Improved algorithm for supervisory control and data acquisition of combined vessel’s energy system

Abstract

Main development trends of modern ship power systems have been analyzed. The purpose of the paper is the analysis of energy modes and the development of criteria for transitions between different modes of an integrated marine vessel’s power system, providing maximum efficiency in the use of fuel and motor resources of main vessel engines. It is proposed to identify, in addition to the shore-to-ship mode, four main operating modes in the presence of a synchronous machine on a propeller shaft and a converter that ensures an operation of this machine in both motor and generator modes. By dividing the main engine load into four levels – small, medium, nominal and large – an automatic system can accordingly control (or recommend in semi-automatic mode) the switching sequence of power equipment and actuating machines and mechanisms. Using a few container ships as an example, it is shown when the ship moves at a low speed, the main engine load becomes so low that it can be provided by diesel generators of the ship’s energy system (“Power-Take-Home” mode). This, on the one hand, allows to save fuel, and on the other hand increases the completeness of fuel oil consumption, since diesel generators operate at an optimal load unlike the main engine, the load of which reaches only 10 percent. Similarly, in case of medium loading of the main engine, it is recommended to switch to the power supply of ship’s grid from the main engine with the shaft generator (“Power-Take-Off” mode), and if it is necessary to obtain increased power of the propulsion system, the synchronous machine is switched to the engine mode powered by diesel generators (“Power-Take-In” mode). In addition, the ability to switch of these and main modes in emergency situations quickly increases the vessel’s survivability and safety. Based on the analysis, an algorithm for switching between modes is proposed, which can be implemented in Supervisory Control Ad Data Acquisition of ship’s energy systems, in particular, on a physical simulator at the National University “Odessa Maritime Academy”.