Hydraulic Turbine Grid Coupling with Fast Phase Synchronization
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Solution Overview
Problem
Existing methods for coupling a hydraulic turbine to the grid are slow, typically taking around 90 seconds, which is not compatible with maximum revenue efficiency and result in inefficient use of water reserves and abnormal wear on turbines.
Innovation Solution
A method that simultaneously stabilizes the generator frequency and aligns the generator phase with the grid phase, allowing for faster coupling by closing the circuit breaker when both conditions are met within specified tolerance intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the traditional multi-step starting method is used, then the synchronization is achieved reliably, but the coupling time is too long (90 seconds)
Solution Approach 1:
The patent combines the frequency stabilization step and phase alignment step into a single simultaneous operation. The control system adjusts guide vane opening and rotor excitation current together to achieve both frequency matching and phase alignment at the same time, eliminating the sequential execution delay of the traditional method.
Solution Approach 2:
The patent applies preliminary action by pre-adjusting the rotor excitation current and guide vane opening before the actual coupling moment. The control system prepares the generator's frequency and phase in advance during the acceleration phase, so that when the circuit breaker closes, synchronization is already achieved or nearly achieved, reducing the required coupling time.
2Loss of time
If the unit is maintained synchronized at very low power, then the coupling time is reduced, but water reserves are consumed at low efficiency and abnormal wear occurs
Solution Approach 1:
The patent employs dynamic control of the guide vane opening and excitation current during the starting process. Instead of maintaining a static low-power synchronized state, the system dynamically adjusts parameters during acceleration to reach optimal coupling conditions faster, then transitions to efficient full-power operation, avoiding prolonged low-efficiency operation.
3Loss of time
If the dewatered mode is used to keep the unit synchronized, then the coupling time is reduced, but specific investments are required and electrical power from the grid is consumed
Solution Approach 1:
The patent makes the hydraulic unit self-sufficient during the starting process by using its own water flow and mechanical inertia to achieve synchronization, without requiring external dewatering systems or grid power assistance. The system uses its inherent capabilities (water flow control via guide vanes and rotational inertia) to perform the synchronization function independently.
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 method reduces the time needed to couple the hydraulic unit to the grid from 90 seconds to 60 seconds without requiring additional investments or consuming water reserves or grid electrical power.
Implementation Method 1
a synchronous generator whose rotor is driven in rotation by a turbine
Implementation Method 2
a hydraulic turbine provided with a runner mechanically coupled to the rotor of the synchronous generator via a shaft line to drive the synchronous generator
Data Source
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AI summary
The invention concerns a method for coupling to the grid a hydraulic unit (1) having a synchronous generator (2), a runner (6), and wicket gates, the method comprises: a) a step of increasing the flow of water into the runner (6) from a time t0 to a time t1 so that the rotation frequency of the rotor of the synchronous generator (2) is, at time t1 equal to the frequency of the grid (3); b) a step of closing the circuit breaker at time t1, step a) further comprises a sub-step a1) executed from a time t2 to time t1, wherein the flow of water is adjusted so that, at time t1, the phase of the synchronous generator (2) is aligned with the grid phase.