The Study And Design Of Cooling Water Temperature Control System Of Marine Diesel Engine

Marine diesel engine is a power plant with big inertia, multi-variable, multi-output and complexity operating conditions. Its working conditions have direct impaction on navigation security and ships operating profits. The temperature of cooling water of marine diesel engine is an important reference. It is very significant to control the temperature of cooling water accurately. For improving the power performance of diesel engine, decreasing the exhausting and saving fuel. If the temperature of cooling water is very high. the high temperature will speedup the ageing speed of lubricate oil.and accelerate the wear and tear of parts: if the temperature is very low (below 30℃). the acid radical in combustion air and water come into new acid. and the new acid also accelerate the corruption of the parts. So the temperature of cooling water affects the performance of diesel engine. However,due to the heat transfer process and the pipeline delay,there is a long delay and big inertia for the temperature of cooling water, combining with the complexity operating conditions of the engine, it is very difficulty to control the temperature of cooling water.In this paper. for big inertia. long delay and easy overshooting of the temperature, thermodynamic model and control system model of cooling water of marine diesel engine are studied. Based on feedforward control theory, two fuzzy controllers are designed. and control effects of the controllers are compared in MATLAB. The simulation results show that the control speed and anti-disturbance ability are significantly improved after feedforward fuzzy controller introduced. In order to improve reliability, control speed and accuracy of the control syste, in this paper, a new temperature control system based on S7-200 PLC is designed. The new control system has the function of feedforward fuzzy control, automatic and manual operation modes. With the HIM of the control system, system parameters can be set and modified, also abnormal condition such as high and low temperature can be alarmed.