JP2013503279A - Energy extraction device and method of operating energy extraction device - Google Patents

Abstract

  According to the present invention, a hydraulic pump that is driven by a rotating shaft and applies torque to the rotating shaft, a hydraulic motor that drives a load, an outlet of the hydraulic pump, and an inlet of the hydraulic motor are in fluid communication, Windmill-like energy extraction comprising a high pressure manifold selectively placed in fluid communication with a fluid accumulator and at least one low pressure manifold in fluid communication with the outlet of the hydraulic motor and the inlet of the hydraulic pump A method of operating the apparatus is provided. At least one of the hydraulic pump and the hydraulic motor is a digital hydraulic machine, wherein fluid communication between the fluid accumulator and the high pressure manifold is blocked in response to detection of an abnormal event.

Description

  The present invention relates to a renewable energy device such as a wind power generator (WTG).

  Renewable energy devices such as wind generators and tidal power generators are becoming increasingly important as power sources for AC power networks. Such devices have traditionally been gearboxes (increased speeds) to convert the slow input speed of an energy extraction mechanism, such as a wind turbine or tidal turbine rotor, to a fast output speed to drive a generator. Has been adopted. Such gearboxes are difficult to design and manufacture because they are prone to failure and are expensive to maintain and replace or repair.

  Therefore, it has been proposed to construct a transmission for a renewable energy device that uses a fluid working machine, and this makes it possible to obtain a hydraulic (hydrostatic) gear ratio that is variable on a large scale. Such hydraulic transmissions are also lighter and more robust than gearboxes, and even lighter than other direct generator drive systems that will exhibit similar functions. Therefore, the overall cost for generating electric power can be reduced. U.S. Pat. No. 4,503,673 (Schachet) discloses a plurality of variable displacement motors driven by a plurality of pumps, which have a pressure vs. pressure. As a whole, the displacement volume is variable so as to control the pressure of the hydraulic oil according to the function of the rotor speed. International Publication No. 2007/053036 (Chappel) discloses a variable displacement motor driven by a fixed displacement pump, and the displacement of the motor is controlled based on the measured value of the wind speed. It is like that.

  However, experience has shown that the power input to renewable energy devices is unpredictable from moment to moment due to gusts and turbulence. This causes undesirable fluctuations in the power output to the power system. Additional problems arise when the power system is instantaneously disconnected from the device or when the power system requires additional energy from the device for a short time. For this reason, a fluid reservoir connected between the pump and motor is used to control the pump and / or motor to store in and out of the fluid reservoir in seconds. It has been proposed to realize the recovery of surplus energy.

  U.S. Pat. No. 4,496,847 (Parkins and Salter &Rae; 1984) describes an electrically rectified pump (i.e., individual working chambers with displacement of fluid per pump revolution (and consequently applied to the rotor). A WTG with a pump) that can be disabled to change the torque also) is disclosed. The rotor torque is controlled while the turbine (functionally equivalent to the motor) or the motor is controlled to keep the pressure in the fluid reservoir (pressure vessel and flywheel or vacuum reservoir, respectively) constant. Control is performed to maintain a desired ratio of speed to measured wind speed. In US Pat. No. 4,428,0061 (Lawson-Tancred), the displacement of the pump is controlled based on the square of the rotor speed, the motor is controlled to maintain a constant pressure, and the fluid reservoir is weighted Different types of WTGs are disclosed which are hydraulic rams. U.S. Pat. No. 4,274,010 (Lawson-Tancred) further discloses the ability to intermittently turn the generator / motor switch on and off based on power availability.

  Rampen, Taylor Riddoch (2006) discloses a WTG with an electrically rectified pump and a hydraulic accumulator as an energy reservoir, but realizes storage and recovery of surplus energy in seconds There is no description on how to control the pump, motor and accumulator.

  While accumulators are cheap and reliable energy stores, their fluid pressure must vary over a very wide range in operation to provide a smoothing action. Further, since the efficiency of the fluid working machine varies depending on the operating pressure, it is desirable to optimize the operating pressure used. In particular, when the operating pressure is low, fluctuating energy inputs generate rotor torque beyond the pump's ability to deliver torque that is constrained to the current pressure without any warning, making the rotor dangerous. It will be accelerated so much. Other emergency stop conditions (e.g., blade, incidental equipment, tower or hydraulic circuit failure) may also require a rapid application of sufficient torque to the rotor. However, WTGs with accumulator energy stores are difficult to quickly increase torque because the accumulator must be filled with fluid in order to increase operating pressure.

For this reason, U.S. Pat. No. 4,496,847 discloses a controllable restricting valve for disconnecting the pump from the turbine when needed, thereby increasing the pressure and the rotor. The device can be controlled against overspeed. However, these limiting valves cause losses that reduce the power generation efficiency of the WTG, even if they are open. In addition, power generation stops while the limiting valve is functioning.
Accordingly, a first object of the present invention is a hydraulic transmission that maximizes energy generation efficiency during normal operation, maintains energy generation throughout the increase in torque demand, and can respond more quickly to detected anomalies. Another object of the present invention is to provide a method for controlling a renewable energy device including an energy storage device that is inexpensive and excellent in reliability.

According to a first aspect of the invention,
A method of operating an energy extraction device that extracts energy from a fluctuating energy stream from a renewable energy source, comprising:
The energy extraction device includes:
A hydraulic pump driven by a rotating shaft driven by the renewable energy source and applying torque to the rotating shaft;
A hydraulic motor that drives the load;
A high pressure manifold in fluid communication with an outlet of the hydraulic pump and an inlet of the hydraulic motor and selectively placed in fluid communication with a fluid accumulator;
A low pressure manifold in fluid communication with an outlet of the hydraulic motor and an inlet of the hydraulic pump;
An abnormal event sensor for detecting an abnormal event,
At least one of the hydraulic pump and the hydraulic motor is an electrically controlled variable displacement hydraulic machine, and is provided between a plurality of working chambers whose volumes change periodically, and between each working chamber and each manifold A plurality of valves for adjusting the net displacement of the working fluid, wherein at least one valve associated with each working chamber is an electrically controlled valve, the electrically controlled valve being Selecting the volume of working fluid displaced by each working chamber in each cycle of working chamber volume, thereby adjusting the net displacement of hydraulic fluid by the electrically controlled variable displacement hydraulic machine Was made to work,
An operation method for an energy extraction device, wherein the fluid pressure in the high pressure manifold is increased in response to detection of an abnormal event by blocking fluid communication between the fluid accumulator and the high pressure manifold. Is provided.

  In contrast to prior art energy extraction devices, the device according to the present invention has a faster response time to certain abnormalities and is therefore less susceptible to damage. Also, the device according to the present invention does not rely on a variable limiting valve that causes a huge energy loss by dissipating high pressure as heat (the working fluid may boil thereby). Limit valves are not practical in many large scale energy extractors (eg, energy extractors above 3 MW). In addition, a variable restriction valve placed directly in the fluid flow reduces the efficiency of the device. In contrast, in the present invention, only a small energy flow passes through the means for blocking the fluid connection between the fluid accumulator and the high pressure manifold.

  An electrically controlled variable displacement device that is controlled at each cycle of the working chamber volume by active control of a valve in which the volume of working fluid moved by each working chamber is electrically controlled is The displacement volume is much faster and more accurate than the hydraulic system. Thus, an energy extraction device equipped with one or more such hydraulic devices maintains control when the fluid connection between the fluid accumulator and the high pressure manifold is interrupted (which means that the torque of the shaft and load is The likelihood of being continuous) increases. Thus, prior art systems have been kept away from the features of the present invention to date.

  Preferably, the fluid pressure in the high pressure manifold is increased in response to detecting an abnormal event. The fluid pressure in the high pressure manifold may be decreased in response to detecting an abnormal event. Due to the increased fluid pressure within the high pressure manifold, one or more pressure relief valves may open following the disconnection of the fluid connection between the fluid accumulator and the high pressure manifold.

  The present invention is particularly useful as a response to abnormal events that can be mitigated by an increase or decrease in torque to be applied to the rotating shaft by a hydraulic pump. Therefore, it is preferable that mitigating the abnormal event includes increasing or decreasing the torque to be applied to the rotating shaft by the hydraulic pump.

  In response, fluid communication between the outlet of the hydraulic pump and the inlet of the hydraulic motor is maintained upon detection of an abnormal event that would block fluid communication between the fluid accumulator and the high pressure manifold. It is preferable to do.

  The net moving rate of the working fluid by the hydraulic motor may be decreased in response to detecting an abnormal event. Thereby, less fluid is absorbed by the hydraulic motor and the pressure in the high pressure manifold rises. The decrease in the net moving rate of the working fluid by the hydraulic motor may be temporarily performed after detection of an abnormal event, and the net moving rate of the working fluid by the hydraulic motor may be increased after the pressure increase in the high pressure manifold. . Preferably, the hydraulic motor is the electrically controlled variable displacement hydraulic device.

  Preferably, the method further comprises increasing a net movement rate of the working fluid by the hydraulic pump in response to detecting an abnormal event. As a result, more fluid is pumped up by the hydraulic pump, and the pressure in the high-pressure manifold increases. The increase in the net moving rate of the working fluid by the hydraulic pump may be temporarily performed after detecting an abnormal event, and the net moving rate of the working fluid by the hydraulic pump is decreased after the pressure in the high pressure manifold is increased. May be. Preferably, the hydraulic pump is the electrically controlled displacement variable hydraulic device.

  Preferably, the fluid accumulator is placed in selective fluid communication with the high pressure manifold by a separation valve. Preferably, the energy extraction device comprises a controller operable to control the separation valve. Preferably, the controller is operable to control the hydraulic pump and the hydraulic motor.

  The abnormal event is preferably one or more of an overspeed condition, a gust, an extreme gust, a request to stop the rotating shaft, and an undesirable structural condition. Extreme gusts may be wind speeds that are 30%, 50% or 100% greater than the current average wind speed. For example, the request to stop the rotating shaft is due to detecting a damaged bearing on the rotor shaft, leakage of working fluid, abnormal pitch system, loss of generator field current, critical electrical control module abnormality. There may be.

  Preferably, the abnormal event is detected in response to a calculation that an acceptable operating range of the energy extraction device has been exceeded or is about to exceed. “Immediately” here means between the current time (“present”) and a future time horizon. Considering all possible operating conditions between the current and time horizon, it will prevent current actions from exceeding the allowable operating range at any point between the current and future time horizons. .

  Preferably, the allowable operating range is an allowable speed range (e.g. of the rotating shaft or load), an allowable torque range (e.g. of the rotating shaft or load) of the energy extraction device (e.g. Allowable pressure range (for fluid accumulator pressure or high pressure manifold), acceptable voltage range (for example, load as generator), acceptable temperature range (for example, hydraulic pump and hydraulic motor working fluid or load) , Including one or more of an allowable frequency range (eg, of a load as a generator) and an allowable range of motion (eg, of a first portion relative to a second portion of an energy extraction device). Yes.

  Preferably, the abnormal event sensor comprises one or more of a shaft speed sensor, a wind speed sensor, a pressure sensor, a motion / vibration sensor, a voltage sensor, a current sensor, a frequency sensor or a temperature sensor. The abnormal event sensor may include a comparison means operable to compare the measured value of the sensor with the allowable operation range of the energy extraction device.

  Preferably, the fluid accumulator is generally in fluid communication with the hydraulic pump and the hydraulic motor except in response to detecting an abnormal event. Thus, during normal use (ie, use before an abnormal event is detected), preferably the fluid accumulator absorbs energy to the hydraulic motor and hydraulic pump in response to fluctuating energy flows or load fluctuations. Or release.

  The fluid accumulator includes a plurality of small fluid accumulator modules, and the method abnormally reduces fluid communication between the plurality of small but not all fluid accumulator modules and the high pressure manifold. It may further comprise blocking in response to detecting the event.

  Preferably, at least one accumulator regulating valve is provided to interrupt or permit fluid connection between the fluid accumulator and the high pressure manifold. Preferably, the accumulator regulating valve is a valve having an open state in which the fluid accumulator is in fluid communication with the high pressure manifold and a closed state in which the fluid accumulator is not in fluid communication with the high pressure manifold. Preferably, the fluid connection between the fluid accumulator and the high pressure manifold is direct in the open state, in other words not through other fluid flow restriction devices. The accumulator regulating valve may have one or more partial states in which the fluid accumulator is fluidly connected to the high pressure manifold so that fluid can gradually flow between the fluid accumulator and the high pressure manifold. . Here, “gradually” means that it may take several seconds to several minutes to equalize the pressure between the fluid accumulator and the high pressure manifold.

  Preferably, the renewable energy device further comprises at least one additional fluid accumulator in permanent fluid communication with the high pressure manifold.

  Preferably, the method detects that fluid communication between the fluid accumulator and the high pressure manifold is blocked, detects a first pressure in the high pressure manifold and a second pressure in the fluid accumulator, The volume of the working fluid moved by each working chamber of at least one of the hydraulic pump and the hydraulic motor is selected so that the first pressure and the second pressure converge, and the first pressure and the second pressure are The method further comprises fluidly communicating the fluid accumulator and the high pressure manifold with each other when an equality criterion is met. For example, the equality criterion may be expressed in absolute language, or may be equal to the extent that it falls within a predetermined tolerance range that may be expressed as a ratio.

  The energy extraction device includes a bleed valve provided to bring the pressure of the high pressure manifold and the pressure of the fluid accumulator close to the same value, and the method includes a fluid between the high pressure manifold and the fluid accumulator. The bleed valve may be closed when general communication is blocked, and the bleed valve may be opened before fluid communication between the high pressure manifold and the fluid accumulator is restored. .

  The controller may send a pitch drive signal to control the pitch of the blades before, after, or simultaneously with interrupting the fluid connection between the high pressure manifold and the accumulator.

  An energy extraction device is an energy extraction device for extracting energy from a renewable energy source, such as a stream of air or water, using one or more turbines, propellers or other devices. For example, the energy extraction device may be a wind power generation device (WTG) or a power generation device (for example, a tidal current power generation device) for extracting energy from flowing water. The extracted energy flow typically varies from one minute to the next, and if there is no effect by the fluid accumulator, the energy flow to the load will vary. Renewable energy devices that produce a smoothed energy output can require a higher price for the energy they produce compared to devices that produce a fluctuating output, Linkage becomes easier.

  The load is typically a generator (particularly a synchronous generator) for generating electric power supplied to the power system, but may be a pump, a fan, or a compressor. Different loads may be connected at different times.

A fluid accumulator is typically a gas charged accumulator filled at one end with pressurized nitrogen or other gas. Alternatively, the fluid accumulator may be any other device suitable for accumulating pressurized hydraulic fluid. A plurality of fluid accumulators may be provided, and each fluid accumulator may be filled with different gases at different pressures. A plurality of hydraulic pumps and / or a plurality of hydraulic motors may be provided. The fluid pressure in the high pressure manifold is typically slightly higher than atmospheric pressure, for example 2-5 Bar, but may be near atmospheric pressure. A low pressure pump and a pressure relief valve may connect the low pressure manifold to the reservoir of working fluid, and a low pressure accumulator may be provided in fluid communication with the low pressure manifold.
Selecting the net movement rate of the working fluid means selecting the net displacement volume of one or more working chambers over a period of time or the number of working chambers that form the net movement of the working fluid over a period of time. And the net displacement of such a working chamber.

  Selecting the net displacement of the working fluid is in sync with each cycle of the working chamber volume by actively controlling at least one electrically controlled valve associated with a working chamber. Means flowing a volume of fluid into or out of the high pressure manifold.

  Preferably, the net displacement of the working fluid is cycled for each individual working chamber so that all working chambers operating together meet the net displacement rate requirement that can be achieved by the displacement of the fluid. Selected. Preferably, the net travel rate requirement for the pump's working chamber is calculated from the net torque applied to the rotating shaft. Preferably, the net moving rate requirement of the motor's working chamber is calculated from the net torque or power applied to the load, or the moving rate of fluid from the high pressure manifold.

  Preferably, the torque applied to the rotating shaft by the hydraulic pump is adjusted according to a function comprising one or more of the current rotational speed of the rotating shaft and the rate of change of the rotational speed of the rotating shaft. Preferably, the torque applied to the rotating shaft by the hydraulic pump may be adjusted to fall within at least one constant lambda range that substantially follows a function of the square of the rotating shaft's rotational speed. Preferably, the torque applied to the rotary shaft by the hydraulic pump is adjusted by a function of the rate of change of the rotational speed of the rotary shaft.

  Adjusting the torque means selecting the net moving rate of the working fluid by the hydraulic pump according to the torque demand function. The torque demand function may be a function of one or more measured parameters of a renewable energy source or energy extraction device. The torque demand function may be a function of the speed of the rotating shaft or the speed of the fluctuating energy flow. The torque demand function may describe the time averaged net torque applied to the rotating shaft by a plurality of working chambers of the pump. Preferably, the net movement rate of the working fluid by the hydraulic pump is selected in response to the torque demand function, the one or more parameters measured and the pressure measurement. Preferably, the net displacement of the working fluid is cycle by cycle for each working chamber so that the time averaged net torque applied to the rotating shaft by the active working chamber of the pump satisfies the torque demand function. Selected. Preferably, the torque imparted to the rotating shaft by the working chamber actively controls at least one electrically controlled valve associated with the working chamber to pressurize the working chamber and torque by the working chamber. Is selected on a cycle-by-cycle basis by causing the movement of the to the rotating shaft synchronously with each cycle of the working chamber volume.

  Preferably, the pressure in the high pressure manifold is adjusted towards a target pressure (typically optimum pressure) or pressure range. Adjusting the pressure in the high pressure manifold means selecting the net moving rate of the working fluid by the other of the hydraulic pump or hydraulic motor relative to the net moving rate of the working fluid by one of the hydraulic pump or hydraulic motor. , Including increasing or decreasing the amount of fluid accumulated in the accumulator, thereby increasing or decreasing the pressure of the working fluid in the high pressure manifold toward the target pressure.

  Preferably, when the pressure exceeds a (fixed or variable) threshold, an action is taken to reduce the torque transmitted to the hydraulic pump via the rotating shaft. Preferably, the renewable energy source is controlled such that when the pressure exceeds the threshold, the torque transmitted to the rotating shaft by the renewable energy source is reduced. Preferably, when the pressure exceeds a (fixed or variable) threshold, the method comprises reconfiguring the energy extraction device to extract less energy from a fluctuating energy source. If the energy extraction device is a turbine, the reconfiguration of the energy extraction device may include one or more of blade pitch change, blade feathering, mechanical brake application, or hydraulic brake application.

  Preferably, the method comprises adjusting the time averaged net transfer rate of the working fluid by each working chamber. Net displacement of fluid means the net fluid that flows into or out of the high pressure manifold by a hydraulic pump or hydraulic motor in one complete cycle of the working chamber volume.

  The energy extraction device preferably has a topological relationship with the working chamber volume cycle and actively controls the electrically controlled valves to adjust the net rate of movement of the working fluid by each working chamber. It has a controller to do.

  Preferably, each of the hydraulic pump and the hydraulic motor includes a rotating shaft that periodically drives the working chamber or is periodically driven by the working chamber. Preferably, the shaft is an eccentric cam shaft, and the shaft may include a ring cam. The hydraulic pump may function only as a pump, and the hydraulic motor may function only as a motor. Alternatively, either the hydraulic pump or the hydraulic motor may function as a motor or a pump in the selective operation mode.

  Preferably, each working chamber has an active cycle in which each working chamber volume causes a net movement of the working fluid, or an idle cycle in which the working chamber does not substantially cause a net movement of the working fluid. It is operable to perform. Each working chamber may be operable to move one of a plurality of volumes of working fluid (eg, a range of working fluid volumes) during the active cycle. The aforementioned volume range may be discontinuous, for example, the working fluid volume range may be from a first minimum value where there is substantially no net fluid movement to a maximum value of net fluid movement in the working chamber. The maximum value of the net fluid movement in the working chamber from a second minimum value that extends to a first maximum value of at most 25% or 40% and then at least 60% or 75% of the net fluid movement in the working chamber. A range extending up to the second maximum value that is 100% of the above may be provided. This can be done, for example, when the operating pressure of the working fluid is high enough that the valve cannot be opened and closed in the middle of the expansion or contraction stroke of the working chamber volume, or in a continuous volume range. It may occur when the fluid flow rate is high enough to damage the working chamber, the working chamber valves, or other parts of each working fluid machine.

  “Active control” is a control mechanism that, in at least some circumstances, consumes power and is not a passive response at all (eg, opening and closing the valve solely depending on the pressure differential across the valve). Means that the controller can influence the state of the valve. Related terms such as “aggressive control” should be interpreted accordingly. Nevertheless, the valve is preferably openable and closable by passive means. The valve typically opens passively due to a pressure drop in the working chamber, such as during an intake stroke. For example, the valve can be passively opened by a pressure differential during at least some cycles and can be selectively opened and closed under active control by the controller during part of the cycle. Preferably, the valve is biased to open or biased by the biasing means. Preferably, the valve is movable from the first position to the second position under active control, and is movable from the second position to the first position by biasing means. Preferably, one of the first position and the second position is a closed position, and the other is an open position.

  "Active control" (and related terms such as "active control") includes the action of the controller opening, closing, maintaining an open state and / or maintaining a closed state The possibility of being operable to cause the valve to selectively perform one or more of the above. The controller may only be able to influence the state of the valve during part of the operating cycle. For example, the controller may not be able to open the low pressure valve against the pressure differential during most of the operating cycle when the pressure in the working chamber increases. Typically, the controller actively controls the valve by sending a control signal directly to the valve or sending a control signal to a valve driver such as a semiconductor switch. Sending a control signal means a signal that means the intended state of the valve (eg, open or closed), or that the state of the valve should be changed (eg, the valve should be opened or closed) It also includes sending a pulse that means that it should be) and a pulse that means that the state of the valve should be maintained. The controller may constantly send a signal and stop or change the signal to cause a change in the state of the valve. The valve may be provided with a normally closed and solenoid-open valve that is kept open by providing current and is actively closed by cutting off the current.

  “In phase relationship with the working chamber volume cycle” means that the timing of the positive control by the controller of the valve is determined in relation to the phase of the working chamber volume cycle. Therefore, each fluid working machine typically includes working chamber phase detection means such as a position sensor. For example, if the working fluid volume cycle is mechanically coupled to the rotation of the shaft, each fluid working machine includes a shaft position sensor (and optionally a shaft speed sensor), and the controller determines the shaft position from the shaft position sensor. It is preferably operable to receive a signal (and optionally a shaft speed signal from a shaft speed sensor). In embodiments with multiple working chambers, the controller will typically be operable to determine the phase of each working chamber due to the phase difference between the volume chambers of the different working chambers.

  Preferably, the one or more actuations operable to displace the fluid during one or more cycles of the working chamber volume if the selected net transfer rate of the fluid by the working chamber of the hydraulic pump or hydraulic motor is too low The chamber is made redundant. In other words, if the working chamber does not exist or is not operating, the hydraulic pump or hydraulic motor device will somehow displace enough fluid to change the overall frequency of the active cycle of the working chamber volume. Would have been able to meet the requirements without having to. Preferably, can be used to provide a selected displacement volume during at least some cycles of the working chamber volume if the selected net transfer rate of fluid by the working chamber of the hydraulic pump or hydraulic motor is too low The selected fluid volume displaced by at least one of the active working chambers is set to substantially zero. In some embodiments, if the selected net transfer rate of fluid by the hydraulic pump or hydraulic motor working chamber is too low, at least one of the working chambers available to provide the selected displacement volume is Performing an idle cycle for at least some cycles of the working chamber volume. In some embodiments, the working chamber is operable to displace one of the plurality of volumes of working fluid, and the selected net transfer rate of fluid by the working chamber of the hydraulic pump or hydraulic motor is low. If so, the selected fluid volume displaced by at least one of the available working chambers is less than the maximum volume of working fluid that the at least one of the working chambers can displace.

According to a second aspect of the invention,
An energy extraction device for extracting energy from a fluctuating energy stream from a renewable energy source,
A hydraulic pump driven by a rotating shaft driven by said renewable energy source (and thus applying torque to the rotating shaft in use);
A hydraulic motor that drives the load;
A fluid accumulator;
A high pressure manifold in fluid communication with the outlet of the hydraulic pump and the inlet of the hydraulic motor;
At least one low pressure manifold in fluid communication with an outlet of the hydraulic motor and an inlet of the hydraulic pump;
An abnormal event sensor for detecting an abnormal event,
At least one of the hydraulic pump and the hydraulic motor is an electrically controlled variable displacement hydraulic machine, and a plurality of working chambers whose volumes change periodically, and between each working chamber and each manifold. A plurality of valves for adjusting the net displacement of the working fluid, wherein at least one valve associated with each working chamber is an electrically controlled valve, the electrically controlled valve being Selecting the volume of working fluid displaced by each working chamber in each cycle of working chamber volume, thereby adjusting the net displacement of hydraulic fluid by the electrically controlled variable displacement hydraulic machine Was made to work,
The fluid accumulator is selectively fluidly connected to the high pressure manifold via an accumulator adjustment valve to increase the fluid pressure in the high pressure manifold,
An energy extraction device is provided wherein the accumulator regulating valve is operable to block fluid communication between the fluid accumulator and the high pressure manifold in response to detection of an abnormal event.

  The present invention includes computer software according to a third aspect (provided with program code that, when executed by a computer, causes the computer to operate a renewable energy device according to the method of the first aspect). Computer software). The present invention extends to a computer-readable medium storing the computer software according to the third aspect.

FIG. 1 is a schematic diagram of a wind turbine generator connected to a power network for carrying out the present invention. FIG. 2 is a schematic diagram of a hydraulic motor used in the wind turbine generator shown in FIG. FIG. 3 is a view showing a cross section of a pump used in the wind turbine generator shown in FIG. FIG. 4 is a diagram showing a time series when stopping the overspeed condition of the wind turbine generator shown in FIG. 1 according to the present invention.

  FIG. 1 illustrates a possible embodiment of the present invention as a wind power generator (WTG) 100 connected to a power network 101 and functioning as an energy extractor. Different layouts that provide similar functionality are not excluded. The WTG includes a nacelle 103 that is pivotably mounted on a tower 105, and a hub 107 that supports three blades 109 is mounted on the nacelle 103. Hub 107 and blade 109 are collectively known as rotor 110. An anemometer 111 attached to the outside of the nacelle supplies a wind speed measurement value signal 113 to the controller 112. The rotor speedometer 115 in the nacelle (acts as an abnormal event sensor in some embodiments) provides a rotor speed signal 117 to the controller. In the exemplary system, a pitch actuator 119 allows adjustment of the angle of attack of each blade relative to the wind. The pitch actuator 119 exchanges the pitch drive signal and the pitch detection signal 121 with the controller. The present invention is also applicable to a WTG that does not include a pitch actuator.

  The hub is directly connected to the pump 129 by a rotor shaft 125 that acts as a rotating shaft and rotates in the rotor rotating direction 127. The pump is preferably of the type described with reference to FIG. 3, and is fluidly connected to a hydraulic motor 131, preferably of the type described with reference to FIG. The fluid connection between the pump and the hydraulic motor is made through a high pressure manifold 133 and a low pressure manifold 135 connected to the high and low pressure ports of the pump and motor, respectively. This fluid connection is straightforward in the sense that no flow regulating valve is present. The pump and hydraulic motor are preferably mounted directly one on the other, and a high pressure manifold and a low pressure manifold are formed between them between the pump and the hydraulic motor. The charge pump 137 continuously draws fluid from the reservoir 139 into the low pressure manifold to which the low pressure accumulator 141 is connected. The low pressure relief valve 143 returns fluid from the low pressure manifold to the reservoir. The smooth accumulator 145 is connected to a high pressure manifold between the pump and the hydraulic motor. A first high pressure accumulator 147 and a second high pressure accumulator 149 are connected to the high pressure manifold via a first separation valve 148 and a second separation valve 150 (both functioning as an accumulator adjustment valve), respectively. The first separation valve and the second separation valve include a bleed valve provided in parallel with the main stage, and are operable to cause a relatively low flow rate between the accumulator and the high pressure manifold. The first high pressure accumulator and the second high pressure accumulator may be preliminarily provided with different pressures (precharge pressures), or may be additionally provided with a plurality of high pressure manifolds having a wider precharge pressure zone. Good. The states of the first separation valve and the second separation valve are set by the controller by a first separation valve signal 151 and a second separation valve signal 152, respectively. The fluid pressure in the high pressure manifold is measured by a pressure sensor 153 that provides a high pressure manifold pressure signal 154 to the controller. The high pressure relief valve 155 connects the high pressure manifold and the low pressure manifold.

  The hydraulic motor is connected to a generator 157 that functions as a load via a generator shaft 159. The generator is connected to the power network via the contactor 161. The contactor 161 receives a contactor control signal 162 from the generator / contactor controller 163. The generator / contactor controller obtains voltage, current, and frequency measurement results from the power supply signal 167 and the generator output signal 169 measured by the power supply sensor 168 and the generator output sensor 170, respectively, and outputs them to the controller 112. The output of the generator is controlled by adjusting the field voltage generator control signal 165 based on the generator / contactor control signal 175 from the controller.

  The hydraulic pump and hydraulic motor report the instantaneous angular position, the speed of each rotating shaft, and the temperature and pressure of the hydraulic oil to the controller. The controller sets the valve states of the pump and the motor based on the pump drive signal / pump shaft signal 171 and the motor drive signal / motor shaft signal 173. The controller uses the power amplifier 180 to amplify the pitch drive signal, the separation valve signal, the pump drive signal, and the motor drive signal.

  FIG. 2 shows a hydraulic motor 131 as an electrically rectified hydraulic pump / motor with a plurality of working chambers 202 (each labeled A to H). The working chamber 202 has a volume defined by the inner surface of the cylinder 204 and the piston 206. The piston 206 is driven by the eccentric cam 209 with the driving force from the rotating crankshaft 208, and reciprocates in the cylinder so that the volume of the working chamber changes periodically. The rotating crankshaft is firmly fixed to the generator shaft 159 and rotates together. The shaft position / speed sensor 210 detects an instantaneous angular position and rotational speed of the shaft, and notifies the controller 112 via the signal line 211 (a part of the motor drive / motor shaft signal 173). This allows the controller to determine the instantaneous phase of each working chamber cycle. The controller is typically a microprocessor or microcontroller and executes the stored program used.

  Each of the working chambers is associated with a low pressure valve (LPV), which is an electrically driven face-sealing poppet valve 214. The poppet valve 214 faces inwardly toward the working chamber with which it is associated and is operable to selectively close a channel extending from the working chamber to the low pressure flow path 216. The low pressure channel 216 generally functions as a fluid source or sink and connects one or several (or all as shown in the figure) working chambers to a reservoir (not shown) via a low pressure port 217. It may be. The low pressure port 217 is fluidly connected to the WTG low pressure manifold 135. The LPV passively opens when the pressure in the working chamber falls below the pressure in the low pressure manifold (ie, during the suction stroke) to fluidly connect the working chamber to the low pressure manifold, but the LPV control line 218 ( This is a normally open solenoid closed valve that can be selectively closed under active control by a controller via a motor drive / motor shaft signal 173) to disconnect the working chamber from the low pressure manifold. Alternatively, an electrically controllable alternative valve such as a normally closed solenoid open valve may be used.

  Each of the working chambers is also associated with a high pressure valve (HPV) 220, which is a delivery valve driven by pressure. The HPV is operable to open outward from the working chamber and close a channel extending from the working chamber to the high pressure flow path 222. The high pressure flow path 222 may function as a fluid source or sink and connect one or several (or all as shown in the figure) working chambers to the high pressure port 224. The high pressure port 224 functions as an inlet of the hydraulic motor and is fluidly connected to the high pressure manifold 133. The HPV functions as a normally closed, pressure-open check valve that opens passively when the pressure in the working chamber exceeds the pressure in the high pressure manifold. The HPV is normally closed, which may be selectively maintained once opened by the pressure in the working chamber to which the HPV is associated, controlled by the controller via the HPV control line 226. It also functions as a check valve with solenoid open. HPV control line 226 is part of motor drive / motor shaft signal 173. Typically, the HPV is prevented from being opened by the controller against the pressure in the high pressure manifold. HPV further has pressure on the high pressure manifold when, for example, the valve is of this type and is operated according to the method disclosed in WO 2008/029073 or WO 2010/029358. The working chamber may be opened or partially opened under the control of the controller when there is no pressure.

  In the normal mode of operation described in known documents such as, for example, EP 0 361 927, EP 0 494 236, EP 1 537 333, etc. One or more LPVs are actively closed just before the minimum volume point in the chamber cycle to close the flow path to the low pressure manifold (which causes a small amount of fluid to flow out through the associated HPV) and the high pressure from the hydraulic motor Select the net transfer rate of fluid from the manifold. The controller then actively maintains the associated HPV open to near the maximum volume in the associated working chamber cycle, allowing fluid flow from the high pressure manifold, and rotating shaft Torque is applied to. In the optional pump mode, the controller typically closes the flow path to the low pressure manifold by actively closing one or more LPVs near the maximum volume point in the associated working chamber cycle (which continues thereafter). The net rate of transfer of fluid to the high pressure manifold by the hydraulic motor is selected by discharging the fluid through the associated HPV in the contraction stroke. The controller selects the number and sequence of LPV closing and HPV opening operations to generate fluid flow, shaft torque or power to achieve a net fluid transfer rate selection. . While deciding whether to keep the LPV closed or open every cycle, the controller changes the working chamber volume to select the net rate of fluid transfer from the high pressure manifold to the low pressure manifold (or vice versa) And is operable to precisely change the phase of the closing operation of the HPV.

  The arrows at the ports 217 and 224 indicate the direction of fluid flow in the motoring mode. In pump mode, the fluid flow direction is reversed. The pressure relief valve 228 may protect the hydraulic motor from damage.

  FIG. 3 schematically shows part 301 of pump 129 with an electrically rectified valve. The pump comprises a number of similar working chambers 303 arranged radially. In the part in FIG. 3, only three of the working chambers 303 are shown. Each working chamber has a volume defined by the inner surfaces of cylinder 305 and piston 306. The piston 306 is driven by a ring cam 307 via a roller 308, and reciprocates in the cylinder so that the volume of the working chamber changes periodically. The link gum may be divided into separate segments mounted on a shaft 322 that is rigidly connected to the rotor shaft 125. One or more banks including a plurality of working chambers arranged radially may be provided in the axial direction along the shaft. The state in which the roller is in contact with the ring cam is maintained by the pressure of the fluid in the low pressure manifold higher than the pressure around the ring cam (therefore, the fluid pressure in the working chamber) or by a spring (not shown). The shaft position / speed sensor 309 detects the instantaneous angular position and rotational speed of the shaft and reports them to the controller 112 via the electrical connection 311. Electrical connection 311 is part of pump drive / pump shaft signal 171. In this way, the controller can determine the instantaneous phase of each working chamber cycle. The controller is typically a microprocessor or microcontroller and executes the stored program used.

  Each working chamber is provided with a low pressure valve (LPV) which is an electrically driven face-sealing type poppet valve 313, and the poppet valve 313 faces inward toward the working chamber, from the working chamber. The channel extending to the low pressure channel 314 is operable to selectively close. The low pressure channel 314 generally functions (in the pumping mode) as a source of fluid (sink in the motoring mode). The low pressure flow path is fluidly connected to the low pressure manifold 135. The LPV passively opens when the pressure in the working chamber is less than the pressure in the low pressure manifold (ie, during the suction stroke) to fluidly connect the working chamber to the low pressure manifold, but the electrical LPV control signal 315. This is a normally open solenoid closed valve that is selectively closed under active control by the controller via (a part of the pump drive / pump shaft signal 171) and disconnects the working chamber from the low pressure manifold. An alternative valve that is normally closed and electrically controllable, such as a solenoid open valve, may be used.

  The working chamber further includes a high pressure valve (HPV, 317) which is a delivery valve driven by pressure. The HPV is operable to close a channel facing outward from the working chamber and extending from the working chamber to the high pressure flow path 319. The high pressure flow path 319 functions as a fluid source or sink and is fluidly connected to the high pressure manifold 133. The HPV functions as a normally closed, pressure-open check valve that opens passively when the pressure in the working chamber exceeds the pressure in the high pressure manifold. The HPV is normally closed, which may be selectively maintained by the controller via the HPV control signal 321 and by the pressure in the working chamber once the HPV is opened. It also functions as a check valve with solenoid open. The HPV may be opened or partially opened under control of the controller when the high pressure manifold is under pressure and the working chamber is not under pressure.

  In the normal mode of operation described in the known literature (for example EP 0361927, EP 0494236 and EP 1537333), the controller typically Actively closes one or more LPVs near the minimum volume point in the associated working chamber cycle and closes the flow path to the low pressure manifold (so that the subsequent contraction stroke causes the HPV to which the fluid in the working chamber is associated). The net transfer rate of the fluid to the high pressure manifold by the hydraulic pump. The controller selects the number and sequence of LPV closing operations to generate a fluid flow or to apply torque to the shaft 322 to achieve a net fluid movement rate selection. In addition to determining whether to keep the LPV closed or open every cycle, the controller changes the working chamber volume to select the net rate of fluid transfer from the low pressure manifold to the high pressure manifold. It is possible to operate so as to precisely change the phase of the closing operation.

FIG. 4 is a time series illustrating the method of the present invention. This time series maintains the rotor speed within an allowable speed range when a serious gust of wind collides with the WTG. Between times t ₀ and t ₁ , the aerodynamic torque T _aero of the wind acting on the blades fluctuates with a slight change in the wind, so the rotor speed _wr and the pressure P _{HP of the} high pressure manifold change slightly. The pump torque T _pump is controlled by adjusting the net rate of fluid movement by the pump, taking into account P _HP , and roughly follows T _aero according to the control algorithm selected by the designer. In t _1, serious gust hits the _{WTG, T aero} rises rapidly. T _pump rises rapidly and restrains the rotor, but because the pressure is too low, it cannot balance T _aero and the rotor is accelerated. However, an increase in T _pump (and excessive rotor speed) will cause the pump to produce more fluid than is absorbed by the motor, and this excess fluid will accumulate in the first and second accumulators, P _HP increases.

In t _2, the controller anticipates that the rotor speed is approaching the too rapid _{w max} (limit value of the allowable speed range of the rotor), the first isolation valve and the second isolation valve (148, 150) Close and block the fluid connection between the high pressure manifold and each accumulator. The closed state of the first separation valve and the second separation valve is indicated by black boxes at 148 ′ and 150 ′ in the figure. At the moment when the fluid connection is interrupted, the controller HP stores the value of the HP pressure signal 154 as the accumulator pressure. Between t ₂ and t ₃ , the pressure in the high pressure manifold rises rapidly due to the generation of excess fluid, and T _pump can rise in a short time towards T _aero . In t _3, when _{the T pump} matches the _{T aero,} rotor speed stably be controlled.

In t _4, in gust _{ceased, T aero} returns to the original level. Between t ₄ and t ₅ , T _pump decreases somewhat, but until t ₅ it remains higher than T _aero to return the rotor speed _wr to its original level. P _HP decreases sharply, at _{t 5,} the controller detects that the HP pressure signal has coincided with the accumulator pressure stored previously, open the two separate valves 148, 150. The P _HP is now decreasing more slowly as fluid flows out of the accumulator. Alternatively, a bleed valve in the isolation valve may operate to speed up accumulator pressure and high pressure manifold convergence.

  The WTG may also close the isolation valve when the controller detects any of several other abnormal events. Other abnormal events include blade problems (stress or vibration beyond acceptable operating range), hydraulic system problems (fluid contamination beyond acceptable operating range, reservoir fluid level or temperature), load problems ( Grid anomaly, grid power outage, voltage or frequency exceeding allowable operating range).

  In some embodiments, the controller sends a pitch drive signal to control the pitch of the blades before, after or simultaneously with interrupting the fluid connection between the high pressure manifold and the accumulator.

  By closing the isolation valve that does not block the flow of fluid between the pump and the motor during normal use, the WTG can use an inexpensive and reliable energy storage device in the present invention. A rapid response to a sudden increase in torque demand is possible while maximizing the power generation efficiency during operation and maintaining power generation throughout the increase in torque demand.

Claims (16)

A method of operating an energy extraction device that extracts energy from a fluctuating energy stream from a renewable energy source, comprising:
The energy extraction device includes:
A hydraulic pump driven by a rotating shaft driven by the renewable energy source and applying torque to the rotating shaft;
A hydraulic motor that drives the load;
A high pressure manifold in fluid communication with an outlet of the hydraulic pump and an inlet of the hydraulic motor and selectively placed in fluid communication with a fluid accumulator;
A low pressure manifold in fluid communication with an outlet of the hydraulic motor and an inlet of the hydraulic pump;
An abnormal event sensor for detecting an abnormal event,
At least one of the hydraulic pump and the hydraulic motor is an electrically controlled variable displacement hydraulic machine, and is provided between a plurality of working chambers whose volumes change periodically, and between each working chamber and each manifold A plurality of valves for adjusting the net displacement of the working fluid, wherein at least one valve associated with each working chamber is an electrically controlled valve, the electrically controlled valve being Selecting the volume of working fluid displaced by each working chamber in each cycle of working chamber volume, thereby adjusting the net displacement of hydraulic fluid by the electrically controlled variable displacement hydraulic machine Was made to work,
An operation method for an energy extraction device, wherein the fluid pressure in the high pressure manifold is increased in response to detection of an abnormal event by blocking fluid communication between the fluid accumulator and the high pressure manifold. .   The method of operating an energy extracting apparatus according to claim 1, wherein the mitigating the abnormal event includes increasing or decreasing a torque to be applied to the rotating shaft by the hydraulic pump. .   In response, fluid communication between the outlet of the hydraulic pump and the inlet of the hydraulic motor is maintained upon detection of an abnormal event that would block fluid communication between the fluid accumulator and the high pressure manifold. The operation method of the energy extraction device according to claim 1, further comprising: The hydraulic motor is an electrically controlled variable capacity hydraulic machine,
The method of operating an energy extraction apparatus according to claim 1, further comprising reducing a net movement rate of the working fluid by the hydraulic motor in response to detection of an abnormal event. The hydraulic pump is the electrically controlled capacity variable hydraulic machine;
The method of operating an energy extraction device according to claim 1, further comprising increasing a net movement rate of the working fluid by the hydraulic pump in response to detection of an abnormal event.   The energy extraction of claim 1, wherein the abnormal event is one or more of an overspeed condition, a gust of wind, an extreme gust of wind, a request to stop the rotating shaft, and an undesirable structural condition. How to operate the device.   7. The abnormal event is detected in response to a calculation that exceeds or is about to exceed an allowable operating range of the energy extraction device. The operation method of the energy extracting device as described in the item.   The allowable operating range includes an allowable speed range, an allowable torque range, an allowable pressure range, an allowable voltage range, an allowable frequency range, and an allowable motion of the energy extraction device. The operation method of the energy extraction device according to claim 7, comprising at least one of the ranges.   The method of claim 1, wherein the fluid accumulator is generally in fluid communication with the hydraulic pump and the hydraulic motor except when responding to detection of an abnormal event. . The fluid accumulator includes a plurality of fluid accumulator modules,
The fluid communication between the plurality of small, but not all, fluid accumulator modules and the high pressure manifold is further responsive to detecting an abnormal event. The operation method of the energy extraction apparatus as described in 2.   The method of claim 1, wherein the renewable energy device further comprises at least one additional fluid accumulator that is in permanent fluid communication with the high pressure manifold.   Detecting that fluid communication between the fluid accumulator and the high pressure manifold is blocked, detecting a first pressure in the high pressure manifold and a second pressure in the fluid accumulator, and detecting the first pressure and the first pressure When the volume of the working fluid moved by each working chamber of at least one of the hydraulic pump and the hydraulic motor is selected so that two pressures converge, and the first pressure and the second pressure satisfy an equality criterion, The operation method of the energy extraction device according to claim 1, further comprising fluidly communicating the fluid accumulator and the high-pressure manifold with each other. The energy extraction device includes a bleed valve provided to bring the pressure of the high pressure manifold and the pressure of the fluid accumulator close to the same value,
When fluid communication between the high pressure manifold and the fluid accumulator is interrupted, the bleed valve is closed and the fluid communication between the high pressure manifold and the fluid accumulator is restored before the fluid communication is restored. The operation method of the energy extraction device according to claim 1, further comprising opening a bleed valve. An energy extraction device for extracting energy from a fluctuating energy stream from a renewable energy source,
A hydraulic pump driven by a rotating shaft driven by the renewable energy source;
A hydraulic motor that drives the load;
A fluid accumulator;
A high pressure manifold in fluid communication with the outlet of the hydraulic pump and the inlet of the hydraulic motor;
At least one low pressure manifold in fluid communication with an outlet of the hydraulic motor and an inlet of the hydraulic pump;
An abnormal event sensor for detecting an abnormal event,
At least one of the hydraulic pump and the hydraulic motor is an electrically controlled variable displacement hydraulic machine, and a plurality of working chambers whose volumes change periodically, and between each working chamber and each manifold. A plurality of valves for adjusting the net displacement of the working fluid, wherein at least one valve associated with each working chamber is an electrically controlled valve, the electrically controlled valve being Selecting the volume of working fluid displaced by each working chamber in each cycle of working chamber volume, thereby adjusting the net displacement of hydraulic fluid by the electrically controlled variable displacement hydraulic machine Was made to work,
The fluid accumulator is selectively fluidly connected to the high pressure manifold via an accumulator adjustment valve to increase the fluid pressure in the high pressure manifold,
The energy extraction device, wherein the accumulator regulating valve is operable to block fluid communication between the fluid accumulator and the high pressure manifold in response to detection of an abnormal event.   Computer software comprising program code that, when executed by a computer, causes the computer to operate a renewable energy device in accordance with the operating method of claim 1. An energy extraction apparatus comprising a computer that is operated according to the operation method according to claim 1 or that executes the computer software according to claim 15.

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