Hydraulic Machine Speed Stabilization via Electric Torque Mediator
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Solution Overview
Problem
Hydraulic machines with S-characteristics face challenges in stabilizing rotation speed during start-up due to 'S-zones', which are unstable operating points causing significant torque variations, making it difficult to synchronize with the grid using conventional PID loops, and previous solutions either redesign costly hydraulic parts or generate unwanted vibrations.
Innovation Solution
A method involving a control loop feedback system that calculates the orientation of guide vanes and provides electric torque to stabilize the rotation speed, using a variable-frequency drive or battery-powered alternator to adjust the speed difference between the machine and target speed, achieving coarse and fine regulation to couple the machine to the grid outside 'S-zones'.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PID control loop is used to stabilize rotation speed, then the control system remains simple, but the rotation speed cannot be stabilized due to S-zone characteristics causing significant torque variations
Solution Approach 1:
An electric torque source is introduced as an intermediary element to counterbalance the unstable hydraulic torque in S-zones. The electric torque source provides compensating torque to stabilize the total torque on the runner, enabling rotation speed stabilization without redesigning the hydraulic parts. This mediator approach resolves the contradiction by adding a controlled element rather than complicating the existing PID loop.
Solution Approach 2:
The invention changes the torque parameter by superimposing electric torque on the hydraulic torque. By controlling the electric torque source to provide counterbalancing torque when operating points enter S-zones, the total torque is maintained stable, thereby stabilizing rotation speed. This parameter change approach allows maintaining the simple PID control structure while achieving stabilization.
2Reliability
If hydraulic parts are redesigned to avoid S-zones, then rotation speed stabilization is achieved, but the cost increases significantly and performance may be reduced
Solution Approach 1:
Instead of redesigning the hydraulic parts (runner, guide vanes), the invention introduces an electric torque source as a mediator to counterbalance the unstable torque characteristics. This approach avoids the high cost of hydraulic redesign while achieving the same stabilization effect. The electric torque source is controlled to provide compensating torque when the operating point enters S-zones.
Solution Approach 2:
The invention substitutes mechanical/hydraulic redesign with an electric control solution. Rather than physically modifying the hydraulic parts to eliminate S-zones, an electric torque source is used to counterbalance the unstable torque. This substitution achieves stabilization at lower cost and without compromising the hydraulic design.
3Reliability
If non-synchronized guide vanes are used to avoid S-zones, then rotation speed stabilization is achieved, but unwanted vibrations are generated that negatively affect machine behavior
Solution Approach 1:
The electric torque source acts as a mediator that stabilizes torque without disturbing the guide vane synchronization. By providing counterbalancing torque through the electric source, the system achieves stabilization while maintaining synchronized guide vanes, thereby avoiding the vibrations caused by non-synchronized operation.
Solution Approach 2:
The invention replaces the mechanical solution of non-synchronized guide vanes with an electric torque-based solution. Instead of physically desynchronizing the guide vanes to avoid S-zones, the electric torque source counterbalances the unstable torque while the guide vanes remain synchronized, eliminating harmful vibrations.
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
Effectively stabilizes the rotation speed of hydraulic machines with S-characteristics, allowing successful coupling to the grid by reducing speed oscillations and maintaining stability across the machine's functioning range, avoiding costly redesigns and unwanted vibrations.
Implementation Method 1
providing an electric torque to the rotor so as to reach a target speed
Data Source
AI summary
This method for stabilizing the rotation speed of a hydraulic machine having S-characteristic and comprising a distributor (9) is adapted to modify a water flow, so that the machine can be coupled to a grid. The method comprises the steps of calculating an orientation of the distributor (9); and orienting the distributor according to the calculated orientation. The method further comprises the steps of providing an electric torque to the machine so as to reach a target speed.