Hydraulic Machine Electric Torque Control for Mode Transition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hydraulic machines, such as hydro-power plants with pump-turbines, face challenges in reducing the duration of start-up sequences and transient times during transitions between pump and turbine modes.
Innovation Solution
The method employs a control loop feedback system using electric torque to accelerate or decelerate the machine, combining hydraulic and electric torques to quickly adjust the rotation speed and reduce transient times between operation modes, with a variable-frequency drive and a battery providing electric power to achieve target rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional hydraulic torque alone is used to accelerate the machine during start-up, then the system structure remains simple, but the start-up sequence duration is prolonged
Solution Approach 1:
The patent combines hydraulic torque and electric torque from a variable-frequency drive to accelerate the hydraulic machine during start-up. This merging of two torque sources enables faster acceleration and reduces the start-up sequence duration from conventional times to under 28 seconds, while the control system integrates both torque sources through a unified control architecture.
Solution Approach 2:
The variable-frequency drive acts as an intermediary device that provides electric torque to supplement the hydraulic torque during start-up. This intermediary component enables precise control of the acceleration process and facilitates the transition between different operation modes without directly modifying the core hydraulic machine structure.
2Loss of time
If hydraulic torque alone is used during mode transitions, then the control system remains simple, but the transient time between pump and turbine modes is extended
Solution Approach 1:
During transitions between pump and turbine modes, the patent merges hydraulic torque and electric torque to accelerate or decelerate the machine to the target rotational speed. This combination enables rapid mode switching by providing additional torque during the transient phase, reducing the transition time while maintaining a coordinated control system that manages both torque sources.
Solution Approach 2:
The control system prepares for mode transitions by pre-positioning the variable-frequency drive to provide the necessary electric torque before the transition is initiated. This preliminary action ensures that the machine can quickly respond to mode change commands and reach the target rotational speed without delay, minimizing the transient time.
3Productivity
If the machine is accelerated faster to reduce start-up time, then productivity improves, but the risk of mechanical stress and instability increases
Solution Approach 1:
The patent employs a control system that continuously monitors the rotational speed and torque during acceleration, using feedback to adjust the electric and hydraulic torque application. This feedback control ensures that the machine accelerates smoothly and reaches the target speed without excessive mechanical stress or instability, maintaining reliability while improving productivity.
Solution Approach 2:
The variable-frequency drive dynamically adjusts the electric torque during acceleration based on the machine's instantaneous speed and load conditions. This dynamic control allows the system to optimize the acceleration profile, applying higher torque when needed and reducing it when approaching the target speed, thereby improving start-up time while maintaining mechanical stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces the time required to transition between pump and turbine modes, improving operational efficiency by accelerating the machine to target speeds faster than traditional methods, as illustrated by a reduction from 46 seconds to 28 seconds in coupling to the grid.
Implementation Method 1
a variable-frequency drive providing an electric torque to the machine so as to accelerate or decelerate the machine
Implementation Method 2
a battery connected to an alternator of the hydraulic machine
Implementation Method 3
a generator which converts the mechanical energy of the rotating shaft into electrical energy
Implementation Method 4
The hydraulic torque is first applied as from opening of a main inlet valve mounted within a hydraulic pipe upstream of the machine
Data Source
Figure 1
Figure 2
Figure 3
AI summary
This installation for converting a hydraulic energy into electrical energy comprises a hydraulic adapted to be operated either in a pump mode or in a turbine mode. It further comprises means (25) for applying an electric torque to the rotor to control the rotation speed of the machine during transitions between the pump mode and the turbine mode.