Energy storage system for photovoltaic energy and method of storing photovoltaic energy

• US 10,340,703 B2
• Filed: 12/07/2018
• Issued: 07/02/2019
• Est. Priority Date: 05/15/2017
• Status: Active Grant

• Current Assignee: Dynapower Company LLC (Sensata Technologies Holding Plc)
• Original Assignee: Dynapower Company LLC (Sensata Technologies Holding Plc)
• Inventors: Palombini, John C., Somani, Apurva
• Primary Examiner(s): Kessie, Daniel
• Application Number:
  US16/213,317
• Publication Number:
  US 20190115760A1
• Time in Patent Office: 207 Days
• CPC Class Codes: H02J 2300/26 involving maximum power point tracking control for photovoltaic sources maximum power point systems in particular G05F1/67
• CPC Class Codes: H02J 3/32 using batteries with converting means
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 7/35 with light sensitive cells
• CPC Class Codes: H02M 3/33584 Bidirectional converters
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02P 80/20 using renewable energy
• CPC Class Codes: Y02P 90/50 Energy storage in industry with an added climate change mitigation effect

Abstract

An energy system for renewable energy applications includes a renewable energy source, a bidirectional inverter connected an AC bus and a DC bus, an energy storage unit connected to the bidirectional DC/DC converter, and a control system comprising one or more controllers coupled to the bidirectional inverter and the bidirectional DC/DC converter. The bidirectional inverter is connected to the renewable energy source and a bidirectional DC/DC converter through the DC bus. The system is configured to capture low power of a photovoltaic (PV) array, energy typically lost to inverter clipping, and through the utilization of ramp rate control.

Claims

1. A power system for capturing low voltage energy from a power source, the power system comprising:

the power source coupled to a DC bus;

a DC/DC power converter coupled to the DC bus and an energy storage device;

a power inverter coupled to the DC bus and an AC bus, wherein the power inverter has a wake up, or minimum operational, voltage being a voltage magnitude that a voltage at the DC bus must reach for the power inverter to be operational; and

a control system, the control system comprising one or more controllers configured to;

monitor a voltage produced by the power source;

determine whether the power source is producing a voltage greater than a first predetermined threshold, wherein the first predetermined threshold corresponds to an available power level that'"'"'s equal to or greater than expected losses in the DC/DC power converter;

determine whether the power source is producing a voltage less than a second threshold when it is determined that the power source is producing a voltage greater than the first predetermined threshold, wherein the second predetermined threshold is equal to the wake up voltage of the power inverter;

when it is determined that the power source is producing a voltage between the first threshold and the second threshold;

control the DC/DC power converter to operate in an MPPT mode and store energy generated by the power source in the energy storage device; and

control the power inverter not to operate in an MPPT mode; and

when it is determined that the power source is producing a voltage greater than or equal to the second threshold;

control the power inverter to operate in an MPPT mode and supply the energy generated by the power source to a power grid through the AC bus; and

control the DC/DC power converter not to operate in an MPPT mode.

2. The power system of claim 1, wherein the voltage produced by the power source is monitored continuously, and the control system continuously controls the DC/DC power converter and the power inverter to transition between operating in an MPPT mode and not operating in an MPPT mode.

3. The power system of claim 1, wherein in determining whether the power source is producing a voltage less than the second predetermined threshold, the control system is further configured to monitor the voltage at the DC bus.

4. The power system of claim 3, further comprising a sensor sensing the voltage at the DC bus and transmitting the sensed voltage to the power system.