DRIVE TRAIN

REFERENCE TO RELATED APPLICATIONS [0001] The current application claims the benefit of U.S. Provisional Application No. 63/022,807, filed on 11 May 2020, and which is hereby incorporated by reference.

TECHNICAL FIELD

[0002] The disclosure relates generally to power systems, and more particularly, to applying an auxiliary torque to a drive train of a synchronous condenser by using a starting motor for the synchronous condenser.

BACKGROUND ART

[0003] Currently, synchronous condensers have a starting (pony) motor that is used to bring a synchronous condenser from stand-still up to (or near to) synchronous speed so that the synchronous condenser is synchronized with the host power grid. FIG. 1 shows a prior art synchronous condenser drive train 10 that includes a synchronous condenser 12, a starting motor 14, and an optional flywheel 16 that are connected via shafts 18, 19.

[0004] Once the synchronous condenser 12 is excited and synchronized, the system proceeds to deliver a variety of reactive power related services to the host power grid and the starting motor 14 is de-energized. In some applications, the starting motor 14 remains connected to the drive train 10 by a couplingl8, spinning with the condenser 12. In some applications, the inertia of the synchronous condenser 12 is augmented with an additional rotational mass in the form of the flywheel 16. The flywheel 16 can be connected to the drive train 10 by an extension of the drivetrain shaft 19.

[0005] Synchronous condensers, and especially enhanced inertia synchronous condensers, have, by definition, a “reserve” of stored energy that might be used for beneficial power outcomes. Even with enhanced inertia, the characteristics of the synchronous machine limit active power control options.

SUMMARY OF THE INVENTION

[0006] The inventor recognizes that condenser systems could, in theory, have incremental impact on the grid by auxiliary mechanisms, if additional power controls could augment the inherent behavior of the main synchronous machine of a synchronous condenser system. To this extent, the inventor recognizes that the general structure of the starting pony motor presents an opportunity.

[0007] The starting motor is an incremental torque control device. The idea described herein is that, with the right choice of electrical machine, a novel control could impose an auxiliary torque load on the condenser drive-train over the “natural” torque from the grid on the synchronous condenser. The torque on the drive-train and the incremental power exchange that would accompany that control could provide a variety of beneficial services, to both the condenser system and to the host grid.

[0008] Using the variable speed drive (with necessary design modifications) of the pony motor during normal operation, the pony motor could provide transient functions such as:

• A power system stabilizer (PSS) function for oscillations of the synchronous condenser with the grid that is superior to conventional machine field enabled PSS;

• A source of fast frequency response (FFR), including response similar in character to synthetic inertia control on wind turbines;

• A power oscillation damping (POD) on active power, for damping of systemic (e.g. interarea) oscillations;

• Transient power benefits, including improving the synchronous condenser’s (SC) transient stability;

• Torsional benefits to help manage transient torque risk to the SC;

• Torsional benefits to help manage sub synchronous resonance/sub synchronous torsional interaction (SSR/SSTI) risk to the SC; and

• Torsional benefits to help manage SSR/SSTI risk to other rotating equipment in the electrical vicinity.

[0009] Positive considerations for this invention are that the physical and electrical structures required are already present. The starting (pony) motor is needed and can be added, oversized, or otherwise modified from designs based on current practice to achieve desired performance. A variable speed starting motor is already available. Starting motors are already bigger with enhanced inertia synchronous condensers. The markets are emerging for this invention, which adds to the value of the device. The invention has application and synergy with wind and photovoltaic (PV) plant applications in weak grids. Also, the synchronous condenser system could be part of, or integrated with, a larger power installation. In particular, the synchronous condenser system could be integrated with a wind power plant. The controls could be customized and coordinated with wind plant supervisory functions. [0010] Some possible drawbacks are that the starting motor is relatively small and may need to become bidirectional (motor and generator), with no discontinuities in control or topologies, as the sign of torque applied by the starting motor changes. Also, the ability to speed and slow the synchronous condenser can be limited by the angle considerations on synchronous machine. Embodiments of the invention can be more effective with enhanced inertia devices. The extra torque on the drive train also can add duty and design requirements on the coupling, but also can impact additional torque stability considerations for the drive train.

[0011] However, despite these possible drawbacks, there has been explosive growth in inverter-based generation, especially in wind and solar photovoltaic systems, collectively referred to as variable renewable resources (VERs), which has revitalized the synchronous condenser market. New applications, including offerings with enhanced inertia (e.g., a flywheel) are growing. Several applications are encountering some stability and control problems resulting from the combination of remote, high stress grids, lower system inertia, and various high gain controllers.

[0012] Additionally, poor damping of individual machines against the grid have been reported (e.g., oscillations of the variety traditionally addressed by the PSS). There has also been poor damping of exporting regions with high VER penetration, poor transient stability of synchronous condensers, and low grid inertia. The low grid inertia, which increases the market and reliability value of FFR, gives rise to new ancillary service revenue streams for resources that can provide this service. There is also a variety of torsional concerns, both those related to the torsional stress on the synchronous condensers (especially with enhanced inertia) and those related to the torsional behavior of wind turbines and thermal generation.

[0013] Aspects of the invention provide a system and method for providing an auxiliary torque to a drive train of a synchronous condenser by using a starting motor for the synchronous condenser. In an embodiment, the auxiliary torque can provide transient benefits to the power system. A starting motor can be coupled to an alternating current (AC) synchronous condenser. A control system can be operable to receive a set of measured signals relating to operation of the AC synchronous condenser. Based on the set of measured signals, the control system can determine a set of control signals, which can include an auxiliary torque command, for the starting motor and apply the set of control signals to the starting motor to adjust the operation of the AC synchronous condenser.

[0014] A first aspect of the invention provides a system, comprising: a starting motor coupled to an alternating current (AC) synchronous condenser; and a control system operable to: receive a set of measured signals relating to operation of the AC synchronous condenser; determine, based on the set of measured signals, a set of control signals for the starting motor; and apply the set of control signals to the starting motor to adjust the operation of the AC synchronous condenser.

[0015] A second aspect of the invention provides a method, comprising: receiving a set of measured signals relating to operation of an AC synchronous condenser coupled to a starting motor; determine, based on the set of measured signals, a set of control signals for the starting motor; and apply the set of control signals to the starting motor, such that the set of control signals adjust the operation of the AC synchronous condenser.

[0016] A third aspect of the invention provides a method, comprising: coupling a starting motor and an alternating current (AC) synchronous condenser; receiving a set of measured signals relating to operation of the AC synchronous condenser; determine, based on the set of measured signals, a set of control signals for the starting motor; and apply the set of control signals to the starting motor, such that the set of control signals adjust the operation of the AC synchronous condenser.

[0017] The illustrative aspects of the invention are designed to solve one or more of the problems herein described and/or one or more other problems not discussed.

BRIEF DESCRIPTION OF THE DRAWINGS [0018] These and other features of the disclosure will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various aspects of the invention.

[0019] FIG. 1 shows a perspective view of a prior art synchronous condenser drive train. [0020] FIG. 2 shows an electrical diagram of an illustrative synchronous condenser drive train according to an embodiment.

[0021] FIG. 3 shows an electrical diagram of an illustrative synchronous condenser drive train according to an embodiment.

[0022] FIG. 4 shows a perspective view of an illustrative drain train according to an embodiment.

[0023] FIG. 5 shows an illustrative graph of torsional oscillation and device torque of an illustrative drive train according to an embodiment.

[0024] FIG. 6 shows an illustrative graph of applying an auxiliary torque using a starting motor of a synchronous condenser drive train according to an embodiment.

[0025] FIG. 7 shows an illustrative graph comparing the net power to the grid after a grid fault disturbance with and without damping control according to an embodiment. [0026] FIG. 8 shows an illustrative graph comparing the machine speed of a synchronous condenser after a grid fault disturbance with and without damping control according to an embodiment.

[0027] FIG. 9 shows an illustrative graph comparing the net power to the grid after a grid fault disturbance with damping control, the power from synchronous condenser stator towards the grid, and the power from the grid that is applied by the starting motor into the drivetrain to provide the damping control according to an embodiment.

[0028] FIG. 10 shows an illustrative process for a synchronous condenser drive train according to an embodiment.

[0029] FIG. 11 shows an illustrative environment according to an embodiment.

[0030] It is noted that the drawings may not be to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings.

DETAILED DESCRIPTION OF THE INVENTION [0031] As indicated above, aspects of the invention provide a system and method for providing an auxiliary torque by a starting motor on a drivetrain of a synchronous condenser in order to provide transient benefits to the power system. A starting motor can be coupled to an alternating current (AC) synchronous condenser. A control system can be operable to receive a set of measured signals relating to operation of the AC synchronous condenser. Based on the set of measured signals, the control system can determine a set of control signals, which can include an auxiliary torque command, for the starting motor and apply the set of control signals to the starting motor to adjust the operation of the AC synchronous condenser. It is understood that, unless otherwise specified, each value is approximate and each range of values included herein is inclusive of the end values defining the range. As used herein, unless otherwise noted, the term “set” means one or more (i.e., at least one) and the phrase “any solution” means any now known or later developed solution. The singular forms "a," "an," and "the" include the plural forms as well, unless the context clearly indicates otherwise. Additionally, the terms "comprises," “includes,” “has,” and related forms of each, when used in this specification, specify the presence of stated features, but do not preclude the presence or addition of one or more other features and/or groups thereof.

[0032] Turning to the drawings, FIG. 1 shows a perspective view of a prior art synchronous condenser drive train 10. As mentioned above, the drive train 10 can include a rotor of the synchronous condenser 12 and the rotor of the starting (pony) motor 14. A flywheel 16 can be included in the drive train 10, at an end opposite the starting motor 14. The synchronous condenser 12, the starting motor 14, and the flywheel 16 can be coupled via shafts 18, 19. Each shaft 18, 19 can include a protective slip coupling. Although it is not shown, both the synchronous condenser 12 and the starting motor 14 can be magnetically coupled to individually separate stationary stators, which surround the respective rotors.

[0033] As mentioned herein, embodiments of the invention provide a solution for providing an auxiliary torque to a drive train of a synchronous condenser by using a starting motor for the synchronous condenser. The starting motor of the invention can be configured to accept an auxiliary torque command, in addition to an initial command to bring the components of the drive train up to a target speed.

[0034] Turning now to FIG. 2, an electrical diagram of an illustrative synchronous condenser system 100 according to an embodiment is shown. In an embodiment, the synchronous condenser system 100 is connected to a host power grid 152 through a switch/circuit breaker 170 and a point-of-common-coupling 180. The synchronous condenser system 100 includes a synchronous condenser 120 and a starting motor 140. The synchronous condenser 120 has two electrical components: a stator 122 and an excitation system 126 (a bus fed or a rotating variety) that excites the synchronous condenser 120 via a DC field winding 124. The stator 122 is a three-phase connection, which may include an isolating switch or circuit breaker 128, as well as a transformer (not shown). The excitation system 126 is connected via a three-phase circuit 130, which may include an isolation switch and a dedicated transformer.

[0035] The starting motor 140 can have two electrical components: a motor stator 142 and a rotor field 144. In an embodiment, the motor stator 142 is connected through a three-phase circuit 146, which may include a dedicated isolation switch and a transformer. Excitation, including torque control, of the starting motor 140 is through the rotor field 144. The excitation current, which may be DC or AC, is provided by a converter 148, which may be connected through an isolation switch 150.

[0036] In an embodiment, as shown in FIG. 3, the drive train 100 can include a starting motor 140 that is entirely supplied through a converter-based drive system 148. The stator 142 and the excitation of the rotor field 144 are supplied by the converter 148.

[0037] Turning now to FIG. 4, a perspective view of an illustrative synchronous condenser system 100 according to an embodiment is shown. The drive train 100 is similar to the prior art drive train 10 shown in FIG. 1. The synchronous condenser 120 can be a conventional AC synchronous condenser. The flywheel 160 can provide additional or enhanced inertia to the synchronous condenser 120. An embodiment of the invention can provide an auxiliary torque command to the starting motor 140, in addition to an initial basic function of bringing the system 100 up to speed. The auxiliary torque command provided to the starting motor 140 can be added, for example, for the purpose of providing transient functions/benefits. In an embodiment, the starting motor 140 can be resized (e.g., altered in rating or characteristics) in order to handle the auxiliary torque command, e.g., to provide the transient functions.

[0038] In an embodiment, the starting motor 140 can have a partially variable speed asynchronous design, such as a “double-fed” machine, in which a portion of the machine power passes through the machine converter system (e.g., as shown in FIG. 2). In another embodiment, the starting motor 140 can have a fully variable speed asynchronous design, such as a “full-converter” or an “induction motor drive (IMD)” type, in which 100% of the machine power passes through the machine converter system (e.g., as shown in FIG. 3).

[0039] Each shaft 118, 119 can include an additional reinforcement of the coupling normally used between the starting motor 140 and the other portions of the synchronous condenser system 100. For example, a protective slip coupling can be used between the starting motor 140 and the synchronous condenser 120 and/or the flywheel 160. In an embodiment, the protective slip coupling can be a variety used for torsional protection on wind turbine-generator drive trains. [0040] The speed 220 of the synchronous condenser 120 can be nominally a multiple of the grid frequency. For example, the nominal or steady-state speed 220 of the synchronous condenser 120 can be 3600 RPM or an integer fraction thereof, in a 60Hz system. Deviation of this speed 220 from nominal can be one of the available measurements used by the controller. A speed 240 of the starting motor 140 can be equal to the condenser speed 220 under steady-state conditions. Deviation of this speed 240 from nominal also can be one of the available measurements used by the controller. A speed 260 of the flywheel 160 also can be equal to the speed 220 of the condenser 120 under steady state conditions. It is understood that steady-state conditions, in this context, refers to normal operation of the condenser 120 during which there is no variation in the speed of the synchronous condenser 120 or of the conditions of the host power grid. In an embodiment, the speed 260 of the flywheel 160 can be a multiple of the condenser speed 220, e.g., when there is a gearbox located on the shaft 119 between the condenser 120 and the flywheel 160. Deviation of this speed 260 from nominal also can be one of the measurements used by the controller. In an embodiment, deviation of these speeds 220, 240, 260 from nominal occur when the host grid is disturbed. A difference between any of these three speed signals are further available measurements used by the control. [0041] An auxiliary torque 270 for the starting motor 140 is also shown. In an embodiment, this auxiliary torque 270 can be delivered by the starting motor 140 when the condenser 120 is operating under normal, synchronized operating conditions. The auxiliary torque 270 can provide any combination of one or more of a variety of transient grid services, such as PSS function for oscillations of the synchronous condenser 600, a source of FFR, a POD on active power for damping of systemic oscillations, transient power benefits (including the synchronous condenser transient stability), and torsional benefits by helping manage SSR/SSTI/transient torque risk to the synchronous condenser 120, or to other rotating equipment in the electrical vicinity. The auxiliary torque 270 can be used to deliver or consume electric power from the host power system to provide some or all of the variety of grid services. In an embodiment, the auxiliary torque 270 applied using the starting motor 120 can be imposed incrementally. In an embodiment, the reactive power characteristics of the starting motor 120 can be used to deliver or consume reactive power from the host system to provide some or all of the variety of grid services.

[0042] For the variety of transient grid services, the auxiliary torque 270 can be configured to improve the damping to power oscillations that occur in power systems. For example, the auxiliary torque 270 can be configured to improve the damping electromechanical swings of the synchronous condenser 120 (similar to power system stabilizers (PSS)) and provide damping to power swings on the host grid, such as interarea and interregional swings (power oscillation damping (POD) controller function). Additionally, the auxiliary torque 270 can be configured to provide damping to torsional oscillations or vibrations of the synchronous condenser 120, including damping of oscillations between the synchronous condenser 120 and the flywheel 160, which provides incremental inertia to the synchronous condenser drive train system 100. The auxiliary torque 270 also can provide reduction in transient torque between the synchronous condenser 120 and a flywheel 160, such as that associated with grid disturbances such as faults, switching operations, recloser actions, and the like.

[0043] Another benefit can provide damping to oscillations associated with interaction of torsional natural frequencies of the synchronous condenser drive train system 100 and the host grid, or other synchronous machines on the host grid besides the synchronous condenser drive train system 100 and the host grid (e.g., sub-synchronous resonance (SSR)). The auxiliary torque 270 can be configured to provide damping to oscillations associated with interaction of torsional natural frequencies of the synchronous condenser drive train system 100 (or other synchronous machines in the electrical vicinity) and other high speed controls, e.g., those associated with HVDC converters, on the host grid. This specifically in reference to “sub- synchronous control interaction” (SSCI) and “sub-synchronous torsional interaction” (SSTI). [0044] Additionally, for the variety of transient grid services, the auxiliary torque 270 can be configured to provide transient stabilization to power swings that occur in power systems. For example, the auxiliary torque 270 can be configured to improve the transient stability of the synchronous condenser by acting to counter acceleration or deceleration of the synchronous condenser 120 (or parts of the host grid or specific other machines) during and following disturbances to the power grid.

[0045] The variety of transient grid services that can be provided by the auxiliary torque 270 also can include providing arresting power to frequency swings that can occur in power systems. For example, the fast frequency response (FFR) of the host grid can be improved by delivering “arresting” power to the grid following disturbances on the grid (e.g., a trip of a generator) that cause the frequency to decline. This is similar to synthetic inertia control on wind turbines. [0046] In order to determine the auxiliary torque 270 to apply to using starting motor 140, any combination of one or more of a variety of measured signals can be used. For example, the measured signals can include the speed 220 of the synchronous condenser, the speed 240 of the starting motor, the speed 260 of the flywheel, a combination (where combination includes summations, differences, weighted summations, and/or the like) of the speeds 220, 240, 260, the mechanical angles that correspond to the speeds 220, 240, 260, the active power of the synchronous condenser 120, the active power of the starting motor 140, and/or the like.

[0047] Beyond the measured speed signals shown in the figure, a variety of measurements may have utility in the control. Measurements taken at the point-of-common-coupling 180 (FIGS. 2 and 3) can include: the bus voltage, the grid frequency, the active power of the entire synchronous condenser system 100, the reactive power of the entire synchronous condenser system 100, and/or the like. Measurements taken outside of the system can include: the power or current on circuit elements such as transmission lines, through switches or connectors, or other grid elements; the voltage from locations on the grid, including the terminals of the synchronous condenser 120 and the point-of-interconnection of the synchronous condenser 120; the frequency of the grid; the speed or other mechanical metrics from other rotating equipment, such as other synchronous generators, on the grid; grid angles, as measured by phasor measurement units (PMUs), and/or the like; signals, such as speed, torque instructions, currents, power, available power from either individual or collective wind or other generation within an overall project that includes the synchronous condenser system 100. It is understood that variations and processing of these signals, such as by adding, filtering, measuring rate-of- change, or cumulative (integral) are included as possible signals.

[0048] Turning now to FIG. 5, an illustrative graph that shows torsional oscillation and device torque according to an embodiment is shown. A speed signal 320 can be for any of the rotating components (e.g., the starting motor 140, the synchronous condenser 120, or the flywheel 160) of the synchronous condenser drive train system 100 shown in FIG. 4. An auxiliary torque 370 can be applied by the starting motor 140 (FIG. 4), that is phase shifted 315 from the speed signal 320. The magnitude and phase relationship between the measured signal 320 and the applied auxiliary torque 370 can be important elements of the control, and can be a determinant of the efficacy of an embodiment of the invention towards achieving the various objectives enumerated.

[0049] For an objective of providing power system stabilizer function to damp the speed oscillation of the entire drive train relative to the host power system, the auxiliary torque can be configured to target one or more oscillatory modes of the power system. The measurement can include modal information about the oscillation. The auxiliary torque can have a phase relationship with the targeted mode of oscillation that introduces damping to the swings. Similarly, when the objective of the control is damping of the torsional modes of the synchronous condenser drive train system, the measurement can include modal information about those modes. Again, the phase relationship of the auxiliary torque can be such that damping is introduced to that mode. This relationship can apply to any other damping function targeted by the control system.

[0050] For the objective of delivering FFR function, the measurement can include information about the change or rate of change of frequency. The phase relationship of the auxiliary torque can be configured to deliver arresting power to the host grid during the period of frequency decline following any initiating incident. In an embodiment, the signal also can be in the form of a trigger, a kicker, or other open loop type of control. In this case, the auxiliary torque can follow a predetermined response. Furthermore, such a response can be a combination of a close- loop response plus a response to the trigger signal.

[0051] For the objective of providing transient stability benefits, the measured signal can include information indicative of the synchronizing stress or angular separation on the host power system. The auxiliary torque can be configured to have a phase relationship to the measured signal, such that the maximum synchronizing stress which normally occurs during the first swing following a disturbance is reduced. [0052] For the objective of providing transient torque benefits to the synchronous condenser drive train system, the measured signal can include information indicative of torsional stress on the drive train. In one embodiment, the objective comprises reducing the maximum stress of the coupling (118, 119 FIG. 4). In an embodiment, the measurement of angular or speed difference between the synchronous condenser 120 (FIG. 4) and the optional flywheel 160 (FIG. 4) are two examples of measurements that would include this information. The auxiliary torque can be configured to have a phase relationship to the measured signal, such that the maximum torsional stress which normally occurs during the first torsional swing following a disturbance is reduced. [0053] Turning now to FIG. 6, an illustrative graph of applying auxiliary torque according to an embodiment is shown. As mentioned herein, one of the objectives of applying auxiliary torque using the starting motor can be to dampen oscillations. The auxiliary torque 370 can be applied to the speed signal 320. In an embodiment, a limitation 390 is applied to the auxiliary torque 370. The limitation 390 can be imposed as part of the control in the form of an explicit signal limit. Alternatively, the limitation 390 can be reflective of an inherent hardware capability of the starting motor 140 (FIG. 4). As the auxiliary torque 370 is applied, an envelope 395 on the measured speed signal 320 can be indicative of the damping achieved by the controller.

[0054] Turning now to FIGS. 7-9, graphs illustrating an example of the damping control according to embodiments of the invention are shown. The example uses a 208MVA synchronous condenser with a starting motor capable of imposing shaft power up to 3% of the synchronous condenser rating. It is understood that the synchronous condenser and starting motor ratings are exemplary only, and other synchronous condensers and starting motors can be used.

[0055] In FIG. 7, an illustrative graph comparing the net power to the grid after a grid fault disturbance with and without the damping control according to an embodiment is shown. The net power to the grid can be measured at a point-of-common-coupling 180 (FIGS. 2 and 3), as mentioned herein. The grid fault disturbance 400 causes oscillations of the synchronous condenser against the host grid. The oscillation (i.e., amplitude swings) of the net power to the grid due to the grid fault disturbance 402 is shown. In applying an auxiliary torque as described herein, the oscillation of the net power to the grid is dampened so that the amplitude of the oscillations are less and the net power to the grid returns to normal operation sooner.

[0056] Turning now to FIG. 8, an illustrative graph comparing the machine speed of a synchronous condenser after a grid fault disturbance with and without damping control according to an embodiment is shown. This machine speed of the synchronous condenser is the speed 220 shown in FIG. 4. After a grid fault disturbance 400, the machine speed 410 oscillates. In order to dampen these oscillations, the auxiliary torque, as described herein, is applied, and the amplitude of the machine speed 412 oscillations (with damping control) are less and the machine speed 412 returns to normal operation sooner.

[0057] Turning now to FIG. 9, an illustrative graph showing the net power to the grid after a grid fault disturbance with damping control, the power from the synchronous condenser stator towards the grid, and the power from the grid that is applied by the starting motor into the drivetrain to provide the damping control according to an embodiment is shown. After a grid fault disturbance 400, an auxiliary torque from the starting power is applied to the drivetrain (e.g., the power from the grid that is applied by the starting motor into the drivetrain 420). The power 420 can be measured at the point 146 connected to the motor stator 142 of the starting motor 140 (FIGS. 2 and 3). The power from the synchronous condenser 422 towards the grid can be measured at point 128 into the stator 122 of the synchronous condenser 120 (FIGS. 2 and 3). This illustrative graph follows the sign convention that positive values for the synchronous condenser denote power flow from the synchronous condenser to the grid and the sign convention that positive values for the power applied by the starting motor denote power from the grid into the drive-train. The sum of the power applied by the starting motor into the drivetrain 420 and the power of the synchronous condenser 422 is the net power to the grid 424. By applying the auxiliary torque, the oscillation of both the synchronous condenser speed and the net power to the grid are dampened.

[0058] Turning now to FIG. 10, an illustrative control process 500 for a synchronous condenser drive train according to an embodiment is shown. The input signal 510 can be any one or more of the speed signals shown and described in conjunction with FIG. 4. In an embodiment, the input signals 510 can be processed and/or filtered 520. It is understood that variations and processing of these signals, such as by adding, filtering, measuring rate-of- change, or cumulative (integral) are included as possible signals. Filtering could include, for example, targeting torsional frequencies of the synchronous condenser system or of the target systems for damping. Similarly, filtering could target frequencies of sub-synchronous oscillations that are targets for damping. One or more processed signals 525 can be input to a control system 530. The control system 530 can use the processed signals 525 to determine intermediate control signals 535. In an embodiment, control system limiters 540 can impose limits on the intermediate control signals 535. The control system 530 also can include limits on the intermediate control signals 535. Such limiters can be dynamic, with adjustments made based on the state of the synchronous condenser. An example of the effect of the limiter 540 on the auxiliary torque is shown as the limitation 390 in FIG. 6. The output control signals 550 of the control process 500 can be delivered to the starting motor control for the system to achieve the desired functions. In an embodiment, the control system 530 includes gains, time constants, limiters, and other control elements known to those skilled in the art to create intermediate control signals 535 that have amplitude and phase relationships to the measured signals 510 that are configured to achieve the desired functions.

[0059] In an embodiment of the system, the output 550 of the control can include a torque command. For example, for damping of synchronous condenser torsional oscillations between the condenser and a flywheel, a torque command can be added by an incremental torque instruction with the proper magnitude and phase relationship configured to result in a desired behavior. Other outputs from the control can be power commands or reactive power commands. The output signals 550 of the overall control structure can be fed into controls of the starting motor. It is understood that the interface of these signals can be in the form of instructions generally used for motor control.

[0060] The processing of the control system 500 shown in FIG. 10 can be executed on a computer system, which can receive the measured signals from various transducers, process and/or filter the signals, and determine the control signals to apply to the synchronous condenser drive train. The measured signals can be measured from one or more rotating components of the synchronous condenser drive train system 100 (FIG. 4). The measured signals also can be obtained from measurement devices at the point of interconnection 180 (FIGS. 2 and 3) or measurement devices on the host power system 152 (FIGS. 2 and 3).

[0061] To this extent, FIG. 11 shows an illustrative environment 1000 for applying an auxiliary torque using a starting motor 1200 of a synchronous condenser drive train 1010 using a process described herein, according to an embodiment. In this case, the environment 1000 includes a computer system 1020 that can perform a process described herein in order to, for example, provide control signals to achieve the desired function (PSS function for oscillations of the synchronous condenser, a source of FFR, a POD on active power for damping of systemic oscillations, transient power benefits, torsional benefits by helping manage SSR/SSTI/transient torque risk to the synchronous condenser, and/or the like). In particular, the computer system 1020 is shown including a control signal program 1030, which makes the computer system 1020 operable to receive speed signals (signal data 1040) from the synchronous condenser drive train 1010 and determine control signals by performing a process described herein.

[0062] However, it is understood that a programmed computer is only illustrative of various embodiments of a computer system that can be configured to perform a process described herein. To this extent, other embodiments of a computer system can include special purpose hardware configured to implement some or all of the process described herein.

[0063] Regardless, the computer system 1020 is shown including a processing component 1022 (e.g., one or more processors), a storage component 1024 (e.g., a storage hierarchy), an input/output (I/O) component 1026 (e.g., one or more I/O interfaces and/or devices), and a communications pathway 1028. In general, the processing component 1022 executes program code, such as the control program 1030, which is at least partially fixed in storage component 1024. While executing program code, the processing component 1022 can process data, which can result in reading and/or writing transformed data from/to the storage component 1024 and/or the I/O component 1026 for further processing. The pathway 1028 provides a communications link between each of the components in the computer system 1020. The I/O component 1026 can comprise one or more human I/O devices, which enable a human user 1012 to interact with the computer system 1020 and/or one or more communications devices to enable a system user to communicate with the computer system 1020 using any type of communications link. To this extent, the control program 1030 can manage a set of interfaces (e.g., graphical user interface(s), application program interface, and/or the like) that enable human and/or system users 1012 to interact with the control program 1030. Furthermore, the control program 1030 can manage (e.g., store, retrieve, create, manipulate, organize, present, etc.) the data, such as signal data 1040, using any solution.

[0064] In any event, the computer system 1020 can comprise one or more general purpose computing articles of manufacture (e.g., computing devices) capable of executing program code, such as the control program 1030, installed thereon. As used herein, it is understood that “program code” means any collection of instructions, in any language, code or notation, that cause a computing device having an information processing capability to perform a particular action either directly or after any combination of the following: (a) conversion to another language, code or notation; (b) reproduction in a different material form; and/or (c) decompression. To this extent, the control program 1030 can be embodied as any combination of system software and/or application software.

[0065] Furthermore, the control program 1030 can be implemented using a set of modules 1032. In this case, a module 1032 can enable the computer system 1020 to perform a set of tasks used by the control program 1030, and can be separately developed and/or implemented apart from other portions of the control program 1030. As used herein, the term “component” means any configuration of hardware, with or without software, which implements the functionality described in conjunction therewith using any solution, while the term “module” means program code that enables a computer system 1020 to implement the actions described in conjunction therewith using any solution. When fixed in a storage component 1024 of a computer system 1020 that includes a processing component 1022, a module is a substantial portion of a component that implements the actions. Regardless, it is understood that two or more components, modules, and/or systems may share some/all of their respective hardware and/or software. Furthermore, it is understood that some of the functionality discussed herein may not be implemented or additional functionality may be included as part of the computer system 1020.

[0066] When the computer system 1020 comprises multiple computing devices, each computing device can have only a portion of the control program 1030 fixed thereon (e.g., one or more modules 1032). However, it is understood that the computer system 1020 and the control program 1030 are only representative of various possible equivalent computer systems that may perform a process described herein. To this extent, in other embodiments, the functionality provided by the computer system 1020 and the control program 1030 can be at least partially implemented by one or more computing devices that include any combination of general and/or specific purpose hardware with or without program code. In each embodiment, the hardware and program code, if included, can be created using standard engineering and programming techniques, respectively.

[0067] Regardless, when the computer system 1020 includes multiple computing devices, the computing devices can communicate over any type of communications link. Furthermore, while performing a process described herein, the computer system 1020 can communicate with one or more other computer systems using any type of communications link. In either case, the communications link can comprise any combination of various types of optical fiber, wired, and/or wireless links; comprise any combination of one or more types of networks; and/or utilize any combination of various types of transmission techniques and protocols.

[0068] In any event, the computer system 1020 can obtain the signal data 1040 using any solution. For example, the computer system 1020 can obtain data regarding the synchronous condenser drive train 1010 by operating a set of I/O devices 1027 located on the synchronous condenser drive train 1010. The set of I/O devices 1027 can include any combination of the various sensors, emitters, input devices, output devices, and/or the like, as described herein. The signal data 1040 can include data regarding the speed of the synchronous condenser 100, the starting motor 200, the flywheel 300, and/or the like. The computer system 1020 can process data acquired using the set of I/O devices 1027 to generate signal data 1040. Regardless, the computer system 1020 can utilize the signal data 1040 to send control signals to the synchronous condenser drive train 1010 as described herein.

[0069] While primarily shown and described in conjunction with a single synchronous condenser drive train 1010 and user 1012, it is understood that embodiments can include multiple synchronous condenser drive trains 1010 and/or users 1012. For example, an embodiment can include multiple synchronous condenser drive trains 1010.

[0070] In an embodiment, the computer system 1020 and the synchronous condenser drive train 1010 can each include a wireless transmitter and receiver that is configured to communicate with each other and/or a remote location via Wi-Fi, BLUETOOTH, and/or the like. As used herein, a remote location is a location that is apart from the computer system 1020 and the synchronous condenser drive train 1010. For example, the synchronous condenser drive train 1010 and the computer system 1020 can be located at different locations. The synchronous condenser drive train 1010 can transmit speed signals to the computer system 1020 via Wi-Fi, BLUETOOTH, and/or the like, and the computer system 1020 can transmit the control signals to the synchronous condenser drive train 1010 via Wi-Fi, BLUETOOTH, and/or the like.

[0071] While shown and described herein as a method and system for applying an auxiliary torque to a starting motor 100 of a synchronous condenser drive train 1010, it is understood that aspects of the invention further provide various alternative embodiments. For example, in one embodiment, the invention provides a computer program fixed in at least one computer-readable medium, which when executed, enables a computer system to process speed signals of a synchronous condenser drive train and provide control signals for a starting motor using a process described herein. To this extent, the computer-readable medium includes program code, such as the control program 1030 (FIG. 11), which enables a computer system to implement some or all of a process described herein. It is understood that the term "computer-readable medium" comprises one or more of any type of tangible medium of expression, now known or later developed, from which a copy of the program code can be perceived, reproduced, or otherwise communicated by a computing device. For example, the computer-readable medium can comprise: one or more portable storage articles of manufacture; one or more memory/storage components of a computing device; and/or the like.

[0072] In another embodiment, the invention provides a method of providing a copy of program code, such as the control program 1030 (FIG. 11), which enables a computer system to implement some or all of a process described herein. In this case, a computer system can process a copy of the program code to generate and transmit, for reception at a second, distinct location, a set of data signals that has one or more of its characteristics set and/or changed in such a manner as to encode a copy of the program code in the set of data signals. Similarly, an embodiment of the invention provides a method of acquiring a copy of the program code, which includes a computer system receiving the set of data signals described herein, and translating the set of data signals into a copy of the computer program fixed in at least one computer-readable medium. In either case, the set of data signals can be transmitted/received using any type of communications link.

[0073] In still another embodiment, the invention provides a method of generating a system for applying an auxiliary torque to a starting motor of a synchronous condenser drive train 1010 as described herein. In this case, the generating can include configuring a computer system, such as the computer system 1020 (FIG.11), to implement a method applying an auxiliary torque to a starting motor of a synchronous condenser drive train 1010 described herein. The configuring can include obtaining (e.g., creating, maintaining, purchasing, modifying, using, making available, etc.) one or more hardware components, with or without one or more software modules, and setting up the components and/or modules to implement a process described herein. To this extent, the configuring can include deploying one or more components to the computer system, which can comprise one or more of: (1) installing program code on a computing device; (2) adding one or more computing and/or I/O devices to the computer system; (3) incorporating and/or modifying the computer system to enable it to perform a process described herein; and/or the like.

[0074] The foregoing description of various aspects of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously, many modifications and variations are possible. Such modifications and variations that may be apparent to an individual in the art are included within the scope of the invention as defined by the accompanying claims.