M. Andrus

Investigating the Impact of Pulsed Power Charging Demands on Shipboard Power Quality

The impact of pulsed power loads on shipboard power systems need to be properly determined to prevent pulsed loads from causing unacceptable power quality deviations, interference with other loads and degradation of overall system performance. This paper uses a high fidelity modeling and simulation approach to investigate the impact of real and reactive power, pulse ramp rate, pulse duration and frequency of occurrence of the pulsed power load. For this purpose, a notional shipboard power system, modeled in a real-time digital simulator, is used. Most pulsed loads on shipboard systems are not fed directly from the prime power system but via an energy storage system. This energy storage system in turn is interfaced with the shipboard prime power system typically through an electronic front-end charging circuit. In order to evaluate the impact of pulsed loads, existing power quality standards (related to voltage transients, harmonic distortions, and frequency variations) are applied.

Experiences with the simulation of a notional all-electric ship integrated power system on a large-scale high-speed electromagnetic transient simulator

The integrated electric power system (IPS) on an all-electric ship provides advantages to the user (Navy) in areas of improved maneuverability, capability to operate advanced high power weapons, reduced maintenance and manpower, higher flexibility and high levels of fight through capacities. The modeling and simulation of the IPS to a very high degree of accuracy is an important requirement in analysis of the system effects as well as in the production of the prototype. For this purpose, high fidelity and high performance computations of the entire IPS are required. In this paper, experiences with the implementation of a simulation model for a notional, destroyer class electric ship power system in a real-time environment are presented

Integration of a bi-directional dc-dc converter model into a large-scale system simulation of a shipboard MVDC power system

To improve energy flexibility and deal with peak energy demand in shipboard power system, a bi-directional dc/dc converter is investigated for a notional U.S. Navy Medium Voltage DC (MVDC) shipboard power system. Surplus energy due to light electric load or ship-speed variation can be captured by energy storages distributed in 800 V load zones and during heavy load or black starting condition, supplied to the rest of the 5 kV MVDC system through the bi-directional dc/dc converters. This paper presents the controller optimization process using the particle swarm optimization for an isolated-type bi-directional dc-dc converter. The control performance of the proposed controller is evaluated using small-signal average models and a large-scale simulation of the notional U.S. Navy MVDC system using the real-time digital simulator.

Cross-platform validation of notional baseline architecture models of naval electric ship power systems

To support efforts in assessing the relative merit of alternative power system architectures for future naval combatants, the Electric Ship Research and Development Consortium (ESRDC) has developed notional baseline models for each of the primary candidate architectures currently considered, medium-voltage DC (MVDC), conventional 60 Hz medium-voltage (MVAC), and high-frequency medium-voltage (HFAC). Initial efforts have focused on the development of a consistent set of component models, of which the system models can be comprised, and the basic definition of the system models. The broader objectives of the consortium, however, go beyond the definition of the baseline models. The focus is on the process by which the models are implemented in software and validated, the process by which the performance of the disparate system models are objectively and quantitatively assessed and compared, and, ultimately, the process by which the relative merits of the architectures may be assessed. This paper focuses specifically on cross-platform component validation.

Approach to develop ship design evaluation rule-base

The Smart Ship Systems Design (S3D) prototype is a comprehensive engineering and design environment capable of performing concept development and comparison (weights, power demand, speed, range, hull-form etc.), and high level ship system tradeoff studies. This online collaborative design environment is expected to be applied at the early stages of a ship design problem. Currently, the S3D environment contains tools for the development and simulation of the electrical, piping, and mechanical ship systems and the arrangement of the system and is capable of static power flow simulation for all major disciplines. However, the tool does not have a robust capability to evaluate designs using well established engineering guidelines. The research described herein aims to address this gap and this paper presents proposed approaches and outcomes of preliminary studies.

Application of distubance metrics for reducing impacts of energy storage charging in an MVDC based IPS

The goal of the study in this paper is to analyze the impact of charging an energy storage supplying power to the pulsed power load in an integrated power system onboard a ship. The work in this paper focuses on developing a disturbance metrics based control scheme for maintaining the optimal balance between the rapidity of ES charging and meeting the power quality requirements, at the same time, for a Medium Voltage Direct Current (MVDC) based IPS.

Conversion of PSS®E models into RSCAD models: Lessons learned

The use of real time digital simulation of large power systems is widely spreading due to its high precision result and increasing computing capability. However, in many cases, especially when large power system networks are to be modeled, the interconnection data and parameter data are available in flies which are used as input to simulation programs. Most transmission utilities use dynamic studies using PSS®E, PSLF or similar type of tools. Since most of the system data are available in PSS®E data format, it will be easier to develop an electromagnetic transient model if those data files can be used without putting much effort. Considering the benefit in huge savings in time, RTDS® Technologies Inc. has developed a conversion routine to generate transient model of power system network using the data files available in PSS®E. This paper discusses the conversion process and uses two test cases to verify the accuracy of the conversion tool. IEEE 39 bus test system and a notional 311 bus system were used for this purpose. Both steady state and transient test results of PSS®E and RSCAD model are then compared with each other. This paper also discusses the limitations and challenges of the conversion process, as well as potential solutions. In essence, this study evaluates the accuracy of model conversion from PSS®E to RSCAD for large power systems and highlights the lessons learned from the whole exercise.

System studies for a bi-directional advanced hybrid drive system (AHDS) for application on a future surface combatant

A project is currently underway to develop a bi-directional advanced hybrid drive system (AHDS) for application to a future surface combatant. This system would support propulsion powered through ship service gas turbine generators, as well as ship service power supplied from the mechanical propulsion gas turbines. This paper discusses system studies currently being conducted to assess the requirements and implications of incorporation of two such AHDS units on a future surface combatant.

Considerations in Simulation of a Notional All-Electric Ship AC/DC Conversion System

In order to characterize and understand the behavior of a simulation model of the AC/DC conversion system of a notional all-electric ship system, experimental design methodology is applied in the construction of surrogate models. Confidence in the fidelity of the simulation is assessed through sensitivity and uncertainty analyses applied to the surrogate models.