For many offshore activities, including offshore oil and gas exploration and offshore wind farm construction, it is essential to keep the position and heading of the vessel stable. The dynamic positioning system is a progressive technology, which is extensively used in shipping and other maritime structures. To maintain the vessels or platforms from displacement, its thrusters are used automatically to control and stabilize the position and heading of vessels in sea state disturbances. The theory of dynamic positioning has been studied and developed in terms of control techniques to achieve greater accuracy and reduce ship movement caused by environmental disturbance for more than 30 years. This paper reviews the control strategies and architecture of the DPS in marine vessels. In addition, it suggests possible control principles and makes a comparison between the advantages and disadvantages of existing literature. Some details for future research on DP control challenges are discussed in this paper.

The shunt active power filters (SAPFs) are broadly utilized to improve the power quality (PQ) issues of electric power systems. A crucial issue in implementing these filters is the accurate estimation of the grid voltage phase/frequency. Indeed, the dynamic behavior and the performance of the SAPF strongly rely on this point. To deal with this challenge, a fast yet effective open-loop synchronization (OLS) technique based on Cascaded Delayed Signal Cancellation (CDSC) is presented in this paper. The proposed technique can reject the odd-order harmonics, the DC offset of the grid voltage, and its dynamic response during transients take an only half cycle of the fundamental frequency. To adapt the proposed OLS technique to the frequency changes, an efficient frequency estimator is also presented. The effectiveness of the proposed OLS technique is demonstrated using simulation and experimental results.

The dynamic positioning (DP) system is a progressive technology, which is used in marine vessels and maritime structures. To keep the ship position from displacement in operation mode, its thrusters are used automatically to control and stabilize the position and heading of vessels. Hence, the DP load forecasting is already an essential part of DP vessels, which the DP power demand from the power management system (PMS) for thrusting depends on weather conditions. Furthermore, the PMS is used to control power generation, and prevent power failure, limitation. To perform station keeping of vessels by DPS in environmental changes such as wind, waves, capacity, and reliability of the power generators. Hence, a lack of power may lead to lower DP performance, loss of power, and position, which is called shutdown. Therefore, precise DP power demand prediction for maintaining the vessel position can provide the PMS with sufficient information for better performance in a complex decision-making process for the DP vessel. In this paper, the concept of deep learning techniques is introduced into DPS for DP load forecasting. A Levenberg–Marquardt algorithm based on a nonlinear recurrent neural network is employed in this paper for predicting thrusters’ power consumption in sea state variations due to challenges in power generation with the relative degree of accuracy by combining weather parameter dependencies as environmental disturbances. The proposed method evaluates with three traditional forecasting methods through a set of practical real-time DP load and weather parametric data. Numerical analysis has shown that with the proposed method, the future DP load behavior can be predicted more accurately than that obtained from the traditional methods, which greatly assists in operation and planning of power system to maintain system stability, security, reliability, and economics.

Over recent years, due to the fast expansion of power electronics technology onboard shipboard power systems (SPSs), harmonic contamination has become one of the main concerns. Moreover, the SPSs are characterized by heavy pulsed loads, which can draw a large amount of power in a short duration, which usually causes a voltage drop. If the latter exceeds the norms, a voltage collapse might occur and leads to the blackout of the ship. The contribution of this paper is to propose a combined topology, which consists of a hybrid active power filter (HAPF) connected to the switchboard via a series passive filter (hereafter called HAPF), and a parallel fixed capacitor-thyristor controlled reactor (FC-TCR) to overcome the aforementioned deficiencies of the SPS. Based on the model predictive control (MPC) and synchronous reference frame technique (SRF), the HAPF estimates the harmonics of the system and counter them, while the FC-TCR is designed to act as a low-pass filter and a reactive power compensator to enhance the stability and reduce the distortion of the voltage. The modeling and control of the proposed topology are presented. Furthermore, the voltage stability analyses of the SPS are conducted. Finally, the performance of the proposed topology is carried out under MATLAB/Simulink environment, and the results demonstrate the efficacy of the HAPF and the FC-TCR in suppressing harmonics and improving the voltage stability of the SPS.

In recent years, due to the large spread of power electronics converters onboard shipboard power systems (SPSs), harmonic contamination became an inherent problem. Moreover, as the SPSs are mostly operating in an islanded mode with a limited rating of the generators that feed heavy variable loads, voltage stability issues became a challenge as well. To address these issues, implementing PWM-based FACTS devices using IGBTs such as the active power filters may not be very practical for high-power SPSs due to their limited rated powers, high implementation cost, and high losses. The passive power filters (PPFs) and fixed capacitor-thyristor controlled reactors (FC-TCR) can be effective alternatives due to their capability to operate in high-power applications, smaller losses and, lower cost. The aim of this article is to provide more in-depth analytical investigations to evaluate and compare the behavior of the PPFs and the FC-TCR compensator in reducing the harmonics and enhancing the voltage stability concurrently of high-power SPSs. In addition, details of the voltage stability concept are addressed to visualize the potential risk of the voltage collapse. Besides, the modeling of the FC-TCR and design of the closed-loop control algorithm to ensure voltage stability is conducted. Via intensive simulation studies of a practical ship, which are carried out in MATLAB/Simulink environment, it has been demonstrated that the FC-TCR based on the proposed design can enhance the power quality and voltage stability of SPSs better than traditional PPFs filters.

Recently, the evolutionary development in power electronics (PE) technologies onboard shipboard micro-grids (SMs) has been receiving significant attention. Indeed, this evolution added enormous advantages such as enhanced maneuverability and controllability. However, the installation of PE converters onboard SMs results in serious power quality issues. The application of the fixed capacitors-thyristor controlled reactors (FCs-TCRs) is largely used to improve some of the power quality issues. However, the non-linearity of the firing angle equation increases the complexity of controlling this sophisticated technology. In this paper, three simple and yet effective numerical algorithms are proposed to estimate the firing angle of the FC-TCR compensator. These algorithms that are based on Newton-Raphson, Bisection, and false position methods have proved their reliability and efficacy in estimating the firing angle under load and frequency variation. The effectiveness and robustness of the proposed methods are demonstrated via modeling an electrical power system of a practical hybrid ferry under MATLAB/Simulink environment, then the results are compared with the traditional technique.