Abstract: A method for operating a renewable energy power system driven by at least one renewable energy power source and having at least one current conversion device includes determining a temperature of power semiconductor device(s) of the current conversion device(s). The method also includes determining whether an amount of power of the renewable energy power source(s) is above a predetermined threshold. Further, the method includes increasing or maintaining the temperature of the power semiconductor device(s) during periods of time when the amount of the renewable energy power source(s) is below the predetermined threshold.

Abstract: There are provided methods and systems for interfacing converters and solar power arrays. For example, there is provided a method for interfacing a solar power generation apparatus with an electricity grid. The method can include connecting a first level and a second level of the solar power generation apparatus to a two-level converter. Furthermore, the method can include interfacing the two-level converter with the electricity grid via a four-wire connection.

Abstract: There are provided methods and systems for interfacing converters and solar power arrays. For example, there is provided a method for interfacing a solar power generation apparatus with an electricity grid. The method can include connecting a first level and a second level of the solar power generation apparatus to a two-level converter. Furthermore, the method can include interfacing the two-level converter with the electricity grid via a four-wire connection.

Abstract: A system and method of using one or more DC-DC/DC-AC converters and/or alternative devices allows strings of multiple module technologies to coexist within the same PV power plant. A computing (optimization) framework estimates the percentage allocation of PV power plant capacity to selected PV module technologies. The framework and its supporting components considers irradiation, temperature, spectral profiles, cost and other practical constraints to achieve the lowest levelized cost of electricity, maximum output and minimum system cost. The system and method can function using any device enabling distributed maximum power point tracking at the module, string or combiner level.

Abstract: A system for determining the output capacity of a power generating system including a sensor that monitors at least one condition of the power generating system and outputs the monitored condition data, and a power capability determination device that dynamically determines a full capacity of the power generating system based upon the outputted environmental data from the electronic controller.

Abstract: A power conversion system for providing power to an electrical grid is described. The system includes a power converter coupled to a direct current (DC) power source. The system also includes a contactor coupled to the power converter and the electrical grid and configured to selectively electrically couple the power converter to the electrical grid. The system also includes a system controller communicatively coupled to the power converter and the contactor and configured to close the contactor to electrically couple the power converter to the electrical grid and to activate the power converter when a DC voltage provided has remained higher than a voltage level for a length of time. The system controller is also configured to deactivate the power converter, while the contactor is maintained in the closed position, when an alternating current (AC) power output has remained lower than a power level for a length of time.

Abstract: Methods for determining a ground fault or insulation degradation condition within energy conversion systems are described. A method for determining a ground fault within an energy conversion system may include, in part, a comparison of baseline waveform of differential current to a waveform of differential current during operation for a plurality of DC current carrying conductors in an energy conversion system. A method for determining insulation degradation within an energy conversion system may include, in part, a comparison of baseline frequency spectra of differential current to a frequency spectra of differential current transient at start-up for a plurality of DC current carrying conductors in an energy conversion system. In one embodiment, the energy conversion system may be a photovoltaic system.

Abstract: A power conversion system for providing power to an electrical grid is described. The power conversion system includes a power converter coupled to a photovoltaic (PV) array and configured to control a PV array voltage. The power conversion system also includes a system controller communicatively coupled to the power converter and configured to select from a first reduced power operating point and a second reduced power operating point when a power available from the PV array is greater than a rated output power of the power conversion system.

Abstract: A distributed photovoltaic (PV) power plant includes a plurality of distributed dc-dc converters. The dc-dc converters are configured to switch in coordination with one another such that at least one dc-dc converter transfers power to a common dc-bus based upon the total system power available from one or more corresponding strings of PV modules. Due to the coordinated switching of the dc-dc converters, each dc-dc converter transferring power to the common dc-bus continues to operate within its optimal efficiency range as well as to optimize the maximum power point tracking in order to increase the energy yield of the PV power plant.

Abstract: Methods for determining a ground fault or insulation degradation condition within energy conversion systems are described. A method for determining a ground fault within an energy conversion system may include, in part, a comparison of baseline waveform of differential current to a waveform of differential current during operation for a plurality of DC current carrying conductors in an energy conversion system. A method for determining insulation degradation within an energy conversion system may include, in part, a comparison of baseline frequency spectra of differential current to a frequency spectra of differential current transient at start-up for a plurality of DC current carrying conductors in an energy conversion system. In one embodiment, the energy conversion system may be a photovoltaic system.

Abstract: Power inverters are controlled in response to reactive power support commands received from a power grid such that at least one power inverter provides reactive power to the power grid. The reactive power provided is based on each power inverter's reactive power capacity only while the total power capacity of each power inverter providing the reactive power is not exhausted in generating real power.

Abstract: A system and method of using one or more DC-DC/DC-AC converters and/or alternative devices allows strings of multiple module technologies to coexist within the same PV power plant. A computing (optimization) framework estimates the percentage allocation of PV power plant capacity to selected PV module technologies. The framework and its supporting components considers irradiation, temperature, spectral profiles, cost and other practical constraints to achieve the lowest levelized cost of electricity, maximum output and minimum system cost. The system and method can function using any device enabling distributed maximum power point tracking at the module, string or combiner level.

Abstract: A power inverter system includes a plurality of power semiconductor switching devices. Each switching device includes a corresponding gate turn off resistance configured to increase during starting up periods of the inverter system such that the open circuit voltage of a corresponding power source providing power to the power inverter system does not exceed the switching device blocking voltage ratings during the corresponding switching turn-off periods. The starting up period is the time required to bring the corresponding power source voltage from its open circuit voltage level to a predetermined voltage which constitutes a safe operating condition for the plurality of power semiconductor switching devices.

Abstract: A fault protection scheme for a photovoltaic power converter system is provided. According to aspects of the present disclosure, a fault protection circuit is coupled between a power converter and a ground reference. The fault protection circuit includes a fuse and a current sensor coupled in series with the fuse. A controller is configured to receive current readings from the current sensor and compare the current readings to a current threshold. The current threshold is selected to be less than the fuse current rating of the fuse. The controller identifies a fault condition if the current flowing through the ground protection circuit exceeds the current threshold value. A contactor can also be provided to temporarily lift the power converter relative to the ground reference to determine the existence of other fault paths in the system.

Abstract: A power conversion system for providing power to an electrical grid is described. The system includes a power converter coupled to a direct current (DC) power source. The system also includes a contactor coupled to the power converter and the electrical grid and configured to selectively electrically couple the power converter to the electrical grid. The system also includes a system controller communicatively coupled to the power converter and the contactor and configured to close the contactor to electrically couple the power converter to the electrical grid and to activate the power converter when a DC voltage provided has remained higher than a voltage level for a length of time. The system controller is also configured to deactivate the power converter, while the contactor is maintained in the closed position, when an alternating current (AC) power output has remained lower than a power level for a length of time.

Abstract: A system for determining the output capacity of a power generating system including a sensor that monitors at least one condition of the power generating system and outputs the monitored condition data, and a power capability determination device that dynamically determines a full capacity of the power generating system based upon the outputted environmental data from the electronic controller.

Abstract: System, power modules, and methods for supplying an output voltage to an electric grid are provided. One example power module includes a switching device configured to supply an output from a power generator to an electric grid, a feedback unit configured to provide a feedback signal indicative of a deviation of a parameter associated with the electric grid, and a controller coupled to the feedback unit and the switching device. The controller is configured to adjust a reactive current of the output in response to at least one grid fault event to ride through the at least one grid fault event, to modify the deviation provided from the feedback unit, to control the switching device based on the modified deviation, and to detect an islanding condition based on the parameter associated with the electric grid.

Abstract: A system and method are provided for enabling a PV inverter to be connected to a string of series connected PV modules without exposing the inverter to elevated voltage stresses. The input voltage to the inverter is gradually built up by sequentially switching in more series PV modules. This system and method are simple to implement in both centralized and distributed PV power plants and in either case, it significantly increases the utilization of the PV inverter. The input switching elements can be implemented using a wide variety of parts including electro-mechanical switches, semiconductor switches (IGBTs, MOSFETs . . . , etc.) as well as MEMS devices depending on the current level and target cost. A mix of switches can also be used to assist in minimizing impedance of the final switching stage that remains connected during normal operation.

Abstract: A power conversion system for providing power to an electrical grid is described. The power conversion system includes a power converter coupled to a photovoltaic (PV) array and configured to control a PV array voltage. The power conversion system also includes a system controller communicatively coupled to the power converter and configured to select from a first reduced power operating point and a second reduced power operating point when a power available from the PV array is greater than a rated output power of the power conversion system.

Abstract: A power curtailment system is electrically coupled to a power converter and configured to control the power converter to adjust output power of the power converter in response to a power curtailment requirement condition. The power curtailment system includes at least one sensor configured to measure at least one environmental factor in an environment of the power converter over time. The power curtailment system further includes a controller configured to adjust a power curve over time based on the at least one environmental factor and, upon the power curtailment requirement condition, control the power converter to provide an adjusted output power based on data from the power curve and the power curtailment requirement condition.