Single-Phase Inverter for Gas Turbine AC Exciter
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Solution Overview
Problem
Existing AC exciter systems for gas turbine power generation require complex configurations with three-phase induction apparatuses and thyristors for start-up, which are inefficient at low rotation speeds and necessitate separate AC and DC excitation circuits, leading to increased complexity and size.
Innovation Solution
A single-phase inverter system that switches between AC and DC excitation modes using IGBT modules and DC capacitors, allowing for high-speed operation and simplified circuitry by providing excitation power to synchronous apparatuses with two-axis field magnet winding wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a three-phase induction apparatus with thyristors is used for AC excitation during start-up, then excitation can be provided at low rotation speeds, but the device complexity and circuit configuration increase significantly
Solution Approach 1:
The patent merges the AC excitation function during start-up and the DC excitation function during normal operation into a single inverter device. The inverter can operate in AC output mode for low-speed start-up excitation and switch to DC output mode for normal operation excitation, eliminating the need for separate three-phase induction apparatus and thyristor circuits.
Solution Approach 2:
The inverter device is designed with multi-functionality to perform both AC excitation during start-up and DC excitation during normal operation. By controlling the switching elements (IGBTs) and using the same inverter circuit for both AC and DC output, the system achieves universal excitation capability across different operational phases.
2Adaptability or versatility
If separate AC and DC excitation circuits are used for different operational phases, then excitation requirements are met, but the overall system complexity increases
Solution Approach 1:
The patent combines multiple excitation circuits (AC excitation circuit and DC excitation circuit) into a single inverter device that can output both AC and DC. The inverter uses the same hardware platform with switching elements to provide different excitation modes, reducing the total number of circuits while maintaining adaptability.
Solution Approach 2:
The inverter device dynamically switches between AC output mode and DC output mode based on the operational phase. During start-up, it operates in AC mode; during normal operation, it switches to DC mode. This dynamic reconfiguration allows one circuit to fulfill multiple excitation requirements.
3Device complexity
If a brushless excitation method is used, then the structure is simplified, but sufficient excitation cannot be achieved at low rotation speeds
Solution Approach 1:
The patent changes the output parameters of the excitation device based on rotation speed. At low rotation speeds during start-up, the inverter outputs AC with appropriate frequency and voltage to ensure sufficient excitation. As rotation speed increases, it transitions to DC output for normal operation, optimizing performance across the entire speed range.
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
Enables efficient start-up and normal operation of gas turbines at low speeds with reduced circuit complexity, sharing excitation devices for both AC and DC modes, improving control accuracy and response time.
Implementation Method 1
a single-phase inverter that supplies a current to each of field magnet winding wires of a synchronous apparatus that is an AC exciter having the field magnet winding wires of two axes and is configured by switching elements, in which the single-phase inverter performs an inverter operation in a case of AC excitation
Implementation Method 2
an AC exciter which generates magnetic flux using a current flowing through the field magnet winding wire, and as an armature winding wire of the AC exciter which is directly coupled to the field magnet winding wire of the power generator through a rotation shaft is interlinked with the magnetic flux, excitation power necessary for power generation is generated
Data Source
AI summary
A gas turbine power generation system is configured by a gas turbine, a main power generator which is coupled to a rotor of the gas turbine through a rotation shaft, a rotation rectifier which converts a three-phase AC current into a DC current and transfers the DC current to a field magnet winding wire of the main power generator, an AC exciter which is configured by an armature winding wire, a d-axis field magnet winding wire, and a q-axis field magnet winding wire, and transfers the three-phase AC current generated at the armature winding wire to the rotation rectifier, an excitation device which drives the AC exciter at the time of start-up of the main power generator, and an excitation power supply which supplies a current to the excitation device.