# US 2021/0340956 A1 · Systems and methods for optimal speed protection for power turbine governing

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- Number: US 2021/0340956 A1
- Document ID: US20210340956A1
- Status: Published application
- Kind: A1
- Application number: 17/376,965
- Filed: 2021-07-15
- Published: 2021-11-04
- Earliest claimed: 2018-05-04
- Assignees: Raytheon Technologies Corporation
- Applicants: Raytheon Technologies Corporation
- Inventors: Chaohong Cai; Timothy J. Crowley; David Lei Ma; Richard P. Meisner
- Web page: https://patentgrep.com/patent/US20210340956A1

## CPC

- F02C 9/00: Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants (controlling air intakes F02C7/057; controlling turbines F01D; controlling compressors F04D27/00; controlling in general G05)
- F03D 7/043: {characterised by the type of control logic}
- F03D 7/0224: {Adjusting blade pitch}
- F03D 7/0272: {by measures acting on the electrical generator}
- F03D 7/0276: {controlling rotor speed, e.g. variable speed}
- F05B 2270/327: Rotor or generator speeds
- F05D 2220/329: in helicopters
- F05D 2270/02: to control rotational speed (n)
- F05D 2270/021: to prevent overspeed
- F05D 2270/053: Explicitly mentioned power
- F05D 2270/335: Output power or torque
- Y02E 10/72: Wind turbines with rotation axis in wind direction
- F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00)
- F03D: WIND MOTORS
- F05B: INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A control system for limiting power turbine torque (QPT) of a gas turbine engine includes a controller including a processor and memory configured to control the gas turbine engine, the controller including an engine control module that provides an effector command signal to a gas generator of the gas turbine engine; a power turbine governor module that outputs a preliminary torque request (QPT_req_pre); and a power turbine torque (QPT) optimal limiter module that outputs a maximum torque topper (QPT_max) to limit a power turbine speed overshoot of the gas turbine engine; wherein the controller outputs a minimum value between the preliminary torque request (QPT_req_pre) and the maximum torque topper (QPT_max) to the engine control module.

## Claims

### Claim 1

A method, comprising:
commanding, via a processor, an effector command signal to a gas generator of a gas turbine engine;
determining, via the processor, a preliminary torque request;
determining, via the processor, a maximum torque topper to limit a power turbine speed overshoot of the gas turbine engine; and
commanding, via the processor, operation of the gas turbine engine in accordance with the maximum torque topper.

### Claim 2 (depends on 1)

The method of claim 1, wherein the determining the maximum torque topper includes calculating, by the processor, a relative torque limiter signal.

### Claim 3 (depends on 2)

The method of claim 2, wherein the determining the maximum torque topper further includes estimating, by the processor, a torque signal of a load system.

### Claim 4 (depends on 3)

The method of claim 3, wherein the determining the maximum torque topper includes calculating the maximum torque topper based on the relative torque limiter signal and the torque signal of the load system.

### Claim 5 (depends on 4)

The method of claim 4, wherein calculating the relative torque limiter signal comprises subtracting, by the processor, a real-time output signal from a desired power turbine speed to produce a signal difference.

### Claim 6 (depends on 5)

The method of claim 5, wherein subtracting the real-time output signal from the desired power turbine speed to produce the signal difference further comprises comparing, by the processor, the signal difference against a baseline of zero to output a larger positive number between the signal difference and zero.

### Claim 7 (depends on 3)

The method of claim 3, wherein the load system is in communication with the gas turbine engine.

### Claim 8

A method of limiting power turbine torque of a gas turbine engine, comprising:
calculating, by a controller, a relative torque limiter signal;
estimating, by the controller, a torque signal of a load system;
calculating a maximum torque topper to limit a power turbine speed overshoot of the gas turbine engine using the relative torque limiter signal and the torque signal of the load system; and
operating the gas turbine engine according to the maximum torque topper.

### Claim 9 (depends on 8)

The method of limiting power turbine torque of claim 8, wherein calculating the relative torque limiter signal comprises subtracting, by the controller, a real-time output signal from a desired power turbine speed to produce a signal difference.

### Claim 10 (depends on 9)

The method of limiting power turbine torque of claim 9, wherein subtracting the real-time output signal from the desired power turbine speed to produce the signal difference further comprises comparing, by the controller, the signal difference against a baseline of zero to output a larger positive number between the signal difference and zero.

### Claim 11 (depends on 10)

The method of limiting power turbine torque of claim 10, further comprising multiplying, by the controller, the larger positive number by twice an inertia of the power turbine and rotor load, an estimated power turbine torque rate limit (QRL), and a scaling factor to generate a multiplication product.

### Claim 12 (depends on 11)

The method of limiting power turbine torque of claim 11, further comprising calculating, by the processor, a square root of the multiplication product to calculate the relative torque limiter signal.

### Claim 13 (depends on 12)

The method of claim 12, further comprising adding, by the processor, the torque signal of the load system and the relative torque limiter signal to the calculate the maximum torque topper.

### Claim 14 (depends on 8)

The method of claim 8, wherein the load system is in communication with the gas turbine engine.

### Claim 15

An article of manufacture including a tangible, non-transitory computer-readable storage medium having instructions stored thereon that, in response to execution by a processor, cause the processor to perform operations comprising:
calculating, via the processor, a relative torque limiter signal;
estimating, by the processor, a torque signal of a load system;
calculating a maximum torque topper to limit a power turbine speed overshoot of a gas turbine engine using the relative torque limiter signal and the torque signal of the load system, wherein the gas turbine engine is operated in accordance with the maximum torque topper.

### Claim 16 (depends on 15)

The article of claim 15, wherein calculating the relative torque limiter signal comprises subtracting, by the processor, a real-time output signal from a desired power turbine speed to produce a signal difference.

### Claim 17 (depends on 16)

The article of claim 16, wherein subtracting the real-time output signal from the desired power turbine speed to produce the signal difference further comprises comparing, by the processor, the signal difference against a baseline of zero to output a larger positive number between the signal difference and zero.

### Claim 18 (depends on 17)

The article of claim 17, wherein the operations further comprise multiplying, by the controller, the larger positive number by twice an inertia of the power turbine and rotor load, an estimated power turbine torque rate limit, and a scaling factor to generate a multiplication product.

### Claim 19 (depends on 18)

The article of claim 18, wherein the operations further comprise calculating, by the processor, a square root of the multiplication product to calculate the relative torque limiter signal.

### Claim 20 (depends on 19)

The article of claim 19, wherein, the operations further comprise adding, by the processor, the torque signal of the load system and the relative torque limiter signal to the calculate the maximum torque topper.