The present invention relates to solar energy systems utilizing battery super charger system, capable of maximizing solar energy usage by extending sun peak hour, such as but not limited to solar energy systems with built-in battery super charger and it's method.
As the world's population increases, the demand for electric power usage also increases proportionally. Fossil fuels based electric power generation causes environmental pollution and degradation to global warming and the attendant climate change. Therefore it is necessary for humanity to resort the use of energy that is non-polluting, renewable and sustainable. Solar energy is one of the desirable types of renewable energy because it is a free, clean and environmentally friendly energy source that doesn't contribute to climate change. For years it has been touted as the most promising energy source for our increasingly industrialized society.
The most popular application of solar energy is grid-connected solar system. It connects to the electric power grid. The two main components of such system are the solar modules and the solar power converter. A grid-connected solar power system, also called grid-tied system, has the main objective of extracting as much energy as possible from the solar modules when sunlight impinges on them while maintaining acceptable power quality, reliability and cost-competitiveness. However, achieving this objective is fraught with many challenges such as low conversion efficiency of the system, intermittency and variability nature of solar energy, Load variations and high cost of system. In order to mitigate the aforementioned problems, attempts have been made to produce an improved solar energy system. For example, adding an energy storage battery in such system mitigates some of these challenges, as it provides stored energy during nights, resulting in minimizing solar energy intermittency and variability effects and reducing customers' utility bills. However, such systems still have general shortcomings and do not adequately address the aforementioned problems.
The techniques disclosed in U.S. Pat. Application US 2011/0210694 A1 and U.S. Pat. No. 5,522,944 represent the prior art of solar energy system with storage battery technology. These systems suffer three major deficiencies: (1) low battery charging efficiency because it requires two stages of power conversions (DC-AC and AC-DC); (2) long battery charging time because its battery charger is limited to low power charger due to cost; the typical battery recharging time is in several hours compared to in several minutes by a high power charger; thus, it cannot charge or discharge storage battery several times during the day to maximize the solar energy use; even if a separate high power battery charger is installed with a high cost, it still has very low battery charging efficiency as indicated in (1) above; (3) lack of optimal energy management control method for varying load power because it cannot quickly charge/discharge storage battery several times during the day. Therefore, a solar energy system with a high power single stage battery super charger system along with optimal energy management control method is best solution for the future solar energy system.
The object of this invention is to provide a solar energy conversion system with a built-in high power storage battery super charger/discharger system and an optimal energy management control method to maximize solar energy usage by extend sun peak hour resulting in consuming less grid power.
One non-limiting aspect of the present invention contemplates a solar energy converter with built-in high power storage battery charger/discharger to produce electricity, quickly charge/discharge storage battery, and maximize solar power usage comprising a solar power system architecture with a Multi-Function Power Conversion System (MFPCS), several operation switches, LCL filters plus a transformer, multiple DC inductors, a solar power source, a storage battery power source, an AC grid power source and numerous operation modes including an interleaved multi-phase super charger mode (Mode 1), a solar power generation plus direct battery charging mode (Mode 2), a solar power generation mode (Mode 3), a solar/storage battery discharger mode (Mode 4), and a PWM rectifier battery charger mode (Mode 5).
One non-limiting aspect of the present invention contemplates a MFPCS to provide DC/AC, AC/DC, DC/DC power conversion hardware functions comprising a three phase IGBT module, a liquid cooled heatsink, a DC-link capacitor, a IGBT drive circuit card, a DSP interface circuit card, and a Texas Instrument (TI) DSP control Card.
One non-limiting aspect of the present invention contemplates a TI DSP control Card to be responsible for power conversion and battery charging software control functions comprising a Mode 1 control library comprising interleaved multi-phase battery charging control algorithms, a Mode 2 control library comprising optimized solar power generation plus direct battery charging control algorithms, a Mode 3 control library comprising a three-phase solar power grid-tied inverter control algorithms, a Mode 4 control library comprising a three-phase solar/battery power grid-tied inverter control algorithms, and a Mode 5 control library comprising PWM rectifier battery charging control algorithms.
One non-limiting aspect of the present invention contemplates a Mode 1 control library comprising an optimal solar power tracking means for regulating charging current of storage battery in constant current mode, a battery voltage control means for regulating charging voltage of storage battery in constant voltage mode, a multi-phase DC current control means for regulating DC currents of DC inductors, and an interleaved multi-phase PWM means for controlling three-phase IGBT module to convert solar power to storage battery power.
One non-limiting aspect of the present invention contemplates a Mode 2 control library comprising a Maximum Power Point Tracking (MPPT) means to extract the maximum solar power, a DC voltage control means to regulate the output voltage of solar power, a battery charging power calculation means, a inverter power command generation means, a AC current reference generation means, a AC current control means, and a Space Vector Modulation (SVM) means to produce AC grid power plus directly charge storage battery.
One non-limiting aspect of the present invention contemplates Mode 3 control library comprising a MPPT means, a DC voltage control means, a AC current reference generation means, a AC current control means, and a SVM means to convert solar power to AC grid power.
One non-limiting aspect of the present invention contemplates Mode 4 control library comprising an active power control means, a AC current reference generation means, a AC current control means, and a SVM means to convert both solar power and storage battery power to AC grid power.
One non-limiting aspect of the present invention contemplates Mode 5 control library comprising a battery voltage control means and a battery current control means to control charging voltage and current of storage battery power source, a AC current reference generation means, a AC current control means, and a SVM means to convert AC grid power to storage battery power.
One non-limiting aspect of the present invention contemplates an interleaved multi-phase battery charging control algorithms in Mode 1 control library comprising a single layer current (Imp) control loop for Constant Current (CC) mode with the current reference Impr generated by optimal solar power tracking function to ensure the maximum battery charging current and optimal solar power extraction, a two layers cascade control loop structure for Constant Voltage (CV) mode with a battery voltage loop as the outer loop and a current loop as the inner loop.
One non-limiting aspect of the present invention contemplates a three-phase grid-tied inverter control algorithms in Mode 3 control library and an optimized solar power generation plus direct battery charging control algorithms in Mode 2 control library comprising two layers cascade control loop structure with a DC voltage control loop as the outer loop and an AC current loop as the inner loop.
One non-limiting aspect of the present invention contemplates operation mode switches which are operable to select configurations of operation mode being controlled by a controller based on an operation mode control table.
One non-limiting aspect of the present invention contemplates an interleaved multi-phase super charger mode (Mode 1) comprising a configuration of a MFPCS connecting to solar power source with intermedium of three DC inductors and storage battery power source through operation switches and Mode 1 control library, when solar power voltage is less than battery voltage (Vmp<Vb).
One non-limiting aspect of the present invention contemplates a solar power generation plus direct battery charging mode (Mode 2) comprising a configuration of a MFPCS connecting to solar power source, storage battery power source and LCL filters plus a transformer which also connecting to AC grid power source through operation switches and Mode 2 control library, when solar power voltage is greater than battery voltage (Vmp>Vb).
One non-limiting aspect of the present invention contemplates a solar power generation mode (Mode 3) comprising a configuration of a MFPCS connecting to solar power source and LCL filters plus a transformer which also connecting to AC grid power source through operation switches and Mode 3 control library.
One non-limiting aspect of the present invention contemplates a solar/storage battery discharger mode (Mode 4) comprising a configuration of a MFPCS connecting to solar power source, storage battery power source and LCL filters plus a transformer which also connecting to AC grid power source through operation switches and Mode 4 control library.
One non-limiting aspect of the present invention contemplates a PWM rectifier battery charger mode (Mode 5) comprising a configuration of a MFPCS connecting to storage battery power source and LCL filters plus a transformer which also connecting to AC grid power source through operation switches and Mode 5 control library.
One non-limiting aspect of the present invention contemplates a solar power extension method to expand solar power usage, i.e. to maximize peak sun hour comprising a minimum grid power import means with charge/discharge of storage batteries to make the most of solar power and minimize grid power usage.
One non-limiting aspect of the present invention contemplates a minimum grid power import means comprising the steps of: calculating a output power PS of solar power source, a load power PL, a State of Charge (SOC) of battery power source; sensing a output voltage VMP of solar power source, a terminal voltage VB of battery power source; determining on peak-hour/off peak-hour periods in accordance with time of the day; performing comparison logic operations of SOC, PS and PL, VMP and VB.
One non-limiting aspect of the present invention contemplates a minimum grid power import means comprising the steps of: setting Mode=1 when VMP is less than VB, battery is within normal range and PS is greater than PL, or when VMP is less than VB and battery is fully discharged; setting Mode=2 when VMP is greater than VB battery is within normal range and PS is greater than PL, or when VMP is greater than VB and battery is fully discharged; setting Mode=3 when Ps is greater than PL, battery is within normal range and during off peak-hour period, or when Ps is greater than PL and battery is fully charged; setting Mode=4 when in on peak-hour period, battery is within normal range and PS is greater than PL, or when in off peak-hour period, battery is fully charged; setting Mode=5 when PS=0, during off peak-hour period and battery needs charge.
One non-limiting aspect of the present invention contemplates a solar power conversion system with built-in high power storage battery charger/discharger and a method to maximize solar power use and minimize grid power expenditure comprising a MFPCS to convert solar power to AC grid power and charge/discharge storage battery in high power, set battery charging power reference and inverter power reference based on logic comparison operations and execute control functions through selected operation mode, such as operation mode 1 of interleaved multi-phase battery charger; or operation mode 2 of solar power converter plus direct battery charger; or operation mode 3 of solar power converter; or operation mode 4 of solar power converter plus battery discharger; or operation mode 5 of AC PWM rectifier battery charger.
The present invention is pointed out with particularity in the appended claims. However, other features of the present invention will become more apparent and present invention will be best understood by referring to the following detailed description in conjunction with the accompany drawings in which:
As required, detailed embodiments of the present invention are disclosed herein; However, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some figures may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
In a solar power system with built-in super charger 26 as disclosed in this invention and illustrated in
In
The detailed control loop diagram 156 illustrates two layers control loop used in control algorithms 128. This cascade control structure is based on the balance of solar power command PR 158, battery charging power command Pbatr 160, inverter power command PINVR 162 (PINVR=PR−Pbatr) and relationships of solar voltage VMP 176, solar current Imp 164, battery charging current Ibr 166, inverter current √{square root over (2)} Ia sin (wt) 182, and DC current Idc 170 where
Imp=f(Vmp). In control loop diagram 156, MPPT 116 determines solar voltage reference VMPR 174. VMPR 174 is subtracted from measured DC voltage VMP 176, the error is fed into DC voltage control 178 which produces solar power command PR 158. Under constant current mode, the battery charging current is controlled by its reference Ibr 166 while the battery voltage VB 262 increases, resulting in an increased battery charging power command Pbatr (160)=Ibr×VB. The solar power command PR 158 is subtracted from Pbatr 160 to obtain inverter power command PINVR 162. PINVR is fed to an AC current reference generation circuit to create an AC current command IR=√{square root over (2)} Iar sin(ωt) 180. Then it is compared with measured current √{square root over (2)}Ia sin(ωt) 182. The error is fed to current control 184 which generate a PWM command. The PWM command is amplified by PWM inverter 186 as an input voltage 188 (V) of LCL filter 190. The sum of three phase output power of inverter Sa 192, Sb 194, Sc 196 is equal to DC power Pdc 198 at inverter DC-link. The DC power Pdc 198 is divided by measured DC voltage Vdc 200 to obtain DC current Idc 170 which is changed to DC voltage VMP 176 with the block 202.
In constant current control loop diagram 208, the battery voltage Vb 226 and solar voltage Vmp 228 are used by function block 230 to derive the inverse duty cycle
The solar current reference Impr 234 is related to battery charging current reference Ibr 236 with
The current reference Impr 234 is compared with the measured current Imp 238 and the error is fed into current control 240 which generates a PWM command. This command is amplified by interleaved multi-phase DC/DC converter 242 as input voltage 244 (V) of plant block 246 to force solar current Imp 238 to follow its reference Impr 234.
In constant voltage control loop diagram 210, battery voltage reference Vbr 248 is compared with measured battery voltage Vb 250 and the error is fed into battery voltage control 252 which produces a solar current reference Impr 254. The solar current Imp 256 is controlled to follow the current reference Impr 254 with the current loop. The current Imp 256 is transformed to battery voltage Vb 250 by the Interleaved Multi-Phase Power Converter transfer function 258 and the battery voltage Vb 250 is regulated to match its reference Vbr 248.
Referring to the flow chart of
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention, rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without depart from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.
This application claims the benefit of U.S. Provisional Application 62/350,829 and hereby incorporates the application by reference.
Number | Date | Country | |
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62350829 | Jun 2016 | US |