Integrated Control System for Diesel Genset Load Transients
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Solution Overview
Problem
Conventional diesel genset control systems face challenges in managing sudden load changes, leading to generator speed and voltage deviations due to cross-coupling between voltage and speed control loops, resulting in oscillations and poor recovery times, which are nonlinear and difficult to parameterize for optimal performance.
Innovation Solution
An integrated control system that decouples cross-coupling terms between voltage and speed control loops using a Feedback Linearizing Control (FLC) subsystem and Load Anticipation Control (LAC) subsystem, which measures real power changes and adds a feed-forward signal to the governor error summing point during transients, effectively reducing generator speed deviations and improving voltage regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional separate control loops are used for voltage and speed regulation, then the control system structure is simple, but cross-coupling causes oscillations and poor recovery during sudden load changes
Solution Approach 1:
The patent combines the voltage control loop and speed control loop into an integrated control system that processes both signals together. The AVR receives both terminal voltage feedback and generator speed feedback, allowing simultaneous regulation of both parameters while accounting for their cross-coupling effects, thereby improving load acceptance performance without excessive complexity
Solution Approach 2:
The system implements dual feedback loops: one from terminal voltage to the AVR for voltage regulation, and another from generator speed to the AVR for speed regulation. This multi-feedback approach allows the controller to respond to deviations in both voltage and speed simultaneously, reducing oscillations and improving recovery during transient load changes
2Stability of the object's composition
If PID control is used in the AVR, then voltage regulation is stabilized, but cross-coupling with speed loop causes oscillations during transients
Solution Approach 1:
The generator speed signal acts as an intermediary that bridges the voltage and speed control loops. By feeding speed feedback into the AVR along with voltage feedback, the system accounts for the cross-coupling effect where speed changes affect voltage and vice versa, thereby reducing oscillations during transients while maintaining PID-based voltage regulation stability
3Ease of manufacture
If governor responds slowly to load changes, then fuel control is simple, but generator speed deviates significantly during sudden load acceptance
Solution Approach 1:
The system anticipates the need for speed correction by continuously monitoring generator speed and proactively adjusting the AVR output accordingly. When speed deviation is detected, the AVR modifies the excitation signal in advance to counteract the effect on terminal voltage, thereby reducing overall system oscillation without requiring complex governor modifications
Solution Approach 2:
Generator speed feedback is fed into the AVR to create a coupled control response. When speed deviates during sudden load changes, the AVR receives this feedback and adjusts the field current to the exciter, which indirectly supports speed recovery by maintaining voltage stability, thereby reducing speed deviation without complicating the governor mechanism
Data Source
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AI summary
An integrated control system and method which improves load application/rejection performance for diesel generating sets is disclosed. Feedback-linearizing control is used for voltage regulation, which removes interaction between automatic voltage regulation and speed regulation. A proper feed-forward signal is sent to the governor using load anticipation control. The integrated control reduces engine speed and voltage deviations. It is implemented in the voltage regulator, since it recognizes load changes before the engine. The integrated control helps the engine anticipate throttle adjustments in advance of load being recognized by the engine. Test results show an improvement in engine speed recovery after a large increase or decrease in load.