Rectifier Bridge Closed-Loop Excitation for Stable Generator Voltage
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Solution Overview
Problem
Existing excitation processes in generators face challenges in achieving quick voltage establishment with minimal oscillation and overshoot, and the initial anode voltage establishment is unreliable, particularly in generators with varying time constants and residual magnetism levels, leading to potential excitation failures.
Innovation Solution
A rectifier bridge closed-loop control method that adjusts the control angle using a PID algorithm and a sine curve-based given value, combined with an initial anode voltage establishment method that utilizes full conduction of the rectifier bridge and initial excitation power supply to ensure smooth voltage build-up and reduce reliance on the latter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rectifier bridge closed-loop control is used to establish voltage quickly, then excitation speed improves, but voltage overshoot and oscillation increase
Solution Approach 1:
The patent applies dynamic control by adjusting the rectifier bridge control angle α in real-time based on the excitation process stage. During initial excitation, a smaller control angle (5°-15°) is used to limit voltage rise rate and reduce overshoot. As excitation progresses and voltage approaches the given value, the control angle is dynamically increased to accelerate voltage establishment, thereby resolving the contradiction between excitation speed and voltage stability
Solution Approach 2:
The patent changes the control parameter (control angle α) according to different excitation stages and generator characteristics. By modifying the control angle from small initial values to larger values during the process, the system adapts to varying excitation requirements, achieving both quick voltage establishment and minimal oscillation through parameter optimization
2Reliability
If initial excitation power supply is used to ensure reliable anode voltage establishment, then excitation reliability improves, but contactor wear and maintenance requirements increase
Solution Approach 1:
The patent implements self-service by using the rectifier bridge's full conduction capability to establish initial anode voltage without relying on the initial excitation power supply. The system utilizes its own rectifier bridge circuit to provide the necessary initial voltage, eliminating the need for external excitation power supply and its associated contactor, thereby improving reliability while reducing mechanical wear
Solution Approach 2:
The patent extracts and eliminates the initial excitation power supply component from the excitation system by utilizing the rectifier bridge's inherent full conduction function. This removal of the external power supply and contactor reduces system complexity, eliminates a potential failure point, and extends system maintenance intervals
3Stability of the object's composition
If rectifier bridge control angle is kept small to ensure stable control, then control stability improves, but voltage rise speed decreases
Solution Approach 1:
The patent applies periodic action by dividing the excitation process into distinct stages with different control strategies. During the initial stage, a small control angle ensures stability; during the intermediate stage, the control angle is increased to accelerate voltage rise; and during the final stage, control is refined to achieve precise voltage establishment. This staged approach resolves the contradiction between control stability and voltage rise speed
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 method enables rapid and stable voltage rise with minimal oscillation and overshoot, enhances excitation reliability by leveraging the rectifier bridge's full conduction as an emergency measure, and prolongs the life of contactors by minimizing initial excitation power supply usage.
Implementation Method 1
A relationship between an input voltage and an output voltage of a three-phase fully-controlled rectifier bridge may be expressed as: Uout=1.35Uin cos α
Implementation Method 2
In closed-loop control, a deviation between the voltage U and the given value Ref passes through a PID link to obtain a control amount
Data Source
AI summary
A rectifier bridge closed-loop control excitation method and an initial anode voltage establishment method are provided. In the method, an excitation function is periodically invoked to calculate a given value Ref, a rectifier bridge control angle is calculated, and a bridge rectifier is controlled; the whole excitation process is under closed-loop control, a terminal voltage of a generator rises quickly and smoothly, an excitation voltage is almost free of oscillation, overshoot is small, and adaptability to generator sets with different time constants is good; and when an initial anode voltage is established, excitation reliability is improved by combining an initial excitation power supply and a full conduction function of the bridge rectifier, and the full conduction control of the rectifier bridge is used as an emergency measure when the initial excitation power supply fails, so that the initial anode voltage is established with a relatively large probability.