WO2019083567A1 - Centrale électrique photovoltaïque - Google Patents

Centrale électrique photovoltaïque

Info

Publication number
WO2019083567A1
WO2019083567A1 PCT/US2018/035454 US2018035454W WO2019083567A1 WO 2019083567 A1 WO2019083567 A1 WO 2019083567A1 US 2018035454 W US2018035454 W US 2018035454W WO 2019083567 A1 WO2019083567 A1 WO 2019083567A1
Authority
WO
WIPO (PCT)
Prior art keywords
power
energy
phase
reservoir
converter
Prior art date
Application number
PCT/US2018/035454
Other languages
English (en)
Inventor
Geoffrey Wen-Tai Shuy
Jau-dar LIAO
Hsin-Chen Lai
Feng-Tse Chung
Hsiu-Wen Han
Original Assignee
Shuy Geoffrey Wen Tai
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US15/796,506 external-priority patent/US10381840B2/en
Priority to MX2020004135A priority Critical patent/MX2020004135A/es
Priority to CN201880069621.1A priority patent/CN111492553A/zh
Priority to KR1020207011703A priority patent/KR102376838B1/ko
Priority to CA3077416A priority patent/CA3077416A1/fr
Priority to EP18870842.4A priority patent/EP3701614A4/fr
Application filed by Shuy Geoffrey Wen Tai filed Critical Shuy Geoffrey Wen Tai
Priority to BR112020007759-3A priority patent/BR112020007759B1/pt
Priority to EA202091048A priority patent/EA202091048A1/ru
Priority to JP2020543462A priority patent/JP7212050B2/ja
Priority to AU2018355030A priority patent/AU2018355030B2/en
Publication of WO2019083567A1 publication Critical patent/WO2019083567A1/fr
Priority to PH12020550459A priority patent/PH12020550459A1/en
Priority to CONC2020/0005190A priority patent/CO2020005190A2/es

Links

Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/66—Regulating electric power
    • G05F1/67—Regulating electric power to the maximum power available from a generator, e.g. from solar cell
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
    • H02J7/35—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering with light sensitive cells
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • H02J2300/26—The renewable source being solar energy of photovoltaic origin involving maximum power point tracking control for photovoltaic sources
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/40—Synchronising a generator for connection to a network or to another generator
    • H02J3/44—Synchronising a generator for connection to a network or to another generator with means for ensuring correct phase sequence
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/493—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode the static converters being arranged for operation in parallel
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E70/00—Other energy conversion or management systems reducing GHG emissions
    • Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
    • Y02P90/50—Energy storage in industry with an added climate change mitigation effect

Definitions

  • PV power stations generate electricity by converting solar energy to electricity. That generated electricity is then provided to an electric power grid.
  • the solar energy source i.e., the received rays of the sun
  • the solar energy source i.e., the received rays of the sun
  • the solar energy source is characterized as having time varying intensity.
  • PV power generators in such PV power stations incorporate a power generation optimization device (also referred to as an "optimizer”).
  • MPPT maximum power point tracker
  • MPPT device MPPT device
  • MPPT device which tracks an instantaneous maximum power production point (MPPP) voltage that the MPPT device uses to control operation of the PV power station.
  • MPPP maximum power production point
  • the MPPT device typically is software or firmware; and keeps track of the time varying voltage resulting in the maximum power production from the time varying solar energy source.
  • each AC power production unit comprises a DC power generator, first DC/ AC 3-phase converter(s), an energy reservoir, and second DC/AC 3-phase converter(s).
  • the DC power generator is composed of x MW solar strings, where x is a positive number.
  • the first DC/ AC 3-phase converter(s) have a total declared power rating of y MW.
  • the first DC/ AC 3-phase converter(s) receive DC power provided by the DC power generator, convert the received DC power into AC power, and provide that converted AC power through a transformer to a power grid.
  • the energy reservoir receives at least some of a remaining portion of the DC power generated by the DC power generator.
  • the second DC/AC 3-phase converter(s) having a total declared power rating of z MW, where z is a positive number, and the sum of y and z is greater than x.
  • the second DC/AC 3-phase converter(s) receive DC power from the energy reservoir, convert the received DC power from the energy reservoir into AC power, and provide that converted AC power through a transformer to the power grid. Because the sum of y and z is greater than x, the power station in accordance with this embodiment delivers more power to the power grid.
  • each AC power product unit includes a DC power generator composed of x MW solar strings, and energy reservoir, and DC/AC 3-phase converters having a total declared power rating of z MW, where z is greater than x.
  • the energy reservoir receives at least some of a remaining portion of the DC power generated by the DC power generator.
  • the DC/AC 3-phase converter(s) receive DC power from the energy reservoir, convert the received DC power from the energy reservoir into AC power and providing that converted AC power through a transformer to the power grid. Because z is greater than x, the power station in accordance with this embodiment delivers more power to the power grid.
  • each AC power production unit comprises a DC power generator composed of solar strings.
  • the DC/ AC 3-phase converter(s) receives DC power from the DC power generator through a decoupler, convert the received DC power into AC power, and provides that converted AC power through a transformer to the power grid.
  • the use of the decoupler avoids the problems that the inventors discovered relating to the power annihilation phenomenon, thereby increasing the amount of power that the power station can deliver to the grid.
  • FIGS 1 A through 1C illustrate block diagrams of various power stations in which decoupling devices are used in conjunction with an energy reservoir
  • Figure 2A illustrates a block diagram of a power station that was set up in an experiment, and in which there are two AC power production units that are set up conventionally, and with power and energy meters that measure output of each power production unit;
  • Figure 2B illustrates a block diagram of the power station of Figure 2A after modification to including decoupling devices and an energy reservoir, and that was used to verify improved energy output to the grid;
  • Figure 3 illustrates a block diagram of a power station in which there are two channels of power delivery, one channel invoking the use of an energy reservoir, and one not invoking the user of the energy reservoir;
  • Figure 4 illustrates a block diagram of a power station that represents a broader embodiment of Figure 3;
  • Figure 5 illustrates a block diagram of a power station in which power is delivered via the use of an energy reservoir
  • Figure 6 illustrates a block diagram of a power station that represents a broader embodiment of Figure 5;
  • Figure 7 illustrates a block diagram of a power station
  • Figure 8 illustrates a block diagram of a Maximum Energy Utilization Point Tracking (MEUPT) controller in accordance with the principles described herein; and
  • Figure 9 illustrates a block diagram of the MEUPT controller of Figure 8 in the context of a power station.
  • Patent publications, US2016/0036232 and US2017/0149250 Al disclose that the PV energy systems that practice of the blind MPPT conformation achieving suboptimal amounts of electricity provided to the grid.
  • These patent publications teach that in order to efficiently extract electricity for energy utilization, one should match the characteristics of the energy extraction device to effectively and efficiently extract the produced electric energy.
  • these patent applications teach that the related devices should also be matched to condition and/or deliver the extracted electricity for efficient energy utilization.
  • the referenced patent publications proposed to use a "maximum energy utilization point tracker", or the "MEUPT device” as the PV power station optimizer.
  • Such an optimizer will be referred to as an "MEUPT optimizer” herein.
  • the MEUPT optimizer is designed to capture what it refers to as “surplus energy”, which it defines as the electric energy that is produced but not extracted and/or delivered to the power grid for utilization. That definition of "surplus energy” is also used herein.
  • the MEUPT optimizer is also designed to temporarily store the captured surplus energy within an energy reservoir; and then prepare and deliver this electric energy to the power grid for utilization.
  • the electricity sales revenue of the PV power station can be enhanced when incorporating the MEUPT optimizer.
  • the MEUPT optimizer of one embodiment disclosed herein comprises a surplus energy extractor, an energy reservoir, and an MEUPT controller.
  • the MEUPT controller works in concert with energy extractors and DC/ AC converters.
  • power and energy are used interchangeably in the art. Thus, unless otherwise specified, each term has the same meaning.
  • An energy extractor extracts an initial oscillating power train from the produced DC electric power source.
  • the extracted initial power chain conforms to the AC power grid requirements of the power grid.
  • the extracted initial power chain has a time varying sinusoidal voltage that having a peak voltage that conforms to power grid voltage range.
  • the electrical power (which is proportional to the square of the voltage) takes the form (sin 2 (cot) or cos 2 (cot)), which is synchronized (with the same phase and same frequency) with the power grid.
  • a surplus energy extractor extracts a remaining oscillating power train that remains from subtracting out the initial oscillating power train from the produced DC power.
  • this remaining oscillating power train is a left-over oscillating power train that remains after providing the initial oscillating power train to the power grid.
  • the remaining oscillating power train has a 90° phase shift as compared to the initial oscillating power train that was provided to the power grid. Due to the 90° phase shift, this remaining oscillating power train cannot be immediately converted into AC power for providing onto the same power grid.
  • An energy reservoir is thus used to temporarily store the surplus energy of the remaining oscillating power train. Thereafter, the stored energy is supplied to a DC/ AC converter; such that the stored surplus energy can be converted to AC power that is synchronized (with the same phase and frequency) with the same power grid.
  • the MEUPT controller measures the energy level of the reservoir; estimates the amount of the energy in reservoir that can be extracted; and delivers this information to the associated DC/ AC converter(s) such that this energy amount can be extracted by the DC/AC converter(s).
  • the DC/ AC converter(s) then extract the stored energy from the reservoir for conversion into AC power in the form of a suitable pulsating power train and provides that AC power to the power grid.
  • the PV power stations can thus provide almost all the produced electric energy to a power grid when incorporating the MEUPT optimizer. In contrast, without the MEUPT optimizer, the PV power station in according to the referred patent publications can only provide less than half of the produced power/energy to a power grid.
  • Section Two Improve conventional PV power station with MEUPT
  • Solar power stations are often rated in terms of some number of MegaWatts (MW). Conventionally, when a solar power station is declared to be rated at x MW (where x is some positive number), this means that the sum total of the DC power production rating of all solar strings is x MW. Such conventional solar power stations also have 3-phase DC/AC converters have a total maker declared DC/AC conversion capability that is no greater than x MW. This principle summarizes the convention power station's operations in according to the conventional MPPT practice.
  • the conventional PV power station of rating x MW consists of strings of x MW PV solar panels, which convert solar energy to DC electricity.
  • the generated DC electricity is then extracted and converted by 3-phase DC/ AC converters to suitable AC electric power that conforms to all the AC power requirements of a power grid, and is then provided to the power grid.
  • This AC electrical power provided to the power grid is also referred to herein as the "initial oscillating power train”. Recall that the total maker declared DC/ AC conversion capability of the DC/AC converters is no greater than x MW, which is the total amount of the installed solar panels' DC generation capability declared by the solar panel industry.
  • an energy reservoir temporarily stores the energy containing in this 90° out of phase remaining oscillating power train (which when stored represented surplus energy). After this surplus energy is stored into the energy reservoir, the surplus energy can serve as a DC energy that can be supplied to a DC/AC converter. This surplus energy can then be converted to an AC power which conforms to all the power grid requirements (including synchronization with the power grid), such that the resulting AC power may be provided to the same grid.
  • the solar panel strings can have a very high resistance at dusk, but the solar panel string can conduct significant electric current in either direction when the sun is strong at mid-day. Therefore, the electric energy stored in the reservoir may leak through and heat the solar panels during the daytime. Accordingly, decoupling diodes may be added to each of solar panel strings such that electric energy can flow from each solar panel string to charge the reservoir, but the energy in the reservoir cannot back flow back from the reservoir into the solar panel strings.
  • decoupling diodes may be added to each of solar panel strings such that electric energy can flow from each solar panel string to charge the reservoir, but the energy in the reservoir cannot back flow back from the reservoir into the solar panel strings.
  • Figure 1 A depicts a block diagram that illustrates an energy reservoir 1300A that is designed to temporarily store the surplus power resulting from a power stream produced from a set of solar strings 1100 A subtracting out the power drawn by a DC/ AC converter 1200A when the DC/ AC converter 1200A converts that power to AC power.
  • the AC power is provided to an AC power grid 1600A through a transformer 1500A.
  • the reservoir 1300A receives the remaining oscillating power train through a decoupling diode set 1400A.
  • this energy reservoir 1300 A is designed to temporarily store the surplus energy of a 1 MW PV power station for 2 minutes.
  • the estimated ratio of the surplus energy to the produced DC electric energy is over 0.5 for typical conventional PV power stations.
  • the PV power station has 1 MW PV solar panel strings; and the DC power is converted to AC power to provide to a grid that is 50 hertz and line voltage 380 VAC 3-phase AC power.
  • the duration time of one power cycle is equal to about 0.01 seconds and the total phase current is up to 1,000,000/(380/1.732), where 1.732 is the value of square root of 3.
  • This ratio is the ratio of the peak voltage to line voltage (line-to-phase voltage, or "phase voltage", in 3-phase AC power).
  • the operating voltage of the MEUPT optimizer is to be within 75% of the PV maximum power production voltage.
  • the voltage range of the 75% maximum power production is to be observed in those embodiments of the MEUPT optimizer.
  • the measured I-V data indicates that typically this range is about 80 volts.
  • V 80 volts
  • the charge capacity of an energy reservoir is about 0.1 Faradays per MW, per power cycle (where the power cycle lasts 0.01 second).
  • the required equivalent charge capacity is equal to 1200 Faradays (100* 120* 0.1) for the 1 MW PV power station. This required equivalent charge capacity is referred as the "full maximum charge capacity” and the amount of reservoir stored energy associated is referred as the “full maximum energy reservoir-capacity", or “full maximum surplus energy” herein.
  • electrolytic capacitors can substantially reduce the required capital cost. However, such would increase the operating cost due to the relatively short life of such capacitors. Thus, at present, the use of electrolytic capacitors is not practical either. Therefore, the brute force way does not achieve economically beneficial designs with the required full maximum energy reservoir-capacity.
  • a MW-level PV power station (rated greater than 1 MW) may occasionally experience a ramping-up rate larger than 10 kW per second during a short power burst. However, the energy contained in this short burst (or even in larger 100 kW per second burst) is insignificant when compared with the total daily energy produced in MW-level power stations.
  • the inventors determined that (1) the power generation in each of the solar panel strings starts from zero every morning; and (2) the PV generator does not generate full power instantly. Thus, the remaining oscillating power train does not ramp up to its maximum value instantly. In other words, the remaining oscillating power train increases typically much more graceful than the ramp up rate of the DC/AC converters. Furthermore, the amount of energy in any short ramp-up burst is not a significant issue in energy collection for PV stations rated 1 MW or higher.
  • Figure IB depicts a block diagram that symbolically illustrates an energy reservoir 1300B that stores surplus power resulting from a power stream produced from a set of solar strings 1100B subtracting out the power drawn by a DC/AC converter 1201B.
  • another DC/AC converter 1202B is directed by the MEUPT controller 1310B to receive approximately the same amount of DC energy from the energy reservoir 1300B (containing the surplus power).
  • Both of the DC/AC converters 1201B and 1202B simultaneously convert received DC energy to AC power, and provide that AC power to the same grid 1600B through the same transformer 1500B. In doing so, the net energy storage burden to the reservoir 1300B can be reduced to a very small capacity when compared with that of the reservoir 1300 A depicted in Figure 1A.
  • Figure 1C depicts a configuration that is modified from the configuration depicted in Figure IB, but has approximately the same performance of the configuration depicted in Figure IB.
  • an energy reservoir 1300C stores the DC power stream produced by PV solar strings 1 lOOC through a diode set 1400C.
  • Two DC/AC converters 1201C and 1202C are directed by the MEUPT controller 13 IOC to receive (in the aggregate) approximately the same total DC power from the energy reservoir 1300C in an amount that approximately equals the DC energy input produced by the PV strings.
  • the MEUPT controller 13 IOC to receive (in the aggregate) approximately the same total DC power from the energy reservoir 1300C in an amount that approximately equals the DC energy input produced by the PV strings.
  • both 1201 C and 1202C simultaneously convert the received DC power to AC power provided to the same grid 1600B through the same transformer 1500C.
  • the energy reservoir can extract and store the surplus energy in the form of a remaining oscillating power train that remains after the produced DC power is extracted by an energy extractor (which can be built-in as a module of the DC/ AC converter 120 IB).
  • the other DC/ AC converter 120 IB is designed to extract an approximately equal amount of energy out of the energy reservoir 1300B to reduce the net amount of surplus energy stored into the reservoir.
  • a relatively small reservoir is adequate.
  • the energy reservoir 1300C can receive all the produced DC power from the PV strings 1100C.
  • An oscillating power train is then extracted by the DC/AC converters 1201C and 1202C, while the surplus energy (the left-over power) is also implicitly stored within the energy reservoir 1300C in the form of a 90° out of phase remaining oscillating power train.
  • this surplus energy is also implicitly automatically extracted and stored into the reservoir 1300C.
  • the designed energy reservoir can serve as the energy reservoir purposed for an MEUPT optimizer; which temporarily stores small amount of net surplus energy that is 90° out of phase.
  • the hard task of energy reservoir design is now shifted to the task of designing a proper MEUPT controller.
  • Section Five Necessary functions of the MEUPT controller
  • the controller should be able to direct the associated DC/AC converter(s) to consistently draw a proper amount of energy from the reservoir that is substantially equal to the amount in the surplus power charging into the reservoir. In doing so, one can minimize the net amount of energy storage into the reservoir; and maintain adequate balanced energy storage in the reservoir to stabilize system operation. When so doing, the energy reservoir only needs to store (or to provide) the energy difference between the charging surplus power and the power drawn by the DC/AC converter(s) within a small time duration.
  • the energy difference can be designed to be manageably small.
  • the time duration can be designed to be long enough to ramp up or down for the DC/ AC converter(s) in matching the surplus energy; and short enough to significantly reduce the capacity of the reservoir while still keeping the system operation stable.
  • the estimated reservoir's capacity can thus reduce to be less than 0.001 times that of the maximum full surplus energy. This capacity is less than 2 Faradays per 1 MW PV power station; a manageable charge capacity even if using thin film capacitors.
  • An example of a suitable MEUPT controller will be described below with respect to sections Twelve through Fourteen below.
  • the decoupling technique applied in Figure IB and Figure 1C allows the strings of solar panels to charge the energy reservoir; but prevents the power from flowing back from the reservoir into the PV solar strings.
  • this technique not only prevents the energy leakage from the reservoir through the PV solar panel strings, but also can prevent a phenomenon discovered by the inventors. This phenomena is referred to herein as the "mutual power annihilation among PV strings phenomena", the “mutual power annihilation phenomena”, or the "power annihilation phenomena”.
  • This phenomenon occurs when parallel-connected serval PV strings collect the produced power. This phenomenon is especially pronounced when the parallel-connected PV strings having very different I-V characteristics, photo-electric conversion efficiencies, and/or maximum power production voltages.
  • the power annihilation phenomenon can also occur when parallel-connected PV strings have very different maximum power production voltages. For instance, suppose that there are two solar panel strings connected in parallel-connected - one having 15 stringed solar panels and another having 19 stringed solar panels. The power generated in the string with 19 panels will definitively flow through the string with 15 panels and the power annihilation phenomenon occurs. Experiments show that the power received from the above parallel-connected two strings can reduce to less than half of that produced by the string with 19 panels alone. When properly decoupled, the power received from the above two parallel-connected strings can recover to about 1.53 times that produced by the string with 19 panels alone. The above described experiment shows that (a) the mutual power annihilation phenomenon does exist; and (b) properly decoupling techniques can prevent the phenomenon.
  • a PV plant was arranged to have two power production units; each unit consisting of 85 solar panels of the same maker and model.
  • Each of the two power product units was configured with five (5) parallel-connected PV strings to collect the produced DC energy.
  • Two PV strings were configured with series-connected 15 panels, two strings with series-connected 17 panels, and another string with series-connected 21 panels. When these 10 strings' maximum power production voltages are measured separately at high noon with clear skies, the maximum power production voltages ranged from 420 volts as the lowest to 610 volts at the highest. Thus, these parallel-connected PV solar strings have very different maximum power production voltages under the same clear sky.
  • Each of the power production units converts the collected DC power via a different DC/ AC converter into AC power.
  • a kilowatt-hour meter and a watt meter were connected to the AC output of each of the DC/AC converters of each production unit. These units were then connected to a transformer to provide the AC power to a grid. With 72 identical readings of the two power meters over a 36 day period, and with identical readings of the two kilowatt-hour meters at the end of the 36 day period, it is confirmed that all elements in these two power production units (including the two sets of measuring meters) were substantially identical.
  • One power production unit was then modified to be configured with 4 strings of 21 panels (and 1 panel not in use); while the other power production unit was left unchanged from the above described 5 strings.
  • the measured power production of the modified power production unit was typically greater than 4.1 times that of the other power production unit at high noon and clear skies.
  • the modified power production unit provided energy to the grid of 3.38 times that of the unmodified power production unit.
  • FIG. 2A depicts the starting set up of a PV power station 2000A comprising 2 AC power production units 2100A and 2200A.
  • Each of the AC power production units 2100A and 2200A practices blind MPPT conformation; and provides 3-phase AC power to a power grid 2600 A.
  • the AC power production unit 2100A consists of a DC power generator 2110A and a 3-phase DC/AC (15 kW) converter 2130A.
  • the AC power production unit 2200A consists of a DC power generator 2220A and a 3-phase DC/AC (15 kW) converter 223 OA.
  • the power generator 211 OA uses 2 parallel-connected PV strings 2111A and 2112A to generate DC electricity.
  • the power generator 2220A uses another 2 parallel-connected solar strings 2221A and 2222A to generate DC electricity.
  • Each of the 4 PV strings consists of 25 series-connected solar panels; each panel capable of producing 250W of power at high noon and with clear skies.
  • the DC power generator 2110A supplies DC power to the 3-phase DC/ AC converter 2130A; and the DC power generator 2220A supplies DC power to the 3-phase DC/ AC converter 2230A. These two converters 2130A and 2230A then convert the supplied DC power into 3-phase AC power.
  • the AC output power of the power production units 2100A and 2200A were measured by two 3-phase AC watt-meters (in kW) 2351A and 2352A, respectively.
  • the AC energy production (in kW*hour) of these two power production units 2100A and 2200A were also measured by two kW-hour-meters 2361A and 2362A, respectively.
  • the produced 3-phase AC power was then provided to the grid 2600A via transformer 2500A.
  • the PV power station was operated; and the energy production of the two AC power production units 2100A and 2200A was measured for 7 days.
  • the power production unit 2200B of Figure 2B is the power production unit 2200A of Figure 2A unmodified.
  • the elements 235 IB, 2361B, 2352B, 2362B, 2500B, 2600B of Figure 2B are the same as the elements 2351A, 2361A, 2352A, 2362A, 2500A, 2600A, respectively, of Figure 2A.
  • the configuration of the power production unit 2100B is different in Figure 2B than the power production unit 2100 A of Figure 2A, some of the elements of the power production unit 2100B of Figure 2B are the same as those that are included within the power production unit 2100A of Figure 2A.
  • the PV strings 211 IB and 2112B of Figure 2 are the same as the PV strings 2111 A and 2112A, respectively, of Figure 2A.
  • the DC/AC converter 2130B of Figure 2B is the same as the DC/ AC converter 2130 A of Figure 2 A.
  • Step 1 was to add a set of decoupling diodes 231 IB in-between the solar strings 211 IB and 2112B and the 3-phase DC/AC converter 2130B, which is practicing the blind MPPT conformation.
  • Step 2 was to add an energy reservoir 2410B into the configuration.
  • Step 3 was to connect the energy reservoir 2410B to the DC terminals of the DC/AC converter 2130B through another set of decoupling diodes 2312B and through a switch SW1.
  • Step 4 was to add another 3-phase DC/AC converter 2130S (20 kW) into the configuration, which converter 2130S was operated in according with the direction of a designed MEUPT controller 2420B.
  • Step 5 was to connect the DC/AC converter 2130S to the energy reservoir 2410B through another set of decoupling diodes 2313B and through a switch SW2.
  • Step 6 was to connect the output terminals of the converter 2130S to the power and energy measurement instrument set 235 IB and 2361B through a switch SW3.
  • the referenced "decoupling diode set” may be those diodes that are termed "blocking diodes" in the art.
  • switches SW1, SW2, and SW3 are added as depicted in Figure IB, such that the relevant devices can be introduced to (or removed from) the experiments at a proper time in the designed experimental execution steps described below.
  • the switches SW1, SW2, and SW3 were turned on the night after first day operation (the second night).
  • the converters 2130B and 2230B started to run early in the early morning (the second day), while the converter 2130S started to run at lower power conversion level at about 15 minutes after the converters 2130B and 2230B started to run. Thereafter, the converter 2130 increased its conversion power level about every 2 minutes; that is consistent with the controller design and increment of the reservoir energy level.
  • the reading of the power meter 235 IB (for unit 2100B) reached about double of reading of the power meter 2352B (for unit 2200B) for the entire day - until nearly sunset.
  • the energy provided from the two power production units 2100B and 2200B by the end of the second day were derived from the two kW-hour-meters' readings.
  • the result showed that the energy provided from the modified power production unit 2100B was more than double the energy provided from the unmodified power production unit 2200B.
  • the switches SW1, SW2 and SW3 remained on, and the energy provided from the modified power production unit 2100B was consistently more than double that of the power production unit 2200B each day.
  • the modified power generation unit 2100B (as described above and depicted in Figure 2B) can serve as an example of a PV power generation unit incorporating an MEUPT optimizer.
  • the MEUPT optimizer comprises three decoupling diode sets 231 IB, 2312B, and 2313B; a reservoir 2140B, and an MEUPT controller 2320B. Notice that the decoupling diode set is referred as the "decoupling device", hereinafter.
  • FIG. 3 Another embodiment is depicted in Figure 3.
  • This embodiment illustrates a configuration of the PV power station 3000 incorporating an MEUPT optimizer which comprises only one AC power production unit 3100 which uses 500 kW solar panels 3110 to convert solar power into DC electric power.
  • the AC power production unit 3100 consists of a DC power generator 3110 and a 3-phase DC/AC (500 kW) converter 3130.
  • the power generator 3110 uses 80 parallel-connected solar strings to generate DC electricity. Each of the 80 solar strings consists of 25 series-connected solar panels; each panel is declared to have 250W DC power production capability at high noon and clear skies.
  • the power generator 3110 supplies DC power to a 3-phase DC/ AC converter 3130 (with declared 500 kW) through a decoupling device 3311.
  • the generator 3110 also supplies DC power to the energy reservoir 3410 through decoupling device 3312, and servers as a DC energy source that charges the energy reservoir 3410. Therefore, the surplus energy is passively extracted by the reservoir 3410.
  • the reservoir 3410 then supplies (or discharges) DC power to another 3-phase DC/AC converter 3130S (with declared 500 kW) through decoupling device 3313.
  • the converter 3130 operates as an MPPT optimizer, while the converter 3130S operates as an MEUPT controller.
  • Converters 3130 and 3130S convert the separately supplied DC power into 3-phase AC power and deliver to power a grid 3600 via the same transformer 3500.
  • the DC/AC converters used in the above descriptions can be categorized into two types; namely, one type that receives its DC power directly from the PV solar strings, and another type that receives its DC power from the energy reservoir.
  • the type of converter distinction is necessary in the disclosure and in the following detail description, the one receiving DC power from PV solar strings is also referred as the "PS DC/AC converter”; while the other one receiving DC power from the energy reservoir is also referred as the "ER DC/ AC converter” herein.
  • PS DC/AC converter the one receiving DC power from PV solar strings
  • ER DC/ AC converter the other one receiving DC power from the energy reservoir
  • this MEUPT optimizer provides optimization service to an x MW PV power station which has properly arranged solar panel strings with rated x MW power generation capability.
  • the produced DC power is extracted by a maker declared y MW "PS 3-phase DC/AC converter" 4130 through a decouple device 4311.
  • the left-over power is charged into an energy reservoir 4410 through another decoupling device 4312; thus extracting and storing the surplus energy.
  • the stored surplus energy is then converted by another maker declared z MW "ER 3-phase DC/ AC converter" 4130S through another decoupling device.
  • FIG. 5 depicted another embodiment of incorporating an MEUPT optimizer in a large PV power station.
  • the power station is equipped with rated 0.5 MW solar panel strings 5110 and two declared 500 kW 3-phase DC/ AC converters 5130 and 5130S.
  • This embodiment illustrates another configuration for the MEUPT optimizer.
  • the PV power station 5000 can be thought of as comprising one AC power production units (hereinafter referred to also as "AC power production unit 5100").
  • the AC power production unit 5100 consists of a DC power generator 5110 that is comprised of rated 500 kW solar panels, and two 3-phase DC/AC (each declared as 500 kW) converters 5130 and 5130S.
  • the power generator 5110 uses 80 parallel-connected solar strings that generate DC electricity.
  • Each of the 80 solar strings consists of 25 series-connected solar panels; each solar panel rated to have 250W power production capability.
  • the energy reservoir 5410 receives the DC electric power from the generator 5110 through a decoupling device 5311.
  • the two 3-phase DC/AC converters 5130 and 5130S receive DC power from the reservoir 5410 through two separate decoupling devices including decoupling device 5312 for the converter 5130, and decoupling device 5313 for the converter 5130S.
  • Converters 5130 and 5130S are regulated by the MEUPT controller to draw the appropriate amount of power from the reservoir 5410, and convert the DC power to 3-phase AC power to provide to the power grid 5600 via transformer 5500.
  • the MEUPT optimizer provides optimization service to an x MW PV power station.
  • This PV power station has one AC power production unit with solar panel strings having a total rated DC power generation capability x MW.
  • the DC generator charges an energy reservoir through a decoupling device.
  • the energy reservoir supplies DC electricity to two 3-phase DC/AC converters through two separate sets of decoupling devices.
  • the two converters are regulated by a MEUPT controller to convert a proper amount of DC power into 3-phase AC power.
  • the electricity produced by the two converters is provided to a power grid via the same transformer.
  • the only remaining design issue for the MEUPT optimizer is to identify the optimum power matching relationship between the parameters representing the rated capability of the solar strings and that of the converters. Specifically, the task is to identify the relationship between the value of x, y, and z in the optimum situation. As a reminder, the value of the sum y + z is no greater than the value x in a conventional PV power station as described in Section Two.
  • the value x is designated for the MW value of rated DC power production capability of the PV strings; the value y is designated for the total MW value of maker declared capability of "PS 3-phase DC/ AC converter” that converts the DC energy supplied by the PV strings; while the value z is designated for the total MW value of maker declared capability of "ER 3-phase DC/ AC converter” that converts the DC energy supplied by the energy reservoir.
  • the value of y + z is no less than 2 times the value of x value in both of the configurations described above.
  • the term “capability” is also referred as the "power rating" of the device; and inter changeable hereinafter, unless otherwise indicated.
  • Section Ten The optimum power matching relationship.
  • the power rating of the solar panels is defined as the maximum DC power that a solar panel can produced at high noon with clear skies.
  • the solar panel manufacturing industry uses a predetermined type of illuminating lamp (called herein a "standard lamp") to simulate clear skies; and high noon is simulated by illuminating light flux perpendicularly through the solar penal surface. Therefore, the maker declared power production capability can be very close to the real DC generator's capability. Experiments performed by the inventors also confirm the above statement.
  • the total DC power generation capability of PV solar strings is therefore judged to be credible; and the title "maker declared capability” is omitted herein when describing the power rating of the solar strings.
  • the DC/ AC converter manufacturing industry defines the power-rating of DC/ AC converters in according with the convention of power grid industry, referred as the "power grid convention” herein. This convention and the definition of the DC/AC converter capability are elaborated as follows.
  • the AC Power grid industry enforces a convention (referred as the power grid convention) to assure the constructed 3 -phase AC power grid can fulfil the declared power delivery capability.
  • the 3-phase AC power grid consists of 3 or 4 power lines which can deliver time varying sinusoidal functions of voltage and current in each pair of power lines as one phase.
  • the power grid convention defines the voltage declared in the specification as the "standard" maximum voltage for the power lines to endure (referred to as the "line voltage”).
  • the specified maximum current declared in the specification is the maximum current for the power lines to carry (referred to as the "maximum phase current").
  • the voltage declared in the specification of the device is the maximum voltage that all the related components shall endure.
  • the maximum current declared in the specification is the maximum current-carrying capability for all the related components of one phase, connecting to one pair of power lines.
  • the time varying functions of the device's voltage and current also need to conform to the sinusoidal function of the each phase in the AC power grid.
  • the specified voltage of a 3-phase DC/ AC converter is defined as the line voltage of the 3-phase power;
  • the specified maximum current is defined as the maximum current carrying capability of the pair of power lines for each phase;
  • the specified maximum power is defined as the sum total of the maximum power capability that the three phases can endure.
  • the power lines of each phase and the connected power devices are to be capable of transmitting one third (1/3) of the specified maximum power, to state in other way, the "maker declared power rating" of the 3-phase DC/AC converter is 3* U* I, where the U is the phase voltage and the I is the phase current.
  • Each pair of power lines is capable of delivering U* I power, or 1/3 of "maker declared power rating"; and each module connecting to the pair of power line is also required to carry or deliver 1/3 of the specified power rating declared, when conforming to the power grid convention.
  • the 3 phases in a 3-phase DC/ AC converter are strictly correlated to have 120° phase differences.
  • one pair of power lines (phase) delivers time varying power of U* I sin 2 (cot); while the second phase delivers time varying power of U* I sin 2 (cot + 120°); and the third phase delivers time varying power of U* I sin 2 (cot - 120°).
  • Each pair of power lines of the three phases delivers three oscillating AC power trains related to each other with a strict correlation.
  • the power conversion capacity, P(t) is not equal to the defined "maker declared power rating".
  • the power conversion capacity, P (t) is expressed as a function of time and derived in accordance with the defined 3-phase AC power restrictions.
  • the DC/ AC power conversion capacity, P (t) is derived from the sum of the time varying power outputs of the 3 phases; with a strictly correlated phase difference of 120°; and with power wave forms that conform to the square sinusoidal oscillations of sin 2 (cot), or cos 2 (cot); and synchronized with the power grid (same phase and frequency) which forces the angular frequency co to be constant.
  • P (t) U* I* (sin 2 (rot) + sin 2 (rot +120°) + sin 2 (rot - 120°)).
  • U the phase voltage
  • I the phase current
  • co the constant angular frequency of the power grid.
  • sin 2 (rot +120°) + sin 2 (rot - 120°) cos 2 (rot) + 1/2.
  • the sum total of these strictly correlated three pulsating power trains in the three phases is a constant.
  • the sum total power delivery of these three pair of power lines is a constant.
  • the sum total of the three modules related to the three phases is a constant.
  • this constant is only equal to half (1/2) of the "declared power capability". This is the relationship between the power conversion capacity and the defined “declared power capability" of a 3-phase DC/AC converter when conforming to the power grid convention.
  • the optimum power matching relationship for the parameters x, y, and z (as defined) is that the value of (y + z) shall be no less than that of 2x.
  • the related PV power station is composed of x MW PV solar strings; with the "PS 3-phase DC/AC converters” having total “maker declared power capability” of y MW; and with the "ER 3-phase DC/ AC converters” having total “maker declared power capability” of z MW.
  • the "PS 3-phase DC/ AC converters" and the “ER 3-phase DC/ AC converters” can either be operated by one or more MPPT controllers, or by one or more MEUPT controllers. To practice MEUPT optimization, it is preferred to operate all the DC/AC converters by MEUPT controller(s).
  • FIG. 7 abstractly illustrates the configuration of a PV solar power station 7000.
  • the power station comprises x MW solar panels in total arranged in solar strings 7100.
  • the DC power generated in solar strings 7100 provides DC power input to a group of 3-phase DC/ AC converters 7301 through a decoupling device 7201 ; and charges the surplus power into a reservoir 7400 through a decoupling device 7202.
  • the energy reservoir 7400 provides DC power input to a group of 3-phase DC/ AC converters 7302 through a decoupling device 7203.
  • Both 3-phase DC/ AC converters 7301 and 7302 provide the converted 3-phase AC power to a power grid 7600 through a transformer 7500.
  • the total "maker declared capability" of the converters 7301 is y MW.
  • the total "maker declared capability" of the converters 7302 is z MW.
  • the value of the sum (y + z) is no less than the value of 2x. Please be reminded that when using a similar configuration to describe a conventional PV power station as described in Section Two, the value of (y + z) is no greater than the value of x. Therefore, when a design with value of (y + z) is greater than x or even better 1.1 times x; it means some of the surplus energy can be captured to enhance the electric energy provided to the power grid.
  • the converters 7301 and 7302 can all be operated by the MEUPT controller(s) described above. In some embodiments, some, one, or even none of the converters are operated by an MEUPT controller. Furthermore, in some embodiments, one or some of the decoupling devices 7201, 7202, and 7203 can be omitted in the configuration.
  • the PV solar strings 7100 provide DC power input to the converters 7301. Therefore, they are referred as the "PS converters” herein.
  • the energy reservoir 7400 provides DC power input to the converters 7302. Therefore, they are referred as the "ER converters” herein.
  • the terms total "maker declared power rating” and total “maker declared power capability” shall be abbreviated as the "declared power” herein.
  • a PV power station 7000 comprises x MW solar strings 7100 as DC power generator.
  • the DC power generator 7100 provides input to the "PS converters” 7301 with “declared power” of y MW, through the decoupling device 7201 ; and charges the left-over power to the reservoir 7400 through another decoupling device 7202.
  • the reservoir 7400 provides input to the "ER converters” 7302 with “declared power” of z MW through the decoupling device 7203. All the 3-phase DC/ AC converters 7301 and 7302 provide the converted 3-phase AC power to a power grid 7600 through a transformer 7500.
  • the value of (y + z) is no less than the value of 2x. However, when the value of (y + z) is greater than the value of x, the design can receive a partial benefit to enhance the electric energy sale to the power grid.
  • An MEUPT optimizer in accordance with the principles described herein can serve a small PV power station or a large PV power station comprising one or more AC power production unit(s). Furthermore, with properly designed decoupling device, energy leakage from the energy reservoir through the PV solar strings can be prevented. Furthermore, with properly designed decoupling device, the discovered "mutual power annihilation" phenomenon can be prevented. Also, the energy reservoir can be used to receive only the surplus energy after the energy extraction of the "PS converter", or to receive all the produced DC energy before any extraction. Finally, the MEUPT optimizer can also provide service for PV power station equipped with a single-phase DC/ AC converter(s).
  • FIG 8 illustrates a MEUPT controller 8000 (also referred to as a "system controller") that represents an example of the MEUPT controller 2320B of Figure 2B.
  • the MEUPT controller 8000 is comprised of 3 executable components: a detection component 8100, a determination component 8200, and a delivery component 8300.
  • the detection component 8100 measures the stored energy level in a reservoir 8400.
  • An example of the reservoir is the reservoir 2410B of Figure 2B, the energy reservoir 3410 of Figure 3, the energy reservoir 4410 of Figure 4, the energy reservoir 5410 of Figure 5, the energy reservoir 6410 of Figure 6, and the energy reservoir 7410 of Figure 7.
  • a determination component 8200 determines the proper power drawing level to nearly balance the charge provided to and discharged from the energy reservoir 8400.
  • a delivery component 8300 delivers a coded message of the above determined proper power drawing level to the surplus DC/AC converter(s) 8500.
  • the converters interpret the coded message, and comply with the coded message, such that the converter(s) can continuously operate at the directed power level to nearly balance the in-charging energy.
  • An example of the converters 8500 that draw from the reservoir 8400 are the converters 2130S of Figure 2B, the converters 3130S of Figure 3, the converters 4130S of Figure 4, the converters 5130S of Figure 5, the converters 6130S of Figure 6, the converters 7302 of Figure 3.
  • the design of the MEUPT controller takes into consideration the following parameters and variables, (1) the capacity of the energy reservoir 8400; (2) the ramping up/down speed of DC/ AC converters 8500; (3) the I-V characteristics of the solar strings; (4) the climate at the location of PV power plant; and (5) the ability of MEUPT controller working with the surplus DC/ AC converter minimize the difference between (or balance) the amount of charge provided to the energy reservoir, and the amount of charge drawn from the energy reservoir.
  • a straight-forward design can only be derived when applying a custom designed controller for each and every PV power station taking into consideration these parameters and variables.
  • the voltage interval table can work in concert with an industrial controller to accomplish the required MEUPT controller functions.
  • the industrial controller is then comprised of a detection component, a determination component, and delivery component as also illustrated in Figure 8.
  • the detection component 8100 measures the terminal voltage of the energy reservoir 8400.
  • the determination component 8200 compares the measured voltage with the voltage interval table; and determines the proper power drawing amount to nearly balance the in-charging energy.
  • a delivery component 8300 again delivers the coded message of the above determined proper power drawing level to the surplus DC/ AC converter(s); such that the converter(s) can continuously operate at the directed power level to nearly balance incoming and outgoing charge of the energy reservoir 8400.
  • the detection component 8100 of the MEUPT controller 8000 measures the terminal voltage of the surplus energy reservoir 8400 in real time. Even so, the determination component 8200 may still perform the comparison (of the measured voltage against the voltage interface table) every designated time interval compare. This comparison may result in one of the following three situations:
  • the controller 8000 can request (through the delivery component 8300) that the 3-phase DC/AC converter 8500 increase by one level of power extraction and conversion for the next designated time interval;
  • the controller 8000 can request (through the delivery component 8300) that the 3-phase DC/AC converter 8500 decrease by one level of power extraction and conversion for the next designated time interval; (3) If comparison of the measured voltage and voltage interval table indicates that the power level is just-right, the controller 8000 can request the 3-phase DC/AC converter 8500 to stay at the same power extraction level for the next designated time interval, at least until the next occurrence of the comparison.
  • Typical conventional centralized 3-phase DC/ AC converters can operate at very small adjustment steps when directed.
  • the equipped communication channel referred as the "dry connection box" in the art (and so referred herein) has typically only 6-bit communication channels via optical messages.
  • the MEUPT controller 9200 comprises 3 executable components; namely, a detection component 9211 to measure the terminal voltage of the surplus energy reservoir 9400; a determination component 9212 to compare the measured voltage with the voltage interval table of the PV station; and a delivery component 9213 to notify the 3-phase DC/ AC converter 4502 to boot-up, to drop-down, or to stay the same via the delivery component 4213.
  • the components 9211, 9212 and 9213 of Figure 9 are examples of the components 8100, 8200 and 8300, respectively of Figure 8.
  • the energy reservoir 9400 of Figure 9 is an example of the energy reservoir 8400 of Figure 8.
  • the converters 9502 are examples of the converters 8500 of Figure 8.
  • the PV power station 9000 also comprises of PV solar-strings 9100.
  • the solar strings 9100 convert solar energy to electricity; and deliver the generated DC power to the surplus energy reservoir 9400 through decoupling device 9320.
  • the 3 -phase DC/ AC converter 9502 receives DC power input from the surplus energy reservoir 9400 through the decoupling device 9330.
  • the solar strings 9100 of Figure 9 are collectively a DC energy source for charging the energy reservoir, and are examples of the solar strings 2111A and 211 IB of Figure 2B, the solar string 3110 of Figure 3, the solar string 4110 of Figure 4, the solar string 5110 of Figure 5, the solar string 6110 of Figure 6, and the solar string 7110 of Figure 7.
  • the decoupling device 9320 of Figure 9 is an example of the decoupling device 2312B of Figure 2B, decoupling device 3312 of Figure 3, decoupling device 4312 of Figure 4, decoupling device 5311 of Figure 5, decoupling device 6311 of Figure 6, and decoupling device 7202 of Figure 7.
  • the decoupling device 9330 of Figure 9 is an example of the decoupling device 2313B of Figure 2B, decoupling device 3313 of Figure 3, decoupling device 4313 of Figure 4, decoupling device 5313 of Figure 5, decoupling device 6313 of Figure 6, and decoupling device 7203 of Figure 7.
  • the MEUPT controller 9210 directs the 3-phase DC/AC converter 9502 to draw appropriate amount of energy from the energy reservoir 9400 to balance the input energy charging from the solar-strings 9100; which resulted in a near zero energy in-charging or out-drawing into the reservoir 9400.
  • a small energy reservoir 9400 is adequate for the PV station.
  • the converted AC power from the DC/ AC converter is provided to the connecting power grid 9700 through the transformer 9600.
  • executable component is used with respect to Figures 8 and 9.
  • executable component is the name for a structure that is well understood to one of ordinary skill in the art in the field of computing as being a structure that can be software, hardware, firmware or a combination thereof.
  • structure of an executable component may include software objects, routines, methods that may be executed on the computing system, whether such an executable component exists in the heap of a computing system, or whether the executable component exists on computer-readable storage media.
  • the structure of the executable component exists on a computer-readable medium such that, when interpreted by one or more processors of a computing system (e.g., by a processor thread), the computing system is caused to perform a function.
  • Such structure may be computer-readable directly by the processors (as is the case if the executable component were binary).
  • the structure may be structured to be interpretable and/or compiled (whether in a single stage or in multiple stages) so as to generate such binary that is directly interpretable by the processors.
  • executable component is also well understood by one of ordinary skill as including structures that are implemented exclusively or near-exclusively in firmware or hardware, such as within a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or any other specialized circuit. Accordingly, the term “executable component” is a term for a structure that is well understood by those of ordinary skill in the art of computing, whether implemented in software, hardware, or a combination.
  • FPGA field programmable gate array
  • ASIC application specific integrated circuit

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Abstract

L'invention concerne une centrale électrique photovoltaïque (PV) qui comprend au moins une unité de production d'énergie électrique à courant alternatif (CA). L'unité de production d'énergie électrique CA comprend un réservoir d'énergie qui est alimenté en énergie à courant continu (CC) à partir d'un générateur d'énergie électrique CC, tel que des panneaux PV. Le réservoir d'énergie est utilisé comme tampon afin de stocker de l'énergie et d'améliorer l'efficacité de la centrale électrique PV. Qu'un réservoir d'énergie soit utilisé ou non, des dispositifs de découpleur peuvent être utilisés afin d'empêcher une annihilation d'énergie électrique qui peut diminuer la quantité d'énergie électrique fournie par la centrale électrique au réseau. Lors de l'intégration du système pour une centrale électrique PV, on constate que la caractéristique nominale déclarée du convertisseur CC/CA dans la convention de réseau électrique ne devrait pas être considérée en tant que capacité de conversion de puissance.
PCT/US2018/035454 2017-10-27 2018-05-31 Centrale électrique photovoltaïque WO2019083567A1 (fr)

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