Improved reversible pump-turbine installation

Abstract

To provide a reversible pump-turbine used for storage of electric energy.SOLUTION: The present invention establishes a required plant cavitation factor by locating a reversible pump-turbine associated with a motor generator in a substantially vertical borehole, generally well below a tailwater level. The present invention is a reversible pump-turbine installation location in a vertical shaft as an alternative to conventional underground power plants or deep concrete power plants. The required plant cavitation factor can be achieved by simply drilling a vertical shaft to a required depth, rather than routing a water flow to and from a deeply-buried power plant. A pneumatically-controlled pressure relief valve may be incorporated into the present invention.SELECTED DRAWING: None

Description

[Background technology]

[0001] The present invention relates to a reversible pump-turbine used for the storage of electrical energy. Conventional pumping plants, such as that shown in FIG. 2a, generally use underground power plants and provide sufficient absolute pressure in the runner to prevent destructive cavitation. The depth of the runner may be, for example, 100 meters below the tailwater. Building and maintaining such underground plants is expensive, and even for smaller plants, the cost does not decrease with size. Thus, there are very few pumping plants in North America below 100 MW. A cross-sectional elevation of a typical conventional pump-turbine is shown in FIG. 2a. A prior art pump-turbine flowpath with a 90° bend angle in the meridian plane is illustrated in FIG. 2b, which is similar to the flowpath in the meridian plane of a conventional Francis turbine. The present invention relates to a dedicated turbine and pump and a reversible pump-turbine. For a prior art multi-stage pump, the relationship between the impeller and the diffuser in the meridian plane is shown in Figure 2 (not shown), where the acceleration on the fluid imparted by the runner (impeller) is outward and downward, which in this case results in an unnecessarily small runner tip diameter compared to the maximum channel diameter occurring in the diffuser. This unnecessarily small diameter results in a limited head difference across each stage, and thus more stages and lower overall efficiency. Summary of the Invention [Means for solving the problem]

[0002] The present invention establishes the required plant cavitation coefficient by locating a reversible pump-turbine with motor-generator in a substantially vertical borehole, generally well below tailwater level. The reversible pump-turbine with motor-generator will be referred to herein simply as the "pump-turbine" or "machine." The term "borehole" rather than "shaft" is used herein to avoid confusion with the rotating shaft of the pump-turbine located therein.

[0003] Conventional pumping installations position the runner well below the tailwater depth to suppress cavitation while keeping engine power and specific speed high. The critical cavitation coefficient for a reversible pump-turbine is higher than for either the turbine or the pump because the hydraulic cross section is compromised between pumping and power generation and is not optimized for either. Positioning the runner below the tailwater traditionally required deep and expensive excavation regardless of machine size and rating. The cost of excavation and underground construction was prohibitive even for small installations, e.g., below 100 MW. Suitable sites for large installations are limited by geology, geography, competing land uses, and sufficient transmission lines. Many suitable smaller sites exist, but even when scaled down in size and rating, existing reversible pump-turbines still require prohibitive excavation and construction costs.

[0004] The proposed configuration utilizes a simple and inexpensive borehole, perhaps 1-3 meters in diameter, and positions a high specific speed output reversible pump-turbine well below the tailwater depth to inhibit cavitation. Such boreholes are routinely drilled as general purpose construction work at reasonable prices. For example, steel liners and conduits for pumping, electrical cables and control cables may be routed in place within the borehole. Pump-turbines adapted for this type of installation may be configured as single stage machines, or as multi-stage machines utilizing specially configured "diffuser bowls" similar in function to those used on multi-stage submersible pumps. These pump-turbines would not normally use conventional volute casings. Thus, the stages of these pump-turbines may be stackable to allow a standard hydraulic design to be used over a wide range of head conditions. The use of standard pump-turbine stages is further facilitated by the fact that the required plant cavitation coefficient can be achieved simply by establishing the required vertical borehole depth. Compared to conventional underground power plant pump turbine installations, there is less need to design and manufacture site-specific machinery, which would be prohibitively expensive in conjunction with the installation of small pumped storage hydroelectric plants in most locations, and neither headrace conduits nor tailraces need to be transported to extraordinary depths. The use of standard components results in an increased quantity of similar parts at reduced costs. The reduced costs in turn allow a greater number of projects to be built with increased quantities of parts.

[0005] Water flow to and from the reversible pump-turbine may be through a coaxial water conduit located in the shaft above the pump-turbine assembly. An associated motor-generator may be submersible and, in a preferred embodiment, located below the pump-turbine. Locating the motor-generator below the pump-turbine allows for a larger diameter, and therefore more economical, motor-generator for a given borehole size. Allocating substantially all of the borehole cross-sectional area to water conveyance (up and down) rather than to space for the motor-generator allows for a maximum power rating for a given diameter of borehole.

[0006] The generator may alternatively be located outside the waterway and connected to the runner with a shaft. Such an arrangement may be less expensive than providing an underground power station large enough to incorporate a volute casing, while allowing the use of readily available air-cooled generators.

[0007] In a preferred embodiment, a removable manifold may be used to connect the inner pipe to the tailwater and the outer pipe to the headwater leading to the headwater. Generally, it is more efficient to connect the smaller diameter pump inlet / turbine outlet to the smaller of the coaxial pipes while connecting the larger pump outlet / turbine inlet to the larger of the two coaxial pipes. Alternative embodiments of the invention may utilize other arrangements, as may be the case when multiple pump-turbines may be installed, for example, on bulkheads in a common borehole. The removable manifold may include an integral pneumatically controlled pressure relief valve. This integral pressure relief valve would itself reduce civil engineering costs by eliminating the need for a pressure relief shaft and by reducing headwater surge pressures and headwater costs. Additionally or alternatively, an air cushion may be left under the borehole cover. Removal of the manifold allows removal of machinery from the borehole. Dedicated pumping equipment would facilitate installation, inspection, and maintenance without the need for confined space operations. A hydraulically actuated piston attached to the bottom of the reversible pump turbine may be used to raise and lower. A spacer between the piston and the machine may be used to allow the machine to be raised and clear the borehole completely.

[0008] Variable speed operation is facilitated by the availability of power control electronics developed for the wind industry. As in the case of wind turbine power converters, a full power converter may be used with a permanent magnet motor-generator, and a partial power converter may be used with a (generally larger) doubly-fed induction generator.

[0009] The borehole in which the reversible pump turbine is laid may include a supply for delivery of pressurized water to the bottom of the shaft through a conduit separate from the main borehole for hydraulically lifting equipment for maintenance and repair and controllably lowering the equipment to an operating position. The power connection is preferably configured to automatically engage when the machine is lowered and automatically disengage when the machine is raised. Such connectors may use conventional "wet mating" marine electrical connector technology or may use a combination of compressed gas, insulating oil, and inflatable seals to establish a robust electrical connection that is isolated from, for example, ground potential.

[0010] The borehole in which the equipment is located may terminate at the upper portal, the lower portal, or any convenient intermediate location. For installation in conjunction with an existing pipeline, the vertical shaft may be located according to the desired pressure profile resulting from operation, load rejection, and other considerations. A shaft cover may incorporate a pressure relief valve and may be used to cover the pressure relief shaft containing air.

[0011] Multiple machines may be mounted in a single shaft, for example on a common bulkhead. A reversible pump-turbine according to the present invention may be used in conjunction with a Pelton turbine, for example, to facilitate power generation at low power levels when required. A reversible pump-turbine may be used in conjunction with an off-season reservoir whose primary purpose is to raise water up to the reservoir during periods of high flow and recover energy while returning the stored water when it is required downstream.

[0012] According to certain embodiments of the present invention, a gas pressure balanced pressure relief valve may be used to limit overpressure from water hammer.

[0013] A flexure with an actuatable seal may be used to connect the draft tube to the spillway during operation. An inflatable seal may be used to seal the flexure in its operating position while allowing it to move freely during lifting and lowering operations. Inflatable seals or supports may also be used to secure the machine in position during operation and release to allow it to be raised for maintenance.

[0014] According to a further aspect of the invention, a reversible pump turbine runner or pump impeller is provided that adds an upward velocity component to the flow. This upward velocity component allows the ratio of the impeller tip diameter to the maximum water passage diameter to be maximized while the flow proceeds straight up through the diffuser, or a combination of guide vanes and diffuser in the case of a reversible pump turbine, or directly to the diffuser (stator) stage in the case of a multi-stage pump. In the case of the present invention, this ratio may be 1.00. This maximizes the head per stage and allows a larger head to be achieved with a single stage machine. Figures 19a, 19b, and 19c illustrate the flow in the meridian plane and the appearance of the X-shape of the impeller blades when viewed towards the aft end. The present invention provides, for example, the following: (Item 1) 1. A water pumping system comprising an upper water storage tank, a lower water storage tank, and a reversible pump-turbine connected to the upper water storage tank by a water conduit conduit and connected to the lower water storage tank using a discharge conduit, the pump-turbine being positioned in a vertical shaft at a depth below a surface of the lower water storage tank, the pump-turbine being axially removable from the vertical shaft. (Item 2) Item 1. The system of item 1, wherein the pump-turbine comprises multiple stages. (Item 3) 2. The system of claim 1, wherein the headwater conduit and the discharge conduit are coaxially positioned within the vertical shaft above the pump-turbine. (Item 4) Item 1. The system of item 1, further comprising a motor-generator operably connected to the pump-turbine. (Item 5) 5. The system of claim 4, wherein the motor-generator is positioned below the pump-turbine. (Item 6) 5. The system of claim 4, wherein the motor-generator is above the pump-generator and operatively connected thereto by means of a vertical drive shaft. (Item 7) Item 4. The system of item 3, wherein the coaxial conduit comprises an inner conduit and an outer conduit, and further comprises a removable manifold for directing water in the inner conduit to the lower water storage tank and for directing water from the upper water storage tank to the water conduit. (Item 8) 8. The system of claim 7, wherein the manifold further comprises a pneumatically controlled pressure relief valve to reduce surge pressure in the water conduit. (Item 9) 2. The system of claim 1, further comprising a hoist piston positioned below the pump-turbine for selectively raising and lowering the pump-turbine within the vertical shaft. (Item 10) 1. A water pumping system comprising an upper water storage tank, a lower water storage tank, and a reversible pump-turbine connected to the upper water storage tank by a water conduit and connected to the lower water storage tank using a discharge conduit, the pump-turbine being positioned within a vertical shaft at a depth below a surface of the lower water storage tank, the pump-turbine being axially removable from the vertical shaft, and the conduit being positioned coaxially with the vertical shaft. (Item 11) 1. A reversible pump-turbine located within a vertical shaft, the reversible pump-turbine being removable from the vertical shaft. (Item 12) Item 12. The apparatus of item 11, further comprising an underwater motor-generator. (Item 13) Item 13. The apparatus of item 12, wherein the motor-generator is located directly below one or more pump-turbine stages. (Item 14) Item 12. The apparatus of item 11, further comprising a removable manifold secured to an upper portion of the shaft during operation. (Item 15) Item 15. The apparatus of item 14, wherein the removable manifold includes a pressure relief valve to relieve excess head pressure to the discharge conduit. (Item 16) Item 16. The apparatus of item 15, wherein the pressure relief valve comprises an elastic diaphragm held by controlled gas pressure against one or more orifices that are subjected to headwater pressure. (Item 17) Item 12. The apparatus of item 11, wherein the motor-generator is located above a water intake that connects the water source to the vertical shaft. (Item 18) Item 12. The apparatus of item 11, wherein the pump-turbine is comprised of multiple stages. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram of a conventional (prior art) pumping installation. [Figure 2a] 2a and 2b are cross-sectional elevation views of a conventional pump-turbine. [Figure 2b] 2a and 2b are cross-sectional elevation views of a conventional pump-turbine. [Figure 3a] FIG. 3a is an elevational view of the pumping installation of FIG. 3a shown with the pump-turbine assembly partially removed. [Figure 3b] With reference to Figures 3a and 3b, a reversible pump-turbine installation according to the present invention is shown. [Figure 4a] 4a and 4b are cross-sectional elevational views of a pressure relief valve configured for use with the present invention. [Figure 4b]4a and 4b are cross-sectional elevational views of a pressure relief valve configured for use with the present invention. [Figure 5a] 5a-c are cross-sectional elevation views of a reversible pump-turbine according to the present invention. [Figure 5b] 5a-c are cross-sectional elevation views of a reversible pump-turbine according to the present invention. [Figure 5c] 5a-c are cross-sectional elevation views of a reversible pump-turbine according to the present invention. [Figure 6] FIG. 6 is a cross-sectional rendering of a reversible pump-turbine and associated water pumping equipment in accordance with the present invention. [Figure 7] FIG. 7 is a cross-sectional view of a bent connection to a tailrace tunnel with an inflatable seal to secure and seal it in accordance with the present invention. [Figure 8] FIG. 8 is a cross-sectional elevation view of a pump-turbine installation in a vertical borehole adjacent to a headworks according to the present invention. [Figure 9] FIG. 9 is a cross-sectional elevation view of a pump-turbine installation in a vertical borehole in juxtaposition with a spillway portal according to the present invention. [Figure 10] FIG. 10 is a cross-sectional elevation view of a pump-turbine installation in a vertical borehole located between a headworks and a spillway portal according to the present invention. [Figure 11] FIG. 11 is a cross-sectional elevation view of a pump-turbine installation in a vertical borehole located in conjunction with an underground pressurized water storage cavity serving as an "upper" reservoir. [Figure 12] FIG. 12 is a schematic diagram of a pump according to the invention, typically in association with an underground air / water accumulator and a gas turbine. [Figure 13] FIG. 13 is a schematic diagram of a pump according to the present invention in association with an air / water accumulator, typically underground, and a gas turbine, where air can be compressed near isothermally with the aid of water spray cooling. [Figure 14]14 illustrates a spillway connection flexure in accordance with the present invention incorporating an inflatable seal that also serves as an adjustable pressure relief element. The inflatable seal (63) features flow isolation control fins 51 for reducing vibration during operation. [Figure 15] FIG. 15 illustrates a water pumping system installation according to the present invention, including a tailrace connection bend. [Figure 16] FIG. 16 illustrates a water pumping system installation according to the present invention including a tailrace connection bend and a headrace that enters the borehole at a higher elevation than the tailrace tunnel. [Figure 17] FIG. 17 illustrates a water pumping system installation according to the present invention, including a tailrace connection bend. [Figure 18] FIG. 18 illustrates a water pumping system installation according to the present invention, including a tailrace connection bend. [Figure 19a] 19a and 19b are meridional cross-sections of a multi-stage pump impeller in accordance with the present invention. [Figure 19b] 19a and 19b are meridional cross-sections of a multi-stage pump impeller in accordance with the present invention. [Figure 20] FIG. 20 is a plan schematic diagram of three pump-turbines installed in association with a single headrace and single tailrace tunnel. [Figure 21] With reference to Figures 21-23, various pressure relief valve configurations are shown. [Figure 22a] FIG. 22a is a pump-turbine installation including a pressure relief valve. [Figure 22b] FIG. 22b is a schematic diagram of a torque key positioned at the bottom of the borehole for the purpose of preventing unintentional rotation of the pump-turbine. [Figure 23] FIG. 23 is a pressure relief valve according to the present invention. [Figure 24a] 24a and 24b are a pressure relief valve according to the present invention shown closed and open, respectively. [Figure 24b] 24a and 24b are a pressure relief valve according to the present invention shown closed and open, respectively. [Figure 25a] 25a and 25b are a pressure relief valve according to the present invention shown closed and open, respectively. [Figure 25b] 25a and 25b are a pressure relief valve according to the present invention shown closed and open, respectively. [Figure 26a] 26a and 26b are a pressure relief valve according to the present invention shown closed and open, respectively. [Figure 26b] 26a and 26b are a pressure relief valve according to the present invention shown closed and open, respectively. [Figure 27] Figures 27a and 27b show the installation of multiple pump-turbines / motor-generators in a single borehole. [Figure 28] FIG. 28 shows diagrammatically one type of pump-turbine of the present invention. [Figure 29] FIG. 29 shows another type of pump-turbine of the present invention. [Diagram 30] FIG. 30 illustrates another version of the pump-turbine of the present invention which incorporates a cylindrical gate rather than a ticket barrier type gate. [Diagram 31] Figures 31-37 show various installation alternatives. [Diagram 32] Figures 31-37 show various installation alternatives. [Diagram 33] Figures 31-37 show various installation alternatives. [Diagram 34] Figures 31-37 show various installation alternatives. [Diagram 35] Figures 31-37 show various installation alternatives. [Diagram 36] Figures 31-37 show various installation alternatives. [Figure 37] Figures 31-37 show various installation alternatives. [Figure 38] 38-43 show various embodiments of a reversible pump-turbine. [Figure 39] 38-43 show various embodiments of a reversible pump-turbine. [Diagram 40] 38-43 show various embodiments of a reversible pump-turbine. [Diagram 41] 38-43 show various embodiments of a reversible pump-turbine. [Figure 42a] 38-43 show various embodiments of a reversible pump-turbine. [Figure 42b] 38-43 show various embodiments of a reversible pump-turbine. [Diagram 43] 38-43 show various embodiments of a reversible pump-turbine. [Figure 44a] Figure 44a-b shows the flow inverter section. [Figure 44b] Figure 44a-b shows the flow inverter section. [Figure 45a] (Not stated) [Figure 45b] (Not stated) [Diagram 46] (Not stated) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] 1, 2a and 2b, a conventional pumping plant with a reversible pump turbine is shown. In such a conventional installation, there are several particularly expensive features. These include: 1) Pressure relief shafts, typically required to mitigate water hammer that can result from load rejection. 2) Underground power plants below tailwater level. Such power plants are expensive to build and are at risk of flooding due to human error or component failure. Flooding of underground power plants is a hazard to the facility itself and its operators. 3) The headrace and tailrace conduits must be routed at the same low elevation as the power plant itself, at great expense.

[0017] With reference to Figures 3a and 3b, a reversible pump-turbine installation according to the invention is shown. An underground powerhouse is not required. Instead, a vertical borehole or shaft 4 allows the pump-turbine and motor-generator assembly 1 to be installed, removed for maintenance and reinstalled as necessary, while providing the desired low elevation setting of 3 units below the tailwater. The elevation setting must be low enough so that the plant cavitation number (plant sigma) exceeds the critical cavitation number (critical sigma), which is defined as the ratio of the absolute pressure on the low pressure side of the runner divided by the water vapor pressure at the water temperature. A shaft 16 connects the submersible motor-generator 8 to the pump-turbine stages 9, 10, 11 and 12. A vertical tailwater conduit 5 connects to a diffuser 14 above the inlet point of the conduit 2. A pressure relief valve 7 is preferably mounted on a removable manifold 6. The removable manifold 6 is bolted to the foundation 13 and connects to the tailrace conduit 3 at flange 15a. The tailrace conduit 3 leads to a lower reservoir, not shown. Note that the number of stages can be adjusted according to head, elevation setting, speed, fill rating, and other factors. The tailrace 2 connects to the upper reservoir 70. The tailrace conduit 3 connects to the lower reservoir 71. Water flows through the outer annulus 17 of the borehole 4 towards the upper reservoir 70 as a pump and towards the pump turbine 43.

[0018] It should be noted that the removable portions may be further divided into conveniently separable subassemblies 6, 7, 14, and 5. For example, the manifold 6 may be lifted first, the vertical portion of the tailrace conduit 5 may then be lifted, and the pump-turbine stages 9, 10, 11, and 12 may be lifted last along with the motor-generator 8. In the case of the upper motor-generator, the rotor, shaft, and remainder of the assembly may be lifted last, while the stator is left in place.

[0019] 4a and 4b, cross-sectional views of a pressure relief valve suitable for use with the present invention are shown in its open and closed positions, respectively. Diffuser 14 is connected to ribs 25. Ribs 25, rings 23, and rings 24 together support bladder 18 radially on its inner diameter surface when its expansion pressure exceeds the pressure in shaft 17. Inflatable bladder 18 is supported from below by flange 26 and on its outer diameter by enclosure 7. Air pressure in bladder 18 can be precisely adjusted only to stop leakage (at discharge pressure) from shaft 17 into manifold 6.

[0020] With reference to Figures 5a and 5b, a cross-sectional elevation of the pump-turbine according to the invention is shown. The runner 27 is designed around a toroidal flow passage where the water reverses direction by approximately 180° in the meridian plane. A wicket gate 28 constitutes the axial flow distributor. A turbine diffuser 29 recovers the turbine runner exit energy. Fixed vanes 30 provide mechanical support for the distributor hub 31, the turbine diffuser 29, and the wicket gate servo system 32. A generator 33 is preferably located below the turbine. A hoist piston 34 can be used to raise and lower the entire pump-turbine assembly with the connected draft tube section, pressure relief valve, and bends using water pressure. The hoist piston 34 incorporates an upper seal ring 35 and a lower seal ring 36 and can pass across the tailrace connection while maintaining the seal.

[0021] A hollow shaft 72 may be used as a heat pipe evaporator with runner 27 acting as a condenser. When the machine is lowered, electrical connector 73 engages electrical outlet assembly 74. Bias rings 75 and 76 provide the torque to actuate wicket gate 28.

[0022] The borehole 4 is associated with a rock face 77 , grout 78 , and a steel liner 79 .

[0023] The shaft seal assembly 80 keeps the generator enclosure dry.

[0024] 6, the piston assembly 34 supports the generator 33 and pump turbine 37 during ascent and descent. A valve 38 can be used to shut off water from the headwater conduit 39. A tailwater conduit 40 connects to the tailwater. A cover assembly 41 is removable.

[0025] 6, a valve 42 may be used to fill the vertical shaft 4 during hydraulic raising and lowering of the pump-turbine motor-generator assembly 43 with attached pipes, bends, and pressure relief assembly 44, a lower portal 45 serves to start the TBM during the construction phase and serves as a pumping inlet station. A headworks 47 serves as an upper portal during construction and as an inspection platform during maintenance. A crane 48 may be used to disassemble the draft tube section, bend assembly, and pressure relief valve from the pump-turbine for maintenance.

[0026] Referring to Figure 7, the flexure assembly 49 is shown. An inflatable seal 50 seals the top end. An inflatable seal 51 closes the bottom end. A flexure 52 directs the flow into the tailrace conduit. A spool 53 travels with the pump turbine during maintenance moves.

[0027] Referring to FIG. 8, a laying is shown in which the machine shaft 54 ​​is located below the headworks 55 .

[0028] Referring to FIG. 9, a machinery shaft 54 ​​is located below the tailwater portal 56 .

[0029] Referring to FIG. 10, a machinery shaft 54 ​​is located between the headworks 55 and the spillway portal 56 .

[0030] Referring to FIG. 11, a mechanical shaft 54 ​​provides a connection to a pressurized reservoir 58 and a tailrace tunnel 59 .

[0031] 12, a pressurized water reservoir 58 is shown along with a pressurized air column 59. A pump or pump / turbine 60 may be in accordance with the present invention or may be conventional. Air 59 may be delivered to a gas turbine generator set 61.

[0032] Referring to FIG. 13, spray cooling of the air being compressed may be used to provide isothermal air compression.

[0033] Figures 6, 7, 16, and 17 depict one of many possible construction sequences.

[0034] Referring to FIG. 17, another embodiment is shown in which the inflatable seal 63 can also act as a pressure relief valve.

[0035] 18, a combined seal and PRV 63 is shown positioned within the machine shaft 54 ​​along with the bend 52 and tailwater conduit 40. The machine shaft liner 64 is shown.

[0036] Referring to FIG. 17, another embodiment is shown in which the inflatable seal 63 can also act as a pressure relief valve.

[0037] Referring to FIG. 18, another embodiment is shown with vanes 65 within bend 52 .

[0038] Referring to Figures 19a and 19b, a runner for a pump or reversible pump-turbine is shown in which the flow is directed along a smooth sinusoidal path in the meridian plane. The blades impart a circumferential acceleration vector and an acceleration vector in the meridian plane, directing the water through the water passage. The blade sequence may be normal to the vector sum. The larger the impeller, the more efficient it is, providing a higher head per stage. The impeller may best be made by 3D printing. Figure 19c is an end view looking into the discharge edge of the impeller of Figure 19b.

[0039] With reference to Figures 21-23, various pressure relief valve configurations are shown.

[0040] Referring to FIG. 24, an intermediate vane is used.

[0041] Referring to FIG. 27, multiple pump-turbines are shown sharing a common headrace 2 and tailrace duct 3 .

[0042] 27A and 27b, multiple submersible pump-turbines 62a-62f co-located within the same machine shaft 54 ​​are shown.

[0043] 28 to 30 show a pump-turbine configured for installation on a bulkhead in a common machine shaft.

[0044] 31, a medium / high voltage permanent magnet motor / generator 95 and a battery storage array 98 are connected to a power grid 90 through a single cascaded multilevel power converter. The power converter comprises a phase shifted input transformer 92, power cells 93 incorporating a regenerative front end, an isolated DC bus 95, and a load side inverter 94. The DC bus of each power cell is connected to a battery bank 98 through a disconnect switch 97.

[0045] The voltage of each individual DC bus 96 is actively managed during operation to charge or discharge the battery bank 98 independently of the power consumed or generated by the motor / generators 95 .

[0046] Referring to Figure 32, a low voltage permanent magnet motor / generator 95 and a battery storage array 98 are connected to a power grid 90 via a single two-level power converter. The power converter comprises an active front end 93 with a line side reactor, an intermediate DC bus 96, and a motor side two-level inverter 94. The power converter is connected to the power grid through a disconnector 100 and a step-up transformer 99. The power converter DC bus 96 is attached to the battery array 98 through a disconnect switch 97. The voltage of the DC bus 96 is actively managed during operation to charge or discharge the battery array 98 independent of power consumption or generation by the motor / generator 95.

[0047] Referring to Figure 33, a permanent magnet motor / generator 95 and a battery storage array 98 are connected to a power grid 90 using parallel and independent power converters. The converters may be connected using individual disconnectors 91 that incorporate protection features. The motor / generator 95 is connected using a regenerative AC / AC power converter 102. The battery array 98 is connected to a grid tie inverter 101 through a DC bus disconnector 97. A step-up transformer 99 increases the output of the inverter 101 to the grid voltage. Optionally, a disconnector 100 is installed between the transformer 99 and the battery inverter 101.

[0048] Referring to Figure 34, a medium / high voltage doubly fed induction machine 103 and battery storage array 98 are connected to the utility grid 90. The rotor winding of the generator is connected to a cascaded multi-level AC / AC drive with battery storage connected as described in Figure 31. The stator winding of the generator is connected to the utility grid through a disconnector 104.

[0049] Referring to Figure 35, a medium / high voltage doubly fed induction machine 103 and battery storage array 98 are connected to the utility grid 90. The rotor winding of the generator is connected to a low voltage two level AC / AC drive with battery storage connected as described in Figure 32. The stator winding of the generator is connected to the utility grid through a disconnector 104.

[0050] Referring to Figure 36, a medium / high voltage doubly-fed induction machine 103 and a battery storage array 98 are connected to the utility grid 90. The generator rotor windings are connected to a regenerative AC / AC drive 102. The generator rotor windings are connected to the utility grid through a disconnector 104. The battery storage array is connected to a separate and independent DC / AC inverter 101 as illustrated in Figure 33.

[0051] Referring to FIG. 37, multiple medium / high voltage permanent magnet motors / generators 95 are connected to the utility grid 90 in an arrangement that allows direct synchronous connection of either one, with direct on-line contacts 105 and forward / reverse selection contacts 106 / 107 interlocked to prevent simultaneous closure. A regenerative power converter 102 can be used to allow the generators to reach synchronous speed in either pumping or generating mode, or to operate at variable speed rather than synchronous speed. A phase shifted input transformer 92 connects the active front end of the converter 102 to the utility grid via a disconnector 91. A matrix of disconnectors 108 allows any of the generators to be operated or started using any of the power converters.

[0052] As can be easily understood from the foregoing, the basic concept of the present invention can be embodied in various ways. It involves both water control and actuator techniques and devices for performing the appropriate water control or actuation. In this application, water control techniques are disclosed as part of the results shown to be achieved by the various devices described, and as steps that are inherent to the application. They are simply the natural results of using the devices as intended and described. In addition, while several devices are disclosed, it should be understood that these do not only achieve a certain method, but can be varied in several respects. Importantly, with respect to all of the foregoing, all of these aspects should be understood to be encompassed by the present disclosure.

[0053] The discussion contained in this application is intended to serve as a basic description. The reader should be aware that the specific discussion may not explicitly describe all possible embodiments, and many alternatives are implicit. It may also not fully describe the general nature of the invention, and may not explicitly show how each feature or element can actually represent a broader function or a wide variety of alternative or equivalent elements. Again, these are implicitly included in this disclosure. When the invention is described in device-oriented terms, each element of the device implicitly performs a function. Not only may an apparatus claim be included for the device described, but method or process claims may also be included to address the invention and the function each element performs. Neither the description nor the terminology is intended to limit the scope of the claims that may be included in this patent application.

[0054] It should also be understood that various modifications may be made without departing from the essence of the invention. Such modifications are also implicit in the description. They still fall within the scope of the invention. The broad disclosure, encompassing both the explicit embodiments shown and the wide variety of implicit alternative embodiments, and the broad method or process and equivalents, are encompassed by this disclosure and may be relied upon in the claims for this patent application. It should be understood that such language may vary and that broad claims may be pursued in this application. This patent application will seek consideration of the basis of claims as broadly as is deemed within the applicant's rights, and will be designed to bring about a patent that covers multiple aspects of the invention, both independently and as an overall system.

[0055] Moreover, each of the various elements of the invention and claims may also be accomplished in various ways. The present disclosure should be understood to encompass each such variation, whether it is a variation of any apparatus embodiment, method or process embodiment, or even simply a variation of any of these elements. In particular, as the present disclosure relates to the elements of the invention, it should be understood that the words for each element may be expressed by equivalent apparatus terms or method terms, even if only the function or result is the same. Such equivalent, broader, or even more general terms should be considered to be encompassed in the description of each element or action. Such terms may be substituted where desired to make explicit the implicitly broad claims to which the invention is entitled. As an example only, it should be understood that every action may be expressed as a means for taking every action, or as an element that causes that action. Similarly, each physical element disclosed should be understood to encompass a disclosure of the action that the physical element facilitates. With respect to this last aspect, by way of example only, the disclosure of a "means for actuating" or "actuator" should be understood to encompass the disclosure of the act of "actuating," whether or not expressly discussed, and conversely, if there is in fact a disclosure of the act of "actuating," such disclosure should be understood to encompass the disclosure of an "actuator" and also a "means for actuating." Such variations and alternative terms are intended to be expressly included in the description.

[0056] Any act of law, statute, ordinance, or regulation referred to in this patent application, or any patent, publication, or other reference referred to in this patent application, is hereby incorporated by reference. In addition, it is understood that for each term used, the common dictionary definition contained in The Random House Webster's Unabridged Dictionary (2nd Edition), etc., which is incorporated by reference herein, should be understood as being incorporated for each term, all definitions, alternative terms, and synonyms, unless its use in this application is inconsistent with such interpretation. Finally, all references listed in the list of references incorporated by reference pursuant to this patent application, or statements of other information filed in this application, are attached hereto and incorporated by reference, however, with respect to each of the above, to the extent that such information or statements incorporated by reference may be deemed to be inconsistent with the patent of this / these inventions, such statements shall not be expressly deemed to have been made by the applicant. [Table 1] [Table 2-1] [Table 2-2] [Table 3] [Table 4-1] [Table 4-2]

Claims

[Claim 1] The invention described herein.

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