Variable Frequency Generator Switching for Grid Stability
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Solution Overview
Problem
Synchronous generator systems face challenges in maintaining stable frequency on the grid when load fluctuations occur, leading to potential slowing or acceleration of generators, which can result in frequency deviations.
Innovation Solution
A variable frequency generator (VFG) system with a dual-converter configuration and switchable connections between the stator and rotor portions, allowing for efficient power management during starting and running conditions, including the use of a DC link and dynamic brake to regulate generator operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a dual-converter configuration is used for VFG operation, then the generator can be started and operated efficiently, but the device complexity and cost increase
Solution Approach 1:
The patent implements dynamic switching between different converter configurations based on operational mode. During starting, the first converter connects to the stator while the second converter connects to the rotor. During running, the switches reconfigure to connect both converters in parallel to the rotor. This dynamic reconfiguration allows the system to adapt its complexity to the operational requirements, using full dual-converter capability only when needed for starting and running control.
Solution Approach 2:
The patent divides the power conversion function into two separate converters with distinct roles. The first converter handles stator power conversion during starting, while the second converter handles rotor excitation. This segmentation allows each converter to be optimized for its specific function and enables independent control of stator and rotor circuits during the starting phase.
2Ease of manufacture
If converter count is reduced during starting, then cost-effectiveness improves, but the ability to control both stator and rotor independently is compromised
Solution Approach 1:
The switching mechanism dynamically adjusts the converter configuration based on operational phase. During starting, only the first converter is active for stator control, reducing complexity. During running, both converters are activated and connected in parallel to the rotor, providing full independent control capability when needed.
Solution Approach 2:
The first converter is pre-configured to handle stator power conversion during the starting phase before the second converter is activated for rotor excitation. This preliminary action sequence allows the system to achieve starting control with minimal converter configuration, then adds the second converter's functionality only when required for running operation.
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
The system effectively limits generator slowing during increased grid load by optimizing power distribution and maintaining grid frequency stability through efficient converter operation and reduced converter count during starting, enhancing reliability and cost-effectiveness.
Implementation Method 1
a first converter, operative to convert DC current to AC current connected to a DC link
Implementation Method 2
a second converter, operative to convert DC current to AC current connected to the DC link
Implementation Method 3
a variable frequency generator (VFG) exciter, wherein the VFG exciter includes... a first converter, operative to convert DC current to AC current connected to a DC link
Data Source
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AI summary
An electrical generation system comprising a generator (102). The generator (102) including, a stator portion (stator), and a rotor portion (rotor), and a variable frequency generator (VFG) exciter (104). The VFG exciter (104) including, a first converter (120), operative to convert DC current to AC current connected to a DC link (106) and a second converter (122), operative to convert DC current to AC current connected to the DC link (106). The system including a first switch (103) operative, when closed, to connect the first converter (120) to the stator portion while the generator (102) is operating in a starting condition, wherein the first switch (103) is open while the generator (102) is operating in a running condition. The system including second switch (105) operative, when closed, to connect the first converter (120) and the second converter (122) in parallel to the rotor portion (rotor) while the generator (102) is operating in a running condition, wherein the second switch (105) is open while the generator (102) is operating in the starting condition.