Angle determination for a generator

Patent metadata

Field	Value
Publication number	US-11079255-B2
Application number	US-201916401638-A
Country	US
Kind code	B2
Filing date	May 2, 2019
Priority date	May 30, 2018
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

A method determines a generator system load and/or rotor angle. The generator system has a generator with a generator terminal outputting electrical power generated by the generator, a transformer and a point of common coupling, PCC, terminal. The transformer is between the generator and PCC terminals. The method includes: determining the generator field current; determining the output voltage, the output current and the power factor and/or angle of the output voltage and output current from the generator terminal, and determining the load angle of the generator system, output voltage from the generator terminal, output current from the generator terminal and the power factor and/or angle; and/or determining the output voltage, the output current and the power factor and/or angle of the output voltage and output current, and determining the rotor angle of the generator system, output voltage, output current from the PCC terminal and the power factor and/or angle.

First claim

The invention claimed is:

1. A method of determining a load angle and/or rotor angle of a generator system comprising a generator that is a cylindrical rotor, the generator having a generator terminal for outputting electrical power generated by the generator, a transformer and a point of common coupling (PCC) terminal, the transformer being arranged between the generator terminal and the PCC terminal, the method comprising:
determining a field current of the generator;
determining an open circuit voltage of the generator in dependence on the field current and open circuit characteristics of the generator; and
determining the load angle and/or rotor angle of the generator system in dependence on the determined open circuit voltage of the generator;
determining an output voltage from the generator terminal, an output current from the generator terminal and a generator power factor angle and/or a generator power factor of the output voltage and output current from the generator terminal, and determining the load angle of the generator system in dependence on the determined field current, output voltage from the generator terminal, output current from the generator terminal and the generator power factor angle and/or the generator power factor; and/or
determining an output voltage from the PCC terminal, an output current from the PCC terminal and a PCC power factor angle and/or a PCC power factor of the output voltage and output current from the PCC terminal, and determining the rotor angle of the generator system in dependence on the determined field current, output voltage from the PCC terminal, output current from the PCC terminal and the PCC power factor angle and/or the PCC power factor,
wherein the load angle is determined as:

δ
=

θ
+

cos

-
1

(

V
t

E

⁢
cos
⁢

⁢
θ

+

RI
t

E

)

where:
δ is the rotor angle;
V t is the rms value of the output voltage from the generator terminal;
I t is the rms value of the output current from the generator terminal;
E is the rms value of determined open circuit voltage;
θ is the generator power factor angle; and
R is the internal resistance of the generator.

2. The method according to claim 1 , wherein the generator system further comprises a mechanical drive system arranged to drive the generator so that the generator generates electrical power.

3. The method according to claim 1 , wherein determining the output voltage and output current from the generator terminal and/or PCC terminal comprises measuring properties of the output voltage and output current.

4. The method according to claim 1 , wherein determining the field current of the generator comprises measuring the field current of the generator.

5. The method according to claim 1 , further comprising filtering one or more of the determined output voltage, output current and field current to remove noise components.

6. The method according to claim 1 , wherein the open circuit characteristics of the generator are pre-determined data that have been one or more of calculated, simulated, estimated and measured.

7. The method according to claim 1 , wherein the generator is a cylindrical rotor; and
the rotor angle is determined as:

δ
=

θ
+

cos

-
1

(

V
p

E

⁢
cos
⁢

⁢
θ

+

RI
p

E

)

where:
δ is the rotor angle;
V p is the rms value of the output voltage from the PCC terminal;
I p is the rms value of the output current from the PCC terminal;
E is the rms value of determined open circuit voltage;
θ is the PCC power factor angle; and
R is the internal resistance of the generator.

8. The method according to claim 1 , wherein the electrical power output from the generator system is less than 30 MW.

9. A method of determining whether or not an out-of-step condition has occurred, the method comprising:
determining a load angle and/or rotor angle of a generator system according to the method of claim 1 ; and
determining whether or not an out-of-step condition has occurred in dependence on the determined load angle and/or rotor angle.

10. A generator system comprising:
a generator with a generator terminal for outputting electrical power generated by the generator, a transformer and a point of common coupling (PCC) terminal, wherein the transformer is arranged between the generator terminal and the PCC terminal; and
one or more computing devices configured to determine an out-of-step condition according to the method of claim 9 .

11. A computing device configured to determine a rotor angle of a generator system and/or an out-of-step condition by executing the computing program of claim 10 .

12. A generator system comprising:
a generator with a generator terminal for outputting electrical power generated by the generator, a transformer and a point of common coupling (PCC) terminal, wherein the transformer is arranged between the generator terminal and the PCC terminal; and
one or more computing devices configured to determine a load angle and/or rotor angle of the generator system according to the method of claim 1 .

13. A computer program that, when executed by a computing device, causes the computing device to determine a load angle and/or rotor angle of a generator system according to the method of claim 1 and/or an out-of-step condition.

14. A method of determining a load angle and/or rotor angle of a generator system comprising a generator that is a cylindrical rotor, the generator having a generator terminal for outputting e

Assignees

• Rolls Royce Plc
• Mtu Friedrichshafen Gmbh
• Mtu Onsite Energy Gmbh

Inventors

• Demharter Johannes
• Dasgupta Souvik
• Kreissl Michael
• Gupta Amit K
• Balijepalli Vsk Murthy

Classifications

• G01D5/242 Primary

  by carrying output of an electrodynamic device, e.g. a tachodynamo · CPC title

• H02P9/006 Primary

  Means for protecting the generator by using control (control effected upon generator excitation circuit to reduce harmful effects of overloads or transients H02P9/10) · CPC title

• G01R31/343

  in operation · CPC title

• H02P9/36

  using armature-reaction-excited machines · CPC title

• H02J3/40

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