Smart grid synchronization scheme

Patent metadata

Field	Value
Publication number	US-10181728-B2
Application number	US-201615077665-A
Country	US
Kind code	B2
Filing date	Mar 22, 2016
Priority date	Mar 22, 2016
Publication date	Jan 15, 2019
Grant date	Jan 15, 2019

Abstract

A control system includes memory storing instructions and a processor configured to execute the instructions. The processor is configured to receive a first indication of a power grid voltage, receive a second indication of a power grid phase angle, receive a third indication of a generator voltage of power provided by a generator, and receive a fourth indication of a generator phase angle of power provided by the generator. The processor is configured to determine a voltage gap between the generator voltage and the power grid voltage and a time difference between the generator phase angle and the power grid phase angle. The processor is configured to generate a signal to cause the generator voltage and the generator phase angle to synchronize with the power grid voltage and the power grid phase angle, respectively.

First claim

The invention claimed is:

1. A control system, comprising:
memory storing instructions; and
a processor coupled to the memory and configured to execute the instructions and configured to:
receive a first indication of a power grid voltage;
receive a second indication of a power grid phase angle;
receive a third indication of a generator voltage of power provided by a generator;
receive a fourth indication of a generator phase angle of the power provided by the generator;
calculate a voltage gap between the generator voltage and the power grid voltage and determine a time difference between the corresponding phase angles of the generator phase angle and the power grid phase angle; and
generate a signal to cause the generator to set a generator speed to synchronize the generator voltage and the generator phase angle with the power grid voltage and the power grid phase angle, respectively, based at least in part on the calculated voltage gap and the time difference.

2. The control system of claim 1 , wherein the processor is configured to send the signal to a voltage regulator that controls the generator voltage such that the voltage gap is reduced.

3. The control system of claim 1 , wherein the processor is configured to send the signal to adjust at least one of a proportional, integral, or derivative (PID) gain factor of a controller during synchronization between the power grid and the generator.

4. The control system of claim 3 , wherein the processor is configured to comprising adjust at least one of the PID gain factors based on a magnitude of the voltage gap.

5. The control system of claim 1 , wherein the processor is configured to obtain thresholds of an accepted tolerance between the power grid voltage and the generator voltage, via human machine interface (HMI) or retrieved from the memory, to control when the generator voltage and the generator phase angle are deemed to be synchronized with the power grid voltage and power grid phase angle.

6. The control system of claim 1 , wherein the processor is configured to receive the first and second indications from a voltage sensing transformer.

7. The control system of claim 1 , wherein the processor is configured to:
obtain measured samples of the power grid voltage and the generator voltage at corresponding points;
subtract the sampled power grid voltage from the sampled generator voltage; and
identify the voltage gap as the difference between the sampled power grid voltage and the sampled generator voltage.

8. The control system of claim 1 , comprising:
a first voltage sensing transformer that receives the first and second indications from the power grid; and
a second voltage sensing transformer that receives the third and fourth indications of power provided by the generator.

9. The control system of claim 1 , wherein the processor is configured to determine a root means square of multiple sampled voltage gaps as the voltage gap.

10. A non-transitory computer-readable medium comprising instructions configured to be executed by a processor of a control system, wherein the instructions comprise instructions configured to cause the processor to:
receive a first indication of a power grid phase angle of power on a power grid;
receive a second indication of a generator phase angle of power provided by a generator;
receive a third indication of a power grid voltage of the power grid;
receive a fourth indication of a generator voltage of the power provided by the generator;
determine a time difference between the generator phase angle and the power grid phase angle;
calculate a voltage gap between the generator voltage and the power grid voltage;
send a first signal to set a generator speed based
at least in part on the time difference and the voltage gap; and

send a second signal to a circuit breaker to close the circuit breaker when the time difference is within a tolerance, thereby electrically coupling the power grid to the generator.

11. The non-transitory computer readable medium of claim 10 , comprising instructions configured to cause the processor to send the first signal to a voltage regulator that controls the generator speed to control the generator phase angle, wherein the generator speed is controlled based at least in part on a current generator speed and the time difference.

12. The non-transitory computer readable medium of claim 10 , comprising instructions configured to cause the processor to adjust the generator speed by adjusting a current generator speed to an updated speed based on a constant value divided by the time difference.

13. The non-transitory computer readable medium of claim 10 , comprising instructions configured to cause the processor to determine the time difference by comparing when the generator voltage crosses a zero voltage line with when the power grid voltage cross the zero voltage line.

14. The non-transitory computer readable medium of claim 10 , comprising instructions configured to cause the processor to obtain a selection threshold of an accepted tolerance between the power grid phase angle and the generator phase angle, via a human machine interface (HMI) or retrieved from a memory operatively coupled to the processor, to when the generator phase angle is deemed to be synchronized with the power grid phase angle.

15. A method, comprising:
receiving, via a processor, a power grid signal indicating a power grid voltage of power on a power grid;
receiving, via the processor, a generator signal indicating a generator voltage of power provided by a generator;
calculating, via the processor, a voltage gap between the generator voltage and the power grid voltage; and
sending, via the processor, a control signal to adjust a controller to set a generator speed of the generator to cause the generator to synchronize the power grid voltage and the generator voltage based at least in part on a magnitude of the voltage gap.

16. The method of claim 15 , comprising sending the control signal to a voltage regulator that controls the generator voltage, via generator excitation, such that the voltage gap is reduced.

17. The method of claim 15 , comprising adjusting at least one of a proportional, integral, or derivative (PID) gain factor of the controller during synchronization between the power grid and the generator based on the control signal.

18. The method of claim 17 , comprising adjusting the PID gain factor in proportion to the magnitude of the voltage gap.

19. The method of claim 15 , comprising:
obtaining measurement samples of the power grid voltage and the generator voltage at corresponding points;
subtracting the sampled power grid voltage from the sampled generator voltage; and
identifying the voltage gap as the difference between the sampled power grid voltage and the sampled generator voltage.

Assignees

• Gen Electric

Inventors

• Shakeel Tabrez
• Kleen Randall John
• Rahim Muhammed

Classifications

• H02J3/40 Primary

  Synchronisation of generators for connection to a network or to another generator · CPC title

• H02J3/42 Primary

  with automatic parallel connection when synchronisation is achieved · CPC title

• H02J3/44

  with means for ensuring correct phase sequence · CPC title