CN102882233A - Medium-voltage distribution type maximum power point tracking (MPPT) large-power photovoltaic grid-connected power station - Google Patents
Medium-voltage distribution type maximum power point tracking (MPPT) large-power photovoltaic grid-connected power station Download PDFInfo
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- CN102882233A CN102882233A CN2012103847294A CN201210384729A CN102882233A CN 102882233 A CN102882233 A CN 102882233A CN 2012103847294 A CN2012103847294 A CN 2012103847294A CN 201210384729 A CN201210384729 A CN 201210384729A CN 102882233 A CN102882233 A CN 102882233A
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Abstract
The invention discloses a medium-voltage distribution type maximum power point tracking (MPPT) large-power photovoltaic grid-connected power station and belongs to the technical field of solar energy utilization. The medium-voltage distribution type MPPT large-power photovoltaic grid-connected power station comprises battery panel set strings, a front-stage boosting circuit composed of a plurality of front-stage boosting circuit units containing MPPT and an integrated inversion grid-connection device and is characterized in that each front-stage boosting circuit unit is formed by chopping boosting circuits of MPPT, and each front-stage boosting circuit unit is in one-to-one corresponding connection with the group of battery panel set strings; and a rear-stage boosting circuit is further arranged between the front-stage boosting circuit and the integrated inversion grid-connection device and is formed by rear-stage boosting circuit units in parallel mode, wherein each rear-stage boosting circuit unit is formed by a chopping boosting circuit containing MPPT and a bypass diode, the rear-stage boosting circuit units are in one-to-one corresponding serial connection with the front-stage boosting circuit, and an output end of the rear-stage boosting circuit is connected with an input end of the integrated inversion grid-connection device. The medium-voltage distribution type MPPT large-power photovoltaic grid-connected power station can enable photovoltaic power-connection power stations to be in megawatt (MW) or even gigawatt (GW) level.
Description
Technical field
The present invention relates to the solar photovoltaic grid-connection power station technology.Belong to application of solar.
Background technology
The pv grid-connected plant of present domestic mainstream technology scheme (referring to the 64th page of China Machine Press's " solar photovoltaic grid-connection generating and inversion control thereof "), to form cell plate group string array after the cell panel series connection, be directly connected to the inversion gird connecting device that contains MPPT maximum power point tracking control circuit (MPPT), by grid-connecting apparatus electric energy be defeated by electrical network.Consist of the photovoltaic combining inverter in the grid-connecting apparatus, peak power output 250-1000KW, output voltage 270V-400V, MPPT is generally 450V-820V in the operating voltage range of DC loop, adopt a MPPT that whole cell plate group string array is carried out MPPT maximum power point tracking control, because standby MPPT control circuit of each serial array assignment, this structure can only guarantee that the output of each cell plate group string reaches current total maximum power point, and can not guarantee that each cell plate group string exports the maximum power point separately.Because the electrical characteristic discreteness of each cell plate group string and attenuation characteristic is inconsistent, MPPT can only trace into the power output of the less cell plate group string of energy output, and the generating efficiency of whole pv grid-connected plant is greatly affected.This scheme can't achieve effective control on greater than the photovoltaic combining inverter of 1000KW in power output, and system effectiveness is low, and loss is large.
Existing a kind of parallel networking type photovoltaic power station that adopts multiple branch circuit structure in parallel, (referring to the 65th page of China Machine Press's " solar photovoltaic grid-connection generating and inversion control thereof "), this scheme is series-connected to the DC/DC converter that contains M PPT by cell plate group, then be connected to concentrated inversion gird connecting device after being confluxed by many groups of identical DC/DC converter parallel connections, by grid-connecting apparatus electric energy be defeated by electrical network.We know that the station capacity of this structure is little.When setting up the high-power photovoltaic synchronization power station, need with after several cell plate group connection in series-parallel, be connected to the DC/DC converter, control the some groups of cell plate group strings that are connected in parallel by the MPPT in each DC/DC converter.Its shortcoming is the power stage that can not guarantee each cell plate group string of being connected in parallel at separately maximum power point, and has the problem of power mismatch and many crests; In addition, be subjected to the restriction of cell plate group string insulation voltage and power device operating voltage, cause the expansion of capacity in power station limited.On the other hand, because the electrical characteristic discreteness of its each cell plate group string and attenuation characteristic is inconsistent, MPPT can only trace into the power output of the less cell plate group string of energy output, and the generating efficiency of whole pv grid-connected plant is greatly affected.The direct current transmission voltage of this pv grid-connected plant is up to 850V, and power station internal transmission loss is large.Therefore, the parallel networking type photovoltaic power station of present various structures all can not solve and increase photovoltaic DC-to-AC converter single-machine capacity and the low problem of system's generating efficiency, can not consist of the pv grid-connected plant of MW level even GW level.
Summary of the invention
For overcoming the above-mentioned shortcoming of prior art, the purpose of this invention is to provide a kind of generating efficiency height, the low distributed MPPT high-power photovoltaic synchronization of the middle pressure power station of internal transmission loss.
The formation that realizes the distributed MPPT high-power photovoltaic synchronization of the middle pressure power station of the object of the invention comprises the cell plate group string, the prime booster circuit that is composed in parallel by several prime booster circuit unit that contain the MPPT maximum power point tracking control circuit and the concentrated inversion gird connecting device that is consisted of by combining inverter and the step-up transformer that is incorporated into the power networks, it is characterized in that described prime booster circuit unit is made of the copped wave booster circuit that contains the MPPT maximum power point tracking control circuit, each prime booster circuit unit and a Battery pack plate group string be corresponding joining one by one, between described prime booster circuit and concentrated inversion gird connecting device, also be provided with a rear class booster circuit, described rear class booster circuit is made of the copped wave booster circuit that contains the MPPT maximum power point tracking control circuit rear class booster circuit unit parallel connection that consists of in parallel with bypass diode several, described rear class booster circuit unit and prime booster circuit connect one to one, and the output of rear class booster circuit is connected with the input of concentrated inversion gird connecting device.
Press the operation principle in distributed MPPT high-power photovoltaic synchronization power station as follows in this:
1, when solar radiant energy 〉=1%, press each cell plate group serial connection in distributed MPPT high-power photovoltaic synchronization power station to be subjected to solar energy in this, after converting direct current to, be passed to the prime booster circuit unit that connects one to one with it, by the MPPT maximum power point tracking control circuit in the prime booster circuit unit, make the cell plate group string stably be operated on the maximum power point, copped wave booster circuit in the prime booster circuit unit rises to direct current transmission voltage in the direct current and presses, a plurality of prime booster circuit unit parallel connections gather with capacity increasing, so that the bypass diode conducting in the rear class booster circuit unit, electric energy directly is sent to concentrates the inversion gird connecting device inversion, the backward electric power network that boosts is powered.
2, when solar radiant energy≤1%, press each cell plate group serial connection in distributed MPPT high-power photovoltaic synchronization power station to be subjected to solar energy in this, after converting direct current to, because capacity is set in the work less than MPPT maximum power point tracking control circuit in the prime booster circuit unit after its electric energy transmitting confluxes, this moment, bypass diode was closed condition, the direct current that the cell plate group string sends is transferred to rear class booster circuit unit after prime booster circuit unit gathers, by the MPPT maximum power point tracking control circuit in the rear class booster circuit unit, the cell plate group string stably is operated on the maximum power point.Copped wave booster circuit in the rear class booster circuit unit rises to direct current transmission voltage in the direct current and presses, a plurality of rear class booster circuit unit parallel connections gather with capacity increasing, be sent to concentrated inversion gird connecting device, again by concentrated inversion gird connecting device inversion, the backward electric power network power supply of boosting.Thereby solved present pv grid-connected plant and can not increase the problem that photovoltaic DC-to-AC converter single-machine capacity, generating efficiency lowly reach low light level generating difficulty.
Major advantage of the present invention is:
What 1, solved the existing power station of being incorporated into the power networks shares the variety of issue that MPPT brings by many groups batteries in parallel connection plate group string, as long as solar radiant energy is arranged, the cell plate group string stably is operated on the maximum power point, even under low light condition, also can generate electricity, thereby has improved generating efficiency.
2, by the copped wave booster circuit direct current transmission voltage is risen in the direct current and press, increased the electric energy transmitting of single loop dc transmission system; Loss when having reduced the internal system transmission.
3, can satisfy the instructions for use of middle press polish volt inverter, press polish volt inverter can make the photovoltaic DC-to-AC converter conversion efficiency greatly improve in the employing, transmission power loss reducing at double.
4, set up the rear class booster circuit, by the setting to the conducting voltage that is arranged on the bypass diode in each rear class booster circuit unit, realize the automatic switchover of high light generating and low light level power generation mode, solved all irrealizable low light level generating problems of present pv grid-connected plant.
The number of shunt circuit that 5, prime booster circuit unit can be set arbitrarily to be consisting of the prime booster circuit of different capabilities, thereby can adopt corresponding jumbo inverter to make pv grid-connected plant realize MW level even GW level.
Below in conjunction with embodiment content of the present invention is described in further details.
Description of drawings
Press the structural representation in distributed MPPT high-power photovoltaic synchronization power station in Fig. 1 basis
Embodiment:
Referring to Fig. 1, press that the formation in distributed MPPT high-power photovoltaic synchronization power station comprises cell plate group string 1 in this, the prime booster circuit A that is composed in parallel by several prime booster circuit unit 2 that contain MPPT and the concentrated inversion gird connecting device C that is consisted of by combining inverter 4 and the step-up transformer 5 that is incorporated into the power networks, it is characterized in that described prime booster circuit unit 2 is made of the copped wave booster circuit that contains MPPT, each prime booster circuit unit 2 and a Battery pack plate group string 1 be corresponding joining one by one; Between described prime booster circuit A and concentrated inversion gird connecting device C, also be provided with a rear class booster circuit B, described rear class booster circuit B by several by the copped wave booster circuit that contains MPPT and bypass diode VD
bThe rear class booster circuit unit that consists of in parallel 3 formations in parallel, described rear class booster circuit unit 3 connects one to one with prime booster circuit A, and the output of rear class booster circuit B is connected with the input of concentrated inversion gird connecting device.
Each cell plate group string 1 of present embodiment is made of 24 cell panel series connection.Cell panel is selected 235W universal serial polycrystal silicon cell plate, its output voltage 30.5V.MPPT and copped wave booster circuit can be used prior art and consist of.Each cell plate group string output voltage is 732V, power output is 5.64KW, after confluxing, electric energy after 9 * 6 such cell plate group string 1 parallel connections is input to prime booster circuit A, the output voltage of each prime booster circuit A is 1150V, and power output then is 9 * 6 * 5.64KW=304.56KW.Present embodiment has 20 prime booster circuit A, is 20 * 304.56KW=6091.2KW so deliver to total electric energy of concentrated inversion gird connecting device.
1, when solar radiant energy 〉=1%, (output voltage is 732V to each cell plate group string 1, power output is 5.64KW) accept solar energy, after converting direct current to, be passed to the prime booster circuit unit 2 that connects one to one with it, by the MPPT maximum power point tracking control circuit in the prime booster circuit unit 2, make the cell plate group string stably be operated on the maximum power point, copped wave booster circuit in the process prime booster circuit unit 2 rises to direct current transmission voltage presses 1150V in the direct current, unit 2 parallel connections of a plurality of prime booster circuits gather with capacity increasing, are arranged on the bypass diode VD in the rear class booster circuit unit 3 this moment
bConducting, electric energy is sent to directly concentrate that separate unit rated power is the photovoltaic combining inverter 4 of 5000KW among the inversion gird connecting device C, its output voltage is the three-phase alternating current of 690V after the inversion, boosts to by the step-up transformer 5 that is incorporated into the power networks and exchanges 35KV, powers to electric power network.
2, when solar radiant energy≤1%, accept solar energy by the cell plate group string 1 that connects among 9 * 6 prime booster circuit unit, the 2 prime booster circuit A that consist of in parallel, after converting direct current to, because capacity is set in the work less than MPPT in the prime booster circuit unit after its electric energy transmitting confluxes, at this moment bypass diode VD
bClosing, does not work in prime booster circuit unit 2, and the direct current that cell plate group string 1 sends directly is transferred to rear class booster circuit unit 3.MPPT in the rear class booster circuit unit starts working, this electric energy is passed to the rear class booster circuit unit 3 that connects one to one with it, by the MPPT in the rear class booster circuit unit 3, make the cell plate group string stably be operated on the maximum power point, copped wave booster circuit in the process rear class booster circuit unit 3 rises to direct current transmission voltage presses 1150V in the direct current, the rear class booster circuit B parallel connection that is made of 20 rear class booster circuit unit 3 parallel connections gathers with capacity increasing, electric energy is sent to concentrates that separate unit power is the photovoltaic combining inverter 4 of 5000KW among the inversion gird connecting device C, its output voltage is the three-phase alternating current of 690V after the inversion, boost to by the step-up transformer 5 that is incorporated into the power networks again and exchange 35KV, power to electric power network.
In the present embodiment, separate unit photovoltaic DC-to-AC converter power 250KW-1000KW with existing pv grid-connected plant, output voltage is designed to three-phase alternating current 270V-400V and compares, transmit the electric energy of same capacity, the quantity of photovoltaic combining inverter reduces at double, whole efficiency is higher, transmission capacity is larger, makes pv grid-connected plant can realize the engineering application of MW level even GW level.
Claims (1)
1. the distributed MPPT high-power photovoltaic synchronization of middle pressure power station, comprise the cell plate group string, the prime booster circuit that is composed in parallel by several prime booster circuit unit that contain the MPPT maximum power point tracking control circuit and the concentrated inversion gird connecting device that is consisted of by combining inverter and the step-up transformer that is incorporated into the power networks, it is characterized in that described prime booster circuit unit is made of the copped wave booster circuit that contains the MPPT maximum power point tracking control circuit, each prime booster circuit unit and a Battery pack plate group string be corresponding joining one by one, between described prime booster circuit and concentrated inversion gird connecting device, also be provided with a rear class booster circuit, described rear class booster circuit is made of the copped wave booster circuit that contains the MPPT maximum power point tracking control circuit rear class booster circuit unit parallel connection that consists of in parallel with bypass diode several, described rear class booster circuit unit and prime booster circuit connect one to one, and the output of rear class booster circuit is connected with the input of concentrated inversion gird connecting device.
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| CN104377827A (en) * | 2014-11-21 | 2015-02-25 | 南车株洲电力机车研究所有限公司 | Photovoltaic direct-current power source |
| CN104393833A (en) * | 2014-11-21 | 2015-03-04 | 南车株洲电力机车研究所有限公司 | Photovoltaic intelligent power |
| CN104821735A (en) * | 2015-04-17 | 2015-08-05 | 青岛艾迪森科技有限公司 | Special electric energy optimizing box for photovoltaic power station |
| CN106300327A (en) * | 2016-08-29 | 2017-01-04 | 三门峡速达节能新能源科技研究院 | A kind of distributed MPPT and the switchable topological structure of centralized MPPT and control method |
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| US10651735B2 (en) | 2017-02-06 | 2020-05-12 | Futurewei Technologies, Inc. | Series stacked DC-DC converter with serially connected DC power sources and capacitors |
| CN111313471A (en) * | 2020-03-30 | 2020-06-19 | 科华恒盛股份有限公司 | Inverter boost bypass switching method and photovoltaic power generation system |
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| CN106300327A (en) * | 2016-08-29 | 2017-01-04 | 三门峡速达节能新能源科技研究院 | A kind of distributed MPPT and the switchable topological structure of centralized MPPT and control method |
| US10651735B2 (en) | 2017-02-06 | 2020-05-12 | Futurewei Technologies, Inc. | Series stacked DC-DC converter with serially connected DC power sources and capacitors |
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| US10665743B2 (en) * | 2017-02-16 | 2020-05-26 | Futurewei Technologies, Inc. | Distributed/central optimizer architecture |
| CN111313471A (en) * | 2020-03-30 | 2020-06-19 | 科华恒盛股份有限公司 | Inverter boost bypass switching method and photovoltaic power generation system |
| CN111313471B (en) * | 2020-03-30 | 2021-10-01 | 科华恒盛股份有限公司 | Inverter boost bypass switching method and photovoltaic power generation system |
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Application publication date: 20130116 |