FIELD

The present disclosure relates generally to active stability control of rotating compression systems utilizing an electric machine operatively coupled thereto.

BACKGROUND

Compression systems may be subject to certain flow instabilities during operation, including rotating stall and surge. Example compression systems include rotating compressors and pumps. Generally, surge is caused by oscillations of mass flow and pressure through the compression system and rotating stall is caused by locally reduced or blocked flow within the compression system. Both surge and rotating stall are undesirable. Particularly, surge oscillations or rapid pulsations in the flow may damage components of the compression system as well as other components positioned upstream and/or downstream of the compression system. Rotating stall results in inefficient operation of the compression system. Rotating stall and surge have other drawbacks as well.

Many compression systems, such as axial and centrifugal compressors for turbine engines, have an associated compressor map that describes the compressor's characteristics. For instance, compressor maps typically include a surge line that demarcates a stable operating region from an unstable operating region for various characteristic curves, e.g., speed settings of the turbine engine. If the mass flow through the compressor falls above the surge line, or more particularly to the left of the surge line, a flow instability results. On the other hand, if the mass flow through the compressor is below the surge line, or more particularly to the right of the surge line, the compression system is operating at a stable operating point or range.

Conventionally, to prevent surge, a surge margin or surge control line is drawn at a distance from the surge line and surge avoidance controls of the compression system ensure that the operating point of the compression system does not cross the surge control line. That is, the surge avoidance controls ensure that the operating point is at or right of the surge control line. However, such surge avoidance schemes restrict the operating range of the compression system and thus limit efficiency.

Other techniques for accounting for surge and rotating stall in addition or alternatively to surge avoidance controls include active surge control schemes that seek to stabilize surge and rotating stall rather than avoiding them. For instance, compressors may include various variable geometry components that may be actuated to control surge and rotating stall. For example, recycle, bleed, and throttle valves, variable guide vanes, etc. have been utilized for active surge control. While such active surge components are generally effective in controlling surge and rotating stall, they add extra weight, require additional components, and in many instances impart a penalty on the efficiency of the compression system.

Thus, a compression system and methods of operating the same that address one or more of the challenges noted above would be useful.

BRIEF DESCRIPTION

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

In one aspect, the present disclosure is directed to a turbine engine. The turbine engine includes a compressor configured to pressurize an incoming air stream into a pressurized air stream. The turbine engine also includes a combustion chamber fluidly connected with the compressor and configured to receive the pressurized air stream from the compressor, wherein fuel is injected into the pressurized air stream and ignited in the combustion chamber so as to raise a temperature and energy level of the pressurized air stream. Further, the turbine engine includes a turbine fluidly connected with the combustion chamber and configured to receive combustion products that flow from the combustion chamber. The turbine engine also includes a shaft system and an electric generator operatively coupled with the compressor via the shaft system. Moreover, the turbine engine includes one or more electrical loads electrically connectable with the electric generator via a power bus system. In addition, the turbine engine includes a controller configured to: receive control data indicative of a system state of the compressor; determine a damping control command representative of instructions for adjusting a control parameter of at least one of the electric generator and the one or more electrical loads based at least in part on the control data; and control at least one of the electric generator and the one or more electrical loads to adjust the control parameter based at least in part on the damping control command to change an output of the shaft system for damping instability fluctuations of the pressurized air stream within the compressor.

In another aspect, the present disclosure is directed to a method for active stability control of a compression system operatively coupled with an electric generator via a shaft system. The method includes receiving control data indicative of a system state of the compression system. The method also includes determining a damping control command representative of instructions for adjusting a control parameter of at least one of the electric generator and one or more electrical loads electrically connectable with the electric generator based at least in part on the control data. Further, the method includes adjusting the control parameter of at least one of the electric generator and the one or more electrical loads based at least in part on the damping control command to change an output of the shaft system for damping instability fluctuations of a fluid stream within the compression system.

In yet another aspect, the present disclosure is directed to a compression system. The compression system includes a pump configured to pressurize a fluid stream. The compression system also includes a shaft system and an electric machine operatively coupled with the pump via the shaft system. The compression system further includes a controller configured for controlling the electric machine and configured to: receive one or more compression system parameters indicative of a system state of the pump; and control a torque output of the electric machine to dampen pressure fluctuations of the fluid stream based at least in part on the system state of the pump.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

