Energy generation (EG) system generating failsafe level of energy in case of communication failure

Patent metadata

Field	Value
Publication number	US-9811064-B2
Application number	US-201514697353-A
Country	US
Kind code	B2
Filing date	Apr 27, 2015
Priority date	Apr 27, 2015
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

Embodiments may include a method of curtailing an output level of an EG system. The method may include receiving, at a processor, a first dynamic control signal. The first dynamic control signal may include an instruction to adjust an output level of an EG system to a first output level. The method may also include maintaining the output level of the EG system at the first output level for a predetermined period. The method may further include determining, by the processor, whether a second dynamic control signal is received during the predetermined period. If a second dynamic control signal is not received during the predetermined period, the method may include ramping down the output level at a predetermined rate after the predetermined period until a predetermined failsafe output level is achieved. The predetermined failsafe output level may be maintained until a third dynamic control signal is received by the processor.

First claim

What is claimed is:

1. A method comprising:
receiving, at a processor, a first control signal comprising an instruction to adjust an energy generation output level of an energy generation (EG) system to a first energy generation output level;
maintaining the energy generation output level of the EG system at the first energy generation output level for a time period;
determining, by the processor, whether a second control signal is received during the time period, wherein the second control signal comprises an instruction to adjust the energy generation output level; and
if a second control signal is not received during the time period: (i) ramping down the energy generation output level at a rate after the time period until a failsafe output level is achieved, and (ii) maintaining the failsafe output level until a third control signal is received by the processor, wherein the failsafe output level is based on a historical load requirement.

2. The method of claim 1 , wherein the time period is between 3 seconds and 10 seconds.

3. The method of claim 1 , wherein the EG system comprises a photovoltaic inverter and ramping down the energy generation output level comprises changing an electrical characteristic of the photovoltaic inverter.

4. The method of claim 1 , wherein the EG system comprises a plurality of photovoltaic inverters and ramping down the energy generation output level comprises changing an electrical characteristic of a photovoltaic inverter of the plurality of photovoltaic inverters.

5. The method of claim 1 , wherein the first energy generation output level enables the EG system to match a corresponding load requirement during an overgeneration condition, and the overgeneration condition occurs when the EG system generates more power than the corresponding load requirement.

6. The method of claim 1 , wherein the first energy generation output level enables the EG system to match the sum of a corresponding load requirement and an additional margin during an overgeneration condition, and the overgeneration condition occurs when the EG system generates more power than the sum of the corresponding load requirement and the additional margin.

7. The method of claim 1 , wherein the rate has a larger average magnitude than a historical ramp rate at the same time of day.

8. The method of claim 1 , wherein the failsafe output level is based on the historical load requirement for the time of day.

9. The method of claim 1 , wherein the rate varies based on the energy generation output level of the EG system.

10. The method of claim 1 , wherein ramping down the energy generation output level to the failsafe output level takes between 10 seconds and 10 minutes.

11. The method of claim 1 , further comprising:
receiving, at the processor, a third control signal comprising an instruction to adjust the energy generation output level of the EG system to a second energy generation output level; and
adjusting the energy generation output level of the EG system to the second energy generation output level.

12. The method of claim 1 , wherein prior to receiving, at the processor, the first control signal, the energy generation output level of the EG system is at a second energy generation output level not equal to the first energy generation output level.

13. The method of claim 1 , wherein the EG system is one EG system of a plurality of EG systems, and the method further comprises:
maintaining a total energy generation output level of the plurality of EG systems at a first total energy generation output level for the time period;
if the second control signal is not received during the time period: (i) ramping down the total energy generation output level at the rate after the time period until a total failsafe output level for the plurality of EG systems is achieved, and (ii) maintaining the total failsafe output level until the third control signal is received by the processor.

14. A method of responding to a loss of communication for an energy generation (EG) system connected to an energy grid as part of a distributed generation system, the EG system method comprising:
receiving, at a processor coupled to the EG system, control messages at a predetermined interval while the EG system is in normal communication with a control network;
setting an energy generation output of the EG system to a first level based on a first control message;
thereafter, receiving, at the processor, a second control message comprising an instruction to adjust an energy generation output level of the EG system to a second level;
maintaining the energy generation output level of the EG system at the second level; and
if a third control message comprising an instruction to adjust the energy generation output level of the EG system is not received within the predetermined interval after the second control message:
determining a loss of communication with the control network,
reducing the energy generation output level to a failsafe output level, wherein the failsafe output level is based on a historical load requirement, and
maintaining the failsafe output level until communication with the control network is reestablished and a fourth control message is received by the processor to change the energy generation output level.

15. The method of claim 14 , wherein the predetermined interval is between 3 and 10 seconds.

16. The method of claim 14 , wherein reducing the energy generation output level to the failsafe output level comprises ramping down the energy generation output level at a rate until the failsafe output level is achieved.

17. The method of claim 14 , wherein the failsafe output level is greater than the second level.

Assignees

• Solarcity Corp

Inventors

• Carlson Eric Daniel
• Murthy Nathan

Classifications

• H02J7/35

  with light sensitive cells · CPC title

• Y04S40/124

  using wired telecommunication networks or data transmission busses · CPC title

• Y04S10/123

  the energy generation units being or involving renewable energy sources · CPC title

• Y04S10/30

  State monitoring, e.g. fault, temperature monitoring, insulator monitoring, corona discharge · CPC title

• Y04S40/126

  using wireless data transmission · CPC title