Installation and method comprising a steam turbine and an electric machine

Abstract

The invention relates to an installation (1) comprising a steam turbine (2) and an electric machine (4), wherein the electric machine (4) is connected to the steam turbine (2) in a torque-transmitting manner, wherein a coupling (3) is arranged between the electric machine (4) and the steam turbine (2), wherein the electric machine (4) has a first operating mode, in which the electric machine (4) can be operated as a generator for generating active power, wherein the electric machine (4) has a second operating mode, in which the electric machine (4) can be operated as a phase shifter for generating reactive power.

Description

Description TITLE The system and process comprise a steam turbine and an electric machine TECHNICAL AREA

[0001] Modern energy generation and transmission systems are subject to increased demands. If an energy generation system includes an electric machine, this machine is used to generate electrical energy and thus active power. The energy generated by the electric machine, which then operates as an electric generator, is fed into energy transmission networks.

[0002] Scenarios are now also known in which the energy transmission grid is supplied with energy from different sources, such as wind and solar power. In such cases, the electrical machine in the power generation plant may no longer operate as an electric generator, but rather as a phase shifter to generate reactive power if required. BACKGROUND

[0003] Currently, electric machines are operated in a gas turbine train, whereby, in the case of operation of the electric machine as a synchronous phase shifter, the electric machine is separated from the gas turbine by means of a coupling. This enables synchronous phase shifter operation.

[0004] The disadvantage here is that the generator must first be shut down from phase-shifting operation in order to then serve as a starter motor for the gas turbine with the clutch locked. This can result in the power generation plant being unavailable for active power generation for a period exceeding 30 minutes. In other words: This means an unavailability of more than 30 minutes for Network services during the switchover process from reactive power to active power operation.

[0005] Furthermore, the use of flywheels is more difficult, as the starting inverter also has to set the flywheel in motion, meaning it has to be significantly larger than is common today.

[0006] This is where the invention comes in.

[0007] The object of the invention is to provide an improved system for switching from reactive power to active power.

[0008] This problem is solved by a system comprising a steam turbine and an electric machine, wherein the electric machine is connected to the steam turbine in a torque-transmitting manner, wherein a coupling is arranged between the electric machine and the steam turbine, wherein the electric machine has a first operating mode in which the electric machine can be operated as a generator to produce active power, and wherein the electric machine has a second operating mode in which the electric machine can be operated as a phase shifter to produce reactive power.

[0009] It is also an object of the invention to provide a method by which the switching from reactive power to active power is improved.

[0010] This problem is solved by a method for operating a plant, wherein the plant comprises a steam turbine and an electric machine, wherein the electric machine is driven by the steam turbine, and wherein the electric machine is operated in a first operating mode as a generator to produce active power and in a second operating mode as a phase shifter to produce reactive power.

[0011] Advantageous embodiments are the subject of the dependent claims. Further advantages are listed in the dependent claims, which can be combined arbitrarily to achieve further advantages. DESCRIPTION OF THE INVENTION

[0013] A key aspect of the invention is that the drive unit for the electric machine is now a steam turbine, rather than a gas turbine. The use of a pure steam turbine train eliminates the starting problem associated with gas turbines. A pure steam turbine train means the absence of a gas turbine. The steam turbine starts automatically when the live steam valves open and then engages with the generator, which remains synchronized.

[0014] A key difference is that the steam turbine train takes on the role of a flexible operating element – ​​switching between active and reactive power operation. Previously, this was only used in gas turbine trains.

[0015] A key advantage is that no switching time needs to be considered, as the electric machine is permanently synchronized. Another advantage is that the starting inverter no longer needs to be oversized.

[0016] In a first advantageous further development, a flywheel is coupled to the electric machine to transmit torque. This allows the transmission network to be stabilized even better.

[0017] In a further advantageous embodiment, the flywheel is arranged between the clutch and the electric machine.

[0018] In a further advantageous development, two flywheels can be used: one flywheel in front of the electric machine and another flywheel between the clutch of the electric machine. Advantageously, the clutch is designed as a switchable clutch, in particular as a self-synchronizing clutch. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] An embodiment of the invention will be explained in more detail below with reference to the following figures.

[0020] The properties, features and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more easily understood in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawings.

[0021] Identical components or components with the same function are marked with the same reference numerals.

[0022] Exemplary embodiments of the invention are described below with reference to the drawings. These drawings are not intended to be drawn to scale; rather, where helpful for explanation, they are presented in a schematic and / or slightly distorted form. For further details regarding the teachings directly apparent from the drawings, reference is made to the relevant prior art.

[0023] They show:

[0024] FIG 1 shows a schematic representation of a system according to the invention in Grid Stability Mode

[0025] FIG 2 shows a schematic representation of a system according to the invention in power generation mode. DESCRIPTION OF THE EXECUTION FORM EN

[0026] Figure 1 shows a schematic representation of a system 1 according to the invention in the so-called Grid Stability Mode, which will be explained in more detail below. The system 1 comprises a steam turbine 2. For the sake of clarity, the steam turbine 2 is represented by a symbol. Those skilled in the art will recognize that the symbol indicates that the steam turbine 2 is composed of several sub-turbines. The steam turbine 2 can thus be composed of a high-pressure sub-turbine, an intermediate-pressure sub-turbine, and a low-pressure sub-turbine.

[0027] The steam turbine 2 has a rotatably mounted rotor (not shown) which is connected to a coupling 3 to transmit torque.

[0028] Clutch 3 can be configured as a switchable clutch. Alternatively, clutch 3 can also be configured as a self-synchronizing clutch.

[0029] Downstream of the coupling 3, an electric machine 4 is connected for torque transmission. The electric machine 4 fulfills a dual function, i.e., it can be used in two operating modes. In a first operating mode, the electric machine 4 is used as a phase shifter to generate reactive power. The steam turbine 2 is stopped and the coupling 3 is disengaged. This process is illustrated in Figure 1.

[0030] The electric machine 4 is connected to a transmission network 6 via a transformer 5.

[0031] Optionally, a flywheel 7 can be arranged between the electric machine 4 and the clutch 3. Also optionally, a flywheel 8 can be arranged at the end of the electric machine 4. Figures 1 and 2 should be understood to show either no flywheel or, optionally, a flywheel 7 or 8 arranged either before or after the electric machine 4. or optionally, a flywheel 7 and 8 can be arranged both before and after the electric machine 4.

[0032] Figure 2 shows the second operating mode, also known as Power Generation Mode. In this second operating mode, the steam turbine 2 runs at rotational speed, and the transmitted energy is used to generate active power in the electric machine 4. The electric machine 4 is used as an electric generator in this operating mode. In this second operating mode, the influence of renewable energies is lower.

[0033] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variants can be derived by a person skilled in the art without leaving the scope of protection of the invention.

Claims

Claims 1. Plant (1) comprising a steam turbine (2) and an electric machine (4), wherein the electric machine (4) is connected to the steam turbine (2) in a torque-transmitting manner, wherein a coupling (3) is arranged between the electric machine (4) and the steam turbine (2), wherein the electric machine (4) has a first operating mode in which the electric machine (4) can be operated as a generator to produce active power, wherein the electric machine (4) has a second operating mode in which the electric machine (4) can be operated as a phase shifter to produce reactive power.

2. System (1) according to claim 1, wherein a flywheel (7, 8) is coupled to the electric machine (4) in a torque-transmitting manner.

3. System (1) according to claim 1, wherein the flywheel (7) is arranged between the clutch (3) and the electric machine (4).

4. System (1) according to claim 1, wherein the electric machine (4) has a first shaft end which is coupled to the coupling (3) in a torque-transmitting manner, wherein the electric machine (4) has a second shaft end which is coupled to a flywheel (8) in a torque-transmitting manner.

5. System (1) according to claim 4, wherein a further flywheel (7) is coupled to the electric machine (4) in a torque-transmitting manner between the electric machine (4) and the clutch (3).

6. System (1) according to one of the preceding claims, wherein the clutch (3) is a switchable clutch.

7. System (1) according to one of the preceding claims, wherein the coupling (3) is a self-synchronizing coupling.

8. Plant (1 ) according to one of the preceding claims, wherein the plant (1 ) is designed as a pure steam turbine train.

9. Method for operating a plant (1) wherein the plant (1) comprises a steam turbine (2) and an electric machine (4), wherein the electric machine (4) is driven by the steam turbine (2), wherein the electric machine (4) is operated in a first operating mode as a generator to produce active power and in a second operating mode as a phase shifter to produce reactive power.

10. Method according to claim 9, wherein a coupling (3) is arranged between the steam turbine (2) and the electric machine (4).

11. Method according to claim 10, wherein the clutch (3) is designed as a switchable clutch.

12. Method according to one of claims 9 to 11, wherein a flywheel (7) is arranged between the electric machine (4) and the clutch (3).

13. Method according to one of claims 9 to 11, wherein a flywheel (8) is arranged after the electric machine (4).

14. The method of claim 13, wherein a further flywheel (7) is also arranged upstream of the electric machine (4).

15. The method of any one of claims 9 to 14, wherein the system (1) is designed as a pure steam turbine train.

Images