Ship Propulsion Control for Fuel Efficiency
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Solution Overview
Problem
Existing controllable pitch propeller systems for ships operate inefficiently at lower speeds due to a fixed relationship between engine speed and propeller pitch, limiting maximum efficiency and requiring separate auxiliary engines for electricity generation, which is not optimal for fuel consumption.
Innovation Solution
Adaptive control system that continuously adjusts engine speed and propeller pitch independently to maintain the lowest allowable engine speed and maximum output within the engine's load limit curve, optimizing fuel consumption by varying torque and speed based on load conditions, weather, and current conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed relationship between engine speed and propeller pitch is used, then the system is simple to operate, but the propulsion efficiency deteriorates at lower speeds
Solution Approach 1:
The control system transitions from a fixed static relationship to a dynamic adaptive relationship between engine speed and propeller pitch. The system continuously adjusts both parameters based on real-time operating conditions (ship speed, load, weather, current) to maintain optimal propulsion efficiency across the entire operating range, particularly improving performance at lower speeds where the fixed relationship fails.
Solution Approach 2:
The system changes the operating parameters (engine speed and propeller pitch) adaptively rather than maintaining a fixed relationship. By continuously varying these parameters based on actual conditions, the system optimizes the propulsion efficiency at each operating point, resolving the contradiction between operational simplicity and energy efficiency.
2Reliability
If engine speed is kept constant to maintain generator frequency, then the generator frequency remains stable, but the propulsion efficiency deteriorates at lower ship speeds
Solution Approach 1:
The system implements a dynamic control strategy where engine speed is allowed to vary adaptively based on ship speed and operating conditions. This replaces the static constant engine speed approach, enabling the system to maintain propulsion efficiency across varying speeds while using alternative methods (such as auxiliary engines or energy storage systems) to maintain generator frequency stability when needed.
Solution Approach 2:
The control system segments the functions of engine speed control and generator frequency control. By separating these two functions, the system can optimize engine speed for propulsion efficiency independently while maintaining generator frequency through other means (auxiliary generators, power management systems), thus resolving the contradiction between frequency stability and propulsion efficiency.
3Reliability
If the fixed combination curve is used with margin to maximum allowable load, then the engine operates safely within limits, but the maximum efficiency of the engine cannot be achieved under multiple conditions
Solution Approach 1:
The system dynamically adjusts operating parameters (engine speed and propeller pitch) to track the optimal efficiency curve rather than operating on a fixed conservative combination curve. By continuously adapting parameters based on actual conditions, the system achieves maximum engine efficiency under varying conditions while maintaining safety through real-time monitoring and adaptive control within manufacturer-defined thresholds.
Solution Approach 2:
The control system incorporates feedback mechanisms that continuously monitor engine operating conditions, ship speed, load, and environmental factors. This feedback enables the system to adjust engine speed and propeller pitch in real-time to maintain optimal efficiency while ensuring operation remains within safe limits, thus achieving both high productivity and reliability.
4Reliability
If Load Control safety function limits maximum torque, then the pitch is limited to prevent exceeding set values, but the engine speed becomes higher and torque lower than optimal
Solution Approach 1:
The system simultaneously optimizes both engine speed and propeller pitch rather than limiting pitch through torque restrictions. By adaptively changing both parameters together based on actual operating conditions, the system achieves the desired pitch limits for safety while maintaining optimal engine speed and torque combinations for minimum fuel consumption, eliminating the need for conservative torque limiting that causes suboptimal operation.
Data Source
AI summary
The present invention relates to a method for controlling the fuel consumption of a ship, the ship comprising an engine and a controllable pitch propeller, wherein torque and engine speed are adjusted to correspond to an output set point value. The adjustment is such that the engine is operated in an operating condition with an engine speed and a propeller pitch of the controllable pitch propeller such that the fuel consumption of the ship is brought and/or held within a desired fuel consumption range.