CN205389108U - Little electric wire netting isolated island operation detection device - Google Patents
Little electric wire netting isolated island operation detection device Download PDFInfo
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- CN205389108U CN205389108U CN201520965717.XU CN201520965717U CN205389108U CN 205389108 U CN205389108 U CN 205389108U CN 201520965717 U CN201520965717 U CN 201520965717U CN 205389108 U CN205389108 U CN 205389108U
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Abstract
The utility model provides a little electric wire netting isolated island operation detection device, includes DSP control chip, sampling modulate circuit, PWM isolating driver circuit, DA digital analog conversion circuit, electrical unit, communication unit, expander circuit unit and voltage current protection circuit unit, wherein, DSP control chip all is the both way junction with sampling modulate circuit, PWM isolating driver circuit, DA digital analog conversion circuit, electrical unit, communication unit, expander circuit unit and voltage current protection circuit unit respectively. Its superiority: 1. Adopt negative sequence voltage positive feedback method can realize the quick island protection under the uneven condition of electric wire netting. 2. Adopt varying coefficient can realize all can realizing non -blind area short -term test isolated island when the current given value of difference.
Description
(1) technical field
This utility model relates to microgrid field, mainly a kind of micro-capacitance sensor islet operation detecting device, and it belongs to the interleaving techniques field of generation of electricity by new energy and control system and power electronics.
(2) background technology
Along with distributed power generation is gradually converted into, by Independent Power Generation pattern, the pattern of generating electricity by way of merging two or more grid systems, islanding problem also highlights day by day.So-called island effect refers to when there are the other reasonses such as accident, fault or maintenance power failure and cause electric power system not to be operated, distributed grid-connected electricity generation system is owing to can not detect that the power down mode of electric power system can not cut off with electrical network in time effectively in time, thus causing inverter to the electric phenomenon of the electrical equipment of surrounding constantly continued power.The equipment of a whole set of distribution system and user side not only can be caused very big harm by island effect, also can people self be damaged simultaneously, and therefore isolated island detection tool is of great significance.
Traditional island effect detection technique can be divided into two big classes according to the difference of detection mode: passive type and active.Passive type detection technique judges the generation of island effect by monitoring the change of the voltage at point of common coupling (PCC) place, phase place, frequency and harmonic wave, although passive type method is easily achieved, but this method exists bigger check frequency.Active detection technologies refers in systems on one's own initiative plus certain disturbing signal, such as meritorious/reactive current, phase place, frequency or meritorious/reactive power etc..When isolated island occurs, these disturbances will make the voltage magnitude at PCC place, frequency or harmonic wave change, until beyond normal range, thus detecting isolated island.Although the check frequency of active detection method is only small, but system quality of power supply time properly functioning can be impacted by these disturbing signals.In practice, electrical network also there will be transition effect in short-term simultaneously, and as grid voltage amplitude changes, when this pseudo-isolated island, traditional island detection method likely there will be maloperation.Isolated island can be detected rapidly and accurately, the quality of power supply will not be damaged again, be the basic demand to isolated island detection.
(3) utility model content
The purpose of this utility model is the deficiency in order to overcome current passive type to exist with active alone island detection method, it is provided that a kind of micro-capacitance sensor islet operation detecting device.This apparatus structure is simple, has the feature such as non-destructive and non-blind area detection, can be effectively prevented from the maloperation in pseudo-isolated island situation simultaneously.
The technical solution of the utility model: a kind of micro-capacitance sensor islet operation detecting device, it is characterised in that it includes DSP (DigitalSignalProcessing digital signal processor) control chip, sampling modulate circuit, PWM (PulseWidthModulation pulsewidth modulation) isolated drive circuit, DA D/A converting circuit, power subsystem, communication unit, expanded circuit unit and voltage x current protection circuit unit；Wherein, described DSP control chip protects circuit unit all in being bi-directionally connected with sampling modulate circuit, PWM isolated drive circuit, DA D/A converting circuit, power subsystem, communication unit, expanded circuit unit and voltage x current respectively.
The digital signal processor that described DSP control chip unit adopts is the TMS320F2812 chip of American TI Texas Instruments.
Described PWM isolated drive circuit adopts the SN74LVCC3245 of TI company, is 5V level by the 3.3V level conversion of pwm signal, then the pwm signal of 5V level is inputted isolation drive unit, then drives IGBT.
Method of work of the present utility model:
(1) photovoltaic system is connected with electrical network with three-phase three-wire system form, ignores zero-sequence component.Extract the positive and negative sequence voltage component of photovoltaic system；
(2) three-phase input voltage is transformed under dq coordinate system, as the input signal of phaselocked loop, obtain photovoltaic system and place an order the Controlling model of synchronous coordinate system software phase-lock loop；
(3) introduce the of ac of 100Hz as current disturbing amount, fed back by negative sequence voltage and constantly increase voltage unbalance factor, obtain the reference current of the combining inverter after adding disturbance；
(4) judge whether isolated island occurs by the negative sequence voltage of detection PCC point；
The algorithm of the positive and negative sequence voltage component extracting photovoltaic system in described step (1) is:
For realizing the decomposition operation of above-mentioned positive-negative sequence component, it is contemplated that in complex variable, imaginary part j is relative to 90 ° of skews of real part, it is possible to realized by the wave filter delayed with 90 ° and constant ratio gain.
Three-phase input voltage is transformed under dq coordinate system by described step (2), as the input signal of phaselocked loop, obtains photovoltaic system and place an order the Controlling model of synchronous coordinate system software phase-lock loop, it may be assumed that
By three-phase input voltage uga、ugb、ugcTransform under synchronous rotary dq coordinate system, obtain the DC component u of alternating voltaged、uq；By q axle component rated value and uqDiffer from, obtain deviation, after PI regulates, with specified angular frequency0Be added, obtain actual angular frequency, finally integrated obtain phase angle θ, i.e. the phase angle of line voltage, obtain the Controlling model of phaselocked loop.
Described step (3) introduces the of ac of 100Hz as current disturbing amount, fed back by negative sequence voltage and constantly increase voltage unbalance factor, obtain the reference current of the combining inverter after adding disturbance.
Operation principle of the present utility model: photovoltaic system is connected with electrical network with three-phase three-wire system form, ignores zero-sequence component.Extract the positive and negative sequence voltage component of photovoltaic system.Three-phase input voltage is transformed under dq coordinate system, as the input signal of phaselocked loop, obtain photovoltaic system and place an order the Controlling model of synchronous coordinate system software phase-lock loop.Introduce the of ac of 100Hz as current disturbing amount, fed back by negative sequence voltage and constantly increase voltage unbalance factor, obtain the reference current of the combining inverter after adding disturbance.Judge whether isolated island occurs by detecting the negative sequence voltage of PCC point.Realized the detection detecting object in conjunction with the algorithm of following ingredient by the implementing procedure (see accompanying drawing 6) detected.
By analyzing above, the algorithm of the positive and negative sequence voltage component extracting photovoltaic system is:
For realizing the decomposition operation of above-mentioned positive-negative sequence component, it is contemplated that in complex variable, imaginary part (j) is relative to 90 ° of skews of real part, it is possible to realized by the wave filter delayed with 90 ° and constant ratio gain.
Three-phase input voltage is transformed under dq coordinate system, as the input signal of phaselocked loop, obtain photovoltaic system place an order synchronous coordinate system software phase-lock loop Controlling model (see accompanying drawing 2) namely:
By three-phase input voltage uga、ugb、ugcTransform under synchronous rotary dq coordinate system, obtain the DC component u of alternating voltaged、uq.By q axle component rated value and uqDiffer from, obtain deviation, after PI regulates, with specified angular frequency0Be added, obtain actual angular frequency, finally integrated obtain phase angle θ, i.e. the phase angle of line voltage, obtain the Controlling model of phaselocked loop.
Introduce the of ac of 100Hz as current disturbing amount, fed back by negative sequence voltage and constantly increase voltage unbalance factor, obtain the reference current of the combining inverter after adding disturbance.The algorithm used is:
Disturbance quantity formula is:
In formula, f is electrical network rated frequency；in=Kumn；umnFor negative sequence voltage amplitude；K is feedback factor.
The reference current formula adding the combining inverter after disturbance is
Through coordinate transform, the reference current formula obtained under three-phase static coordinate system is
In formula, imFor forward-order current amplitude；
In 4th step, judge whether isolated island occurs by detecting the negative sequence voltage of PCC point.(see accompanying drawing 3) its principle is as follows:
When line voltage balances, umn=0, reference current is not had disturbance, grid-connected current balances；When after electric network fault, due to the imbalance of line voltage or partial load so that the voltage magnitude of point of common coupling is uneven; there is negative sequence voltage, reference current now adds disturbance, and can continue to increase the degree of unbalancedness of PCC voltage magnitude; until beyond threshold value, it is achieved isolated island is protected.
Negative sequence voltage positive feedback detection method, using TMS320F2812 single-chip microcomputer as acp chip, is applied in the detection of photovoltaic system isolated island (see accompanying drawing 6) by this utility model.Mainly including main circuit part, sampling conditioning filter circuit, DA change-over circuit, DSP control circuit, isolated drive circuit etc. partly constitutes (see accompanying drawing 4).Mainly realize function as follows: (1) inverter output current, PCC voltage sample, export current/voltage by PI algorithm controls and follow Setting signal.(2) phase place of line voltage is obtained in real time by digital phase-locked loop, as the anglec of rotation of coordinate transform in system.(3) according to corresponding isolated island algorithm, adding corresponding disturbance, whether detection PCC voltage, frequency exceed threshold value, make isolated island action simultaneously.(4), during the faults such as system generation overvoltage, excessively stream, fault can be detected in time and make corresponding protection act.
By controller parameter is debugged repeatedly, it is finally reached desirable Detection results.Select suitable feedback factor K, improve speed and the accuracy of isolated island detection.System is finally made to obtain relatively satisfactory Detection results.
The digital signal processor that described DSP control chip unit adopts is the TMS320F2812 chip of American TI Texas Instruments, it is the high-speed dedicated microprocessor of fixed point 32, processing capability in real time and controller peripheral functionality are rolled into one, calculating speed is fast, operating frequency reaches as high as 150MHz, although being fixed DSP, it is possible to carry out floating-point operation by calling of IQ-math storehouse, improve the precision of system.Additionally, powerful peripheral module, such as task manager EVA/EVB, 16 tunnel AD conversion passages, and serial communication, bus communication module etc., the output of its pwm signal, the down trigger control to sequential, the functions such as signal processing are to the closed loop of whole control system and other designs, it is provided that a desirable solution.
Described sampling modulate circuit (see Fig. 7) mainly has two operational amplifiers to constitute, first function realizing voltage lifting, owing to the analogue signal of sampling is sinusoidal quantity, there is back bias voltage, and the voltage range of the AD port of DSP is 0～3.3V, it is impossible to there is negative voltage, so, adopt operational amplifier that the analog quantity of sampling is raised 1.5V voltage, it is ensured that sampled voltage signal is absent from negative value.Second operational amplifier mainly realizes the function of filtering, and it is second order Butterworth filter, filters the high-frequency harmonic of sampling.Two diodes of last outlet side are coupled with 3.3V and ground, and for preventing sampled signal overtension from burning out DSP, the A/D module being then input to DSP carries out data process.
Described step (3) introduces the of ac of 100Hz as current disturbing amount, fed back by negative sequence voltage and constantly increase voltage unbalance factor, obtain the reference current of the combining inverter after adding disturbance.The algorithm used is:
Disturbance quantity formula is:
In formula, f is electrical network rated frequency；in=Kumn；umnFor negative sequence voltage amplitude；K is feedback factor.
The reference current formula adding the combining inverter after disturbance is
Through coordinate transform, the reference current formula obtained under three-phase static coordinate system is
In formula, imFor forward-order current amplitude；
By the negative sequence voltage of detection PCC point, described step (4) judges whether isolated island occurs.Its principle is as follows:
When line voltage balances, umn=0, reference current is not had disturbance, grid-connected current balances；When after electric network fault, due to the imbalance of line voltage or partial load so that the voltage magnitude of point of common coupling is uneven; there is negative sequence voltage, reference current now adds disturbance, and can continue to increase the degree of unbalancedness of PCC voltage magnitude; until beyond threshold value, it is achieved isolated island is protected.
Superiority of the present utility model: 1. adopt negative sequence voltage positive feedback method when three-phase power grid voltage amplitude imbalance; even if the threshold value that voltage magnitude is protected without departing from overvoltage/undervoltage; and the degree of unbalancedness of voltage is likely to, beyond threshold value, to realize the quick isolated island protection in unbalanced power supply situation.2. variable coefficient is adopted can to realize, when different given value of current values, all can realizing non-blind area and quickly detecting isolated island.
(4) accompanying drawing illustrates:
Fig. 1 is the symmetrical components schematic diagram of the three-phase phasor in a kind of micro-capacitance sensor islet operation detecting device operation principle involved by this utility model.
Fig. 2 is the phase lock control block diagram in a kind of micro-capacitance sensor islet operation detecting device involved by this utility model.
Fig. 3 is the Control system architecture figure of negative sequence voltage positive feedback method in a kind of micro-capacitance sensor islet operation detecting device involved by this utility model.
Fig. 4 is the whole result block diagram of a kind of micro-capacitance sensor islet operation detecting device involved by this utility model.
Fig. 5 is the structural representation of DSP control system in a kind of micro-capacitance sensor islet operation detecting device involved by this utility model.
Fig. 6 is the program flow diagram of a kind of micro-capacitance sensor islet operation detecting device method of work involved by this utility model.
Fig. 7 is the electrical block diagram of modulate circuit of sampling in a kind of micro-capacitance sensor islet operation detecting device involved by this utility model.
(5) detailed description of the invention:
Embodiment: a kind of micro-capacitance sensor islet operation detecting device (see Fig. 4,5), it is characterised in that it includes DSP control chip, sampling modulate circuit, PWM isolated drive circuit, DA D/A converting circuit, power subsystem, communication unit, expanded circuit unit and voltage x current protection circuit unit；Wherein, described DSP control chip protects circuit unit all in being bi-directionally connected with sampling modulate circuit, PWM isolated drive circuit, DA D/A converting circuit, power subsystem, communication unit, expanded circuit unit and voltage x current respectively.
The digital signal processor that described DSP control chip unit adopts is the TMS320F2812 chip of American TI Texas Instruments.
Described PWM isolated drive circuit adopts the SN74LVCC3245 of TI company, is 5V level by the 3.3V level conversion of pwm signal, then the pwm signal of 5V level is inputted isolation drive unit, then drives IGBT.
Claims (3)
1. a micro-capacitance sensor islet operation detecting device, it is characterised in that it includes DSP control chip, sampling modulate circuit, PWM isolated drive circuit, DA D/A converting circuit, power subsystem, communication unit, expanded circuit unit and voltage x current protection circuit unit；Wherein, described DSP control chip protects circuit unit all in being bi-directionally connected with sampling modulate circuit, PWM isolated drive circuit, DA D/A converting circuit, power subsystem, communication unit, expanded circuit unit and voltage x current respectively.
2. a kind of micro-capacitance sensor islet operation detecting device according to claim 1, it is characterised in that the digital signal processor that described DSP control chip unit adopts is the TMS320F2812 chip of American TI Texas Instruments.
3. a kind of micro-capacitance sensor islet operation detecting device according to claim 1, it is characterized in that described PWM isolated drive circuit adopts the SN74LVCC3245 of TI company, it is 5V level by the 3.3V level conversion of pwm signal, then the pwm signal of 5V level is inputted isolation drive unit, then drive IGBT.
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| CN201520965717.XU CN205389108U (en) | 2015-11-26 | 2015-11-26 | Little electric wire netting isolated island operation detection device |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105606921A (en) * | 2015-11-26 | 2016-05-25 | 国家电网公司 | Negative sequence voltage positive feedback-based islanding detection system and method |
| CN106353614A (en) * | 2016-08-29 | 2017-01-25 | 许继集团有限公司 | Islanding detection method and device for direct-current system |
| CN107390067A (en) * | 2017-08-11 | 2017-11-24 | 中国电力科学研究院 | A kind of micro-capacitance sensor isolated island determination methods and device based on current inner loop control |
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2015
- 2015-11-26 CN CN201520965717.XU patent/CN205389108U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105606921A (en) * | 2015-11-26 | 2016-05-25 | 国家电网公司 | Negative sequence voltage positive feedback-based islanding detection system and method |
| CN106353614A (en) * | 2016-08-29 | 2017-01-25 | 许继集团有限公司 | Islanding detection method and device for direct-current system |
| CN106353614B (en) * | 2016-08-29 | 2020-01-21 | 许继集团有限公司 | Island detection method and device for direct current system |
| CN107390067A (en) * | 2017-08-11 | 2017-11-24 | 中国电力科学研究院 | A kind of micro-capacitance sensor isolated island determination methods and device based on current inner loop control |
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