Classifications

• • 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
  • H02J1/00—Circuit arrangements for DC mains or DC distribution networks
• • 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
  • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
  • H02S10/00—PV power plants; Combinations of PV energy systems with other systems for the generation of electric power
  • H02S10/10—PV power plants; Combinations of PV energy systems with other systems for the generation of electric power including a supplementary source of electric power, e.g. hybrid diesel-PV energy systems
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
  • H02S10/00—PV power plants; Combinations of PV energy systems with other systems for the generation of electric power
  • H02S10/20—Systems characterised by their energy storage means
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
  • H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
  • H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
  • H02S40/30—Electrical components
  • H02S40/36—Electrical components characterised by special electrical interconnection means between two or more PV modules, e.g. electrical module-to-module connection
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F77/00—Constructional details of devices covered by this subclass
  • H10F77/95—Circuit arrangements
  • H10F77/953—Circuit arrangements for devices having potential barriers
  • H10F77/955—Circuit arrangements for devices having potential barriers for photovoltaic devices
• • 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
• • 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

Definitions

• the invention relates to a connection of a photovoltaic power plant for generating electrical energy and a battery energy storage system for storing the generated electrical energy, and further relates to a method of handling the generated electrical energy to minimise electrical energy losses in the connection of the photovoltaic power plant and the battery energy storage system.
• a photovoltaic panel converts incident light into electrical energy manifested as electrical voltage and current.
• the electrical voltage can be diverted from the photovoltaic panel directly to the appliance.
• such a direct connection has its limitations, which include the magnitude of the electrical voltage limited by the parameters of the photovoltaic panel, the variability of the photovoltaic panel performance directly dependent on the light conditions prevailing at a given time, and the DC voltage may also be a limitation, as some electrical appliances are designed to operate on the AC voltage used in electricity distribution networks.
• each string has a higher electrical voltage, but other limitations, such as variable performance of the string depending on lighting conditions or DC electrical voltage remain. It is also disadvantageous in series stringing that the electric current of the entire string is controlled by the electric current of the “weakest” PV panel, whether the PV panel in the string is considered to be the weakest due to momentary shading or its current technical condition.
• the problem of setting the electric current of the string according to the “weakest” photovoltaic panel is solved by those skilled in the art in such a way that each photovoltaic panel is equipped with an optimiser forthe generation of electrical energy at the so-called optimal operating point.
• the optimiser features an MPPT circuit, wherein the internationally used abbreviation MPPT derives from the English combination of words “maximum power point tracking”.
• MPPT maximum power point tracking
• Battery energy storage system can store unused electrical energy from the PV plant at one moment, while at another moment, it can compensate for the below-limit production of electrical energy by the PV plant by releasing the stored electrical energy.
• the connection of the photovoltaic power plant and battery energy storage system is suitable both for islanded electrical operations and for connection to the electricity distribution network.
• Battery energy storage system can store surplus energy produced at times when the PV plant’s output is greater than the actual electrical energy consumption, and the battery can also keep discounted electrical energy received from the distribution system for later use at times when there is no longer a surplus in the system, and it is again at a higher price.
• an embodiment is known in which at least one string of PV panels in series is connected to an inverter.
• the inverter produces from the connected sum of DC electrical voltages an AC electrical voltage, either single-phase or three-phase, for electrical appliances of the islanded electrical network or for the electricity distribution network.
• the inverter comprises technical means for further converting the electrical voltage to the charging electrical voltage of the battery energy storage system. The compensation of the actual output of the PV plant by the battery energy storage system is realised in the inverter.
• connection has disadvantages, including the fact that unless the PV panels in the string are equipped with optimisations, the electric current of the string is limited by the weakest PV panel of the string in question.
• known connection has the disadvantage that multiple repetitive voltage conversions result in power losses.
• connection is used together with a super capacitor to feed electrical appliances.
• the individual components of the invented connection are connected to a common DC voltage busbar via the control modules.
• This invention suffers the analogous problems as mentioned above.
• the invented connection is conceptually very complex, thus costly, and it does not solve the problem of repeated conversion of electrical voltage several times and the associated energy losses.
• the object of the invention is to create a PV power plant and battery energy storage system for storing electrical energy, which would allow a reduction in the number of overall conversions of the parameters of the electrical energy generated while maintaining the main advantage of the battery energy storage system of balancing the instantaneous balance of the energy generation of the PV power plant and the energy consumption of the inverter of the PV power plant, which would be conceptually simplified compared to known inventions for ease of realisation and servicing.
• the invention includes a method of handling electrical energy in the connection of a photovoltaic power plant and battery energy storage system to minimise electrical energy losses.
• connection of the photovoltaic power plant and the battery energy storage system for generating and storing electrical energy consists of a busbar to connect individual components of the connection electrically. Another part of the connection are photovoltaic panels equipped with an optimiser to provide an optimal operating point of the photovoltaic panel, which are connected to the busbar via optimisers. Furthermore, the connection includes an inverter for converting the generated electrical energy parameters that is connected to the busbar and a battery energy storage system electrically connected to the inverter.
• the summary of the invention consists in the fact that the optimiser is simultaneously a direct current source and not a voltage source as in the prior art, so it contributes electrical energy from the photovoltaic panels to the busbar in the form of an optimised direct electric current.
• the direct current source is connected in parallel to the busbar and that the busbar is a current busbar.
• the electrical connection between the battery energy storage system and the inverter also comprises a current busbar to which the battery energy storage system and the inverter are connected in parallel. Thanks to this parallel connection, the electrical energy transmitted through the busbar in the form of direct current is automatically split between the battery energy storage system and the inverter. Preferably, there is no need to repeatedly change the parameters of electrical energy for its storage and withdrawal from battery energy storage system, as is the case with existing solutions.
• the electrical energy splitting is automatic, so that no additional control electronics are needed.
• this invented connection does not need the existing architecture of connecting photovoltaic panels to strings, so the design of the entire system is simplified, and the inverter can be simpler to build because it does not contain circuits of the strings, MPPT and possibly inverters for charging the battery energy storage system, and thus may have a lower acquisition cost, meaning that the invention provides a more efficient and less expensive combination of PV power plant and battery energy storage system that will be available to more homes, cabins, RVs, boats, etc.
• an external source of electrical energy from the group consisting of a power plant, a generator of wind power plant, a cogeneration unit is connected directly to the busbar or to the inverter. This is preferred in situations where the combination of electrical energy contributions from the photovoltaic power plant and from the battery energy storage system is insufficient for the energy consumption of the inverter.
• An external source can provide the difference in missing electrical energy needed to operate the inverter during adverse lighting conditions, or during periods of unexpected electrical energy consumption, possibly allowing the battery energy storage system to be recharged. It is preferred if the busbar is equipped with a switch to disconnect the battery energy storage system from the busbar.
• the disconnection of the battery energy storage system means that the optimisers will not supply any electrical voltage, and the bus will be without electrical voltage, making the inventive connection safe, e.g. for firefighters who intervene.
• the only voltage that remains in the connection after the switch is disconnected is the production electrical voltage of each photovoltaic panel separately, which, however, is within the safety limits (up to 50 V) and is located only on the electrically insulated conductor between the photovoltaic panel and the optimiser, i.e. it does not endanger the intervening firefighters with electric shock.
• the invention also includes a method of handling electrical energy in the connection of the photovoltaic power plant and battery energy storage system to minimise energy losses.
• the essence of the invented method is that the photovoltaically generated electrical energy is transformed by a direct current source into an optimised direct electric current.
• the immediate energy contribution in the form of an optimised direct electric current according to the actual operating capabilities of the PV panel does not affect the energy contributions of the other connected PV panels.
• optimised direct electric current is then diverted to the busbar, where the optimised direct electric currents are added up.
• the parallel connection to the common busbar leads to a simple addition of the optimised direct electric currents, so that the sum of the optimised direct electric currents flows through the busbar.
• the direct electric current passes via the busbar to the terminals of the battery energy storage system, wherein the electric voltage of the busbar corresponds to the electric voltage at the terminals of the battery energy storage system.
• the direct electric current passes via the busbar to the terminals of the inverter to distribute electrical energy to the consumer. This is preferred for the reason that the electrical power transmitted by direct electric current is automatically split according to Kirchhoffs first law for consumption in the inverter and for charging the battery energy storage system, without the need to convert the electrical energy into either charging or supplying as in existing solutions, so the invention increases the efficiency of the whole system.
• the positive energy difference between the combined output of the PV panels and the required energy consumption of the inverter is stored in battery energy storage system.
• Excess electrical energy is stored in the battery energy storage system for later consumption, so that the battery energy storage system does not need to be charged, e.g. from the electricity distribution system, as is the case with some existing solutions.
• the negative energy difference between the combined output of the PV panels and the required energy input of the inverter is compensated by the power of the battery energy storage system.
• this is done in the invention automatically and the energy contribution from the battery energy storage system is automatically added to the actual electrical energy generation of the PV power plant.
• the negative energy difference between the combined energy output of the PV panels and the battery energy storage system and the required energy input of the inverter is compensated from an external source of electrical energy. If the actual generation of electrical energy and the actual amount of stored electrical energy are insufficient for the islanded operation of electrical appliances, the missing electrical energy can be supplied from an external energy source, e.g. from a power station or from the electricity distribution system.
• the inverter is switched off. This is important in order not to discharge the battery below a safe limit. Switching off the inverter is a safety procedure step.
• the distribution of electrical energy from the optimisers of the photovoltaic panels is limited to deliver less current.
• battery energy storage systems have their own battery management system from the factory that protects the storage system batteries from damaging conditions, it is a preferred, or in some installations necessary, additional step to ensure that the PV panels or their optimisers limit their electrical energy generation.
• Advantages of the invention include simplifying the architecture of the PV power plant connection including the battery energy storage system. There is no need to connect PV panels together in string, which have dedicated circuits and controls in the PV power plant inverters, but the electrical energy generated is unified on a common direct current busbar. It is advantageous that there is only one conversion in the optimiser in the path of electrical energy from the PV panel to charging the battery energy storage system. It is also advantageous that it is easy to combine and complement different PV panels, e.g. after some time to buy other, newer, etc., which would be complicated within the string. There is also no limit on the number of panels connected to the busbar, while strings have such limits on the number of panels in a string.
• the electrical energy transmitted by direct current in the busbar is automatically split between the battery energy storage system and the inverter, so there is no need to transform the electrical energy into different electrical voltages and currents for charging the battery energy storage system, etc. as is the case with existing solutions, thus avoiding energy losses as with existing solutions.
• Fig. 1 schematically illustrates the invented connection with an inverter for distributing electrical energy in the form of alternating electric current and voltage
• Fig. 2 schematically illustrates an alternative inverter for distributing electrical energy in the form of direct electric current and voltage.
• Fig. 1 shows the connection of a photovoltaic power plant with an inverter 5 for the distribution of electrical energy in the form of alternating current and voltage, including battery energy storage system 1.
• the photovoltaic power plant consists of a group of photovoltaic panels 3, wherein each photovoltaic panel 3 is equipped with an optimiser 4 used as a current source. This approach to optimising the operating point of the photovoltaic panel 3 is known from patent CZ 308 936 B6, where the skilled person has more detailed information about the current source - optimiser 4.
• Fig. 1 shows a difference from the prior art in that the PV panels 3 are not arranged in individual strings, but are connected to a single busbar 2 via optimisers 4. On busbar 2, the optimised direct electric currents (Ii, b, E, In) are added into one direct electric current £.
• Busbar 2 is realised by a suitably sized electric current conductor and the terminals of battery energy storage system j_ are connected to busbar 2.
• the busbar 2 may transfer data between the integrated control system of the battery energy storage system 1 and the optimiser 4, or even between the inverter 5, to control or limit the magnitude of the total generated current £ to the busbar 2.
• this communication can in principle take place over any external busbar, e.g. CAN (Controller Area Network), so that the control electronics of the individual components can communicate with each other. Data on the condition and output of individual photovoltaic panels 3 and optimisers 4 can also be obtained within these communications.
• CAN Controller Area Network
• Battery energy storage system 1 is an assembly of batteries that are capable of storing electrical energy.
• Today’s battery energy storage systems 1 have integrated battery management systems (BMSs), which protect both individual battery cells and the battery as a whole from extreme conditions (overcharging, excessive discharge, inappropriate temperature, excessive charging or discharging current, etc.). Three conditions can occur at the terminals of battery energy storage system 1 and busbar 2.
• BMSs battery management systems
• the inverter 5 is substantially, for those skilled in the art, a standard piece of equipment that changes the parameters of electrical energy between its input from generation/storage and its output for distribution to electrical appliances.
• the difference of the inverter 5 in the invention compared to the inverters of the prior art is that its architecture is simplified, since it neither needs control circuits for the individual strings of the PV panels 3 nor MPPT circuits.
• the inverter 5 must be able to transform the generated DC electrical energy having the DC electrical voltage parameters according to the battery energy storage system 1 and the direct electric current of the busbar2 into the voltage and performance required by the user (whether DC or AC).
• the inverter 5 must also have electronics adapted to communicate with the battery control system of the battery energy storage system 1, and possibly with the optimisers 4, but this is a superstructure solution. From the point of view of the invention, the most important communication takes place between the optimisers 4 and the BMSs of the battery energy storage system 1_.
• Fig. 1 shows the inverter 5 for converting the parameters of the generated electrical energy into the parameters of the distributed electrical energy in the form of alternating electric current and three-phase electrical voltage.
• This inverter 5 is suitable for supplying electrical appliances powered by a single or three-phase standard grid that are made to be supplied from the distribution electrical system (3x240 V, 3x110 V, etc.), wherein when there is a surplus of electrical energy generated, if possible, the surplus is supplied to the distribution electrical system, or when there is a shortage of electrical energy, the distribution electrical system serves as an external source 6 of electrical energy.
• Fig. 2 shows the inverter 5 for converting the parameters of the generated electrical energy into the parameters of the distributed electrical energy in the form of direct electric current and voltage (e.g. 12 V or 24 V).
• This exemplary embodiment of the invention is suitable for DC onboard networks of ships, caravans, etc.
• the skilled person may use any device that allows them to supply electrical energy either directly to the busbar 2 in the form of direct electric current, provided that the external source 6 communicates with the components of the invented connection to control its operation and performance according to the current operating conditions, or directly to the inverter 5 see Fig. 1, in which the summation of energy already occurs.
• the external source 6 can be a power plant, a generator of a hydropower plant or a wind power plant, a cogeneration unit, a distribution electrical system, etc.
• electrical energy is handled by converting electrical energy from each n-photovoltaic panel 3 into an optimised direct electric current I n . All these direct electric currents I n are brought to a common busbar 2 so that they are added together to detect the direct electric current £1 on the busbar. This direct electric current £1 is led to the terminals of battery energy storage system j_. By connecting battery energy storage system 1 to busbar 2, the electrical voltage on busbar 2 is the same as the electrical voltage Ubat at the terminals of battery energy storage system 1.
• the electrical energy from the battery energy storage system 1 is automatically released to compensate for the energy difference.
• the released energy is added as the direct electric current of the battery Ibat to the direct electric current £1 of the busbar 2 and the electrical energy continuing to the inverter 5 is the direct electric current Iconv-
• the battery energy storage system 1 If the sum of the electrical energy currently generated and the contribution from the battery energy storage system 1 is insufficient to cover the consumption of the inverter 5, it is possible to contribute electrical energy from an external source_6.
• the external source 6 may make up the missing energy difference, possibly contributing in excess of the consumption in addition to making up the difference, and this extra electrical energy will be stored by the battery energy storage system k
• the inverter 5 switches off so as not to cause undercharging / deep discharge of the battery energy storage system 1.
• the optimisers 4 limit the current contributions from the PV panels 3 and their optimizers 4 to the busbar 2.
• Fig. 1 shows the switch 7 which allows the battery energy storage system 1 to be disconnected from the busbar 2. As soon as the battery energy storage system 1 is disconnected, the busbar
• connection of the photovoltaic power plant and the battery energy storage system and the method of handling electrical energy in the connection of the photovoltaic power plant and the battery energy storage system according to the invention find application in installations for households, commercial premises, cabins, RVs, boats, houseboats and the like.
• PV photovoltaic
• Ibat direct electric current of the battery energy storage system

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• Engineering & Computer Science (AREA)
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• Charge And Discharge Circuits For Batteries Or The Like (AREA)

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Citations (5)

• 2023
  • 2023-04-17 CZ CZ2023-148A patent/CZ2023148A3/cs unknown
  • 2023-11-02 WO PCT/CZ2023/050075 patent/WO2024217607A1/en active Pending

Patent Citations (5)

Non-Patent Citations (1)

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