Closed Brayton cycle shutdown control with valve system for thermally isolating electrical components

1 . A power-generation system comprising:

an electrical system including a motor-generator and an electric power conditioning and distribution system connected with the motor-generator, the motor-generator operable in a power-generation mode to produce electrical energy and a motor mode to convert the electrical energy into rotational power, and the electrical system configured for fluid cooling for removing heat from the electrical system,

a turbine engine including a compressor configured to receive a working fluid and compress the working fluid to provide a compressed working fluid, a reactor heat-exchanger downstream of the compressor that transfers heat from a nuclear reactor to the compressed working fluid to provide a heated working fluid, a turbine downstream of the reactor heat-exchanger and configured to extract work from the heated working fluid and drive rotation of the compressor and the motor-generator, and a cooling heat-exchanger downstream of the turbine to transfer heat away from the heated working fluid to provide a cooled working fluid, and

a fluid control system fluidly connected with the electrical system and the turbine engine to circulate the working fluid through the electrical system and the turbine engine, the fluid control system including a first valve located upstream of the electrical system, a second valve located downstream of the electrical system, and a controller coupled to the first valve and the second valve, the first valve and the second valve each being configured to change between an open position in which the first valve and the second valve allow the cooled working fluid to flow into and out of the electrical system to transfer heat from the motor-generator and the power conditioning and distribution system and a closed position in which the first valve and the second valve block the working fluid from flowing into and out of the electrical system,

wherein the controller is configured to direct the first valve and the second valve to change from the open position to the closed position in response to a shutdown of the turbine engine in which a speed of the compressor and the turbine is below a predetermined speed to trap a first portion of the working fluid between the first valve and the second valve so that the electrical system is isolated from a second portion of the working fluid in the system to prevent the electrical system from being exposed to a high-temperature of the second portion of the working fluid after the shutdown.

2 . The power-generation system of claim 1 , wherein the power-generation system is a closed-loop system such that the working fluid is recirculated through the power-generation system.

3 . The power-generation system of claim 1 , wherein the first valve is fluidly connected upstream of the electrical system and downstream of the cooling heat-exchanger.

4 . The power-generation system of claim 1 , wherein the first valve is fluidly connected upstream of the cooling heat-exchanger.

5 . The power-generation system of claim 1 , wherein the second valve is fluidly connected downstream of the electrical system and upstream of the compressor.

6 . The power-generation system of claim 1 , wherein the second valve is fluidly connected downstream of the compressor.

7 . The power-generation system of claim 1 , wherein the motor-generator is coupled with the turbine engine and configured to operate in the motor mode to start the turbine engine and to operate in the power-generation mode to be driven by the turbine and generate the electrical energy.

8 . A power-generation system comprising:

an electrical system,

a turbine engine including a compressor configured to receive a working fluid and compress the working fluid to provide a compressed working fluid, a heat source that transfers heat to the compressed working fluid to provide a heated working fluid, a turbine fluidly connected with the compressor to extract work from the heated working fluid and drive rotation of the compressor, and a first heat-exchanger fluidly connected with the turbine to transfer heat away from the heated working fluid to provide a cooled working fluid, and

a fluid control system including a valve system and a controller coupled to the valve system to move the valve system between an open mode in which the valve system allows the cooled working fluid to flow through the electrical system in response to operation of the turbine engine and a closed mode in which the valve system blocks the working fluid from flowing through the electrical system in response to a shutdown of the turbine engine.

9 . The power-generation system of claim 8 , wherein the controller is configured to direct the valve system to be in the open mode at a start-up of the turbine engine to allow the working fluid to flow through the system.

10 . The power-generation system of claim 8 , wherein the valve system includes a first valve fluidly connected upstream of the electrical system and downstream of the first heat-exchanger.

11 . The power-generation system of claim 10 , wherein the valve system further includes a second valve fluidly connected downstream of the electrical system and upstream of the compressor.

12 . The power-generation system of claim 10 , wherein the valve system further includes a second valve fluidly connected downstream of the compressor.

13 . The power-generation system of claim 8 , wherein the valve system includes a first valve fluidly connected upstream of the first heat-exchanger.

14 . The power-generation system of claim 12 , wherein the valve system further includes a second valve fluidly connected downstream of the electrical system and upstream of the compressor.

15 . The power-generation system of claim 12 , wherein the valve system further includes a second valve fluidly connected downstream of the compressor.

16 . The power-generation system of claim 9 , wherein the electrical system includes a motor-generator coupled with the compressor and configured to operate in a motor mode to start the turbine engine and to operate in a power-generation mode to be driven by the turbine and generate electrical energy.

17 . A method of operating a power-generation system, the method comprising:

compressing a working fluid with a compressor,

heating the compressed working fluid,

rotating a turbine with the heated working fluid,

cooling the heated working fluid after rotating the turbine with the heated fluid,

conducting electrical energy to at least one electrical component,

cooling at least one electrical component with the cooled working fluid,

conducting the working fluid from the at least one electrical component to the compressor, and

blocking the working fluid from flowing to the electrical component in response to a speed of the compressor and the turbine being below a predetermined speed.

18 . The method of claim 17 , wherein blocking the working fluid from flowing to the at least one electrical component includes shutting a first valve fluidly connected upstream of the at least one electrical component and downstream of the turbine.

19 . The method of claim 18 , wherein blocking the working fluid from flowing to the at least one electrical component includes shutting a second valve fluidly connected downstream of the at least one electrical component and upstream of the turbine.

20 . The method of claim 17 , further comprising driving a generator with the work extracted from the turbine to produce the electrical energy.