Influence of ship consumers of electric energy on optimal control of electrical propulsion plants

Abstract

The urgency of the problem. The most important condition for ensuring the safety of navigation and reducing accidents in the fleet is to take into account the maneuverability of ships, and especially their inertial characteristics. Electric propulsion vessels have the best maneuverability. Special attention is paid to the issues of control of electrical propulsion plants (EPP) of electric ships during maneuvers. Recently, more and more electric ships with a unified electric power system (UEPS) are being built. Both electrical propulsion plant and electricity consumers of electric ships with the UEPS are supplied with power from the general tires of the ship power plant and have a mutual influence on each other. This effect should be taken into account when optimizing the control of the electrical propulsion plant. The status of the issue. Quality indicators of electric ships’ maneuvering were determined and quality indicators of electric energy of the ship network were selected. A method of optimizing the parameters of the control laws of EPP has been developed. The transition to optimal control leads to an increase in the load on the propulsion motors and on the generating units. This may affect the quality indicators of the electric energy of the ship network. The study of this influence is the purpose of this work. The method of solving the problem. A mathematical model of EPP transient modes as part of the ship propulsion complex is used to evaluate the maneuvering characteristics of electric ships. A method of calculating transient modes of operation during maneuvering has been developed on its basis. It is proposed to form the control signals for frequency and voltage in the form of polynomials. A method of optimizing the parameters of control laws has been developed. The results of the study. Effects of load changes on optimal control laws are the following: load decrease slightly affects the optimal solution; with an abrupt increase in the load the stopping distance grows. The optimal parameters of the control laws vary slightly. The impact of the transition from the classical to the optimal control is the following: the quality indicators of the electric energy of the ship network are deteriorating, but are within acceptable limits. Conclusions. The search for optimal control laws of EPP during maneuvering for electric ships with a unified electric power system can be carried out without taking into account the switching on and off of ship consumers. The change of load in the ship network affects the value of the target function but does not affect the optimal parameters of the control laws.