Combined-Cycle Power Plant Control via Net Electric Power Detection
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Solution Overview
Problem
Combined-cycle power plants face challenges in precisely estimating losses along electric lines and power absorption by auxiliary devices, leading to deviations in electric power delivery to the grid, which are currently compensated by complex and underperforming buffer systems.
Innovation Solution
A control method and device that detects net electric power downstream of the electric-transformer assembly, generates a gross-electric-power reference by adding a net-electric-power error to the gross electric power, allowing precise control of the gas-turbine assembly to match the net-electric-power reference, eliminating the need for estimating power absorption and line losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If buffer systems are used to compensate for estimation errors in line losses and auxiliary device power absorption, then deviations in electric power delivery are reduced, but the system complexity increases and performance remains insufficient
Solution Approach 1:
The patent extracts the problematic estimation and buffer compensation functions, replacing them with direct measurement of net electric power at the delivery point. This removes the complex buffer systems while achieving the same reliability goal through a simpler measurement-based control approach.
Solution Approach 2:
The patent implements a feedback control mechanism where the detected net electric power is continuously compared with the reference value, and the gas turbine assembly is adjusted based on the error signal. This closed-loop feedback eliminates the need for open-loop buffer systems.
2Ease of operation
If estimation methods are used for line losses and auxiliary device power absorption, then control can be implemented without direct measurement, but measurement precision deteriorates due to intrinsic estimation uncertainty
Solution Approach 1:
The patent substitutes the mechanical/estimation-based approach with an electrical measurement approach. Instead of estimating power losses through calculations, a transducer directly measures the net electric power at the delivery point, providing superior precision while maintaining operational simplicity through automated detection.
3Measurement precision
If net electric power is directly detected at the power grid interface, then measurement precision improves, but the control system complexity increases
Solution Approach 1:
The system uses the net electric power measurement directly at the delivery point to control the gas turbine assembly, creating a self-regulating system. The measurement and control are tightly coupled, with the transducer feeding directly into the control mechanism, minimizing additional complexity while maximizing precision.
Data Source
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AI summary
A method for controlling a combined-cycle power plant, the combined-cycle power plant (1) comprising an electric generator (5), connected to a gas-turbine assembly (3) and to a power grid (2) through an electric-transformer assembly (7) for delivering electric power to the power grid (2); the method envisages the steps of detecting a net electric power (WN), delivered to the power grid (2), downstream of the electric-transformer assembly (7), and controlling the gas-turbine assembly (3) on the basis of a net-electric-power reference (WRN), indicating the electric power to be delivered to the power grid (2), and on the basis of the net electric power (WN).