DE102022102237B3 - Pelton Turbine and Operating Procedures - Google Patents

Abstract

Pelton turbine comprising an impeller (1) and several adjustable nozzles (2.1, 2.2) in two groups, and wherein the at least one nozzle of the first group has a larger diameter than the at least one nozzle of the second group, and the Pelton turbine has a control device (3) which is designed in such a way that it can control a water flow through the nozzles as a function of control parameters in normal operation, and wherein the control device is designed in such a way that it controls the water flow through the nozzles in a first predefined control parameter range of normal operation can ensure that water flows through the at least one nozzle of the first group and no water flows through the at least one nozzle of the second group, and that it can control the water flow through the nozzles in a second predefined control parameter range of normal operation in such a way that water flows through the at least one nozzle the second group flows through, and no water, the at least one nozzle flows through the first group.

Description

The invention relates to a Pelton turbine and an operating method for operating the turbine.

Pelton turbines are known from the prior art. For example, the DE 10 2010 024 475 A1 such a turbine. The disclosed Pelton turbine includes an impeller having a plurality of buckets and at least two nozzles for applying a jet of water to the buckets. The jets usually have a mechanism for regulating the flow of water through the jets. The Pelton turbine disclosed in the document mentioned has a horizontal axis of rotation. However, most Pelton turbines are designed with a vertical axis of rotation. In ordinary Pelton turbines, all nozzles are designed in the same way, ie they have the same outlet diameter.

From the FR 2 137 359 A1 a Pelton turbine has become known which includes an auxiliary nozzle which has a smaller outlet diameter than the other nozzles. The auxiliary jet is used for turbine run-up and for fine adjustment of the turbine to synchronous speed. In addition, the auxiliary nozzle is used along with the other nozzles during normal operation.

Typically, Pelton turbines include a synchronous generator for power generation. This means that the regulation must be carried out in such a way that the impeller connected to the generator always rotates at the synchronous speed. There are also Pelton turbines, which include an asynchronous generator for power generation. The impeller can then rotate at speeds within a predefined range. The control parameters for setting the nozzle opening are the inlet pressure of the driving water and the power dissipated at the generator. Efficient operation of a Pelton turbine is possible within certain control parameter ranges. This range is referred to as the operating range of the turbine. I.e. the control parameters can also be referred to as operating parameters.

The object of the invention is to specify a Pelton turbine which can be operated efficiently in a larger operating range than comparable known Pelton turbines.

The object is achieved according to the invention by an embodiment corresponding to the independent claim. Further advantageous embodiments of the present invention can be found in the dependent claims.

• 1 Pelton Turbine gemäß dem Stand der Technik;
• 2 Erfindungsgemäße Pelton Turbine;
• 3 Düsen und Düsendurchmesser;
• 4 Erfindungsgemäße Pelton Turbine in einer weiteren Ausführungsform;
• 5 Erfindungsgemäße Pelton Turbine mit Generator.

The invention is explained below with reference to figures. The figures show in detail:

• 1 Prior art Pelton turbine;
• 2 Pelton turbine according to the invention;
• 3 nozzles and nozzle diameter;
• 4 Pelton turbine according to the invention in a further embodiment;
• 5 Pelton turbine with generator according to the invention.

1 shows a Pelton turbine according to the prior art in a schematic representation. The Pelton turbine comprises an impeller, indicated at 1, which comprises a plurality of buckets. Furthermore, the Pelton turbine includes several nozzles, one of which is denoted by 2 . The nozzles 2 are arranged in such a way that the water jets emerging from the nozzles 2 hit the cups of the impeller 1 and can thus drive the impeller 1 . The nozzles 2 are adjustable, ie they include a so-called needle, which can be moved back and forth. This allows the water flow through the relevant nozzle to be adjusted. In 1 the needles are indicated by the tips at the end of the nozzles 2.

For the sake of simplicity, the following description of the Pelton turbine according to the invention is based on the boundary condition that the output of the turbine should remain constant, i.e. that the only free control parameter is the water inlet pressure.

This means that everything that is said below about the inlet pressure must generally be translated to all freely variable control parameters.

For a given water inlet pressure, the water flow through the nozzles 2 is proportional to the power transported by the water. On the other hand, for a given water flow, the power is proportional to the water inlet pressure. This means that there is a change in the water inlet pressure by changing the water flow through the nozzles 2, ie by adjusting the needles, can be compensated if the performance is to remain constant.

The pressure range [p _min , p _max ] (ie the water inlet pressure range - in the following for the sake of brevity "water inlet pressure" is used for the sake of brevity) that can be compensated in this way depends on the following factors. At the minimum pressure p _min, the nozzles 2 are fully opened. Therefore, the diameter and the number of nozzles 2 are designed in such a way that at p _min the desired water flow can flow through the nozzles. As mentioned, as the pressure increases, the nozzles are gradually closed by moving the needles forward. Eventually, a point is reached where the jet quality is so badly affected by the needles in the jet that the efficiency of the turbine is significantly reduced. The maximum pressure p _max is therefore given by the fact that the required efficiency of the turbine can no longer be guaranteed if the maximum pressure is exceeded.

The inventors have recognized that the pressure range in which the turbine can still be operated efficiently can be increased by using nozzles with different diameters, as will be explained in more detail below.

2 shows a Pelton turbine according to the invention in a schematic representation. In contrast to 1 the Pelton turbine comprises two groups of nozzles with different diameters. In the 2 The embodiment shown comprises a first group of five larger diameter nozzles, one of which is denoted 2.1, and a second group of smaller diameter nozzles. The second group includes only one nozzle, which is denoted by 2.2. The second group could just as well include more than one nozzle. Nozzles that belong to one and the same group have the same diameter, and nozzles that belong to different groups have different diameters.

The Pelton turbine according to the invention comprises a control device, which is denoted by 3 and which is designed in such a way that it can control the water flow through the nozzles of the two groups so that in a first predefined pressure range water flows through the nozzles of the first group and no water flows through the Nozzles of the second group flows, and that in a second predefined pressure range, water flows through the nozzles of the second group and no water flows through the nozzles of the first group. In this case, the two predefined pressure ranges adjoin one another, and the transition from the first to the second pressure range is given by a predefined pressure p ₀ . p ₀ is, so to speak, the switching pressure at which the water flow is switched from the first to the second group of nozzles (and vice versa). Water flows through the nozzles of the first group at lower pressures and through the nozzles of the second group at higher pressures.

It should be mentioned that the switching process described relates to normal operation of the Pelton turbine according to the invention. In the initially described FR 2 137 359 A1 the switching process between the auxiliary nozzle and the other nozzles does not take place during normal operation, but rather when the turbine is started up and synchronized. Normal operation of the turbine only begins after these processes have been completed. According to the FR 2 137 359 A1 the auxiliary nozzle can either be switched off permanently during normal operation or used permanently together with the other nozzles in order to increase performance.

Optionally, there can also be a pressure range in which water flows through all nozzles, ie both through the nozzles of the first group and through the nozzles of the second group. This can be an advantage for small pressures. In this case there is another predefined switching pressure p ₁ , and the control device 3 is designed in such a way that it can set the following states: print area ... water flow ... p _min to p ₁ through all nozzles p ₁ to p ₀ only through the nozzles of the first group p ₀ to p _max only through the nozzles of the second group

Without this optional pressure range with water flow through all nozzles, the following conditions result: print area ... water flow ... p _min to p ₀ only through the nozzles of the first group p ₀ to p _max only through the nozzles of the second group

The Pelton turbine according to the invention can be operated more efficiently at higher pressures than a comparable Pelton turbine of conventional design, since the nozzles with a smaller diameter can provide a jet of good quality even with smaller water flows and thus higher pressures.

The invention is not limited to two groups of nozzles, i.e. in principle there can be as many groups of nozzles with nozzles of different diameters as there are nozzles. In these cases there is more than one switching pressure, because then the groups are switched successively, i.e. first between the first and the second group, then between the second and the third group, etc. It is clear that the nozzles -Diameter decreases with the group number, i.e. the nozzles of the first group have the largest diameter and the following groups always have smaller diameters.

3 shows the nozzles of the first and second group 2 and clarifies the nozzle diameter. The nozzles of the first group 2.1 have a nozzle diameter D ₁ and the nozzles of the second group 2.2 have a nozzle diameter D ₂ , where D ₁ >D ₂ .

The design of the nozzle diameter is based on the following criteria. If only the nozzles of the first group are to be used at the minimum pressure p _min , then the diameter is selected in such a way that the associated water flow can be provided through the nozzles of the first group. The maximum diameter that can be used is limited by the bucket size of the impeller. Of course, in order to achieve the necessary water flow under this boundary condition, the number of nozzles in the first group can be more than one nozzle. Then the water flow and thus the associated pressure is determined, up to which the nozzles of the first group can deliver a jet of sufficient quality. This pressure or a slightly lower pressure is then selected as the switching pressure between the first and second nozzle group. The nozzle or nozzles of the second group are then designed so that a water flow which flows through the nozzles of the first group in the needle position associated with the switching pressure can flow through the nozzles of the second group when they are fully open. The condition of the same water flow always refers to the switchover pressure. The nozzles of the second group can also be made slightly larger in order to achieve a certain overlap. Then the water flow and thus the associated pressure is determined, up to which the nozzle or nozzles of the second group can deliver a jet of sufficient quality. If this pressure has already reached the desired maximum pressure p _max , then the design process is over. Otherwise, one or more additional groups are added according to the criteria described.

If all nozzles are to be used at the minimum pressure p _min , then the diameters of the nozzles in the first group can be selected to be correspondingly smaller. That is, in the first step, the design is carried out according to the previous section, and then the diameters of the first group are reduced. The diameters of the nozzles of the higher groups can then mostly be retained, since this only leads to a slightly larger overlap between the first and second group.

When applying the criteria presented, in some cases there are several possibilities as far as the number of nozzles in the individual groups is concerned. The person skilled in the art can choose between these possibilities by applying the well-known criteria with which he is familiar. This includes considerations of material savings, reduction of machine wear or with regard to the smooth running of the turbines in the individual operating areas.

Switching between the nozzles of two groups or switching on the nozzles of a group can be done using the needles of the relevant nozzles. In this case, the needling operations are controlled by the control device, without this being specifically mentioned below. For the sake of simplicity, a turbine with only two groups of nozzles is also assumed for the following description of the switchover and connection processes. The nozzles of the first or second group are always spoken of in the plural. However, one or both of the groups may just as well comprise only one nozzle.

Switching between the first and the second group then takes place, for example, as follows. The pressure approaches the value p ₀ from below. The nozzles of the first group with their needles are gradually closed. The nozzles of the second group are closed during this time. At pressure p ₀ the nozzles of the first group reach the degree of closure at which a jet of sufficient quality can just about be produced. Then the nozzles of the first group are completely closed and at the same time the nozzles of the second group are opened as far as necessary. If there is no overlap between the two groups, it means that the nozzles of the second group must be fully opened. If there is an overlap, the nozzles of the second group are then only opened almost completely. As the pressure continues to rise, the nozzles of the second group are gradually closed further. When the nozzles of the second group reach the degree of closure at which a sufficiently high jet quality can just still be guaranteed, then the pressure has reached the maximum value p _max .

It is clear that the switching process takes a certain amount of time. At the same time, water emerges from the nozzles of both groups. In addition, it is clear that during the switching process the nozzles of both groups pass through areas in which the emitted jet is of poor quality. It is therefore desirable for the switching process to take place as quickly as possible. However, the risk of a pressure surge must be avoided. However, since the closing of the nozzles in the first group is accompanied by the opening of the nozzles in the second group, the risk of a pressure surge is not very great. In principle, it would also be conceivable for the nozzles in the first group to be closed and the nozzles in the second group to be opened one after the other (in any order). But that would definitely take more time.

The switching process with decreasing pressure runs in reverse. Initially, only the nozzles of the second group are open. When the pressure moves towards p ₀ , the nozzles of the second group are gradually opened wider. When p ₀ is reached, the nozzles of the second group are fully (no overlap) or almost fully (with overlap) open. Then the nozzles of the second group are closed and the nozzles of the first group are opened as far as necessary. The nozzles of the first group are then opened so wide that the jet quality is high enough to ensure the required efficiency.

• - Regeln der Pelton Turbine allein durch Steuerung der Düsen der ersten Gruppe, wenn sich die Regelparameter im ersten vordefinierten Regelparameterbereich befinden, wobei durch die Düsen der zweiten Gruppe kein Wasser strömt;
• - Regeln der Pelton Turbine allein durch Steuerung der Düsen der zweiten Gruppe, wenn sich die Regelparameter im zweiten vordefinierten Regelparameterbereich befinden, wobei durch die Düsen der ersten Gruppe kein Wasser strömt;
• - Unterbinden des Wasserflusses durch die Düsen der ersten Gruppe, wenn sich die Regelparameter vom ersten vordefinierten Regelparameterbereich in den zweiten vordefinierten Regelparameterbereich verlagern;
• - Unterbinden des Wasserflusses durch die Düsen der zweiten Gruppe, wenn sich die Regelparameter vom zweiten vordefinierten Regelparameterbereich in den ersten vordefinierten Regelparameterbereich verlagern.

An alternative description of the processes mentioned can be as follows: The method for normal operation of a Pelton turbine according to the invention comprises the following steps:

• - controlling the Pelton turbine solely by controlling the nozzles of the first group when the control parameters are in the first predefined control parameter range, with no water flowing through the nozzles of the second group;
• - controlling the Pelton turbine solely by controlling the nozzles of the second group when the control parameters are in the second predefined control parameter range, with no water flowing through the nozzles of the first group;
• - preventing the flow of water through the nozzles of the first group when the control parameters shift from the first predefined control parameter range to the second predefined control parameter range;
• - Stopping the flow of water through the nozzles of the second group when the control parameters shift from the second predefined control parameter range to the first predefined control parameter range.

The optional activation of the second group of nozzles at low pressure works as follows. The pressure approaches the switching pressure p ₁ from above. The nozzles of the first group are gradually opened and reach the open position at p ₁ . Now the nozzles of the second group are opened so far that the jet quality is sufficiently high, and at the same time the nozzles of the first group are closed as far as necessary (ie so far that the power remains constant). If the pressure drops further, either the nozzles of the first group can be opened one after the other, or the nozzles of the second group, or the nozzles of both groups simultaneously. It is clear that the nozzles of the respective group can only be opened until they reach the open position. When all nozzles have reached the open position, the minimum pressure p _min has been reached.

The negative circumstances mentioned during the switchover or connection process, ie that the relevant nozzles are temporarily in states in which the jet quality is not sufficiently good, can be avoided This can be avoided by using separate valves instead of the nozzle needles for switching. 4 shows a suitable arrangement in a schematic representation. In addition to the in 2 With the elements shown, the turbine comprises a first valve, indicated 4.1, which is arranged to regulate the flow of water through the nozzles of the first group, and a second valve, indicated 4.2, which is arranged so that it can regulate the flow of water through the jets of the second group. Alternatively, a separate valve 4.1 or 4.2 can be provided for each nozzle. In this case, all valves belonging to a nozzle group are opened or closed simultaneously.

The switching between the first and the second group proceeds in the embodiment according to FIG 4 as follows. The pressure approaches the value p ₀ from below. The valve of the first group 4.1 is open and the valve of the second group 4.2 is closed. The nozzles of the first group are gradually closed with their needles. No water flows through the nozzles of the second group, since the valve 4.2 is closed. The needles of the nozzles of the second group are in the open position (no overlap) or close to the open position (existing overlap). At pressure p ₀ the nozzles of the first group reach the degree of closure at which a jet of sufficient quality can just about be produced. Then the valve 4.1 is closed and at the same time the valve 4.2 is opened. As the pressure continues to rise, the nozzles of the second group are gradually closed further. When the nozzles of the second group reach the degree of closure at which a sufficiently high jet quality can just still be guaranteed, then the pressure has reached the maximum value p _max .

The switching process with decreasing pressure runs in reverse. The valve 4.2 is initially open and the valve 4.1 is closed, ie water only flows through the nozzles of the second group. When the pressure moves towards p ₀ , the nozzles of the second group are gradually opened wider. When p ₀ is reached, the nozzles of the second group are fully (no overlap) or almost fully (with overlap) open. The nozzles of the first group are in the degree of closure at which a jet of sufficient quality can just about be produced. Then valve 4.2 is closed and valve 4.1 is opened.

It is clear from what has been said that even before the valves 4.1 and 4.2 are switched over, the nozzles which are to be subjected to water during the switching process are brought into the position which is required for the respective switching process. It can thereby be ensured that a jet of sufficient quality can be generated by the relevant nozzles directly when a valve 4.1 or 4.2 is opened. The nozzles, which should no longer be subjected to water during the switching process in question, no longer deliver any water jet directly after switching, so that in this respect too no water jet of insufficient quality hits the impeller.

It should be noted that in the embodiment according to 4 the control device 3 can also control the positions of the needles of the nozzles, although this is not specifically in 4 is shown.

A Pelton turbine according to the present invention can advantageously be used in hydroelectric power plants in which the water levels in the headwater basin exhibit great variability. Another advantageous application is compressed air storage systems, in which the energy conversion takes place via water, which is used in a Pelton turbine when discharging the compressed air storage to generate electrical energy, since in this application the inlet pressure of the turbine has a wide range.

It should be noted that it is not absolutely necessary to measure the inlet pressure in order to carry out the operations described. It is also possible that the pressure is derived from other variables, e.g.

A further advantageous embodiment of the Pelton turbine according to the invention results from the use of a variable-speed generator to generate electricity. 5 shows the Pelton turbine according to the invention in a highly schematic representation. In this case, the impeller is denoted by 1 . The impeller is connected to a generator with a shaft. The generator is denoted by 5 and the shaft is denoted by 6. If the generator 5 can rotate at a variable speed, then the condition for controlling the Pelton turbine to a constant speed does not apply. As a result, the control of the turbine is made considerably easier, particularly when there is a requirement to deliver constant power, or the range in which the turbine can be operated efficiently can be further increased. As a variable-speed generator comes with For example, a synchronous generator, which is connected to the power grid via a converter, or an asynchronous generator.

reference list

1

Wheel

2

jet

2.1

Nozzle of the first group

2.2

Nozzle of the second group

3

control device

4.1

Valve of the first group of nozzles

4.2

Valve of the second group of nozzles

5

generator

6

Wave

Claims (8)

Pelton turbine comprising an impeller (1) and several adjustable nozzles (2.1, 2.2), with at least one of the nozzles (2.1) forming a first group and at least one of the nozzles (2.2) forming a second group, and with the at least one nozzle ( 2.1) of the first group has a larger diameter than the at least one nozzle (2.2) of the second group, and wherein the Pelton turbine comprises a control device (3) which is designed in such a way that it controls a flow of water through the nozzles (2.1, 2.2) can control as a function of control parameters in normal operation, characterized in that the control device (3) is designed in such a way that it can control the water flow through the nozzles (2.1, 2.2) in a first predefined control parameter range of normal operation in such a way that water fills the at least one Nozzle (2.1) of the first group flows through, and no water flows through the at least one nozzle (2.2) of the second group, and that it is in a second predefined control parameter range of the Normal operation can control the water flow through the nozzles (2.1, 2.2) so that water flows through the at least one nozzle (2.2) of the second group, and no water flows through the at least one nozzle (2.1) of the first group. Pelton turbine after claim 1 , wherein the nozzles (2.1) of the first group can be flowed through by a flow of water at a predefined position and a predefined pressure, and wherein the water jets generated thereby have a predefined jet quality, and wherein the nozzles (2.2) of the second group are designed in such a way, that at least said water flow can flow through them at the predefined pressure when they are fully open. Pelton turbine after claim 1 or 2 , wherein the Pelton turbine comprises a first valve (4.1) which is designed in such a way that it can regulate the flow of water through the at least one nozzle (2.1) of the first group, and a second valve (4.2) which is designed in such a way that it can regulate the flow of water through the at least one nozzle (2.2) of the second group. Pelton turbine according to one of the preceding claims, wherein the Pelton turbine comprises a synchronous generator (5). Pelton turbine after one of Claims 1 until 3 , wherein the Pelton turbine comprises an asynchronous generator (5). Pelton turbine after one of Claims 4 or 5 , wherein the generator (5) can be operated with variable speed. Method for normal operation of a Pelton turbine according to one of the preceding claims, the method comprising the following steps: - Controlling the Pelton turbine solely by controlling the at least one nozzle (2.1) of the first group if the control parameters are in the first predefined control parameter range, with no water flows through the at least one nozzle (2.2) of the second group; - Controlling the Pelton turbine solely by controlling the at least one nozzle (2.2) of the second group when the control parameters are in the second predefined control parameter range, with no water flowing through the at least one nozzle (2.1) of the first group; - Preventing the flow of water through the at least one nozzle (2.1) of the first group when the control parameters shift from the first predefined control parameter range to the second predefined control parameter range; - Preventing the flow of water through the at least one nozzle (2.2) of the second group when the control parameters shift from the second predefined control parameter range to the first predefined control parameter range. Procedure for normal operation of a Pelton turbine claim 3 , wherein the water flow through the at least one nozzle (2.1) of the first group is stopped by the first valve (4.1), and wherein the water flow through the at least one nozzle (2.2) of the second group is stopped by the second valve (4.2) he follows.

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