Modeling and Analysis of Information-Embedded Power Electronic Converter Systems

A long-term goal of future naval shipboard power systems is the ability to manage energy flow with sufficient flexibility to accommodate future platform requirements such as, better survivability, continuity, and support of pulsed and other demanding loads. To attain this vision of shipboard energy management, shipboard power and energy management systems must coordinate operation of all major components in real-time. The primary components of a shipboard power system are the generators, energy storage modules, and increasingly power electronics that interface those sources and main load centers to the system. Flexible management of energy flow throughout shipboard distribution systems can be realized by automated coordination of multiple power electronic converters along with storage and generation systems. Use of power converters in power distribution systems has continuously increased due to continued development of the power electronics building blocks (PEBB) concept which reduces cost and increasing reliability of converters. Recent developments in SiC power devices are yielding PEBBs with far greater switching frequencies than Si based devices resulting in an order of magnitude reduction of the time scales as compared to converter systems utilizing conventional IGBT based PEBBs. In addition there have also been advancements in highly modularized converter systems with hundreds of PEBBs such as the Modular Multilevel Converter. Both of those trends have resulted in the continued evolution of the Universal Controller Architecture which attempts to standardize control interfaces for modular power electronic systems. Further development of interface definitions and increasing communication and computational capabilities of new FPGA based controllers provides opportunities beyond simply supporting SiC PEBBs. Fast control coordination across the system using an appropriate communication architecture provides a degree of energy management not previously realizable in shipboard power systems. The paper will present recent research results in networked control architectures for power electronic converter coordination and control. It will demonstrate that current FPGA and gigabit speed serial communication technologies allow for a very high degree of energy flow control.

Chapter 31 - Power Electronics Applications in Smart Grid

This paper introduces Smart Grid and associated technical, environmental and socio-economic, and other non-tangible benefits to society, and articulates the need for the concept and the fact that it is a dynamic interactive, real-time infrastructure that responds to the challenges of designing and building the power system of the future, rather than being simply a marketing term. To illustrate the diversity of terminology, the paper compares an Electric Power Research Institute (EPRI) definition with that suggested by a study group of the International Electrotechnical Commission (IEC). Next, a paper sponsored by the Canadian Electricity Association (CEA) that cites three example definitions to highlight the diversity of views of Smart Grid is briefly reviewed. Early misconceptions and characterizations of Smart Grid are discussed as a prelude to addressing challenging issues that motivate developing and implementing related innovative technologies, products and services. The paper then discusses the potential promise of the Smart Grid, which is embedded in its often-cited attributes of efficiency, accommodating, quality focus, enabling and self-healing to name some. The paper then addresses some of the often-cited impediments to accepting Smart Grid which are based on concerns and issues confronting its forward progress, adoption and acceptance. Distribution Automation (DA) and embedded intelligence are discussed emphasising self-healing, optimizing operation and facilitating recreation and recovery from abnormal events. Functional and integration requirements of Distributed Energy Resources (DER,) are detailed. Smart Consumption Infrastructure elements of Distribution Management Systems (DMS,) Automated Metering Infrastructure (AMI,) Smart Homes (SH), and Smart Appliances (SA,) are discussed. Following the introductory section, this paper summarizes contributions included in the double issue 42(3–4) of the Electric Power Components and Systems Journal. To begin, papers are offered discussing smart grid activities in China, India, and the development of a Smart Grid roadmap for the US State of Kentucky. The approaches of each of these cases reflect the diversity of policy initiatives in these jurisdictions. Two state of the art reviews are given next. The first considers distribution network active management and future development trends in technologies and methods, where centralized and decentralized management frameworks and applying agent-based coordination are discussed. The second offers a review of smart home technologies and the goals of an energy management system (SHEMS). This section is concluded by a letter providing an overview of recent and expected advances nanotechnology applications in Smart Grid. Following the state of the art review section, ten papers offering new and innovative research approaches and results are included. These papers cover Smart Grid topics such as real-time energy control approach for smart home energy management systems, optimal operation of energy- efficient buildings with Combined Heat and Power (CHP) systems, energy management and control of Electric Vehicle (EV) charging stations, voltage-frequency control of a voltage source inverter (VSI) in a smart islanded microgrid, smart generation scheduling for wind-thermal-pumped storage systems, optimized power system restoration, robust data transmission upon compressive sensing, data fusion for wide-area oscillation monitoring, satellite based GPS synchronized monitoring systems, stability in Smart Grid with emerging renewable energy techno- logies.

Electrical energy conversion by power electronic systems can be classified into the following four categories: 1. Voltage conversion and power conversion for both direct current (DC) and alternate current (AC) 2. Frequency conversion 3. Wave-shape conversion 4. Poly-phase conversion.

Sensors are crucial for the operation of power electronics converters. Voltage and current sensors, widely used in power electronic converter systems, are prone to malfunction or failure mainly due to varying environmental conditions, broken connectors, and ageing of electronic circuit components. Therefore, it is important to characterize the behavior of these sensors under a number of possible faulty conditions and study their impact on the performance of the system. Further, the distinct behavior of such sensors, under different fault types, encourages us to correlate them with the generic fault models. In this paper, a root cause analysis for each type of sensor fault is presented and experimental validation for five fault models is performed, where the parameters of key components in the power electronics voltage and current sensor are intentionally modified to emulate a specific type of fault. Moreover, the impact of each fault on the power quality of Grid Side Converter (GSC) under various types and magnitudes of sensor faults are assessed and validated experimentally. The results of this work are useful to ensure the design for the reliability approach in power electronics converters and provide an assessment of the impact of a sensor failure in the overall operation of power electronics converters. Further, the impact of sensor faults in the overall operation of a power electronics converters give some directions to design algorithms that can improve the reliability and robustness of the power electronics converters.

Smart grid technologies and applications

Guest Editorial: Situational awareness of integrated energy systems

Trends in the use of renewable energy sources to power buildings do not bypass objects for which maintaining a power supply is critical. This also applies to railway signal boxes. The aim of the research work was to test the multisource power supply system for a railway signal box with power electronic converter systems and a DC bus, built as part of the research project. The assumption for powering the railway signal box building was to use renewable sources, energy storage devices, and a 3 kV DC traction network as the second required power supply grid. Both power grids were connected by power electronic converters, and the power values of the converters were set based on the calculated power balance values using the values measured at the system nodes and the set constraints. The tests primarily tested the response of the power supply system to changes in load power and power generated by the photovoltaic source, as well as the charge level of the energy storage devices. The correctness of the control algorithm’s operation was assessed based on the recorded power values in the power supply system nodes. The tests were carried out for 60 scenarios that covered all normal and emergency operating conditions. During the tests, delays in response to changes in the power supplied to the converters and the values of circular power flow between the power grid connections were recorded. The recorded delays ranged from 2 to about 50 s and the circular power flows did not exceed 1500 W. Based on the results of the tests, it was found necessary to improve the power measurement system in the power supply system nodes and to improve the quality of communication and the transmission time of measurement data transmission time.

Electric vehicles (EVs) are one of the the promising solutions for the environmental issues such as carbon emission and global warming. The high voltage traction battery in EVs is charged from utility grid by an EV charger. The Society of Automotive Engineers (SAE) standardize EV charges into two categories on-board chargers and off-board chargers. Usually, the on-board chargers are located inside the vehicle whereas, off-board chargers are not mounted on the vehicle. For onboard chargers, size and power density of charger become a prior matter of concern. The only way to reduce the size of a converter and thereby increase the power density is to operate power electronic conversion system (PECS) at very high switching frequency (HSF) resulting in reduced size of magnetic component in the charger configuration. However, HSF operation may lead to a high electromagnetic interference (EMI), loss in switch and switch duty. The work in this paper is focused on the development of high frequency bi-directional DC-DC converter (BD2C) stage priory used in on-board chargers due to distributed sources of energy as well as to manage the power distribution in the configuration. The power electronic BDCs are derived from boost and buck unit. The boost derived converter are current fed converters and offers advantages in terms of inherent voltage gain, short circuit protection and lower input current ripple. The voltage spikes across switches, high rated device selection, hard switching, snubber and auxiliary circuit requirements are some of the undesirable factors. This occurrence happened due to unbalance power transfer by the power electronics converter. Similarly, voltage fed converter offers good voltage control during power transfer.

Communication network requirements for major smart grid applications in HAN, NAN and WAN

A Solid-State Transformer as Enabling Technology for Microgrids for Integration into the Power Distribution System: An Overview

The inclusion of renewable energy in the conventional grid system and the digitalization of the various aspects of the power system have precipitated the transformation of the traditional grid system to a smart grid. Key to the implementation of the smart grid is various communication technologies. The emerging dominance of communication technologies in power systems applications is pivotal to modernizing the conventional grid system. This research presented an overview of the application of communication technologies in the digitalization of the power systems network. It reviews smart grid communication technologies, their features, relevance, and various roles being played toward delivering an effective electrical service to stakeholders. Hence, this study focused on wireless and wired communication technologies applicable to smart grid applications. Based on the review, each communication technology has its strengths and weaknesses; hence in selecting the most appropriate technology for application in a smart grid, a compromise must be made. Therefore, for choosing the most preferred communication technology in any smart grid application, it is important to deploy the efficacy of multi-criteria methods. To serve as a case study, a framework for selecting a communication technology for advanced metering infrastructure is proposed and applied. Based on the spectrum, data rate, and coverage range, the study revealed that WiMAX communication technology is the most preferred, followed by Zigbee; the least preferred communication technology for smart grid communication is Power Line Communication (PLC).

This article proposes an intelligent and fast controller for the parallel dc-dc converters in the islanded dc microgrids (DCMGs) in the shipboard power system (SPS) applications. The existence of constant power loads and propulsion loads in the SPS makes the voltage regulation an important issue in the islanded DCMG. In this article, the goal is to provide a fast response and proper voltage regulation and optimal current sharing in the stand-alone shipboard DCMG. To achieve this, a nonlinear I-V droop control is first designed in the primary control level to ensure the basic performance. Then, a new model-independent technique, entitled intelligent single-input interval type-2 fuzzy logic controller (iSIT2-FLC) combined with sliding mode control (SMC), is suggested to further improve the voltage regulation and current-sharing accuracy. In this control scheme, an extended state observer (ESO) is employed to estimate the unknown DCMG dynamics, whereas the SMC is adopted to eliminate the ESO estimation error. Moreover, the dynamic consensus algorithm (DCA) is implemented at the secondary control level to achieve coordinated control between DGs in the SPS. The effectiveness and applicability of the new suggested control approach are validated with hardware-in-the-loop (HiL) experimental results.

Smart Grid is a promising power delivery infrastructure integrated with communication and information technologies. By incorporating monitoring, analysis, control and communications facilities, it is possible to optimize the performance of the power system, allowing electricity to be delivered more efficiently. In the transmission and distribution sector, online monitoring of transmission lines and primary equipments is of vital importance, which can improve the reliability of power systems effectively. Optical fiber sensors can provide an alternative to conventional electrical sensors for such applications, with high accuracy, long term stability, streamlined installation, and premium performance under harsh environmental conditions. These optical fiber sensors offer immunity to EMI and extraordinary resistance to mechanical fatigue and therefore they will have great potential in on-line monitoring applications in Smart Grid. In this paper, we present a summary of the on-line monitoring needs of Smart Grid and explore the use of optical fiber sensors in Smart Grid. First, the on-line monitoring needs of Smart Grid is summarized. Second, a review on optical fiber sensor technology is given. Third, the application of optical fiber sensors in Smart Grid is discussed, including transmission line monitoring, primary equipment monitoring and substation perimeter intrusion detection. Finally, future research directions of optical fiber sensors for power systems are discussed. Compared to other traditional electrical sensors, the application of optical fiber sensors in Smart Grid has unique advantages.

Power electronics are becoming increasingly important in modern ship board power systems. They are used for development and implementation of controls and to interface different electrical modules such as loads, batteries and generators that produce, store or consume energy. Power electronic systems are suitable for control because they provide fast operation in the range of microseconds. However, fast control operations can also add complexity to the system. Unintended complex dynamics can arise if the system (inertia) is unable to adapt to the control actions. This article studies the complexity and emergent phenomena that may develop in a ship board power system because of the power electronic components, coupling between these components, as well as feedback mechanisms such as control loops and those of human and environmental origin. A statistical complexity measure, referred to as structural complexity, is used to quantify the degree of complexity that arises during the system evolution. This metric of complexity is computed using permutation entropy and ordinal patterns. A modified procedure for structural complexity called multivariable structural complexity is developed to compute the system wide complexity. This multivariable structural complexity is also used to assist the modelling process and the decision of the best model candidate that captures observed aspects of complexity from the system data history. Various case studies on complexity quantification are conducted on simulated data from a noise coupled buck converter, two parallel connected buck converters and an electric ship board power system.