Permanent magnet direct-drive horizontal water power generation control method and system

Abstract

The present invention relates to a control method and system for permanent magnet direct-drive horizontal water power generation. A protection switch for controlling the on / off of the generator output is provided on the output end / output line of the permanent magnet direct-drive generator. In the system protection state, when S≤S1 and F≤F1, the protection switch is closed and the system enters the power generation state; in the system power generation state, when S≥S2 and T<T2, the generator torque is increased to reduce S, and the power generation state is maintained under the condition that S≤S1 is satisfied. When S≥S2 and T≥T2, the protection switch is opened and the system enters the protection state, wherein S is the real-time generator speed, T is the real-time generator torque, S1 is a given first speed threshold, S2 is a given second speed threshold, T2 is a given torque upper limit, and S2>S1. The present invention is beneficial for avoiding or reducing damage to the control system caused by generator overspeed / excessive power generation voltage in a permanent magnet direct-drive horizontal water power generation system.

Description

Technical Field

[0001] The present invention relates to a permanent magnet direct-driven horizontal water power generation control method and system, belonging to the technical field of generator intelligent control. Background Art

[0002] A permanent magnet direct-drive horizontal flow hydropower generation system primarily includes a waterwheel, a permanent magnet direct-drive generator, and a control system. It can be used in horizontal flow applications such as power station tailwater and rivers. For example, Chinese patent document CN212406930U discloses a suspended hydropower generation device, comprising a mounting base (1), a generator, and a river. The mounting base (1) has a generator on its upper side, a speed increaser on its right end, a rotating shaft on its right end, and several blades on its shaft. A support (2) is provided on its right end, and a mounting base (2) is provided at its lower end. During use, mounting bases (1) and (2) are conveniently secured via ground insertion holes (1) and (2). A support plate, fixing bolts (1), support (1), fixing bolts (2), support (2), and fixing bolts (3) are provided to facilitate securing the generator, speed increaser, rotating shaft, and blades. The existing riverbank is used as the installation base, and a double-support fixing method is adopted, making construction simple. Both ends are secured with rigid fixing structures, effectively maintaining the operation of the unit. Chinese patent document CN212644093U discloses a fixing device for a horizontal submersible water flow generator, comprising a fixed shell, a side wall of the fixed shell is provided with a slide groove, the inner bottom wall of the fixed shell is fixedly connected to a chain, the inner bottom wall of the fixed shell is fixedly connected to a hydraulic cylinder, the hydraulic cylinder is movably connected to a runner at one end away from the inner bottom wall of the fixed shell, and the chain is movably connected to a chain stretching block at one end away from the inner bottom wall of the fixed shell. The fixing device for a horizontal submersible water flow generator is achieved by arranging a fixed shell on both sides of a river, arranging a chain inside, and meshing the chain with the runner. The rotation of the runner is controlled by the extension and contraction of the hydraulic cylinder to drive the chain to move, drive the chain stretching block to move up and down, drive the load-bearing bottom plate to move up and down, and thus adjust the height of the horizontal submersible water flow generator. The extension height of the hydraulic gas rod can be adjusted at any time according to the rise and fall of the tide to control the up and down of the horizontal submersible water flow generator. However, due to the special circumstances in which this power generation system is used, such as large water flow changes in the four seasons, uncontrolled water inflow to the waterwheel, high requirements for the generator's power generation speed range, and the lack of an adjustable environment for the turbine blade opening and water inflow, the generator is prone to overspeed and loss of control when the water flow is large, which in turn leads to problems such as motor loss of control, overload, or damage to the control system due to exceeding the withstand voltage value due to generator overspeed and excessive power generation voltage, affecting the practical application of this discovery system. Summary of the Invention

[0003] The purpose of the present invention is to avoid or reduce the damage to the control system caused by generator overspeed / excessive generation voltage in a permanent magnet direct-drive horizontal flow water power generation system.

[0004] The technical solution of the present invention is: a permanent magnet direct-drive horizontal flow power generation control method, a protection switch for controlling the on / off of the generator output is provided on the output end / output line of the permanent magnet direct-drive generator, and the switching between the power generation state and the protection state of the system (permanent magnet direct-drive horizontal flow power generation system) is realized by turning on and off the protection switch. In the system protection state, the generator speed is monitored (continuously / periodically detected). When S≤S1, the protection switch is closed and the system enters the power generation state; in the system power generation state, the generator speed is monitored. When S≥S2 and T<T2, the generator torque (torque) is increased to reduce S. When S≤S1 is satisfied, the power generation state is maintained (the closed state of the protection switch is maintained). When S≥S2 and T≥T2, the protection switch is disconnected and the system enters the protection state, wherein S is the real-time generator speed, T is the real-time generator torque, S1 is a given first speed threshold, S2 is a given second speed threshold, T2 is a given torque upper limit, and S2>S1.

[0005] Furthermore, in the protection state, the water flow related to power generation / related to the working state of the water wheel (for example, acting on the water wheel) is also monitored. When S≤S1 and F>F1, the protection switch is not closed, that is, the system power generation state is not entered. In this case, the condition for closing the protection switch can be regarded as S≤S1 and F≤F1, where F1 is a given first water flow threshold.

[0006] Furthermore, when the power generation system is started, the protection switch is in the disconnected state, that is, the system first enters the system protection state after starting.

[0007] The upper limit of the rated speed range of the generator can be S1.

[0008] The maximum speed (maximum overspeed) of the generator can be S2.

[0009] The upper limit of the generator torque can be calibrated based on experiments and used as T2.

[0010] Depending on the characteristics of the power generation system and its related equipment (for example, the control system, the generator, the waterwheel, etc.), the above parameters can be determined in any other appropriate manner based on the purpose / requirement of ensuring / facilitating the avoidance of damage to the control system caused by generator overspeed / excessive power generation voltage.

[0011] A permanent magnet direct-drive horizontal water power generation system adopts any of the permanent magnet direct-drive horizontal water power generation control methods disclosed in the present invention to perform related control of the protection switch, including a water wheel, a generator and a control system, the generator is a permanent magnet direct-drive generator, the rotating shaft of the water wheel (the shaft extension for output) is directly driven and connected to the main shaft (the shaft extension for input) of the permanent magnet direct-drive generator (in a connection method that can achieve direct drive), the output (electrical energy output) of the generator is connected to the control system (the input end of the electric energy transmission circuit in the control system, or the electric energy input end of the control system), and the protection switch is connected in series to the connection circuit between the generator output and the control system (electrical energy input end) to control the on and off of the connection circuit.

[0012] Preferably, the rotating shaft of the waterwheel is connected to the main shaft of the permanent magnet direct drive generator through a coupling, thereby realizing a direct drive connection between the two.

[0013] Preferably, the generator is provided with a rotary encoder, and the output of the rotary encoder of the generator is connected to the control system (control device / control circuit in the control system).

[0014] Preferably, the generator is provided with a torque sensor, and the output of the torque sensor of the generator is connected to the control system (control device / control circuit in the control system). The torque sensor can adopt any suitable circuit, instrument, device, etc. that can be used to detect or obtain the motor torque.

[0015] The protection switch control output of the control system (the control device in the control system) (for example, the control signal output for controlling the protection switch, or the transmission line for outputting the relevant control signal) is connected to the control end of the protection switch to control the switching state of the protection switch.

[0016] Preferably, the protection switch is a three-phase contactor to achieve synchronous switching of the three-phase output of the generator.

[0017] Preferably, a water flow sensor is provided for detecting water flow related to power generation / related to the working state of the waterwheel, and the output of the water flow sensor is connected to the control system (control device in the control system).

[0018] The specific form and specific setting of the water flow sensor depend on the actual conditions. The water flow of a certain flow surface or the water flow of the entire river can be used. Other physical quantities (combinations of physical quantities) related to water flow / capable of reflecting water flow, such as flow velocity and water level, can also be used, with or without conversion, as the water flow related to power generation / related to the working state of the waterwheel (for example, the water flow acting on the waterwheel) referred to in the present invention.

[0019] The beneficial effect of the present invention is that: since a protection switch is provided between the generator and the control system, the protection switch can cut off the electrical connection between the generator output and the control system when the water flow is too large, thereby ensuring that the control system is not damaged by excessively high voltage. When the water flow meets the requirements, the protection switch can be turned on again to restore the normal operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the architecture of the permanent magnet direct-drive horizontal flow water power generation system involved in the present invention;

[0021] Figure 2 It is a schematic diagram of the architecture related to the protection switch;

[0022] Figure 3 This is a schematic diagram of the protection process (process for controlling the disconnection of the protection switch) involved in the present invention;

[0023] Figure 4 This is a schematic diagram of the recovery process (process for controlling the closing of the protection switch) involved in the present invention;

[0024] Figure 5 The present invention relates to a circuit diagram. DETAILED DESCRIPTION

[0025] See also Figure 1-Figure 5 The present invention is applicable to a permanent magnet direct-drive horizontal water power generation system, which uses a permanent magnet direct-drive generator 2 as the power generation equipment. The rotating shaft of the waterwheel (impeller) 1 is coaxially connected to the main shaft (rotating shaft) of the permanent magnet direct-drive generator through a coupling (the axes are located on the same straight line), directly driving the rotor of the permanent magnet generator to rotate and generate electricity. The output (electrical output) of the generator is connected to a control system 3, and is then processed by the control system and transformer 4 before being connected to a power grid 5. The control system includes an electric energy transmission circuit (which may be provided with functional circuits such as current conversion and filtering according to actual needs) and a control device. The output of the generator is transmitted to the transformer via the electric energy transmission circuit. The control device can generate / issue corresponding control signals based on the received sensor signals under the support of preset programs / software or based on corresponding hardware circuit design, thereby controlling the operating status of electronic control components including protective switches, and thus controlling the operating status of the system. The control system of an existing permanent magnet direct-drive horizontal water power generation system can be adopted, and a control device capable of data processing, such as a PLC, is provided. The relevant control / operation of the present invention is implemented by programming or downloading corresponding software.

[0026] A protective switch (or bypass switch) is installed in the circuit between the generator output and the control system. When the protective switch is disconnected, the generator output is no longer connected to the control system, preventing the connected voltage from being too high and damaging the control system. After the protective switch is disconnected, the waterwheel drives the generator rotor to continue rotating. Its speed is mainly limited by the water flow rate, which also prevents the generator from being damaged by excessive current. Therefore, when the water flow rate is too high, the protective switch can be opened to protect the control system (and generator, etc.). After the water flow rate drops to an appropriate level, the protective switch can be closed again to resume power generation. Software can be added to the control system to switch the protective switch by real-time monitoring of the generator speed, torque, water flow rate, or other appropriate parameters to achieve control and protection requirements.

[0027] The control method of the present invention is described in detail below by taking a 100KW power generation system as an example.

[0028] A protection switch K1 is set between the generator and the control system. K1 is selected as a 200A three-phase contactor.

[0029] Before the power generation system is operational, K1 is disconnected. While monitoring the generator speed S, generator torque T, and water flow F, if the generator speed is less than (or not greater than) S1 and the water flow is less than (or not greater than) F1, the system automatically closes K1 and the system enters the power generation (output) state. During this state, the control system must maintain real-time control of the generator's operating status.

[0030] If the generator system is operating, K1 is closed. While monitoring generator speed S, generator torque T, and water flow F, if the generator speed exceeds S2, the system automatically increases the generator torque, forcing the generator speed to decrease. If the generator torque increases to greater than T2, but the speed remains greater than S2, the motor will immediately enter an overspeed or runaway state, forcing the system to open protective switch K1.

[0031] Based on / in combination with other parameters, protection may be implemented by disconnecting the protection switch when a risk that requires protection is caused by other factors or reflected by other parameters.

[0032] The present invention forms a complete closed-loop control system for generator overspeed protection. It can effectively protect the generator from overspeed in horizontal water environments such as power station tailwater and rivers where the water flow fluctuation range is large, thereby avoiding losses in the control system caused by excessive generator voltage and generator overload.

[0033] The present invention has the following characteristics:

[0034] 1) A generator overspeed protection circuit is formed by connecting a protection switch in series between the generator and the control system.

[0035] 2) Use the control system to monitor the generator speed, torque and water flow, make software judgments, and thus control the protection switch in real time to ensure the real-time performance of overspeed protection.

[0036] 3) You only need to select protection switches of different current and voltage levels to meet the application of power generation systems with different voltage and power levels.

[0037] 4) The protection switch can be applied to new equipment or modified equipment, which is easy to implement.

[0038] 5) In the context of existing technologies, the protection function can usually be realized by relying on the existing monitoring parameters of the control system itself. There is no need to add additional sensors / detection devices to realize the protection function of the present invention, and there is basically no need to increase the cost of hardware facilities.

[0039] 6) In the context of existing technologies, this control method can usually be implemented directly on existing control devices (e.g., PLCs) without the need to set up an independent controller or programming platform.

[0040] Unless otherwise specified or when one preferred or optional technical means is a further limitation of another technical means, the preferred and optional technical means disclosed in the present invention can be arbitrarily combined to form several different specific implementation methods.

Claims

1. A permanent magnet direct-drive horizontal water power generation control method, wherein a protection switch for controlling the on / off of the generator output is provided on the output end / output line of the permanent magnet direct-drive generator, and the switching between the system power generation state and the protection state is achieved by turning on and off the protection switch. In the system protection state, the generator speed is monitored, and the real-time water flow F related to power generation / the working state of the waterwheel is also monitored. When S≤S1 and F≤F1, the protection switch is closed and the system enters the power generation state. When S≤S1 and F>F1, the protection switch is not closed. In the system power generation state, the generator speed is monitored. When S≥S2 and T<T2, the real-time generator torque is increased to reduce S. When S≤S1 is satisfied, the power generation state is maintained. When S≥S2 and T≥T2, the protection switch is opened and the system enters the protection state. S is the real-time generator speed, T is the real-time generator torque, S1 is a given first speed threshold, S2 is a given second speed threshold, T2 is a given torque upper limit, F1 is a given first water flow threshold, and S2>S1.

2. The permanent magnet direct drive horizontal water power generation control method according to claim 1, characterized in that When the power generation system is started, the protection switch is in the disconnected state, and the system enters the system protection state after startup.

3. Permanent magnet direct drive horizontal water power generation system, characterized by The permanent magnet direct-drive horizontal water power generation control method described in any one of claims 1-2 is used to perform related control of the protection switch, including a water wheel, a generator and a control system, the generator is a permanent magnet direct-drive generator, the rotating shaft of the water wheel is directly connected to the main shaft of the generator, the output of the generator is connected to the control system, and the protection switch is connected in series to the connection circuit between the generator output and the control system for controlling the on and off of the connection circuit.

4. The permanent magnet direct drive horizontal flow water power generation system according to claim 3, characterized in that The rotating shaft of the waterwheel is connected to the main shaft of the generator through a coupling, thereby realizing a direct drive connection between the two.

5. The permanent magnet direct drive horizontal flow water power generation system according to claim 3, characterized in that The generator is provided with a rotary encoder, and the output of the rotary encoder of the generator is connected to the control system.

6. The permanent magnet direct drive horizontal flow water power generation system according to claim 3, characterized in that The generator is provided with a torque sensor, and the output of the torque sensor of the generator is connected to the control system.

7. The permanent magnet direct drive horizontal flow water power generation system according to claim 3, characterized in that The protection switch is a three-phase contactor to achieve synchronous on-off of the three-phase output of the generator.

8. The permanent magnet direct drive horizontal flow water power generation system according to claim 7, characterized in that The protection switch control output of the control system is connected to the control terminal of the protection switch to control the switching state of the protection switch.

9. The permanent magnet direct drive horizontal flow water power generation system according to any one of claims 3 to 8, characterized in that A water flow sensor is provided for detecting real-time water flow related to power generation / the working state of the waterwheel, and the output of the water flow sensor is connected to the control system.

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