Research On Condition Assessment Of Marine Mechanical And Electrical System

As a typical complex system,the marine mechanical and electrical system can be used in the serious environment for long time. The traditional maintenance which may appear excessive and lack of maintenance can't meet the system, and results the waste of manpower and material resources. The condition maintenance based on condition assessment can determine the state timely and accurately to make reasonable and reliable maintenance.Therefore, it is urgent and important to study the condition assessment of the marine mechanical and electrical system. The paper takes marine mechanical and electrical system as the object, in order to establishing condition assessment index system, to study assessment methods, to make up prediction models. Meanwhile, the paper predicts the future condition of the system with the prediction models. The main research contents are as follows:1. Taking ships' mechanical and electrical system as the object, the paper presets the principle of ships' mechanical and electrical system, and divides the indexes into three categories: on-line monitoring parameters, basic parameters and equipment failure history.Using FMECA method, the paper analyses the typical failure of equipment, and the relevant parameters of each failure. Using expert scoring method to get the risk of failure, the paper select the number more than 6 as the condition assessment indicators. Taking the integrated electric propulsion system as an example, the paper analyzes the typical failures of gas turbine,diesel engine, generator, inverter and motor, to establish the condition assessment index system, which can meet the needs of the assessment.2. The paper researches the process of marine mechanical and electrical system, and established the assessment model with the fuzzy comprehensive evaluation method. Firstly,the paper determines the system task profile, and decides the implement. Secondly, the paper establishes the construction with hierarchical analysis method. Then, the identity matrix is made up to analyze the weight of each element. Third, according the different assessment index, the paper choses different membership functions, and gets the equipment, model and system condition through the first level and second level fuzzy comprehensive evaluation method. Finally, taking the integrated electric propulsion system as an example to prove, the result shows the model can reasonably assess the condition.3. In order to predict the future marine mechanical and electrical system condition, two ways of predicting the original data and predicting the condition result data are used. The first way predicts the original data by using the improvement moving average model. The paper selects the predictions as the input of the assessment model to get the future condition. The second way predict the condition result directly. Taking the motor as an example, the two ways are compared, and the advantage and disadvantage are analyzed.