Automatic control system applied to energy generation systems in hydroelectric power plants

Abstract

An automatic control system applied to an energy generation system in a hydroelectric power plant, the automatic control system comprising: a set of a plurality of pneumatic actuators (1); a compressed air source; a set of a plurality of pneumatic valves (3 and 4); at least one linear position transducer (5); a set of a plurality of emergency valves (6 and 7); and a PID controller (C) which is responsible for controlling the positions of the plurality of pneumatic actuators (1) based on the operation of the plurality of pneumatic valves (3 and 4) and emergency valves (6 and 7) during operation and emergency shutdown of the hydroelectric power plant.

Description

Detailed Description of the Invention

[0001] [Field of the Application] The patent of the present invention is related to the fields of mechanical engineering and automation. More specifically, it is related to the development of an automatic control system for an energy generation turbine with movable blades or a movable needle, which uses a pneumatic actuator (pneumatic actuator) or a hydraulic actuator (hydraulic actuator) to control the rotational movement of a generator / energy generation turbine.

[0002] The above automatic control system controls and optimizes the energy generation process by realizing the angle adjustment of the blades or needles that control the flow rate towards the motor or the hydraulic turbine. Furthermore, in this system, when a failure occurs, the pneumatic component or the hydraulic component can lock the actuator in a predetermined position to prevent the turbine from rotating. Therefore, the system can also improve the operating safety of the plant.

[0003] [State of the Art] Energy generation turbines capable of generating electricity using a barrage (dam) or a dam are well-known in the current state of the art. The barrage forms a reservoir (storage pond) or a hydroelectric basin and causes a waterfall. The waterfall can be used to operate the turbine blades and the rotor (rotor). Similarly, in the application of turbines corresponding to energy generation by the combustion of fossil fuels (natural gas, coal), the exhaust products of the burner are led to the inlet of the turbine to operate the rotating blades of the turbine. In any case, the turbine is connected to a rotating electrical generator. The generator converts the mechanical energy of the turbine into electrical energy.

[0004] To optimize the efficiency of the electricity generated by the energy generation process and to control that electricity, parameters such as the flow rate and pressure at the turbine inlet can be adjusted by opening the barrage valve or by changing the amount of fossil fuel being burned. This increases the rotational speed and torque, and consequently, the amount of electrical energy produced by the generator.

[0005] Furthermore, the turbine efficiency in the energy generation process can be altered by using a turbine with a moving blade rotor. Turbines with moving blades are well-known in the current state of technology and are used to increase the efficiency of the energy generation process. These blades can also be used to control the amount of electrical energy produced. The blades maintain a constant rotational speed for the turbine and generator. Therefore, even if there are fluctuations in the fluid flow rate and pressure at the turbine inlet, energy within the electrical network can be maintained without fluctuations in voltage and frequency.

[0006] In the case of hydroelectric turbines, the power generation process is highly dependent on climatic influences such as drought or excessive rainfall, as well as the water level in the reservoir. If large fluctuations in the water column occur over a short period, the blade opening must be further increased to maintain the same power output. If the machine stops, phenomena such as water hammer, cavitation, or rotational speeds exceeding design limits may occur. In such cases, an emergency shutdown system is necessary. An emergency shutdown system operates the turbine blades or needles at a controlled speed and locks the actuators. This prevents flow through the turbine. In other words, the actuators are locked in a safe position. Therefore, the risk of damage to turbine and generator components is reduced.

[0007] The angle and position of blades are typically adjusted using hydraulic actuators. However, a disadvantage is the high maintenance cost of hydraulic actuators. This is because maintenance of a hydraulic system requires the removal, storage, filtering, and flushing of oil in the hydraulic lines.

[0008] Furthermore, a disadvantage is that the use of hydraulically driven actuators carries a high risk of leakage. In the case of hydroelectric power plants, there are also environmental risks resulting from oil leaks into rivers or the reservoir itself.

[0009] An alternative to hydraulic actuator systems for controlling the rotation of turbine blades or needles is the use of pneumatic actuators. Benefitingly, pneumatic actuators do not cause environmental accidents in the event of a leak in the pneumatic line.

[0010] Reference CN109209974A discloses an automatic control system for an air compressor having movable blades with a blade position detection mechanism and a dual-acting pneumatic actuator that handles pressure fluctuations at the compressor exhaust port (outlet). To optimize process efficiency, the compressor exhaust pressure and blade position control loop are input. The compressor converts electrical energy from the motor into potential mechanical energy, thereby increasing the fluid pressure. Thus, the compressor operates in the reverse manner of a turbine, but the same concept can be applied to the turbine. Therefore, electrical energy can be generated by utilizing the potential mechanical energy of the water column in the barrage.

[0011] A drawback of document CN109209974A is that airflow control for the actuator is performed by a single three-position solenoid directional control valve and multiple stroke end sensors. This solution cannot perform adjustment of the valve's operating closure curve to reduce the risk of water hammer, rotor operation beyond a specified speed, or speed-controlled load movement / acquisition.

[0012] Another drawback of reference CN109209974A is that it does not describe a blade position locking mechanism in case of pneumatic component failure or when an emergency stop is required.

[0013] Reference CN105068424A discloses a closed-loop control model applicable to the position adjustment of energy-generating turbine blades. This control model uses a position sensor and flow meter of a pneumatic actuator to optimize energy generation efficiency.

[0014] However, a disadvantage of the above system is that there is no feedback mechanism to reduce or increase the blade speed. Therefore, it cannot reduce the risk of water hammer or speeds exceeding the turbine operating limits. Furthermore, the system uses flow meters, and the acquisition and maintenance costs of such equipment are high.

[0015] As described above, the use of control systems in turbines with movable blades is known. However, with the current level of technology, the use of hydraulic actuators poses high environmental risks and maintenance difficulties due to the oil used in the hydraulic lines. Furthermore, with the current level of technology, there is no emergency system integrated into an automatic control system that ensures the positioning of the movable blades under conditions that do not pose any risk to turbine operation. Consequently, the probability of failure increases.

[0016] Therefore, in order to overcome the shortcomings of the current state of technology, the present invention aims to provide position control of energy generation turbine rotor blades using a set of multiple pneumatic actuators and multiple pneumatic valves. The arrangement of the valves may include multiple settings depending on the layout of the energy generation plant.

[0017] Another object of the present invention is to provide a safe and emergency stop system that locks an actuator in place and causes the waterway to the turbine to close. Closing the waterway to the turbine initiates the stop, thus reducing the risk of damage to the internal components of the turbine and energy generator.

[0018] Another characteristic of an emergency condition is the presence of leakage or pressure in the pneumatic circuit power supply that falls below the operating limits of the pneumatic circuit.

[0019] Thus, the present invention makes it possible to control the position of the blades of an energy-generating turbine. This makes it possible to optimize process performance using a set of multiple pneumatic components. Benefiting from the present invention, compared to oil-based solutions, maintenance costs are lower, maintenance is easier, and the risk of environmental accidents is reduced. Furthermore, beneficial from the present invention, it is not necessary to monitor the level and temperature of the working fluid.

[0020] The following diagrams illustrate schematic representations of specific embodiments of the present invention; however, the dimensions and proportions in these diagrams are not necessarily those of the actual invention, for they are intended solely to illustrate various aspects. The scope of protection of the present invention is determined solely by the appended claims.

[0021] [Brief description of the drawing] The object of the present invention will be better understood in light of preferred but not limiting embodiments shown in the following detailed description, which are illustrated by the accompanying schematic drawings.

[0022] Figure 1 shows a schematic diagram of the pneumatic valve in the automatic control system of an energy generation turbine.

[0023] Figure 2 shows the control loop of the PID controller (C).

[0024] [Detailed explanation] As shown in the attached drawings, the present invention relates to an energy generation system in a hydroelectric power plant and represents an automatic control system that uses an actuator (preferably a pneumatic actuator) to control the position of a movable blade or movable needle of an energy generation turbine.

[0025] The automatic control system (S) allows for angle adjustment of the motor or pneumatic turbine blades. Therefore, control and performance optimization in the energy generation process can be achieved. The automatic control system also improves the safety of plant operation because, in the event of a failure, the pneumatic or hydraulic component can lock the actuator in place, preventing the turbine blades from rotating.

[0026] From this, as shown in Figure 1, the automatic control system (S) comprises a set of multiple actuators (1), including at least two actuators (1A) and actuator (1B). Actuator (1A) comprises multiple chambers (10A and 11A) and a plunger (12A). Actuator (1B), on the other hand, comprises multiple chambers (10B and 11B) and a plunger (12B). It will be understood that the automatic control system (S) may include actuators capable of operating the blades. The multiple actuators (1) are connected to a compressed air source (2) or a hydraulic source. At least one linear transducer (5) checks the position of at least one actuator from the set of multiple actuators (1). The multiple plungers (12A and 12B) are connected to the blades of the energy generation turbine. This allows for control of the angle of the set of blades of the energy generation turbine.

[0027] At least one of the set of multiple actuators (1) is connected to at least one position transducer (5). The position transducer (5) measures the backward or forward displacement of each plunger of each actuator.

[0028] Furthermore, according to FIG. 1, the automatic control system (S) includes a pneumatic circuit. The pneumatic circuit drives a set of a plurality of pneumatic valves (3 and 4) through a compressed air source (2). The plurality of pneumatic valves (3 and 4) are arranged in parallel with each other and adjust the pressure at the inlets of a set of a plurality of emergency valves (6 and 7). The plurality of emergency valves (6 and 7) are also arranged in parallel with each other. Therefore, the plurality of pneumatic valves (3 and 4) are connected in series with a set of a plurality of emergency valves (6 and 7). The plurality of emergency valves (6 and 7) are arranged between a set of a plurality of pneumatic valves (3 and 4) and a set of a plurality of flow control valves (8 and 9). The set of a plurality of flow control valves (8 and 9) controls the linear displacement speed of each actuator belonging to a set of a plurality of actuators (1).

[0029] Advantageously, the set of flow control valves (8 and 9) controls the linear displacement speed of each actuator belonging to a set of a plurality of actuators (1) by adjusting the flow rate. Therefore, the set of flow control valves (8 and 9) prevents a closure that is too fast, which may cause water hammer. Alternatively, the set of flow control valves (8 and 9) prevents a closure that is too slow, which may cause a pressure deficiency inside the conduit and may cause acceleration or overspeed of the turbine. Thus, either a fast form or a slow form may damage the structure of the hydroelectric power plant.

[0030] According to FIGS. 1 and 2, the automatic control system (S) operates according to the following steps during normal operation: i. The PID controller (C) receives a signal from at least one position transducer (5) of at least one actuator (1A, 1B); ii. The PID controller (C) compares the actual position of each actuator (1A, 1B) with a predetermined reference value (VR); iii. If the actual position is different from the predetermined position, the compressed air source (2) supplies air to the pneumatic valves (3, 4). The opening and closing of the pneumatic valves are controlled by the PID (C); iv. The air flow passes through the sets of emergency valves (6 and 7) and reaches the sets of flow control valves (8 and 9). The air flow controls the forward or backward speed of each actuator (1A, 1B); v. The actuators (1A and 1B) move the turbine blades to the reference position (VR).

[0031] Therefore, simultaneously with the operation of valve (3), due to the pressure drop inside the chamber (10A) released by the pneumatic valve (4), the actuator (1A) retracts the plunger (12A). On the other hand, due to the pressure reduction in chamber (11B) and the pressure increase in chamber (10B), the actuator (1B) advances the plunger (12B).

[0032] Similarly, when moving the actuator in the opposite direction, the automatic control system (S) operates the pneumatic valve (4) to pressurize chambers (10A and 11B). In this case, chambers (10B and 11A) are depressurized by exhausting using the pneumatic valve (3).

[0033] Therefore, it is beneficial that the automatic control system (S) can more appropriately adjust a plurality of turbine blades of the hydroelectric power plant, improve the performance of generating electrical energy, and reduce fluctuations in the network.

[0034] In a preferred embodiment of the present invention, the automatic control system (S) is provided with safety control (safety control). The system operates in an emergency state.

[0035] When the PID controller (C) receives an emergency condition signal, the valve is switched. The emergency condition signal may be caused by a failure in the automatic control system (S) itself. The emergency condition signal may also be caused by a failure in any other critical system in the plant.

[0036] Therefore, in an emergency situation, the automatic control system (S) operates as follows: a) The PID controller (C) receives an emergency status signal; b) The PID controller (C) simultaneously switches off the set of emergency valves (6 and 7) to isolate the set of pneumatic valves (3 and 4); c) The emergency valve (7) connects the chamber (10A) of actuator (1A) and the chamber (11B) of actuator (1B) to atmospheric pressure, and releases the pressure inside these chambers (10A and 11B); d) Simultaneously with step “c”, the emergency valve (6) connects the chamber (11A) of actuator (1A) and the chamber (10B) of actuator (1B) to the pressure of the pneumatic circuit through the compressed air source (2); e) A set of flow control valves (8 and 9) controls the linear displacement rate of the actuators (1A and 1B); f) The plunger (12A) of actuator (1A) retracts completely. Meanwhile, the plunger (12B) of actuator (1B) advances completely at a preset speed and controlled by a set of flow control valves (8 and 9); g) At least one linear transducer (5) checks the position of at least one actuator among a plurality of actuators (1A and 1B) and sends a signal to PID(C) indicating a safe position; h) The above system does not require monitoring of the working fluid level and temperature.

[0037] In this way, the present invention provides even greater safety for hydroelectric power plants. In addition, the present invention also provides even greater performance in generating electrical energy.

[0038] Those skilled in the art will readily understand from this specification and the accompanying drawings various methods for realizing the present invention without departing from the scope of the appended claims. [Brief explanation of the drawing]

[0039] [Figure 1] This shows a schematic diagram of a pneumatic valve in an automatic control system for an energy generation turbine. [Figure 2] This shows the control loop of the PID controller (C).

Claims

1. An automatic control system applied to an energy generation system in a hydroelectric power plant, It comprises a set of multiple actuators (1), including at least two actuators (1A) and actuator (1B), Each set of the multiple actuators (1) comprises a chamber (10A) and a chamber (11A), and a chamber (10B) and a chamber (11B), The set of multiple actuators (1) is connected to a compressed air source (2) and to at least one linear transducer (5) for checking the position of at least one actuator in the set of actuators (1) in order to control the angle of the set of multiple blades of an energy generating turbine. The automatic control system (S) includes a pneumatic circuit that drives a set of multiple pneumatic valves (3 and 4) through the compressed air source (2), The multiple pneumatic valves are arranged parallel to each other and adjust the pressure at the air inlets of the set of multiple emergency valves (6 and 7). The multiple emergency valves are arranged parallel to each other. The multiple pneumatic valves (3 and 4) are arranged in series with the set of multiple emergency valves (6 and 7), The set of multiple emergency valves is positioned between the set of multiple pneumatic valves (3 and 4) and the set of multiple flow control valves (8 and 9) for controlling the linear displacement velocity of each of the multiple actuators (1). The set of multiple emergency valves (6 and 7) fluidly isolates the set of multiple pneumatic valves (3 and 4) in an emergency. The emergency valve (6) simultaneously drives the chambers (11A) and (10B) of the actuator (1A) and actuator (1B), and the emergency valve (7) simultaneously drives the chambers (10A) and (11B) of the actuator (1A) and actuator (1B), An automatic control system that linearly displaces multiple plungers (12A and 12B) to angularly displace multiple blades (P) of the energy generating turbine (T).

2. The chamber (10A) of actuator (1A) is fluidly connected to the chamber (11B) of actuator (1B), and the chamber (11A) of actuator (1A) is fluidly connected to the chamber (10B) of actuator (1B), An automatic control system applied to an energy generation system in a hydroelectric power plant according to claim 1, wherein a plurality of actuators (1A and 1B) maintain balance, and a plurality of plungers (12A and 12B) are displaced by the same amount in opposite directions.

3. The aforementioned automatic control system (S) a) Steps in which the PID controller (C) receives an emergency signal, b) The PID controller (C) simultaneously switches between multiple sets of emergency valves (6 and 7) to isolate multiple sets of pneumatic valves (3 and 4), c) The emergency valve (7) connects the chamber (10A) of actuator (1A) and the chamber (11B) of actuator (1B) to atmospheric pressure, and releases the pressure inside the multiple chambers (10A and 11B). d) Simultaneously with step c, the emergency valve (6) connects the chamber (11A) of the actuator (1A) and the chamber (10B) of the actuator (1B) to the pressure of the pneumatic circuit through the compressed air source (2). e) A set of multiple flow control valves (8 and 9) controls the linear displacement velocity of each actuator (1A and 1B), f) The plunger (12A) of the actuator (1A) is fully retracted, and the plunger (12B) of the actuator (1B) is fully advanced at a preset speed, controlled by a set of the flow control valves (8 and 9), and g) A step in which at least one linear transducer (5) checks the position of at least one actuator among the plurality of actuators (1A and 1B) and transmits a signal to the PID(C) indicating the safe position of the plurality of turbine blade sets, An automatic control system applied to an energy generation system in a hydroelectric power plant, using the automatic control system (S) according to claim 1, which operates in accordance with the above.

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