Method for coupling a hydroelectric power plant comprising at least two hydroelectric units to an electrical grid

Abstract

The present invention relates to a method for coupling a hydroelectric power plant in turbine mode to a power grid to generate power for the grid, the hydroelectric power plant comprising at least a first hydroelectric unit (10) and a second hydroelectric unit (100), each of the first hydroelectric unit (10) and the second hydroelectric unit (100) being provided with: a runner (6) mechanically coupled to an axis (8) and mechanically coupled to a generator; a distributor (4) including guide vanes for controlling the flow of water to the runner, the hydroelectric power plant further comprising a variable frequency drive (20), the method comprising: a) starting at least the first hydroelectric unit (10) and the second hydroelectric unit (100) a) Rotating the electric unit (100); b) Connecting the variable frequency drive (20) to the generator of the first hydroelectric power generation unit (10) and connecting it to the power grid, and stabilizing the speed of the first hydroelectric power generation unit; c) Connecting the first hydroelectric power generation unit (10) to the power grid and disconnecting the generator of the first hydroelectric power generation unit from the variable frequency drive (20); d) Connecting the variable frequency drive (20) to the generator of the second hydroelectric power generation unit (100) and connecting it to the power grid, and stabilizing the speed of the second hydroelectric power generation unit; e) Connecting the second hydroelectric power generation unit (100) to the power grid and disconnecting the generator of the second hydroelectric power generation unit from the variable frequency drive (20).

Description

Technical Field

[0001] This invention relates to a method for coupling a hydroelectric power plant to a power grid (including startup in turbine mode and / or switching from pump to turbine mode), and particularly to a type of hydroelectric power plant comprising at least two hydroelectric generating units, each including a rotor capable of being rotated by water. The invention also aims to provide a method for coupling such a hydroelectric power plant to a power grid in a faster manner than existing methods. Background Technology

[0002] To ensure grid stability and / or prevent grid blackouts, a grid balance must be achieved between power generation and power consumption.

[0003] Hydroelectric power plants have electrical power reserves via water stored in a reservoir, which can be provided as needed by starting hydroelectric turbines to compensate for any changes in electrical power consumption and / or production.

[0004] Therefore, the time response used to provide such power reserves is a key factor, based on which power producers can expect more or less favorable remuneration.

[0005] Existing techniques, such as those described in EP3361088, are used to start a turbine by means of a first control loop and a second control loop, one of which includes a variable frequency drive connected to the power grid.

[0006] However, variable frequency drives are expensive devices.

[0007] Furthermore, existing technologies do not provide any solutions for starting up hydroelectric power plants comprising at least two generators. Therefore, the object of the present invention is to propose a method for coupling hydroelectric power plants to the power grid in a faster manner than known prior art methods, particularly a method for coupling hydroelectric power plants of the type comprising at least two hydroelectric generating units to the power grid.

[0008] Moreover, the purpose of this invention is to provide a method for coupling a hydroelectric power plant to a power grid, particularly a method for connecting a hydroelectric power plant of the type comprising at least two hydroelectric generating units to a power grid, which does not require any additional investment. Summary of the Invention

[0009] The above objective is achieved, at least in part, by a method for coupling a hydroelectric power plant in turbine mode to a power grid to generate power to be injected into the grid. The hydroelectric power plant includes at least a first hydroelectric unit and a second hydroelectric unit, each of which provides: a runner mechanically coupled to an axis and mechanically coupled to a generator; and a distributor including guide vanes for controlling the flow of water to the runner. The hydroelectric power plant also includes a variable frequency drive. The method, after initiating rotation of the two hydroelectric units, sequentially includes:

[0010] - Connect the generator of the first hydroelectric power generation unit to the frequency converter drive, and then to the power grid, thereby coupling the first hydroelectric power generation unit in turbine mode to the power grid;

[0011] -Then the generator of the second hydroelectric power generation unit is connected to the frequency converter drive, and then connected to the power grid.

[0012] If the hydroelectric power plant has more than two hydroelectric generating units, the method further includes the following steps after the above steps:

[0013] - Connect the generator of the third hydroelectric power generation unit to the frequency converter drive, and then connect it to the power grid;

[0014] - And then the generators of any other hydroelectric power generation units are connected in sequence to the frequency converter drive, and then connected to the power grid.

[0015] The above method, or a more specific embodiment of a method for coupling a hydroelectric power plant in turbine mode to a power grid to generate or inject power into the grid, wherein the hydroelectric power plant includes at least a first hydroelectric unit and a second hydroelectric unit, each of the first and second hydroelectric units providing: a runner mechanically coupled to an axis and mechanically coupled to a generator; a distributor including guide vanes for controlling the flow of water to the runner; the hydroelectric power plant further including a variable frequency drive; and the method comprising at least the following in order:

[0016] a) Initiate the rotation of at least the first and second hydroelectric power generation units;

[0017] b) Connect the generator of the first hydroelectric power generation unit to the frequency converter and stabilize the speed of the first hydroelectric power generation unit;

[0018] c) Connect the generator of the first hydroelectric power generation unit to the power grid, and disconnect the generator of the first hydroelectric power generation unit from the frequency converter drive;

[0019] d) Connect the generator of the second hydroelectric power generation unit to the frequency converter and stabilize the speed of the second hydroelectric power generation unit;

[0020] e) Connect the generator of the second hydroelectric power generation unit to the power grid, and disconnect the second hydroelectric power generation unit from the frequency converter drive.

[0021] Any of the above methods, or another specific embodiment of a method for coupling a hydroelectric power plant in turbine mode to a power grid to generate or inject power into the power grid, wherein the hydroelectric power plant includes at least a first hydroelectric unit and a second hydroelectric unit, each of the first and second hydroelectric units providing: a runner mechanically coupled to an axis and mechanically coupled to a generator; a distributor including guide vanes for controlling the flow of water to the runner, the hydroelectric power plant further including a variable frequency drive, and the method comprising at least:

[0022] a) Initiate the rotation of at least the first and second hydroelectric power generation units;

[0023] b) Then connect the generator of the first hydroelectric power generation unit to the frequency converter and stabilize the speed of the first hydroelectric power generation unit;

[0024] c) Then connect the generator of the first hydroelectric power generation unit to the power grid and disconnect the generator of the first hydroelectric power generation unit from the frequency converter drive;

[0025] d) Then connect the generator of the second hydroelectric power generation unit to the frequency converter and stabilize the speed of the second hydroelectric power generation unit;

[0026] e) Then connect the generator of the second hydroelectric power generation unit to the power grid and disconnect the second hydroelectric power generation unit from the frequency converter drive.

[0027] In any of the above embodiments of the method according to the invention, step a) or the step of initiating the rotation of the two hydroelectric power generation units may include partially opening the guide vanes of the distributors of the first and second hydroelectric power generation units.

[0028] The variable frequency drive is shared by two or all hydroelectric power generation units.

[0029] After step c), or after the step of connecting the generator of the first hydroelectric power generation unit to the grid, and / or after step e), or after the step of connecting the generator of the second hydroelectric power generation unit to the grid, the guide vanes of the distributors of the first hydroelectric power generation unit and / or the second hydroelectric power generation unit may be further opened.

[0030] In a particular embodiment, during a portion of the time span between the start of step a) (or the start of rotation of the two hydroelectric generating units) and the start of step c) (or the start of the connection step of the generator of the first hydroelectric generating unit to the grid), the guide vanes of the distributor of the first hydroelectric generating unit are more open than the guide vanes of the distributor of the second hydroelectric generating unit.

[0031] Preferably, the second hydropower generation unit is connected to the frequency converter drive less than 20s or 25s after the first hydropower generation unit is connected to the power grid.

[0032] The present invention also relates to a hydroelectric power plant comprising at least a first hydroelectric power generation unit and a second hydroelectric power generation unit, each of the first and second hydroelectric power generation units being provided with a runner mechanically coupled to an axis and mechanically coupled to a generator, and including a distributor comprising guide vanes for controlling the flow of water to the runner. The power plant also includes a frequency converter and a controller for coupling the hydroelectric power plant to a power grid to implement, for example, the method according to the present invention as described above.

[0033] In the method according to the present invention:

[0034] - The opening of the guide vanes of the distributor of the first hydroelectric power generation unit and / or the second hydroelectric power generation unit or any other hydroelectric power generation unit can be controlled by the first control loop;

[0035] - and / or particularly during steps b) and / or c) and / or d) and / or e), or during the step of connecting the generator of the first hydroelectric power generation unit to the variable frequency drive and then to the power grid, and / or during the step of connecting the generator of the second hydroelectric power generation unit to the variable frequency drive and then to the power grid, the variable frequency drive may be controlled by the second control loop.

[0036] The hydroelectric power plant may include at least a third hydroelectric power generation unit, the third hydroelectric power generation unit further comprising: a runner mechanically coupled to an axis and mechanically coupled to a generator; a distributor including guide vanes for controlling the water flow to the runner of the third hydroelectric power generation unit, the method further comprising:

[0037] a') Start the rotation of the third hydropower unit together with or simultaneously with the first and second hydropower units;

[0038] b') After step e) (or after connecting the generator of the second hydroelectric power generation unit to the grid), connect the frequency converter to the generator of the third hydroelectric power generation unit and connect it to the grid, and stabilize the speed of the third hydroelectric power generation unit;

[0039] c') Then connect the third hydroelectric power generation unit to the power grid and disconnect the generator of the third hydroelectric power generation unit from the frequency converter drive.

[0040] The guide vanes of the distributor of the third hydroelectric power generation unit can be further opened after step c').

[0041] During step b'), the variable frequency drive can be controlled by a second control loop including the variable frequency drive.

[0042] The present invention also relates to a hydroelectric power plant comprising at least a first hydroelectric power generation unit and a second hydroelectric power generation unit, each of the first and second hydroelectric power generation units being provided with a runner mechanically coupled to an axis and mechanically coupled to a generator, and including a distributor comprising guide vanes for controlling the water flow to the runner, the power plant further comprising a frequency converter and a controller.

[0043] The controller can be configured, and the hydroelectric power plant can be used to implement the method according to the invention.

[0044] In a hydroelectric power plant or method according to the present invention, each hydroelectric power generation unit includes a turbine, which may be of the Francis or Kaplan or bulb or Pelton or reversible Francis or pump turbine type.

[0045] According to the method of the present invention or a specific embodiment of a hydroelectric power plant:

[0046] - The first hydroelectric power generation unit and / or the second hydroelectric power generation unit are connected to the frequency converter drive via the first connecting component and / or the second connecting component; and / or:

[0047] - The first hydroelectric power generation unit and / or the second hydroelectric power generation unit are connected to the power grid via a third connecting component and / or a fourth connecting component; and / or:

[0048] - The frequency converter is connected to the power grid via a fifth connection component.

[0049] In the hydroelectric power plant according to the present invention, each hydroelectric power generation unit may include:

[0050] - First control loop, which is used to control the opening of the guide vanes;

[0051] - A second control loop, which is used to control a frequency converter shared by all hydropower units of the hydropower plant.

[0052] An embodiment of a hydroelectric power plant according to the invention may include at least a third hydroelectric power generation unit, the third hydroelectric power generation unit further comprising: a runner mechanically coupled to an axis and mechanically coupled to a generator; a distributor including guide vanes for controlling the water flow to the runner of the third hydroelectric power generation unit, the frequency converter and the controller being configured to couple the hydroelectric power plant to a power grid in order to implement the method according to the invention for coupling the hydroelectric power plant to a power grid in turbine mode, the hydroelectric power plant including at least a third hydroelectric power generation unit.

[0053] The present invention also relates to a hydroelectric power plant comprising a plurality of hydroelectric generating units, each hydroelectric generating unit being provided with a runner mechanically coupled to an axis and mechanically coupled to a generator, and including a distributor comprising guide vanes for controlling the water flow to the runner. The power plant also includes a frequency converter and a controller, and each of the turbines further includes...

[0054] - First control loop, which is used to control the opening of the guide vanes;

[0055] - A second control loop, which is used to control the variable frequency drive, which is shared by all hydropower units of the hydropower plant.

[0056] The controller can be configured, and the hydroelectric power plant can be used to implement the method according to the invention.

[0057] The hydroelectric power plant may also include the above-described features of the power plant according to the present invention.

[0058] The present invention also relates to a computer program comprising instructions for implementing, for example, the method according to the invention as described above.

[0059] This invention allows for a reduction in time response, defined as the time between receiving a command to provide a given power level to the grid and the moment that power level is provided to the grid. Attached Figure Description

[0060] Referring to the accompanying drawings, other features and advantages will become apparent in the following description of embodiments of the method according to the invention for coupling a hydroelectric turbine to a power grid, given by way of non-limiting example, wherein:

[0061] - Figure 1 It is a schematic representation of a hydroelectric power generation unit that includes a water turbine;

[0062] - Figure 2 This is a schematic representation of a frequency converter that can be used in conjunction with the present invention;

[0063] - Figure 3 This is a schematic representation of the connection of the variable frequency drive between the hydroelectric power generation unit and the power grid.

[0064] - Figure 4 This is a schematic representation of a hydroelectric power plant that includes two hydraulic power generation units and associated frequency converters and switches;

[0065] - Figures 5A-5C and Figures 6A-6C The illustration shows different steps of a method for coupling a hydroelectric power plant to a power grid according to the present invention.

[0066] - Figure 7A and 7B It is according to the present invention ( Figure 7A ) and according to existing technology ( Figure 7B A timing diagram of the startup sequence of a hydroelectric power plant. Detailed Implementation

[0067] Figure 1 The diagram illustrates an example of a hydroelectric power generation unit (pump-turbine) 10 that can be used within the framework of this invention. The hydroelectric power generation unit can be implemented in a hydroelectric power plant having a storage tank located upstream of the plant and a storage tank located downstream of the plant. It can be used as a pump to pump water from the downstream side of the plant to the upstream side. Alternatively, it operates in turbine mode to generate electricity for the power grid based on the head difference between the upstream and downstream storage tanks.

[0068] The hydroelectric power generation unit 10 includes a runner 2, a distributor 4, a tailrace pipe 6, and a shaft 8. The spiral casing 12 directs water flow from a pipe 13 connected to the main inlet valve 14 to the distributor downstream of the penstock.

[0069] The rotor 2 is mechanically coupled to the generator rotor via shaft 8; when rotating, the rotor drives the rotor to rotate within the stator windings. The stator windings themselves are connected to the power grid via circuit breakers and transformers.

[0070] Distributor 4 includes guide vanes and is impermeable in the closed position.

[0071] The main inlet valve 14 can be, for example, a ball valve or a butterfly valve. Both valves require a certain amount of time to open, for example, 30 seconds, which can include 5 to 10 seconds, to balance the pressure between the upstream and downstream sides of the valve, for example, by opening one or more bypass pipes 17. After this pressure balance, valve 14 can be opened.

[0072] As disclosed in EP3361088, the variable frequency drive can be used to assist the start-up mode of pump-turbine 10 in turbine mode.

[0073] Electrical torque can be provided by a variable frequency drive of an alternator connected to the power grid and the hydraulic machine 10; it includes, for example, a static frequency converter, which can be a voltage source inverter or a current source inverter. Figure 2 An example of a variable frequency drive 20 is given above: it is a static frequency converter, including a rectifier and an inverter; the static frequency converter includes a network of thyristors that converts current from the power grid at a fixed frequency (50 Hz in this example) into current at a variable frequency; it forms a controlled electric torque provider that operates at a variable frequency.

[0074] As from Figure 3 As can be understood, the static frequency converter 20 can be connected to the turbine's generator and can be connected to the power grid at a fixed frequency (50Hz in this example) via the first connection component or switch 26. The turbine's generator can also be connected to the power grid via the second connection component or switch 28 (or generator circuit breaker). The third switch 29 has connections with switches 32 and 34 ( Figure 4 For the same purpose, switches 32 and 34 are used to connect / disconnect each hydroelectric power generation unit to / from the frequency converter 20.

[0075] Including 2 (or more) hydroelectric power generation units 10, 100 ( Figure 4 In a hydroelectric power plant, a single shared frequency converter 20 can be used for two (or all) generators. Each generator is connected to the frequency converter 20, for example, via corresponding connection components or switches 32, 34 (so-called starting disconnect switches), and connected to the power grid via two other connection components or switches 42, 44 (so-called generator circuit breakers) and two transformers 43, 45. The frequency converter 20 itself can be connected to the power grid via connection components or switches 46. Each connection component or switch may include one or more IGBTs (Insulated Gate Bipolar Transistors). Figure 1 Example of describing hydropower unit 10; hydropower unit 100 (and any additional hydropower unit when the plant has more than 2 hydropower units) is the same as hydropower unit 10.

[0076] The rotational speed of the hydroelectric power generation units 10 and / or 100 is controlled by a first control loop 21 and / or 121, which controls the orientation of the guide vanes of the corresponding machine based on the difference between a target speed N10_sp and / or N100_sp and the corresponding machine rotational speed N10 and / or N100. The rotational speed can be measured using a speed sensor, for example, using an inductive sensor positioned opposite to the gear; alternatively, the speed measurement can be obtained by converting a frequency signal (obtained from the secondary winding of the voltage transformer of the main generator). The first control loop 21 and / or 121 includes guide vane controllers 22 and / or 122 and guide vane actuators 24 and / or 124, which provide guide vane orientation for the guide vanes of the hydroelectric power generation units 10 and / or 100. 10 and / or 100. The first control loop 21 and / or 121 provides coarse adjustment. If the plant has more than two hydroelectric generating units, any additional hydroelectric generating unit also has a first control loop similar to control loop 21 or 121.

[0077] The second control loops 23 and 123 control the electrical torque of the variable frequency drive 20 via the variable frequency drive controller 36 (which is shared by both loops 23 and 123). The input to this second control loop is the difference between the measured rotational speeds N10 and N100 and the target rotational speeds N10_sp and N100_sp. The second control loops 23 and / or 123 provide fine-tuning.

[0078] Control loops 21, 121, 23, and 123 will not be present. Figures 5A-6C As shown above, but included Figures 5A-6C The above refers to a hydroelectric power plant.

[0079] Examples of methods according to the invention will now be described, particularly examples of methods for coupling hydroelectric power plants to the power grid as described above.

[0080] In this example, the method is used to couple a hydroelectric power plant, or each of two hydroelectric power generation units 10, 100 of a hydroelectric power plant, to the power grid, so that the power plant generates maximum power in the shortest possible time.

[0081] Each hydroelectric power generation unit 10, 100 is driven to rotate in turbine mode, wherein water flows from an upstream storage tank to a downstream storage tank. Preferably, both hydroelectric power generation units 10, 100 are driven to rotate simultaneously. The guide vanes of each turbine are controlled by each of the first control loops 21, 121 and are partially opened, and the speed of each turbine gradually increases.

[0082] The speed of the first hydroelectric power generation unit 10 is stabilized by the variable frequency drive 20 (via the second control loop 23), allowing the first hydroelectric power generation unit to be directly connected to the power grid. In other words, the speed of the first hydroelectric power generation unit becomes equal to the speed required to generate power at the frequency of the power grid (e.g., 50 Hz).

[0083] Then, the speed of the second hydroelectric power generation unit 100 is stabilized by means of the frequency converter 20 (via the second control loop 123), so that the second hydroelectric power generation unit can be directly connected to the power grid. In other words, the speed of the second hydroelectric power generation unit becomes equal to the speed required to generate power at the frequency of the power grid (e.g., 50Hz).

[0084] The inventors have noticed that directly connecting the first hydroelectric power generation unit to the power grid causes a disturbance in the speed of the second hydroelectric power generation unit 100 (as described above, the second hydroelectric power generation unit 100 is driven to rotate simultaneously with the first hydroelectric power generation unit). Therefore, after the first hydroelectric power generation unit is connected to the power grid, the speed of the second hydroelectric power generation unit is stabilized as quickly as possible by a frequency converter driver.

[0085] Now combine Figures 5A-5C and Figures 6A-6C Let me elaborate on the different steps of this example in more detail.

[0086] Two hydroelectric generating units 10 and 100 are simultaneously driven to rotate, and the guide vanes of each of them are controlled by control loops 21 and / or 121.

[0087] like Figure 5A As illustrated above, one of the connecting components 32 and 34 (e.g., 32) is initially switched on in a conductive state to connect the corresponding hydroelectric power generation unit 10 to the frequency converter 20, which itself is connected to the power grid via connecting component 46. Therefore, when the speed of the hydroelectric power generation unit 10 exceeds the upper limit of the coupling range, the frequency converter 20 can reduce the rotational speed of the hydroelectric power generation unit 10 (through loop 23). When its speed has reached the specified speed target corresponding to the power grid frequency, connecting component 42 can be switched on in a conductive state, thereby connecting the hydroelectric power generation unit 10 to the power grid. Figure 5B Then you can disconnect connecting parts 32 and 46. Figure 5C It must be noted that after the connection component 42 is turned on, the guide vanes of the first hydroelectric power generation unit 10 (like those of the second hydroelectric power generation unit 100) are only partially opened, and then gradually opened until the power generated by the hydroelectric power generation unit 10 is at the expected level (or set point), such as at maximum power.

[0088] Then the connection component 34 can be connected to connect the corresponding hydroelectric power generation unit 100 to the frequency converter 20, which itself is connected to the power grid via the connection component 46. Figure 6A It must be noted that disconnecting connection component 32 and connecting connection component 34 may take some time, for example, between 10 and 20 seconds, such as 16 seconds. The variable frequency drive 20 reduces the rotational speed of the hydroelectric power generation unit 100 (via loop 123) when the speed of the hydroelectric power generation unit 100 exceeds the upper limit of the coupling range. When the speed has reached the specified speed target corresponding to the grid frequency, connection component 44 can be switched on in the conducting state, thereby connecting the hydroelectric power generation unit 100 to the grid. Figure 6B Then you can disconnect connecting parts 34 and 46. Figure 6C It must be noted that after the connection device 44 is turned on, the guide vanes of the second hydroelectric power generation unit 100 are only partially opened, and gradually opened until the power generated by the generator 100 is at its maximum.

[0089] As described above, the connection component 42 for connecting the first hydroelectric power generation unit 10 to the power grid is activated. Figure 5B This causes a disturbance to the speed of the second hydroelectric power generation unit 100. Therefore, after the connection part 42 is switched on to connect the hydroelectric power generation unit 10 to the power grid, the connection part 32 is switched off and the connection part 34 is switched on as quickly as possible. Due to the switching time, the second hydroelectric power generation unit 100 is coupled to the frequency converter 20 only after 10 to 20 seconds.

[0090] Figure 7A This is a simplified diagram illustrating several parameters of the first hydroelectric power generation unit 10 and the second hydroelectric power generation unit 100 when the method according to the invention is implemented:

[0091] -S1 and / or S2 represent the speeds of the first hydroelectric power generation unit and / or the second hydroelectric power generation unit;

[0092] -GV1 and / or GV2 are the opening of the guide vanes of the first hydroelectric power generation unit and / or the second hydroelectric power generation unit;

[0093] - P1 and / or P2 are the power generated by the first hydroelectric power generation unit and / or the second hydroelectric power generation unit.

[0094] Upon receiving the start command, both hydroelectric generating units are driven to rotate at the same time t1, and the guide vanes of both units rapidly partially open as illustrated by curves GV1 and GV2. The speed of the two hydroelectric generating units thus increases from t1. For example, after receiving the start command, some seconds later (in... Figure 7AIn the example: at approximately 20 seconds, coupling the first hydroelectric generator unit to the frequency converter allows for early speed stabilization and early coupling of the first hydroelectric generator unit to the grid. Figure 7A (U1 coupling at approximately 37s).

[0095] As can be understood from this simplified diagram, according to a particular embodiment, shortly after t1, between t1 (the start-up of both turbines) and the connection of the first hydroelectric unit to the grid (“U1 coupling”), or shortly after the start-up of the rotation of both hydroelectric units, GV1 may be more open than GV2. This dynamic opening of the guide vanes of the first hydroelectric unit can disrupt its speed, and the variable frequency drive 20 absorbs hydraulic fluctuations during its coupling. Alternatively, it is possible to have both GV1 and GV2 open at the same time.

[0096] The first hydroelectric power generation unit generates power P1, which is injected into the power grid via the frequency converter 20. Alternatively, the first hydroelectric power generation unit absorbs power from the power grid. In both cases, after the hydroelectric turbine is coupled to the power grid ("U1 coupling"), the power generated by the first hydroelectric power generation unit increases together with the further opening of the guide vanes GV1.

[0097] As in Figure 7A As can be seen above, the increased load ramp from the first generator to the grid causes a drop in pressure for both machines, and in particular causes a disturbance in the speed S2 of the second hydroelectric unit: curve S2 shows the dip angle (dip) D shortly after the coupling at U1. However, after the second hydroelectric unit is coupled to the frequency converter 20 (in Figure 7A In the example: at approximately 53 seconds, S2 is stable, which then allows the second hydroelectric power generation unit to couple to the power grid ("U2 connection"). The second hydroelectric power generation unit generates power P2 that is injected into the power grid via a frequency converter driver. Alternatively, the second hydroelectric power generation unit absorbs power from the power grid. In both cases, after the second hydroelectric power generation unit is coupled to the power grid, the power generated by the second hydroelectric power generation unit increases together with the further opening of the guide vane GV2.

[0098] The total power generated by the two hydroelectric generating units together is P1 + P2. Full power is generated approximately 60 seconds after t1, during which P1 + P2 approaches its maximum value.

[0099] Figure 7B This is a simplified diagram showing the same parameters S1, S2, GV1, GV2, P1, and P2 of the first hydroelectric power generation unit 10 and the second hydroelectric power generation unit 100 when the start-up method according to the prior art is implemented without a frequency converter.

[0100] Due to the lack of a variable frequency drive, the initial opening of the guide vane GV1 of the turbine 10 of the first hydroelectric power generation unit is less than that at... Figure 7A Open it.

[0101] The coupling of the first hydroelectric power generation unit 10 ("U1 Coupling") was also later than... Figure 7A Coupling on.

[0102] As in Figure 7A The coupling between the first hydroelectric power generation unit and the power grid causes a disturbance in the speed S2 of the second hydroelectric power generation unit. However, due to the lack of a frequency converter, S2 is less affected than in the above-mentioned units. Figure 7A S2 stabilizes later, and the coupling of the second hydroelectric unit to the grid ("U2 coupling") also occurs later (around 80s).

[0103] In the above example, the plant system includes two hydroelectric power generation units. However, the invention is also applicable to plants including, for example, three or four hydroelectric power generation units connected to a common frequency converter drive. A third (and / or fourth) hydroelectric power generation unit may be started simultaneously with the first and second hydroelectric power generation units (and possibly a third hydroelectric power generation unit), but the second (and / or third) hydroelectric power generation unit is connected to the power grid. Figure 5A Following the U2 coupling (as described above) and while the guide vanes of the third (and / or fourth) hydroelectric power generation unit are in the process of further opening, the third (and / or fourth) hydroelectric power generation unit will be connected to the frequency converter drive. In other words, the same sequence of steps described above for the first hydroelectric power generation unit for the second generator can be applied to the third (and / or fourth) hydroelectric power generation unit, etc., for the second hydroelectric power generation unit (and / or this third hydroelectric power generation unit).

[0104] Figure 4 The system, and especially the frequency converter 20, the on / off connection of the connecting parts, the main inlet valve ( Figure 1 The opening and closing of reference numeral 14) and the opening and closing of the guide vanes of the two hydroelectric generating units are controlled by one or more processors or computers 16, or by a computer system configured or programmed to implement the method according to the invention, in particular, in sequence:

[0105] - Initially, two hydroelectric power generation units, 10 and 100, were started, and their speed was increased;

[0106] - Connect the frequency converter 20 to the first hydroelectric power generation unit 10 in order to stabilize the speed of the first hydroelectric power generation unit 10;

[0107] - Connect the first hydroelectric power generation unit to the power grid;

[0108] - Connect the frequency converter 20 to the second hydroelectric power generation unit 100 in order to stabilize the speed of the second hydroelectric power generation unit 100;

[0109] - Connect the second hydroelectric power generation unit to the power grid.

[0110] For example, the processor(s) or computer(s) 16 or the computer system(s) implement a computer program including instructions for implementing the method according to the invention.

[0111] In a particular embodiment, a computer system implementing the method according to the invention includes a central control system that oversees one or more controllers, each of which controls a portion of a hydroelectric power plant comprising two or more hydroelectric generating units.

[0112] This invention proposes a method for coupling a hydroelectric power plant comprising two or more hydroelectric generating units to a power grid in a faster manner than known prior art methods. This reduces the time required to connect the hydroelectric power plant to the power grid.

Claims

1. A method for coupling a hydroelectric power plant in turbine mode to a power grid to generate power for the power grid, the hydroelectric power plant comprising at least a first hydroelectric unit (10) and a second hydroelectric unit (100), each of the first hydroelectric unit (10) and the second hydroelectric unit (100) being provided with: a runner (6) mechanically coupled to an axis (8) and mechanically coupled to a generator; a distributor (4) including guide vanes for controlling water flow to the runner, the hydroelectric power plant further comprising a variable frequency drive (20), the method comprising: a) Initiate rotation of at least the first hydroelectric power generation unit (10) and the second hydroelectric power generation unit (100); b) Connect the variable frequency drive (20) to the generator of the first hydroelectric power generation unit (10) and connect it to the power grid, and stabilize the speed of the first hydroelectric power generation unit; c) Connect the first hydroelectric power generation unit (10) to the power grid and disconnect the generator of the first hydroelectric power generation unit from the frequency converter (20); d) Connect the variable frequency drive (20) to the generator of the second hydroelectric power generation unit (100) and to the power grid, and stabilize the speed of the second hydroelectric power generation unit; e) Connect the second hydroelectric power generation unit (100) to the power grid and disconnect the generator of the second hydroelectric power generation unit from the frequency converter (20).

2. The method as described in claim 1, wherein, Step a) includes partially opening the guide vanes of the first hydroelectric power generation unit (10) and the second hydroelectric power generation unit (100).

3. The method as described in claim 1 or 2, wherein, After step c), the guide vanes of the first hydroelectric power generation unit (10) are further opened.

4. The method as described in any one of claims 1 to 2, wherein, The guide vanes of the second hydroelectric power generation unit (100) are further opened after step e).

5. The method as described in any one of claims 1 to 2, wherein, During a portion of the time span between the start of step a) and the start of step c), the guide vanes of the first hydroelectric power generation unit (10) are more open than the guide vanes of the second hydroelectric power generation unit (100).

6. The method as claimed in any one of claims 1 to 2, wherein, The generator of the second hydroelectric power generation unit (100) is connected to the frequency converter (20) less than 20 seconds after the first hydroelectric power generation unit (10) is connected to the power grid.

7. The method as described in any one of claims 1 to 2, wherein: - The generator of the first hydroelectric power generation unit (10) and / or the second hydroelectric power generation unit (100) can be connected to the frequency converter (20) via the first connecting part (32) and / or the second connecting part (34); and / or: - The generator of the first hydroelectric power generation unit (10) and / or the second hydroelectric power generation unit (100) can be connected to the power grid via the third connecting component (42) and / or the fourth connecting component (44); - The variable frequency drive (20) can be connected to the power grid via the fifth connection component (46).

8. The method as described in any one of claims 1 to 2, wherein: - The opening of the guide vanes of each of the first hydroelectric power generation unit (10) and the second hydroelectric power generation unit (100) is controlled by the first control loop (21, 121); - The variable frequency drive (20) is controlled by the second control loop (23, 123) during each step in steps b) and e).

9. The method of any one of claims 1 to 2, wherein the hydroelectric power plant comprises at least a third hydroelectric power generation unit, the third hydroelectric power generation unit further comprising: a runner mechanically coupled to an axis and mechanically coupled to a generator; The method further includes: a distributor comprising guide vanes for controlling the flow of water to the turbine of the third hydroelectric power generation unit; and a distributor comprising: a') Together with the first hydroelectric power generation unit (10) and the second hydroelectric power generation unit (100), the rotation of the third hydroelectric power generation unit is initiated; b') After step e), the frequency converter (20) is connected to the generator of the third hydroelectric power generation unit and connected to the power grid, and the speed of the third hydroelectric power generation unit is stabilized; c') Connect the third hydroelectric power generation unit to the power grid and disconnect the generator of the third hydroelectric power generation unit from the frequency converter (20).

10. The method of claim 9, wherein, The guide vanes of the third hydroelectric power generation unit are further opened after step c').

11. A hydroelectric power plant comprising at least a first hydroelectric unit (10) and a second hydroelectric unit (100), each of the first hydroelectric unit (10) and the second hydroelectric unit (100) being provided with a runner (6) mechanically coupled to an axis (8) and mechanically coupled to a generator, and including a distributor (4) comprising guide vanes for controlling the flow of water to the runner, the hydroelectric power plant further comprising a frequency converter (20) and a controller (16) configured to start the hydroelectric power plant to implement the method as claimed in any one of claims 1 to 8.

12. The hydroelectric power plant as described in claim 11, wherein, Each of the hydroelectric power generation units includes a turbine of the Francis or Kaplan or bulb or Pelton or reversible Francis or pump turbine type.

13. The hydroelectric power plant as described in claim 11 or 12, wherein, Each of the hydroelectric power generation units (10, 100) includes: - First control loop (21, 121), the first control loop (21, 121) is used to control the opening of the guide vane; - Second control loop (23, 123), which is used to control the variable frequency drive (20) shared by all hydroelectric power generation units (10, 100).

14. The hydroelectric power plant of any one of claims 11 to 12, comprising at least a third hydroelectric power generation unit, the third hydroelectric power generation unit further comprising: a runner mechanically coupled to an axis and mechanically coupled to a generator; a distributor comprising guide vanes for controlling the flow of water to the runner of the third hydroelectric power generation unit, the frequency converter (20) and the controller (16) being configured to implement the method of claim 9 or 10 to couple the hydroelectric power plant to the power grid.

15. A computer program comprising instructions for implementing the method as claimed in any one of claims 1 to 10.

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