Naval Shipboard Power Systems Research Articles

Non-intrusive fault detection in shipboard power systems using wavelet graph neural networks

Naval shipboard power systems (SPS) are rapidly embracing electrification, resulting in loads that generate pulsation currents and encounter substantial transients. However, conventional time-based features alone are inadequate for effectively monitoring and safeguarding these loads against faults. This highlights the critical requirement for advanced machine learning based methods to discern and differentiate between the various transient stages within the load profile. In this paper, we propose a Wavelet Graph Neural Network (WGNN) model for non-intrusive fault detection in SPS. The fault detection system leverages the dynamic model of the SPS to train and test performance with varying fault scenarios. The underlying structure and the interdependence among component states in the SPS network are effectively captured using the WGNN model, resulting in accuracies over 99% for intrusive fault detection and 97% for non-intrusive fault detection. The developed WGNN model has also shown to be robust in the presence of pulse loads and noise, achieving an accuracy of over 95%. At the end, a real-time simulation of the proposed method is validated on a hardware-in-the-loop system, guaranteeing the high fidelity and low latency of the proposed approach. These findings validate the effectiveness of the proposed WGNN model for fault detection and real-world applications in SPS.

STFT Cluster Analysis for DC Pulsed Load Monitoring and Fault Detection on Naval Shipboard Power Systems

Current trends in Naval shipboard power system architecture indicate that the electrification of future warships is inevitable, and it will be equipped with loads that draw periodic pulsed currents from the dc microgrid or have large transients while switching state. In order to monitor the operation of those loads, solely time-based features are not enough as they do not provide sufficiently unique information to differentiate various transient stages of the load profile. The focus of more recent research has been on extracting time–frequency features. However, no comprehensive solution exists that could work for any general load profile. The proposed load monitoring and fault detection method presented in this article outlines a data clustering-based approach to extract unique feature vectors from short-time Fourier transform analysis for any pulsed load. These features can then be used to identify various events in the load transient as well as shunt faults and series arcing faults. Implementation and performance of the scheme for several load profiles and fault scenarios are included.

Characterization and Modeling of 10-kV Silicon Carbide Modules for Naval Applications

This paper presents a detailed characterization and modeling effort applied to a set of 10-kV SiC MOSFET modules, which have not been exhaustively described in the literature to date. This paper builds on a previous effort by the authors, in which an empirical performance evaluation was performed using a reduced-scale variant of the medium-voltage direct current (MVDC)-rated SiC MOSFET module. In this paper, full-scale module samples are used, which are capable of continuous operation at 120 A. Thus, the evaluation provided here offers improved relevance to the category of full-scale MVDC applications of which future naval shipboard power systems are expected to be a part. The evaluation effort described here considers both the static and dynamic performances of the considered 10-kV SiC MOSFET module, along with the identification of integration considerations that will be of use to designers of future applications based on this technology. Specific contributions of this paper that belong to this category include the presentation of a custom gate-drive circuit designed to operate the modules under consideration and the presentation of a detailed behavioral simulation model created to predict the performance of the same. The output of this model is compared with experimental waveforms captured during pulsed switching experiments at a bus voltage of 2 kV and a load current of 100 A. The simulation output is demonstrated to offer good agreement with the experimental waveforms during both turn-on and turn-off transitions. The availability of such a model is important because it makes possible the execution of a wide range of feasibility and trade studies for future applications by researchers without physical access to this technology.

Modeling and detecting the stator winding fault of permanent magnet synchronous motors

Because of its high efficiency, robustness, and high power density, a permanent magnet synchronous machine (PMSM) is a desirable choice for high-performance applications, such as naval shipboard power systems. The stator winding fault is the most common electrical fault in PMSM; thus, detection of this type of fault is very important. The objective of this paper is to model and detect the location and severity of the stator winding fault of PMSM. To achieve this objective, a mathematical model that can describe both healthy and fault conditions is developed. Simulation results match the observations of this type of fault in the literature. According to the fault model, two parameters associated with fault location and fault severity must be identified in order to detect the fault. Because of the complex distribution of these two parameters in the fault model, the identification problem is extremely difficult for nonlinear identification techniques. To overcome this difficulty, the detection/identification problem is first transformed into a corresponding optimization problem and then solved using particle swarm optimization (PSO). By simulating a modified model instead of the original model, the PSO-based identification algorithm is able to identify the fault in real time. The real-time PSO-based identification algorithm also can be applied to many other identification problems.

Self-Healing Reconfiguration for Restoration of Naval Shipboard Power Systems

Naval shipboard power systems form a critical component of the U.S. defense infrastructure. When there is a fault in a shipboard power system either due to battle damage or material casualty, it is important to quickly isolate the fault and restore supply to as many loads as possible. This paper presents an automated self-healing strategy for reconfiguration for service restoration in naval shipboard power systems. The proposed method is illustrated on a system developed based on a typical surface combatant ship.

Service restoration in naval shipboard power systems

Service restoration is an important problem in naval shipboard power systems. When faults occur as a result of battle damage or equipment failure and are isolated by protective devices, some critical loads are left without supply. Fast restoration of supply to these vital loads is necessary for system survivability. Loads have different priorities that must be considered during restoration in the shipboard power systems (SPS). These loads are categorised as vital or non-vital. Vital loads have two paths through which they can be supplied. Under some circumstances, it may be preferred to supply a vital load through one of the two paths. Butler et al have developed a method to restore maximum loads in SPS based on the fixed-charge network flow method. An enhancement to their method is proposed to handle priority for loads and paths while restoring service in SPS. The proposed method is illustrated with some case studies on a simplified SPS.

Current and voltage controlled capacitor charging schemes

Future naval shipboard power systems for electrothermal chemical guns will require power conditioning to charge capacitors from a rectified generator source. This paper describes results of laboratory testing involving two low voltage capacitor charging schemes. These experiments demonstrate the power conditioning equipment's voltage and current control characteristics. The first sequence of tests utilized a phase-controlled rectifier to control the current. A series of constant phase delay angles and a predetermined phase delay angle profile were tested to produce a constant current charge on the capacitors. The second sequence utilized generator field control to ramp the charge voltage through a diode bridge to charge the capacitors. Using the results of each configuration, an optimum design of simultaneous current and voltage control can be developed. The control aspects of using combined generator field control and rectifier current control is addressed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>