jump detection method flow chart;

Figure 14 is one embodiment of the present invention power-frequency rate of change detection method flow chart;

Figure 15 is initiatively isolated island overhaul flow charts of one embodiment of the present invention.

Embodiment

Below in conjunction with accompanying drawing, embodiments of the present invention are described further.

Fig. 1 is the structured flowchart of the island effect checkout gear of multi-process.The island effect checkout gear of multi-process mainly comprises: the power module of signal gathering unit, main control unit, data memory unit, communication unit, liquid crystal display, broken-circuit controller and main control unit.Wherein, signal gathering unit comprises: 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.

In present embodiment, adopt 3 voltage sensors (VT), 3 current sensors (CT), be used for gathering three-phase voltage and electric current that distributed generation system and grid nodes (PCC node) are located, wherein, the model of voltage sensor is HNV500T, and the model of current sensor is ACS712ELCTR-05A5ASOP-8.Adopt 1 Frequency tester to gather the frequency that distributed generation system and grid nodes (PCC node) are located, the model of Frequency tester is BT3C.

The signal that utilizes voltage sensor (VT), current sensor (CT) and Frequency tester to collect passes to bandwidth-limited circuit, and described bandwidth-limited circuit as shown in Figure 2.Frequency signal (the comprising 1 road frequency signal) output of the current signal output end (comprising 3 road current signals) of the voltage signal output end of voltage sensor (VT) (comprising 3 road voltage signals), current sensor (CT) and Frequency tester connects the input u of bandwidth-limited circuit simultaneously _i, the signal collecting is carried out to filtering.Filtered signal is after signal modulation circuit (comprising three-phase voltage sampled signal modulation circuit, three-phase current sampled signal modulation circuit and frequency sampling signal modulation circuit) carries out noise reduction, transformation processing, output amplitude is the voltage signal of 3.3V, passes to main control unit (for example central processing unit DSP).

The output pin u of bandwidth-limited circuit _oexport 7 road signals, wherein, 3 road voltage signals are connected to the u of three-phase voltage sampled signal modulation circuit _a, u _b, u _cinterface, as shown in Figure 3, the output OUT of three-phase voltage sampled signal modulation circuit _a, OUT _band OUT _cthe signal input part (as the ADCINA0 ADCINA2 end of DSP) that connects respectively main control unit; 3 road current signals are connected to the i of three-phase current sampled signal modulation circuit _a, i _b, i _cinterface, as shown in Figure 4, the output OUT of three-phase current sampled signal modulation circuit _a1, OUT _b1and OUT _c1the signal input part (as the ADCINA3 ADCINA5 end of DSP) that connects respectively main control unit; 1 road frequency signal is connected to the input f of frequency sampling signal modulation circuit _g, as shown in Figure 5, 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.

Present embodiment adopts DSP as main control unit, for three-phase voltage, electric current and the electric voltage frequency that the PCC collecting is ordered, carry out A/D conversion, and the signal after conversion is carried out to isolated island and detect, according to the corresponding Trig control signal of detection triggers, drive the actuator at PCC point place to move accordingly.

Its model is TMS320F2812, sees Fig. 6, and Fig. 6 also comprises the power module of DSP, and DSP electric power source pair of module DSP provides the 3.3V voltage that meets job requirement.

The output signal of DSP is delivered to data storage cell, communication unit, liquid crystal display and broken-circuit controller, described data memory unit, liquid crystal display are mainly realized the storage of the critical data of distributed generation system running status and demonstration respectively, 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 data storage cell is CY7C1041BV, and its data input pin D0～D15 pin is connected with XD0～XD15 pin of DSP, and A0～A17 pin is connected with XA0～XA17 pin of dsp chip.As shown in Figure 7.

Described communication unit, for realizing the network communication of isolated island detecting device and host computer, is convenient to dispatcher distributed generation system is made to rational arrangement, realizes the greatest benefit operation of distributed generation system.In present embodiment, adopt RS485 communications protocol, adopt MAX232 to drive chip to realize, its circuit theory diagrams as shown in Figure 8.Its R2OUT, T2IN, R1OUT, T1IN pin are connected with SCIRXDA, SCITXDA, SCIRXDB, the SCITXDB pin of dsp chip respectively.

Described liquid crystal display adopts liquid crystal display to realize, the model of described liquid crystal display is LCM12864ZK, as shown in Figure 9, 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 D0～D7 pin is connected with IOPB1～IOPB7 pin of DSP, liquid crystal display /RST pin is connected with the IOPC1 pin of DSP.

Multi-process isolated island detecting device produces PWM control wave signal by the I/O mouth of DSP, this control signal is after signal amplification circuit amplifies, be docked at the grid-connected control relay (model adopting in present embodiment is DW15 broken-circuit controller) that PCC orders and carry out the control of on off operating mode, realize the excision operation of distributed generation system islet operation state and the distributed generation system reclosing operation of island state.

One embodiment of the present invention provide the flow process of the island effect detection method of multi-process, as shown in figure 10.This flow process starts from step 1001.In step 1002, the three-phase voltage collecting, electric current and frequency (are for example carried out to analog-to-digital conversion, utilize the A/D converter of DSP to realize analog-to-digital conversion), be called the voltage signal that amplitude is 3.3V, and the digital signal after conversion is normalized, deliver to data memory unit and preserve;

In step 1003, initialization system parameter, described system parameters comprises the resistance value R of system, inductance value L and capacitance C;

In step 1004, utilize the data of step 1 storage, the active-power P of computing system and reactive power Q, and deposit active power value and reactive power value in data memory unit preservation;

Wherein, present embodiment adopts three-phase instantaneous power method to calculate active power, reactive power and power-factor angle, and process is as follows:

The three-phase phase voltage that step 1002 samples and triple line electric current are respectively u _a, u _b, u _c, i _a, i _b, i _c, through a, b, c three-phase, after the conversion of alpha-beta two-phase, obtain u _α, u _βand i _α, i _β.

$\left[\begin{array}{c}{u}_{\mathrm{\&alpha;}}\\ u_{\mathrm{\&beta;}}\end{array}\right]=C_{\mathrm{\&alpha;\&beta;}}\left[\begin{array}{c}{u}_a\\ u_b\\ u_c\end{array}\right],$ $\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]=C_{\mathrm{\&alpha;\&beta;}}\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]---\left(1\right)$

In formula $C_{\mathrm{\&alpha;\&beta;}}=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{3}& -\frac{\sqrt{3}}{2}\end{array}\right]$

In alpha-beta plane by vector

with

synthesize respectively (rotation) voltage vector

and current phasor

In formula, u, i are respectively vector mould,

be respectively vector

phase angle.

Calculate the instantaneous active current of three-phase circuit and instantaneous reactive current:

Power-factor angle in formula

U and i _pproduct be three-phase circuit instantaneous active power, u and i _qproduct be three-phase circuit instantaneous reactive power.

p＝ui _p q＝ui _q (3)

In wushu (2) substitution formula (3):

$\left[\begin{array}{c}p\\ q\end{array}\right]=\left[\begin{array}{cc}{u}_{\mathrm{\&alpha;}}& u_{\mathrm{\&beta;}}\\ u_{\mathrm{\&beta;}}& -u_{\mathrm{\&alpha;}}\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]=C_{\mathrm{pq}}\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]---\left(4\right)$

In formula $C_{\mathrm{pq}}=\left[\begin{array}{cc}{u}_{\mathrm{\&alpha;}}& u_{\mathrm{\&beta;}}\\ u_{\mathrm{\&beta;}}& -u_{\mathrm{\&alpha;}}\end{array}\right]$

In wushu (1) substitution formula (4):

P＝u _ai _a+u _bi _b+u _ci _c $Q=\frac{1}{\sqrt{3}}[(u_b-u_c)i_a+(u_c-u_a)i_b+(u_a-u_b)i_c]$

In step 1005, the data in data storage are sent into the CPU of DSP, carry out passive isolated island detection, judge whether isolated island occurs, as shown in figure 11.This flow process starts from 1101.In step 1102, (1) utilizes overvoltage/undervoltage/mistake under-frequency detection method, the active power degree of unbalance that Computation distribution formula electricity generation system and grid nodes (PCC node) are located

with reactive power degree of unbalance, flow process is as shown in figure 12.This flow process starts from step 1201.In step 1202, calculate active power degree of unbalance

with reactive power degree of unbalance, formula is as follows:

$\frac{\mathrm{\&Delta;P}}{P}=1-\frac{u_p^2}{{\mathrm{<figure-callout\; id="2"\; label="u\; g"\; filenames="HDA0000146854510000051.png"\; state="\{\{state\}\}">u</figure-callout>}}_g^{}},$ $\frac{\mathrm{\&Delta;Q}}{Q}=\frac{{\mathrm{\&omega;}}_g}{{\mathrm{\&omega;}}_P}\frac{\mathrm{\&Delta;P}}{P}-(\frac{{\mathrm{\&omega;}}_g}{{\mathrm{\&omega;}}_P}-1)\frac{Q_Z}{Q}-\frac{{\mathrm{\&omega;}}_g}{{\mathrm{\&omega;}}_P}+1$

In formula: ω _gfor electrical network angular frequency, and there is ω _g=2 π f _g, f _gfor mains frequency; ω _pfor PCC place angular frequency, and there is ω _p=2 π f _p, f _pfor PCC Nodes frequency; u _gfor line voltage; u _pfor PCC Nodes voltage; Q _zidle on resonant capacitance, and have $Q_Z={\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="2"\; label="g\; Cu\; g"\; filenames="HDA0000146854510000051.png"\; state="\{\{state\}\}">g</figure-callout>}}{\mathrm{Cu}}_g^{}{}_2^{}.$

In step 1203, by the active power degree of unbalance calculating

with reactive power degree of unbalance

be stored to data memory unit.

(2) utilize Phase jump detection method, calculating voltage phase angle and current phase angle, its flow process is as shown in figure 13.This flow process starts from step 1301.In step 1302, by voltage sensor, measure and be separated by

two instantaneous voltage u _n, u _n-1, current sensor is measured and is separated by

two current instantaneous value i _n, i _n-1.Calculate voltage phase angle and current phase angle, formula is as follows:

In formula,

for voltage phase angle;

for current phase angle.

In step 1303, step 1302 is calculated

substitution formula

obtain the upper phase angle θ of voltage and electric current.

In step 1304, the electric current and voltage phase angle θ that step 1103 is calculated deposits data storage cell in.

(3) utilize power/frequency rate of change detection method, calculate the rate of change of active power of PCC Nodes, the rate of change of the rate of change of reactive power and frequency, flow process as shown in figure 14.This flow process starts from step 1401.In step 1402, calculate the rate of change of active power of PCC Nodes, the rate of change of the rate of change of reactive power and frequency, formula is as follows:

$\frac{\&PartialD;P}{\&PartialD;t}=\frac{P_n-P_{n-1}}{\mathrm{\&Delta;t}},$ $\frac{\&PartialD;Q}{\&PartialD;t}=\frac{Q_n-Q_{n-1}}{\mathrm{\&Delta;t}},$ $\frac{{\&PartialD;f}_P}{\&PartialD;t}=\frac{f_{\mathrm{Pn}}-f_{\mathrm{Pn}-1}}{\mathrm{\&Delta;t}}$

In formula, n, the system data that n-1 represents respectively the n time and the n-1 time sampling obtains; Δ t represents the time interval of the n time and the n-1 time sampling;

be the frequency of the PCC Nodes that collects for the n time, it is the frequency of the PCC Nodes that collects for the n-1 time.

In step 1403: by the rate of change of the active power calculating

the rate of change of reactive power

rate of change with frequency

deposit data storage cell in.

In step 1103, the active power that (1) step 1102 is calculated and the degree of unbalance of reactive power (2) the electric current and voltage phase angle θ that step 1106 calculates; (3) rate of change of the active power that step 1108 calculates

the rate of change of reactive power

interconversion rate with frequency

be updated to passive isolated island and detect overall target judgement schematics, calculate overall target and evaluate β, formula is as follows:

$\mathrm{\&beta;}=\frac{{\mathrm{\&theta;}}^2}{\mathrm{\&pi;}}\sqrt{\frac{{(\mathrm{\&Delta;P}/P)}^2}{\cos \mathrm{\&theta;}}(1+\frac{(\&PartialD;Q/\&PartialD;t)}{\ln (\&PartialD;P/\&PartialD;t)})+\frac{{(\mathrm{\&Delta;Q}/Q)}^2}{\cos \mathrm{\&theta;}}(1+\frac{(\&PartialD;f_P/\&PartialD;t)}{\ln (\&PartialD;P/\&PartialD;t)})}$

In step 1104, judge whether passive detection comprehensive evaluation index value β is less than 10, if meet, carry out 1105, otherwise perform step 1106.

In step 1105, illustrate that passive isolated island detects distributed generation system testing result as being normally incorporated into the power networks, now enable initiatively isolated island testing process the result of passive isolated island detection is checked, perform step 1006;

In step 1106, because of β > 10, illustrate that distributed generation system is in island state, now system DSP sends PWM ripple and drives broken-circuit controller, and distributed generation system is excised from electrical network.

In step 1107, finish.

In step 1006, utilize Active frequency drift method to carry out active isolated island and detect, as shown in figure 15.This flow process starts from step 1501.In step 1502, change inverter output current i _invangular frequency,

In step 1503, gather three-phase voltage, the current value of PCC Nodes, and the phase angle of the voltage after calculation perturbation, electric current

angular frequency value ω with PCC Nodes after disturbance _p, wherein, ω _p=2 π f _p.

In step 1504: the impedance angle of Computation distribution formula electricity generation system, formula is as follows:

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

difference equal load impedance angle

have:

In step 1505, calculate the frequency swing ω of Active frequency drift method _maxand ω _min, formula is as follows:

In step 1506, compare the angular frequency of PCC Nodes _pif, ω _pdo not meet the normal ω of relation _min< ω _p< ω _max, illustrate that the result of passive detection is incorrect, perform step 1508, otherwise perform step 1507.

In step 1507, the result of bright passive detection is correct, performs step 1509.

In step 1508, now, DSP sends PWM ripple and drives broken-circuit controller, distributed generation system is excised from electrical network, and perform step 1509;

In step 1509, finish.

In step 1007, distributed generation system, in islet operation state, utilizes communication unit and host computer to carry out telecommunication, to operating personnel's prompt system, from electrical network, excises.

In step 1008, be stored in the state that the data of data storage element carry out distributed generation system by display unit and show, to system overhaul personnel, provide maintenance foundation.

In step 1009, for the distributed generation system having excised from electrical network, isolated island detecting device can be detected distributed generation system is carried out to active detecting by active isolated island, judge whether distributed generation system meets the requirement of being again incorporated into the power networks, if met, DSP sends PWM ripple and drives broken-circuit controller that distributed generation system is incorporated into the power networks again.

At Figure 10 to the basis of the one or more flow chart described in Figure 15, for one in the art those skilled in the art without creationary work, can develop one or more software.The software of developing like this will be carried out Figure 10 to the passive isolated island testing process described in Figure 14, the active isolated island testing process shown in Figure 15.Described software is kept in main control unit (DSP).

Although more than described the specific embodiment of the present invention, those of skill in the art in the art should be appreciated that these only illustrate, and can make various changes or modifications to these execution modes, and not deviate from principle of the present invention and essence.Scope of the present invention is only limited by appended claims.

Claims (4)

1. an island effect detection method for multi-process, process is as follows:

Step 1: the three-phase voltage collecting, electric current and frequency are carried out to filtering, noise reduction, transformation processing and analog-to-digital conversion, and the digital signal after conversion is normalized, deliver to data memory unit and preserve;

Step 2: initialization system parameter, described system parameters comprises the resistance value R of system, inductance value L and capacitance C;

Step 3: utilize the data of step 1 storage, the active-power P of computing system and reactive power Q, and deposit active power value and reactive power value in data memory unit preservation;

It is characterized in that: further comprising the steps of:

Step 4: the data in data storage are sent into the CPU of DSP, carried out passive isolated island detection, judge whether isolated island occurs, and method is: (1) utilizes overvoltage/undervoltage/mistake under-frequency detection method to calculate the degree of unbalance of active power and reactive power; (2) utilize Phase jump detection method calculating voltage current phase declinate; (3) utilize power/frequency rate of change detection method to calculate the interconversion rate of active power interconversion rate, reactive power interconversion rate and frequency; Utilize the result of above-mentioned (1) (2) (3), calculate passive detection comprehensive evaluation index value, if this value is less than or equal to 10, illustrate that distributed generation system is for the state that is normally incorporated into the power networks, utilize the result that initiatively isolated island testing process detects passive isolated island to check, perform step 5; This value is greater than 10, illustrates that distributed generation system is in island state, and now system DSP sends PWM ripple and drives broken-circuit controller, and distributed generation system is excised from electrical network;

Step 5: initiatively isolated island detects, and method is: the maximum ω that utilizes Active frequency drift method calculating frequency shift _maxwith minimum value ω _min, formula is as follows:

In formula,

for voltage phase angle;

for current phase angle;

The angular frequency at Computation distribution formula electricity generation system and grid nodes place _p, and have ω _p=2 π f _p, f in formula _pfor PCC Nodes frequency, if do not meet ω _min< ω _p< ω _max, illustrate that the result of passive detection is incorrect, now DSP sends PWM ripple and drives broken-circuit controller, and distributed generation system is excised from electrical network; Otherwise the result that passive detection is described is correct, performs step 6;

Step 6: distributed generation system, in islet operation state, utilizes communication unit and host computer to carry out telecommunication, excises from electrical network to operating personnel's prompt system;

Step 7: be stored in the state that the data of data storage element carry out distributed generation system by display unit and show, provide maintenance foundation to system overhaul personnel;

Step 8: for the distributed generation system having excised from electrical network, isolated island detecting device can be detected distributed generation system is carried out to active detecting by active isolated island, judge whether distributed generation system meets the requirement of being again incorporated into the power networks, if met, DSP sends PWM ripple and drives broken-circuit controller that distributed generation system is incorporated into the power networks again.

2. the island effect detection method of multi-process according to claim 1, is characterized in that: the passive isolated island described in step 4 detects, and comprises the following steps:

Step 4-1: utilize overvoltage/undervoltage/mistake under-frequency detection method, the active power degree of unbalance of Computation distribution formula electricity generation system and grid nodes PCC Nodes

with reactive power

degree of unbalance, formula is as follows:

In formula: ω _gfor electrical network angular frequency, and there is ω _g=2 π f _g, f _gfor mains frequency; ω _pfor PCC Nodes angular frequency, and there is ω _p=2 π f _p, f _pfor PCC Nodes frequency; u _gfor line voltage; u _pfor PCC Nodes voltage; Q _zidle on resonant capacitance, and have

Step 4-2: by the active power degree of unbalance calculating

with reactive power degree of unbalance

be stored to data memory unit;

Step 4-3: utilize Phase jump detection method, calculating voltage phase angle and current phase angle:

By voltage sensor, measure and be separated by two instantaneous voltage u _n, u _n-1, current sensor is measured and is separated by two current instantaneous value i _n, i _n-1, calculating voltage phase angle and current phase angle, formula is as follows:

Step 4-4: step 4-3 calculates

substitution formula

obtain the upper phase angle θ of voltage and electric current;

Step 4-5: the electric current and voltage phase angle θ that step: 4-4 is calculated deposits data storage cell in;

Step 4-6: utilize power/frequency rate of change detection method, calculate the rate of change of active power of PCC Nodes, the rate of change of the rate of change of reactive power and frequency, formula is as follows:

In formula, n, the system data that n-1 represents respectively the n time and the n-1 time sampling obtains; Δ t represents the time interval of the n time and the n-1 time sampling;

be the frequency of the PCC Nodes that collects for the n time,

it is the frequency of the PCC Nodes that collects for the n-1 time;

Step 4-7: by the rate of change of the active power calculating

the rate of change of reactive power

rate of change with frequency

deposit data storage cell in.

3. the island effect detection method of multi-process according to claim 1, is characterized in that: the computing formula of the passive detection comprehensive evaluation index value described in step 4 is as follows:

。

4. the device of realizing the island effect detection method of multi-process claimed in claim 1, is characterized in that: comprising:

Signal gathering unit: for gathering three-phase voltage, electric current and the frequency at distributed generation system and grid nodes place and the signal collecting being carried out to filtering, noise reduction, transformation processing;

Main control unit: further process for the signal that signal gathering unit is collected, carry out passive isolated island and detect and initiatively isolated island detection, and according to testing result, control distributed generation system is connected and shutoff with electrical network;

Data memory unit: for storing the interconversion rate of degree of unbalance, electric current and voltage phase angle, active power interconversion rate, reactive power interconversion rate and the frequency of active power and reactive power;

Communication unit: for realizing the network communication of island effect checkout gear and host computer.

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