CN102435882B - Low-voltage ride through detection device of grid-connected photovoltaic converter of passive reactor structure - Google Patents

Low-voltage ride through detection device of grid-connected photovoltaic converter of passive reactor structure Download PDF

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Publication number
CN102435882B
CN102435882B CN2011102861317A CN201110286131A CN102435882B CN 102435882 B CN102435882 B CN 102435882B CN 2011102861317 A CN2011102861317 A CN 2011102861317A CN 201110286131 A CN201110286131 A CN 201110286131A CN 102435882 B CN102435882 B CN 102435882B
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China
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grid
detection
low
photovoltaic
reactor
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CN2011102861317A
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Chinese (zh)
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CN102435882A (en
Inventor
张军军
陈志磊
秦筱迪
李臻
朱松鸣
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国网电力科学研究院
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Abstract

The invention relates to a low-voltage ride through detection device of a grid-connected photovoltaic converter of a passive reactor structure. The low-voltage ride through detection device is characterized in that an AC (alternating current) source input end is connected with a 10 kV utility grid; an isolation transformer is additionally arranged to prevent the influences of detection on the utility grid; one end of the low-voltage ride through detection device is connected with the isolation transformer, and the other end of the low-voltage ride through detection device is connected with a boosting transformer; an independent passive reactor is adopted in the low-voltage ride through detection device; and the device mainly consists of a current limiting reactor X1, a grounding reactor X2 and two circuit breakers S1 and S2. The technical scheme disclosed by the invention provides an another low-voltage ride through detection realization method, which can meet the requirement for low-voltage ride through detection of the existing grid-connected photovoltaic converters of all power levels and voltage levels in the market, for the grid-connected photovoltaic converter. By adopting the independent passive reactor, the method can be used for simulating the transient state process of the utility grid when a real fault occurs, and has the advantages of high test response speed and lower cost.

Description

Low-voltage ride through detection device of grid-connected photovoltaic converter of passive reactor structure

Technical field

The present invention relates to photovoltaic generation access electric power network technique, is a kind of by adopting the low voltage crossing pick-up unit of the grid-connected photovoltaic inverter that the passive reactance device realizes.

Background technology

Traditional low voltage crossing pick-up unit realizes that by adopting the ac-dc-ac inverter device device mainly is comprised of transformer, ac-dc-ac inverter device.The inner transformer of device is used for changing the voltage differences between electrical network and frequency converter, and subsidiary effect with filtering is simultaneously avoided frequency converter that electrical network is injected and polluted harmonic wave.When carrying out low voltage crossing detection test, the amplitude that only need control frequency converter output voltage drops into ratings and gets final product.Because frequency converter has closed-loop control, so pick-up unit can be accomplished fine adjustment and simulation recovery curve.

When using the ac-dc-ac inverter device to carry out low voltage crossing, the net side converter adopts voltage vector to control, and in the power factor that guarantees to flow is under 1 prerequisite, to guarantee that dc voltage is steady state value; The control strategy of inverter side adopts voltage close loop to control, and the phase voltage sampled value is input in controller, through controlling output required voltage amplitude, generates the PWM ripple, thus the amplitude of control inverter output voltage.

By the low voltage crossing pick-up unit that adopts the ac-dc-ac inverter device to realize, no matter be to adopt the high voltage frequency converter of the little electric current of high voltage or the low-voltage frequency conversion device of low-voltage and high-current, cost is all higher; Owing to adopting voltage close loop to control, therefore the response speed of device is slower.

The photovoltaic combining inverter low voltage crossing refers to that in voltage fell scope, photovoltaic DC-to-AC converter can continue to be incorporated into the power networks when utility network fault or disturbance cause that the voltage of photovoltaic electric station grid connection point falls.Low voltage ride-through capability directly plays as a kind of strategy of large capacity photovoltaic system reply utility network fault or disturbance the effect of supporting the continual and steady operation of utility network.Grid-connected following transmission lines of electricity of 110kV that are applied to of following China more, the operation of power networks environment is very complicated, and between grid-connected photovoltaic system and utility network, capacity is greatly different in addition, and it is imperative that low voltage crossing detects.Be the grid-connected market order of standard, for promoting the flourish situation of photovoltaic generation, strive for the initiative of photovoltaic generation access electrical network, guaranteeing that photovoltaic system is safe and reliable is incorporated into the power networks, large capacity grid-connected photovoltaic inverter low voltage crossing detection approach is imperative safely and efficiently to look for one, and has broad application prospects.

Summary of the invention

The purpose of patent of the present invention is to realize that a kind of low voltage crossing that is applicable to the grid-connected photovoltaic inverter of various power grades, electric pressure detects core apparatus, independently passive reactance device is adopted in this device inside, and the low voltage crossing that can satisfy all kinds of grid-connected photovoltaic inverters detects demand.

For achieving the above object, the present invention adopts following technical scheme, low-voltage ride through detection device of grid-connected photovoltaic converter of passive reactor structure, it is characterized in that, the alternating current source input end connects the 10kV utility network, in order to prevent from detecting, utility network is exerted an influence, and increases isolating transformer; Low voltage crossing pick-up unit one end is connected to isolating transformer, and the other end is connected to step-up transformer; Independently passive reactance device is adopted in low voltage crossing pick-up unit inside, and device is mainly by X 1Current limiting reactor, X 2Earthing reactor, isolating switch S 1And S 2Form.

Isolating switch S before the experiment beginning 1Closure, S 2Disconnect the stable normal operation of photovoltaic DC-to-AC converter; During the experiment beginning, disconnect S 1, closed S 2, simulating grid voltage falls.For accurate simulating grid voltage falls, need Rational choice X 1And X 2Reactance value.X 1And X 2The selection of reactance value is subject to the restriction of factors, analyzes according to the principle topological diagram of Fig. 2, and be reactor X with isolating transformer, the equivalence of step-up transformer difference T, X 3, the utility network equivalence is that ideal voltage source, photovoltaic DC-to-AC converter equivalence are ideal current source.

The circuit of stack mutually again after major loop is equivalent to ideal voltage source and current source and acts on respectively, only to send out pure meritorious due to photovoltaic DC-to-AC converter, so utility network and photovoltaic DC-to-AC converter are at reactor X 290 ° of upper dividing potential drop phase differential, to fall the point voltage computing formula as follows for voltage:

As can be seen from the above equation, because tested grid-connected photovoltaic inverter capacity is uncertain, in order to reduce falling impact a little, must reduce the reactance value of passive reactance device at utmost to reduce the photovoltaic DC-to-AC converter electric current to the impact of the drop-off voltage degree of depth; But after dwindling reactance value, will increase passive inductance from the electrical network absorbing reactive power, and consider that the isolating transformer outlet side will have capacity limit, the value of passive reactance device can not infinitely be dwindled; The low voltage crossing test does not require the equipment long-play, because transformer has the function that Short-time Overload is carried out, and generally 2 ~ 3 times of the desirable isolating transformer outlet side of the minimum value capacity of passive reactance device, as shown in the formula:

The low voltage crossing pick-up unit has following two functions:

1) can the simulating grid fault or the voltage during disturbance fall with voltage and recover;

2) energy that grid-connected photovoltaic inverter is sent is fed into utility network.

The present invention program's enforcement, the implementation method of another kind of low voltage crossing detection is provided for grid-connected photovoltaic inverter, the method is by adopting the passive reactance device, and can satisfying equally in the market, the grid-connected photovoltaic inverter low voltage crossing of all power grades, electric pressure detects demand.Adopt the ac-dc-ac inverter device to realize that the method for low voltage crossing detection is different from traditional passing through, the low voltage crossing pick-up unit that the present invention proposes, by adopting independently passive reactance device, can simulate the transient state process of utility network when truly breaking down, test response speed is fast, and cost is relatively low.

Description of drawings

Fig. 1: the grid-connected photovoltaic inverter low voltage crossing pick-up unit block diagram that generally uses at present.

Fig. 2: the grid-connected photovoltaic inverter low voltage crossing pick-up unit block diagram that the present invention proposes.

Fig. 3: low voltage crossing pick-up unit major loop equivalent electrical circuit.

Embodiment

Photovoltaic combining inverter low voltage crossing pick-up unit is used under test electric network fault or state of disturbance, whether inverter has the low voltage ride-through capability that meets standard-required, when detecting test,

(1) with the series connection of low voltage crossing pick-up unit between isolating transformer and step-up transformer, another termination utility network of isolating transformer, another termination grid-connected photovoltaic inverter output terminal of step-up transformer, inverter input terminal connects controllable direct current power supply;

(2) start the low voltage crossing pick-up unit, regulating device internal simulation electrical network exports the invertor operation scope to;

(3) start controllable direct current power supply, selecting the direct supply mode of operation is constant current, constant voltage or MPPT;

(4) start inverter, wait for the normal stable operation of inverter;

(5) voltage that low voltage crossing pick-up unit internal simulation electrical network is set falls parameter, test inverter low voltage ride-through function.

Claims (1)

1. low-voltage ride through detection device of grid-connected photovoltaic converter of passive reactor structure, it is characterized in that: device one end is connected to isolating transformer, the other end is connected to step-up transformer, and isolating transformer is connected with utility network, and step-up transformer is connected with photovoltaic DC-to-AC converter; Device adopts independently the passive reactance device, comprises current limiting reactor X1, earthing reactor X2, isolating switch S1 and S2, the reactance value of described current limiting reactor X1 and earthing reactor X2 by with isolating transformer and step-up transformer respectively equivalence choose for ideal current source for ideal voltage source, photovoltaic DC-to-AC converter equivalence for reactor XT and X3, utility network equivalence; Before the experiment beginning, isolating switch S1 is closed, and S2 disconnects, the stable normal operation of photovoltaic DC-to-AC converter; During the experiment beginning, disconnect S1, closed S2, simulating grid voltage falls.
CN2011102861317A 2011-09-24 2011-09-24 Low-voltage ride through detection device of grid-connected photovoltaic converter of passive reactor structure CN102435882B (en)

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CN2011102861317A CN102435882B (en) 2011-09-24 2011-09-24 Low-voltage ride through detection device of grid-connected photovoltaic converter of passive reactor structure

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CN102684225B (en) * 2012-05-25 2014-12-17 武汉大学 Controllable electric reactor based low-voltage ride through system and test method thereof
CN102721883B (en) * 2012-06-15 2016-02-24 中国电力科学研究院 A kind of low voltage crossing pick-up unit of grid-connected photovoltaic inverter
CN104345222A (en) * 2013-07-29 2015-02-11 青岛菲特电器科技有限公司 Low-voltage ride through system
CN103944507B (en) * 2014-02-18 2017-01-11 国家电网公司 Photovoltaic-power-station low-voltage penetrating performance evaluation method based on inverter model test
CN104124916B (en) * 2014-06-30 2016-09-14 国家电网公司 High aititude photovoltaic plant electric network fault simulated testing system mobile detection apparatus
CN104184410B (en) * 2014-06-30 2016-09-14 国家电网公司 High aititude photovoltaic plant grid disturbance simulated testing system mobile detection apparatus
CN106772114A (en) * 2015-11-18 2017-05-31 中国电力科学研究院 A kind of multiple access voltage class method of testing of low-voltage ride-through detection equipment
CN105425171A (en) * 2015-12-18 2016-03-23 南京南瑞继保电气有限公司 Method for detecting voltage drop of low voltage ride-through power source of frequency converter
CN110672938A (en) * 2019-09-19 2020-01-10 南方电网科学研究院有限责任公司 Method and system for testing low voltage ride through characteristics of photovoltaic inverter and storage medium

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CN102121966B (en) * 2010-01-07 2013-04-10 华北电力科学研究院有限责任公司 Measuring method and analytical system for low-voltage ride through capability of wind driven generator
CN201904625U (en) * 2010-11-17 2011-07-20 浙江运达风电股份有限公司 Low-voltage crossing controller of wind generating set based on converter
CN102129036A (en) * 2011-01-07 2011-07-20 中电普瑞科技有限公司 Movable low-voltage ride-through testing device for wind generating set

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