Table of contents monday, September 9, 1: 30pm-4: 00pm modular Multi-Level Converters, hvdc, and dc grids I 3
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- Bu səhifədəki naviqasiya:
- Energy Harvesting Systems
- Utility Applications V
- Modeling, Analysis, and Control of Grid-Connected Converters IV
- More Electric Aircraft
- DC-DC Converters: High Frequency
| 4:20PM A 3.0MW Case Study of the Influence of PM Cost on Wind Turbine Cost of Energy [#1183]
Matthew Henriksen, Bogi Bech Jensen, Nenad Mijatovic and Holboell Joachim, ABB Corporate Research, United States; University of the Faroe Islands, Faroe Islands; Technical University of Denmark, Denmark A wind turbine generator optimization procedure based on minimization of annual energy losses and drivetrain cost is presented. Pareto fronts for four different 3.0MW wind turbine drivetrains utilizing permanent magnet synchronous machines are presented. The results are given for three different scenarios in which the magnet cost is varied. This variation affects direct- drive machines the most. A number of trends in the direct-drive generator optimization variables are presented as well. 4:45PM Direct Power Control of a Doubly Fed Induction Generator Wind Power System in Stand-Alone and Grid-Connected Modes with Seamless Transition [#1195]
This paper describes a direct power control (DPC) strategy used for a doubly fed induction generator (DFIG) for wind energy system. The system operates in stand-alone (SA) and can connect to the grid through smooth transition. The proposed control structure is capable of regulating the stator voltage and frequency for an isolated load in case of grid outage. Also, when grid is available, it can control the stator voltage phase to be synchronized with grid voltage and connect with seamless transition to the grid. The basic structure of DPC method consists of hysteresis-based controller (HBC) and switching table that are used in both SA and grid-connected (GC) modes. The proposed control strategy is analyzed, simulated using MATLAB/Simulink and PSIM, and also validated experimentally using a 7.5 hp DFIG laboratory set up. Energy Harvesting Systems Wednesday, September 21, 3:30PM-5:10PM, Room: 203C, Chair: Paul Barendse, Xiongfei Wang 3:30PM Temperature Dependence of Efficiency in Renewable Magnetohydrodynamic Power Generation Systems [#615] Eva Cosoroaba and Babak Fahimi, The University of Texas at Dallas, United States Magnetohydrodynamic (MHD) power generation is based on Faraday's law: a magnetic field induces electron movement into a passing, conductive fluid. If captured, these electrons are the source of magnetohydrodynamically generated power. Combustion gas and liquid metal (LM) have been used as work fluid in the research of the '60s, but to gain renewable energy source properties, liquid gallium is used in a circular channel to allow the use of lower temperature thermal energy as the main input. This paper focuses on the detailed description of the proposed renewable system, the efficiency derivation as well as the study of the efficiency sensitivity considering loading conditions, generator dimension, and metal temperature. Conclusions and outlook on specific applications of LM-MHD are given. 3:55PM Modeling, Analysis and Design of An Undersea Storage System [#997]
This paper presents the modeling, performance analysis, and design of an undersea storage system (USS). The USS can be employed for conditioning the output power of wave energy converters (WECs) and floating wind turbines (FWTs) at sea or ocean cites. A mathematical model is developed to describe the governing equations of the USS operation. Next, based on the developed model, a storage system is designed for a 3 MW direct drive WEC. Finally, some guidelines and discussions on determining the USS energy capacity, power capacity, optimum size, and installation depth are presented. 4:20PM The Joint Design of a Compressed Air and Wind Energy System for Mechanical Spillage Recovery [#1186]
A novel configuration of a compressed air assisted wind energy conversion system is proposed to capture the mechanical spillage of a wind turbine and store it as the compressed air. The compressed air storage could be used to supplement electric power generation. The compact design utilizes the surplus capacities of blades and generator, and combines the compressor and expander into one machine. The compressed air subsystem serves as a buffer between the blade power and the electric output power. It mitigates the power discrepancy between them and gives another degree of freedom for energy management. The performance simulation shows that the joint design of compressed air and wind turbine system helps to increase the power generation by 12%. The discounted energy cost during one week is decreased by 15%, compared to a traditional wind turbine. The sensitivity analysis is conducted to evaluate the feasibility of the proposed system in variable conditions. 4:45PM Experimental Control of a Hydraulic Wind Power Transfer System under Wind and Load Disturbances [#1615]
Hydraulic wind power transfer systems deliver the captured energy by the blades to the generators through an intermediate medium i.e. hydraulic fluid. This paper develops a control system for an experimental setup of hydraulic wind power transfer systems. To maintain a fixed frequency electrical voltage by the system, the generator should remain at a constant rotational speed regardless of the wind speed. The fluctuating wind speed from the upstream, and the load variations from the downstream apply considerable disturbances on the system. A controller is designed and implemented to regulate the flow in the proportional valve and as a consequence the generator maintains its constant speed compensating for load and wind turbine disturbances. The control system is applied to the experimental prototype by utilizing MATLAB/Simulink and dSPACE 1104 fast prototyping hardware. Utility Applications V Wednesday, September 21, 3:30PM-5:10PM, Room: 202A, Chair: Olivier Trescases, Srdjan Lukic 3:30PM Field Upgradeable Transformer: A Fractionally-Rated Voltage Regulator for the Distribution System [#1401] Rajendra Prasad Kandula, Hao Chen, Anish Prasai, Joe Schatz and Deepak Divan, Georgia institute of technology, United States; Varentec, Inc., United States; Southern Company, United States The distribution system voltage volatility caused by changing load conditions and penetration of renewable resources presents an increasing challenge in the grid integration of renewables. This paper presents a novel voltage regulator, or field upgradeable transformer (FUT), for the distribution system, targeting at direct voltage regulation at the customer side with a fast dynamic response. Proposed system consists of a conventional medium voltage (MV) distribution transformer interfaced with a fractionally-rated power converter. Compared to other power electronics solutions for grid applications, the proposed device has advantages of low cost, high reliability, and high efficiency. The paper presents the FUT topology, principle of operation, control and protection scheme verified through simulation studies. Experimental results at 7.2 kV, 50 kVA, demonstrating FUT technology are also presented. 3:55PM New Configuration of Multi-Functional Grid-Connected Inverter to Improve Both Current-Based and Voltage-Based Power Quality [#1405]
In this paper, a new configuration of a multi-functional grid-connected inverter is proposed to improve both voltage-based and current-based power quality issue. By implementing bidirectional switches using semiconductor devices, a multi-functional grid-connected inverter can be connected in series or parallel to the grid and provides three modes of operation. This paper presents the control scheme of a multi-functional grid-connected inverter in each operating mode, the realization of bidirectional switches, and simulation results of the proposed multi-functional grid-connected inverter. 4:20PM Model Predictive Control of A Matrix-Converter Based Solid State Transformer for Utility Grid Interaction [#784]
The matrix converter solid state transformer (MC-SST), formed from the back-to- back connection of two three-to-single-phase matrix converters, is studied for use in the interconnection of two ac grids. The matrix converter topology provides a light weight and low volume single-stage bidirectional ac-ac power conversion without the need for a dc link. Thus, the lifetime limitations of dc- bus storage capacitors are avoided. However, space vector modulation of this type of MC-SST requires to compute vectors for each of the two MCs, which must be carefully coordinated to avoid commutation failure. An additional controller is also required to control power exchange between the two ac grids. In this paper, model predictive control (MPC) is proposed for an MC-SST connecting two different ac power grids. The proposed MPC predicts the circuit variables based on the discrete model of MC-SST system and the cost function is formulated so that the optimal switch vector for the next sample period is selected, thereby generating the required grid currents for the SST. Simulation and experimental studies are carried out to demonstrate the effectiveness and simplicity of the proposed MPC for such MC-SST-based grid interfacing systems. 4:45PM A Triple Port Active Bridge Converter based Power Electronic Transformer [#912]
Integration of multiple power sources using power electronic converters and high-frequency isolation links to supply the sustainable electricity is expected to have a significant impact on the future power system. In this paper, a triple port active bridge converter (TAB) based multi-fed power electronic transformer (TMF-PET) is proposed. The proposed PET consists of three ports having the flexibility to connect the power generating units, grid, and loads. The TMF-PET have three power conversion stages: input, isolation, and output. The input stage consists of two active rectifiers for integrating two different ac sources. The isolation stage consists of a triple port active bridge, and the output stage consists of an inverter. A detailed analysis of the principle of operation and the control techniques used for the converters of these stages are presented. The efficacy of the proposed system is verified using the simulation and experimental studies. The illustrated results show that the discussed controllers of TMF-PET are able to maintain the desired powers and voltages at the inputs and outputs of different power conversion stages. As a result, the proposed system can be used as an efficient energy router to interface different sources and loads in the modern power distribution systems. Modeling, Analysis, and Control of Grid-Connected Converters IV Wednesday, September 21, 3:30PM-5:10PM, Room: 202D, Chair: Paolo Mattavelli, John Lam 3:30PM Evaluation of Active Islanding Detection Based Methods Under Non-Liner-loads Scenarios [#805] David Reigosa, Cristian Blanco, Juan Manuel Guerrero and Fernando Briz, University of Oviedo, Spain Islanding detection has been the focus of significant research efforts during the last years. Islanding detection methods can be remote or local, the last being further divided into active and passive methods. Active methods have a reduced non-detection zone (NDZ) and ease of implementation. However they require the injection of some disturbing signal into the grid to measure its response, therefore having a negative impact on the power quality. High frequency signal injection islanding detection methods are a type of active methods that can be used both in single phase and three phase systems. While these methods have been demonstrated to be highly effective in different scenarios, including Single-inverter, Multi-inverter and Microgrid, the analysis reported so far only considered scenarios with linear loads. The proposed paper analyzes the use of high frequency signal injection based islanding detection methods in scenarios including non-linear-loads (NLLs) and active power filters (APFs). The presence of such elements can potentially interfere with the test signals injected for islanding detection; their impact on the method will be studied. 3:55PM Decentralized Adaptive Control for Interconnected Boost Converters based on backstepping approach [#1141]
In this article, the local trajectory tracking control problems are reformulated as adaptive control problems. This approach gives rise to a robust decentralized solution, with virtually no information on local plants interaction dynamics. It is shown that when the interconnection effects are viewed as exogenous, unstructured, disturbances, such disturbance can be actively estimated and canceled from each individual subsystem model dynamics. The case presented deals with two interconnected boost DC-DC power converters feeding a time-varying current demand represented by a DC motor with uncertain load torque. Each subsystem is powered by a time-varying power supply. Additionally, we activate and deactivate both converters to verify the output voltage compensation and the inductor current distribution. The performance of the proposed controller is shown to be robust with respect to interaction, un-modeled nonlinearities, and un-modeled dynamics, that is demonstrated by experimental evidence. 4:20PM Impedance Synthesis by Inverter Control for Active Loads in Anti-Islanding Testbenches [#1553]
This paper discusses the emulation of an active RLC load by means of an inverter. To this purpose, a suitable current control strategy is analyzed and developed. The limitations of this approach are explored, highlighting the requirements of the adopted regulator in order to avoid instability issues. The proposed analysis and model of the controlled system are verified by means of simulations and experimental tests on a 15 kVA prototype. The model is able to predict the presence of the resonant peaks closed to the current control bandwidth, thus giving useful guidelines to minimize such undesired effects. Finally, as a test case, the emulation of a resonant RLC load to be used in anti-islanding tests is considered. 4:45PM A Unified Impedance Model of Voltage-Source Converters with Phase-Locked Loop Effect [#1677]
This paper proposes a unified impedance model for analyzing the effect of Phase- Locked Loop (PLL) on the stability of grid-connected voltage-source converters. In the approach, the dq-frame impedance model is transformed into the stationary frame by means of complex transfer functions and complex space vectors, which not only predicts the stability impact of the PLL, but reveals also its frequency coupling effect in the phase domain. Thus, the impedance models previously developed in the different domains can be unified. Moreover, the impedance shaping effects of PLL are structurally characterized for the current control in the rotating dq-frame and the stationary-frame. Case studies based on the unified impedance model are verified in the time-domain simulations and experiments. More Electric Aircraft Wednesday, September 21, 3:30PM-5:10PM, Room: 102D, Chair: Pat Wheeler, Bulent Sarlioglu 3:30PM An Induction Generator based Auxiliary Power Unit for Power Generation and Management System for More Electric Aircraft [#679] Yijiang Jia and Kaushik Rajashekara, University of Texas at Dallas, United States In more electric aircraft (MEA) systems, the adoption of electro-hydraulic actuators (EHAs) and electro-mechanical actuators (EMAs) requires a power- on-demand electrical power system with regenerative power management capability. This paper proposes an auxiliary power unit (APU) for power generation and management system to supply/absorb the highly dynamic power demand/regeneration from the EHA/EMAs. The proposed system utilizes an open- end winding induction starter/generator (OEWIS/G) to create a separate DC bus for the actuators without adding significant hardware installment to the system. During the entire flight mission, the regenerative power is recovered by one side of the OEWIG terminals; meanwhile, the power delivery to the main DC network of the aircraft electrical power system can be independently controlled by using the same generator through the other side of the terminals. A closed-loop control scheme based on field oriented control and instantaneous power theory is developed to regulate both the main DC bus voltage and the electric actuation DC bus voltage simultaneously in aircraft emergency power mode. 3:55PM Design and Optimization of a High Performance Isolated Three Phase AC/DC Converter for Aircraft Applications [#1334]
This paper presents the design and optimization of a high performance isolated three- phase AC/DC converter that converts variable frequency 115 V AC voltage into isolated 28 V DC voltage. The main design target is to maximize converter rated power within given loss, size limitations and operation requirements. A two-stage structure, consisting of an active front-end (AFE) converter and an isolated DC/DC converter, is employed. To complete the design and optimization of the multi-converter system, a hierarchical design and optimization approach has been developed to explore the system loss-size Pareto front with considerations of thermal management, EMI performance and power quality. Methods for component optimization and loss calculation are introduced. Based on the design results (system loss-size Pareto front), a Vienna rectifier and an LLC resonant converter were selected for AFE and DC/DC stage respectively. Finally, a 1.2 kW convection cooled prototype was built and experimentally tested. It achieved 97.1% full load efficiency and 22 W/inch3 power density. Compliance with EMI and power quality standard was experimentally verified. 4:20PM Taking into account interactions between converters in the design of aircraft power networks [#1137]
This paper presents some key interactions among converters, which need to be taken into account when designing a modern embedded electrical grid, including a large amount of Power Electronics based loads. A design by Optimization method is first used to define the converter parameters. During this step, it is mandatory to account for the interaction between the input and output EMI filters. The second step consists in designing the control strategy; the paper will show that the results are largely improved if all converters are considered simultaneously. Finally, the stability study of the embedded network has to be investigated. All these interactions are studied in the example of a three phases AC network, composed of a Voltage Source Inverter and an Active Front End. 4:45PM Stability Assessment of A Droop-Controlled Multi-Generator System in the More Electric Aircraft Using Parameter Space Approach [#743]
This paper investigates the dynamic stability of a droop-controlled multi-generator system in the more electric aircraft (MEA). Based on the developed state-space model of the potential dc electrical power system (EPS) architecture, the stability boundaries of EPS operation depending on parameter variations including component parameters and operating conditions are investigated. The effect of multiple parametric uncertainties on EPS stability is graphically illustrated by stability regions maps. In addition, the effect of the droop coefficient on the stability is discussed from the impedance point of view. The detailed mathematical models and analytical results of stability assessment are verified by time domain simulation studies. DC-DC Converters: High Frequency Wednesday, September 21, 3:30PM-5:10PM, Room: 102C, Chair: Seth Sanders, Juan Rivas-Davila 3:30PM A GaN-Based Partial Power Converter with MHz Reconfigurable Switched-Capacitor and RF SEPIC [#360] Junjian Zhao and Yehui Han, University of Wisconsin-Madison, United States This paper investigates a new reconfigurable switched-capacitor (SC) based partial power architecture which enhances the performance of radio frequency (RF) resonant DC/DC converters with gallium nitride (GaN) power devices. The proposed architecture has a comprehensive compatibility with existing RF and SC topologies and improves the performance of RF converters through partitioning of energy conversion stage and output regulation stage. Emerging new wide bandgap devices like GaN FETs enable a higher power density DC/DC converter design. A wider input range, larger voltage conversion ratio, smaller size, and excellent transient performance are expected. The prototype of the proposed GaN reconfigurable SC-based partial power RF converter comprises of a 20 MHz resonant single-ended-primary-inductor-converter (SEPIC) as a regulated stage and a high-efficiency 2 MHz reconfigurable SC as an unregulated stage. The GaN RF resonant SEPIC regulates the output using a robust ON/OFF control scheme, which enables fast transient responses. The high-efficiency GaN reconfigurable SC provides 1:1, 2:1 and 3:1 voltage conversion ratio which widens the input voltage range. The power stage of the prototype achieves a peak efficiency of 93 % and a power density of 963 W/in3 at 91.5 W. 3:55PM Monolithic Multilevel GaN Converter for Envelope Tracking in RF Power Amplifiers [#1448]
This paper presents a monolithic multilevel converter realized in a depletion-mode GaN process and intended to operate as a drain supply modulator (DSM) for high efficiency radio-frequency (RF) power amplifiers (PAs). The custom prototype chip includes a four-level power stage with on- chip integrated gate drivers and damping networks designed to mitigate effects of parasitics during output voltage level transitions. An optimization algorithm is described to maximize the drain supply system efficiency using the level voltages and a minimum switching interval as optimization variables. The monolithic multilevel chip is used to construct a four-level converter prototype. Experimental results are presented for tracking 8 MHz sine-wave and 10 MHz LTE envelope signals. The converter output voltage exhibits fast and well damped level-to-level transients. For the 10 MHz LTE envelope signal, the converter achieves greater than 97.3% power stage efficiency at 3.5W average output power level. Modern radio- frequency (RF) communications systems require power amplifiers (PAs) to process signals with high bandwidth and high peak-to-average power ratio (PAPR), which adversely affects PA efficiency. Efficiency improvement techniques include approaches based on drain supply modulation (DSM) or envelope tracking (ET). DSM based systems improve the efficiency of RF transmitters by dynamically adjusting the drain supply voltage of the PA in response to the RF envelope signal.
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