Patent Application
20240328326
The present description relates to operating an in-conduit hydroturbine that controls pressure of a fluid placed in parallel with a pressure control valve of similar function.
A fluid distribution system may receive a fluid at a pressure that is greater than fluid consumers may wish to receive the fluid. For example, a water distribution system may receive water from a pump or from a reservoir that is geographically above water consumers such that the water is supplied at a higher pressure than may be desired. The desired pressure (e.g., a desired downstream pressure) for fluid consumers may fall into an acceptable pressure range (APR). The APR may be based on a maximum pressure limitation of connected equipment (e.g., piping and/or valves), pressure required to reduce leakage, and cost of pumping energy. A minimum pressure of the APR may be based on a minimum operating pressure for connected appliances (e.g., washers, boilers, showers, etc.), and a minimum pressure for fire suppression equipment during a fire flow event. A fluid distribution system may include a plurality of pressure control zones so that fluid consumers receive the fluid in the APR. A pressure control zone pressure of the fluid is an area that is in a specified geographical region and elevation. A pressure control zone may include a pressure reducing station that includes a pressure reducing valve that lowers pressure at an inlet of the pressure reducing valve to a regulated lower pressure irrespective of upstream pressure changes and flow rate changes. While the pressure reducing valve is effective to lower pressure of the fluid, the pressure reducing valve may exhibit energy losses that result in wasted energy. A fixed speed turbine may be deployed in place of the pressure reducing valve or in parallel with the pressure reducing valve, but such a configuration may lack operational redundancy and/or require additional pressure controls to ensure a desired pressure is provided at a downstream position in the fluid distribution system.
The inventors herein have recognized the above-mentioned issues and have developed an electrical power generating system, comprising: a bypass conduit including a bypass control valve and a turbine; a primary conduit including a primary control valve; and a controller including executable instructions stored in non-transitory memory that causes the controller to adjust a speed of the turbine in response to a downstream pressure.
By adjusting a speed of a hydroturbine in response to a downstream pressure in an electrical power generating system, it may be possible to increase operating efficiency of an electrical power generating system that generates electrical power via a fluid. In particular, the speed of the hydroturbine may be increased to increase a pressure drop across the hydroturbine so that pressure drop across a bypass valve may be minimized, thereby maximizing system electrical power output and performance.
The present description may provide several advantages. In particular, the approach may improve electrical power generating system efficiency. Further, the approach may provide a sequenced approach to start a hydroturbine in a way that may reduce losses and improve system efficiency. Additionally, the approach may simplify control of a system in which two devices may be operated to control downstream pressure in a fluid distribution system.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It may be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
The advantages described herein will be more fully understood by reading an example of an embodiment, referred to herein as the Detailed Description, when taken alone or with reference to the drawings, where:
The present description is related to operating an electrical power generating system. In one example, the electrical power generating system may be configured as shown in
Referring to
Pipe or primary conduit 151 includes a primary control valve 150 for controlling pressure of fluid 158 at a location in pipe or primary conduit 151 downstream of primary control valve 150. The fluid 158 flows in pipe or primary conduit 151 in a direction that is indicated by arrows 160 and 166. The fluid 158 may also flow into a bypass conduit 170 as indicated by arrow 162. The fluid 158 may also flow out of bypass conduit 170 as indicated by arrow 164. Upstream pressure of fluid 158 may be measured and determined via upstream pressure sensor 148. Downstream pressure of fluid 158 may be measured and determined via downstream pressure sensor 152. Thus, a downstream pressure is a pressure in primary conduit 151 that is downstream of primary control valve 150.
Bypass conduit 170 is positioned in parallel with pipe or primary conduit 151 and it includes an upstream isolation valve 144 and a downstream isolation valve 132. Flow meter 142 may output a signal that is indicative of a flow rate of fluid 158 through bypass conduit 170. A position of bypass control valve 138 may be monitored via position sensor 140. Midstream pressure sensor 141 provides an indication of pressure of fluid in bypass conduit 170 between bypass control valve 138 and hydroturbine 130. Hydroturbine 130 converts energy from fluid 158 into rotational energy. Fluid may exit hydroturbine 130 and pass through downstream isolation valve 132 as indicated by arrow 164.
Hydroturbine 130 may rotate electrical power generator 120 (e.g., an electric machine) to generate electrical power and a speed of hydroturbine 130 may be determined via a tachometer 122. Electrical power that is output from electrical power generator 120 is supplied to regenerative drive 118. Regenerative drive 118 converts electrical power generated via the electrical power generator 120 to alternating current (AC) power that may be supplied to the grid tie panel 116 and the stationary electrical grid 114. Regenerative drive 118 may include a rectifier 115 and an inverter 117. The rectifier 115 may convert AC power to DC power and the inverter may convert DC power to AC power at grid line frequency.
The electrical power generating system 100 may include a controller 12 to sense system operating conditions and adjust system actuators to adjust an operating state of the electrical power generating system 100. In one example, the controller 12 may include a central processing unit 104, random-access memory 106, read-only memory 102, and input output hardware 108 (e.g., buffer circuits, timers/counters, etc.). The controller 12 manages operation of the electrical power generating system 100 so that flow through the bypass conduit 170 is maximized while maintaining a desired pressure downstream of primary control valve 150. Additionally, fluid flow preferentially follows the path of least resistance between the primary conduit 151 and the bypass conduit 170. The combination of pressure drops through the various devices located along bypass conduit 170 is primarily driven by the position of bypass control valve 138 and the rotational speed of hydroturbine 130. Controller 12 may also include a user interface 110 to receive input from a user (e.g., human) and to provide feedback data to the user. User interface may be a touch screen display, keypad, or other known device. In some examples, controller 12 may also receive input and or commands from an external controller via I/O 108.
Pressures at various locations along bypass conduit 170 are indicated by a letter “P” followed by a location number. For example, “P1” is a fluid pressure at location P1, which is an inlet of the bypass conduit 170. P2 is pressure at an exit of the upstream isolation valve 144. P3 is pressure between flow meter 142 and bypass control valve 138. P4 is pressure between bypass control valve 138 and hydroturbine 130. P5 is pressure at the outlet of the hydroturbine. P6 is pressure at the inlet of the downstream isolation valve 132. P7 is pressure at the exit of the downstream isolation valve 132.
Thus, the system of
The system of
Referring now to
At 202, method 200 determines operating conditions and parameters for the electrical power generating system. In one example, method 200 may receive input values from the various sensors that are described herein to determine bypass valve position, hydroturbine speed, upstream pressure, downstream pressure, bypass conduit flow, and midstream pressure. Method 200 may retrieve values of control parameters from controller memory. The control parameters may be stored in tables, functions, or other memory locations. Method 200 proceeds to 204.
At 204, method 200 judges whether or not a run command has been received or input to the electrical power controller. If so, the answer is yes and method 200 proceeds to 206. Otherwise, the answer is no and method 200 proceeds to 205.
At 205, method 200 assumes an off state. The off state comprises fully closing the bypass control valve and commanding hydroturbine speed to zero. Thus, fluid flow through the hydroturbine and bypass conduit is reduced to zero or nearly zero. Method 200 returns to 202.
At 206, method 200 judges whether or not a fluid flow rate through pipe or primary conduit 151 is greater than a starting threshold flow rate. In one example, the starting threshold flow rate may be based on pipe size or historical water demand. If so, the answer is yes and method 200 proceeds to 208. Otherwise, the answer is no and method 200 proceeds to 207.
At 207, method 200 assumes state A. State A comprises operating the bypass control valve in a pressure control mode according to the method of
At 208, method 200 judges whether or not a fluid flow rate through pipe or primary conduit 151 is greater than a minimum threshold flow rate. In one example, the minimum threshold flow rate may be based on pipe size or historical water demand. If so, the answer is yes and method 200 proceeds to 210. Otherwise, the answer is no and method 200 proceeds to 209.
At 209, method 200 assumes state B. State B comprises operating the bypass control valve in a pressure control mode according to the method of
At 210, method 200 judges whether or not a fluid flow rate through pipe or primary conduit 151 is greater than a maximum threshold flow rate. In one example, the maximum threshold flow rate may be based on pipe size, historical water demand, or hydroturbine minimum operating speed. If so, the answer is yes and method 200 proceeds to 213. Otherwise, the answer is no and method 200 proceeds to 211.
At 211, method 200 assumes state C. State C comprises fully opening the bypass control valve and operating the hydroturbine in a pressure control mode according to the method of FIG. 4. Thus, state C maximizes the pressure drop across the hydroturbine and minimizes the pressure drop across the bypass valve to increase system efficiency. Method 200 returns to 202.
At 213, method 200 assumes state D. State D comprises operating the bypass control valve in a pressure control mode according to the method of
In this way, method 200 may adjust an operating state of an electrical power generating system to increase electrical power generating efficiency. In particular, the method of
Turning now to
At 302, method 300 determines operating conditions and parameters for the electrical power generating system. In one example, method 300 may receive input values from the various sensors that are described herein to determine downstream pressure. Method 300 may retrieve values of control parameters from controller memory. The control parameters may be stored in tables, functions, or other memory locations. Method 300 proceeds to 304.
At 304, method 300 judges whether or not a downstream pressure Pds (e.g., pressure at downstream sensor 152) is greater than a desired downstream pressure or setpoint pressure (Psp) minus an offset pressure (e.g., a pressure value between 0.1 to 2 PSI). If so, the answer is yes and method 300 proceeds to 306. Otherwise, the answer is no and method 300 proceeds to 305.
At 305, method 300 incrementally opens the bypass control valve. In one example, the bypass control valve may be further opened from its present position by a small amount (e.g., 0.5 percent of full valve stroke) by activating a solenoid valve that allows water to flow out of a closing chamber that controls a position of the bypass control valve. Method 300 returns to 302.
At 306, method 300 judges whether or not a downstream pressure Pds (e.g., pressure at downstream sensor 152) is greater than a desired downstream pressure or setpoint pressure (Psp) plus an offset pressure (e.g., a pressure value between 0.1 to 2 PSI). If so, the answer is yes and method 300 proceeds to 309. Otherwise, the answer is no and method 300 proceeds to 307.
At 307, method 300 holds or maintains a present opening amount of the bypass control valve. Method 300 returns to 302.
At 309, method 300 incrementally closes the bypass control valve. In one example the bypass control valve may be further closed from its present position by a small amount (e.g., 0.5 percent of full valve stroke) by activating a solenoid valve that allows water to flow into a closing chamber that controls a position of the bypass control valve. Method 300 returns to 302.
In this way, the bypass control valve position is adjusted in response to a downstream pressure in a primary conduit when a hydroturbine speed is not adjusted in response to the downstream pressure so that a desired downstream pressure may be provided downstream of the primary control valve when water is flowing through the bypass conduit and the primary conduit.
Moving on to
At 402, method 400 determines operating conditions and parameters for the electrical power generating system. In one example, method 400 may receive input values from the various sensors that are described herein to determine downstream pressure. Method 400 may retrieve values of control parameters from controller memory. The control parameters may be stored in tables, functions, or other memory locations. Method 400 proceeds to 404.
At 404, method 400 judges whether or not a downstream pressure Pds (e.g., pressure at downstream sensor 152) is greater than a desired downstream pressure or setpoint pressure (Psp) minus an offset pressure (e.g., a pressure value between 0.1 to 2 PSI). If so, the answer is yes and method 400 proceeds to 406. Otherwise, the answer is no and method 400 proceeds to 405.
At 405, method 400 incrementally decreases hydroturbine speed. In one example, the hydroturbine speed may be decreased by commanding the regenerative drive to output a greater amount of electrical energy. Requesting the regenerative drive to produce a greater amount of electrical energy may cause the torque output of the power generator to increase, thereby slowing the hydroturbine. In this way, the torque output (e.g., torque that resists motion of the hydroturbine) of the power generator may be adjusted to control the hydroturbine speed. Method 400 returns to 402.
At 406, method 400 judges whether or not a downstream pressure Pds (e.g., pressure at downstream sensor 152) is greater than a desired downstream pressure or setpoint pressure (Psp) plus an offset pressure (e.g., a pressure value between 0.1 to 2 PSI). If so, the answer is yes and method 400 proceeds to 409. Otherwise, the answer is no and method 400 proceeds to 407.
At 407, method 400 holds or maintains a present hydroturbine speed. Method 400 returns to 402.
At 409, method 400 incrementally increases the hydroturbine speed. In one example, the hydroturbine speed may be increased by commanding the regenerative drive to output a lower amount of electrical energy. Requesting the regenerative drive to produce a lower amount of electrical energy may cause the torque output of the power generator to decrease, thereby allowing the speed of the hydroturbine to increase. Thus, the torque output (e.g., torque that resists motion of the hydroturbine) of the power generator may be adjusted to increase the hydroturbine speed. Method 400 returns to 402.
In this way, the speed of the hydroturbine may be adjusted in response to the fluid pressure in the primary conduit downstream of a primary valve. By adjusting the speed of the hydroturbine, the pressure drop across the hydroturbine is controlled to a desired downstream pressure drop.
The methods of
Referring now to
Horizontal line 510 represents a level or value of an upstream pressure. Horizontal line 512 represents a level or value of a downstream pressure. The horizontal axis represents positions at which pressure is measured and the positions correspond to the positions that are indicated in
It may be observed that the pressure drop at position P1 relative to the upstream pressure is zero. The pressure drop across the upstream isolation valve that results in the pressure at position P2 is minimal. Additionally, there is minimal pressure drop through the flow meter as indicated by the difference between pressure at P2 and pressure at P3. The pressure drop of the bypass control valve for a fixed speed hydroturbine (e.g., pressure indicated by solid line at P3 minus the pressure indicated by solid line at P4) is more significant. The pressure drop across the bypass control valve in a system with variable hydroturbine speed (e.g., pressure indicated by the dashed line at P3 minus the pressure indicated by dashed line at P4) is significantly less than for the fixed hydroturbine system. This allows for a larger pressure drop across the hydroturbine for increased output and system efficiency. The pressure drop across the hydroturbine for the fixed hydroturbine (e.g., the pressure indicated by the solid line at P4 minus the pressure indicated by the solid line at P5) is greater than the pressure drop across the bypass control valve for the fixed turbine, but less than the pressure drop across the hydroturbine for the variable hydroturbine (the pressure indicated by the dashed line at P4 minus the pressure indicated by the dashed line at P5). Thus, the variable speed hydroturbine may provide additional electrical power output when operated according to the method of
Thus, the pressure drop across the bypass control valve may be minimized and the pressure drop across the hydroturbine may be maximized for the variable speed hydroturbine when the hydroturbine and bypass control valve are operated according to the method of
Referring now to
Line 616 represents an inlet pressure for the electrical power generation system as sensed via upstream pressure sensor 148. Line 614 represents inlet pressure in the system minus losses in pressure from the inlet and outlet isolation valves, system piping, and minimum bypass valve pressure losses (e.g. a pressure and flow limited line). Dashed line 602 represents the pressure drop that may be provided via a variable speed hydroturbine for a given fluid flow rate through the water distribution system. Solid line 604 represents the pressure drop that is across a fixed speed hydroturbine for different fluid flow rates through the water distribution system.
Leaders 606, 608, and 610 represent system fluid pressure drops for the water distribution system at flow rate f1. Dots 650 and 652 correspond to pressures in the system at flow rate f1. Leader 610 represents a minimum pressure loss for piping, bypass control valve, and isolation valves. Leader 608 represents the extra pressure drop across the variable speed hydroturbine that may be available when the electrical power generation system is operated according to the methods of
It may be observed that the pressure drop across the fixed speed hydroturbine changes with the fluid flow rate through the system. Therefore, the pressure drop across the bypass control valve may be adjusted to create the pressure difference between line 604 and line 614 so that the requested or desired downstream pressure may be generated via the electrical power generation system and primary control valve 150. However, the pressure drop across the bypass control valve results in wasted system energy.
The speed of the variable speed hydroturbine may be increased to increase a pressure drop across the hydroturbine, thereby increasing the output and efficiency of the hydroturbine. Consequently, to meet a desired downstream pressure in the water distribution system, less pressure drop may be provided via the bypass control valve.
Turning now to
Line 702 represents an inlet pressure for the electrical power generation system as sensed via upstream pressure sensor 148. Line 704 represents inlet pressure in the system minus losses in pressure from the inlet and outlet isolation valves, system piping, and minimum bypass valve pressure losses (e.g. a pressure and flow limited line). Dashed lines (e.g., 706) represent the pressure drops that may be provided via a variable speed hydroturbine for a given fluid flow rate through the water distribution system. Solid line 708 represents the pressure drop that is across a fixed speed hydroturbine for different fluid flow rates through the water distribution system.
Ideally the electrical power generating system would be sized so that it operates frequently at the pressure and flow limiting conditions (e.g., line 704). However, a fixed speed hydroturbine operates only at such conditions at one set of operating conditions (e.g., point 750). Because fluid flow demand may vary greatly over time, a fixed speed hydroturbine may leave a lot of potential energy to be extracted from the fluid. For a fixed speed hydroturbine operating at pressures and flows to the left of the flow and pressure limiting point of the fixed speed hydroturbine (e.g., 750), the extra pressure drop in the system is provided via the bypass control valve. For operating conditions that are to the right of the flow and pressure limiting point (e.g., point 750), fluid flow through the fixed speed hydroturbine is prevented and the additional system flow is provided via the primary control valve.
The present variable speed hydroturbine may be operated along the pressure and flow limited line 704 according to the method of
Referring now to
Line 802 represents an inlet pressure for the electrical power generation system as sensed via upstream pressure sensor 148. Line 804 represents inlet pressure in the system minus losses in pressure from the inlet and outlet isolation valves, system piping, and minimum bypass valve pressure losses (e.g. a pressure and flow limited line). Dashed line (e.g., 806) represents the pressure drops that may be provided via a variable speed hydroturbine for a given fluid flow rate through the water distribution system. Solid line 808 represents the pressure drop that is across a fixed speed hydroturbine for different fluid flow rates through the water distribution system.
The electrical generating system may be initially in an off state as indicated by the dot F1. The off state may be present when there is no run command for the electrical power generating system. The bypass control valve is fully closed and the hydroturbine rotational speed is commanded to zero when the electrical generating system is in the off state. Thus, the regenerative drive may operate to hold the hydroturbine rotational speed at zero. If the electrical generating system receives a start or run command, the isolation valves and the bypass control valve may be opened so that fluid begins to flow in the bypass conduit, thereby entering operating state A. The fluid flow may increase so that flow through the bypass conduit reaches the level that is indicated at F2 whereby the electrical generating system reaches state B. Once the electrical generating system reaches the flow that is indicated at F2, the hydroturbine may be released from a stopped state and it may rotate.
The fluid flow through the bypass conduit may continue to increase with increased flow through the system and the downstream pressure may be controlled via controlling a position of the bypass valve. The bypass valve may reach a fully open position as flow through the system increases. The dot at F3 indicates the conditions when the bypass valve is fully opened. If fluid flow increases further due to increased demand, speed of the hydroturbine is adjusted via the regenerative drive so that pressure drop across the hydroturbine reaches the level show at dot F4 for a variable speed hydroturbine. However, for fixed speed hydroturbines, the pressure drop at flow rate f5 as indicated at dot F4′ is lower than that of the variable speed hydroturbine as indicated at dot F4. If system flow demand is increased further, the variable speed hydroturbine follows the trajectory of line 804 from F4 to F5. The variable speed hydroturbine may operate in a pressure control mode where hydroturbine speed is adjusted to control the downstream pressure in operating state C as indicated. A fixed speed hydroturbine system would move along a minimum speed curve as indicated by solid line 808 from F4′ to F5 for higher system flow demands. If flow demand is increased further beyond the flow at F5, then the bypass valve may be held full open and the hydroturbine speed may be maintained so that the electric power generating system operates in state D.
Thus, the bypass control valve and hydroturbine speed may be adjusted to control pressures in the electrical power generating system. The pressures may be adjusted to minimize a pressure drop across the bypass control valve and maximize the pressure drop across the hydroturbine. Accordingly, system efficiency and performance may be enhanced.
Note that the example control and estimation routines included herein can be used with various variable hydroturbine system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be carried out by the control system including the controller in combination with the various sensors, actuators, valves, regenerative drives, and other hydroturbine hardware. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various actions, operations, and/or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations and/or functions may be repeatedly performed depending on the particular strategy being used. Further, at least a portion of the described actions, operations and/or functions may graphically represent code to be programmed into non-transitory memory of the computer readable storage medium in the control system. The control actions may also transform the operating state of one or more sensors or actuators in the physical world when the described actions are carried out by executing the instructions in a system including the variable speed hydroturbine hardware components in combination with one or more controllers.
This concludes the description. The reading of it by those skilled in the art would bring to mind many alterations and modifications without departing from the spirit and the scope of the description. For example, fluid (e.g., water) distribution systems that support different fluid flow rates with differently sized hydroturbines could use the present description to advantage.
