Generator Synchronization via Frequency Phase Bias Control
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Solution Overview
Problem
Existing power systems with multiple generator sets face challenges in synchronizing frequency and phase quickly while minimizing thermal stress, as existing methods rely on models that degrade with gas turbine aging and can get stuck in oscillation loops, leading to potential failure in connecting generators to a live bus.
Innovation Solution
A method and system that monitor generator sets and bus conditions, calculate frequency and phase mismatches, and apply weighted biases using PID controllers to synchronize generators with the bus, ensuring voltage, frequency, and phase alignment before connection, thereby avoiding model imperfections and thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If model-based control is used to synchronize generator frequency and phase, then synchronization speed is improved, but reliability deteriorates due to model degradation with turbine aging and oscillation loops
Solution Approach 1:
The patent implements feedback control by continuously monitoring the actual frequency and phase of the generator set and bus, comparing them to calculate mismatches, and adjusting the generator speed based on the calculated speed bias. This closed-loop feedback mechanism replaces open-loop model-based control, ensuring reliable synchronization even as turbine characteristics change with aging.
Solution Approach 2:
The control system uses real-time measurements from the generator set itself (actual frequency, phase) rather than relying on pre-established models of turbine behavior. The system serves itself by using its own operational data to determine synchronization actions, making it adaptive to aging and performance changes without requiring updated models.
2Productivity
If rapid frequency and phase matching is achieved, then productivity is improved, but thermal stress on turbine increases
Solution Approach 1:
The patent applies dynamic control by continuously adjusting the generator speed based on real-time frequency and phase mismatches. The speed bias is calculated dynamically using PID control parameters that respond to changing conditions, allowing the system to achieve rapid synchronization when needed while automatically modulating the rate of change to prevent excessive thermal stress on the turbine.
Solution Approach 2:
The control system changes operational parameters (fuel commands, generator speed) dynamically during the synchronization process. By adjusting these parameters based on calculated speed bias and using derivative feedback to limit rate of change, the system achieves efficient synchronization while controlling thermal stress through parameter modulation rather than aggressive fixed-step changes.
3Measurement precision
If model biases are applied to compensate for oscillation zones, then synchronization accuracy is improved, but device complexity increases
Solution Approach 1:
The patent introduces an intermediary calculation layer that computes speed bias based on frequency and phase mismatches rather than directly applying complex model corrections. This intermediary approach uses standardized PID control parameters and derivative feedback as mediators to achieve accurate synchronization without requiring complex zone-based bias tables or lookup structures.
Solution Approach 2:
The patent replaces complex mechanical-style model-based control (with zones, biases, and lookup tables) with an electronic/software-based PID control system. This substitution uses mathematical algorithms to calculate speed bias in real-time, achieving the same synchronization accuracy with reduced complexity and increased adaptability compared to fixed mechanical control mechanisms.
Data Source
AI summary
A method of operating a power system is provided. The power system has a plurality of generator sets and a bus. The method monitors the bus and generator sets disconnected from the bus. The method supplies to a control device information associated with the operating state of each of the generator sets and the bus. The method determines a relative frequency mismatch, multiplied by a first weight factor, and a relative phase mismatch, multiplied by a second weight factor, between the frequency and phase of the bus and a generator, and generates a frequency speed bias and a phase speed bias for the generator. The method adds the frequency and phase speed biases to form a total speed bias and connects the generator to the bus when the voltage, frequency, and phase of the generator are within a permissible range of the bus.