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:
- Tuesday, September 20, 11:00AM-12:30PM Poster Session: Renewable and Sustainable Energy Applications
- Poster Session: Smart Grid Utility Applications
- Poster Session: Transportation Electrification Applications
| 9:20AM A Wireless Power Transfer System with a Double Current Rectifier for EVs [#1236]
Toshiyuki Fujita, Tomio Yasuda and Hirofumi Akagi, Technova.inc, Japan; Tokyo Institute of Technology, Japan The secondary coil installed on an EV is required to be small in size, light in weight, and efficient in power transfer, as well as tolerant in lateral misalignment with a large air gap. Also, a wireless power transfer system needs high power transfer. Both downsizing and high power transfer bring a thermal problem the secondary coil. This paper proposes a WPT system combining the so-called "series and series" connected resonant capacitors with a double-current rectifier to achieve a secondary coil current reduction that is an essential matter of the problem. The proposed WPT system employs solenoid coils that are superior to circular coils in terms of misalignment and flux-distribution performance. The secondary WPT coil rated at 18 A is designed, constructed, and tested to verify the principles of operation. The system efficiency is 90.0% at nominal air gap 135 mm without misalignment in output power 7 kW. 9:45AM Hybrid Control of Inductive Power Transfer Charger for Electric Vehicles using LCCL-S Resonant Network in Limited Operating Frequency Range [#306]
In this paper, a hybrid control of IPT system is proposed in limited operating frequency range according to coupling coefficients. The coupling coefficient k and self-inductance of pad vary according to misalignment and vertical distance condition in inductive power transfer (IPT) system. Those variation cause change of output voltage and zero phase angle (ZPA) frequency. Proposed method enables the system to operate in zero voltage switching (ZVS) region close to ZPA frequency for low VA rating. Moreover, the excessive output voltage caused by k variation is also controlled by phase-shift control considering the voltage rating of power semiconductor. However the operable frequency of IPT system is restricted in standard of society of automotive engineers. Thus, phase-shift angle beta should be calculated for ZVS operation under limited frequency condition because the frequency range of ZVS operation is reduced depending on the increase of beta. The frequency range to operate system in ZVS region nearby ZPA frequency is deduced from beta according to the coupling coefficient. Considering the limited frequency condition, the coupling coefficient range to apply the hybrid control is derived. The informative simulation and experimental results with a 3.3 kW IPT prototype are provided to verify the numerical analysis. 10:10AM Research on Seamless Transfer from CC to CV Modes for IPT EV Charging System Based on Double-sided LCC Compensation Network [#597]
In this paper, based on a double-sided LCC compensation network, the leakage inductance equivalent model of the loosely coupled transformer (LCT) is built and the constant current (CC) output with load independent is analyzed in an inductive power transfer (IPT) system. This paper proposes four resonance conditions for achieving constant voltage (CV) output in various load conditions for the compensation network. The Zero Voltage Switching (ZVS) operation for the primary side H-bridge converter can be achieved in CC mode and CV mode to minimize the switching loss. A seamless transfer control strategy is also investigated to realize transmission from CC mode to CV mode for IPT EV (electric vehicle) charging system. An IPT EV system with 3.3 kW transmission power is built. The theoretical analyses are confirmed by simulation and experiment results. 10:35AM Closed-Loop Control Design for WPT System Using Power and Data Frequency Division Multiplexing Technique [#173]
For wireless power transfer (WPT) system, close-loop control fed from pick-up side is an important issue, in which a communication link is needed. Power and data frequency division multiplexing (FDM) transfer technique is attractive because it embeds communication into power transfer and uses the same coreless coils. By employing this method, a simplified closed-loop control method for WPT system is proposed in this paper. Compared to conventional closed-loop WPT systems, the proposed design eliminates extra communication channels and enhances the reliability of feedback. Moreover, the phase-shifted control model of the FDM based WPT system is derived, and it provides guideline for the controller design. Based on the analysis, both simulation and experimental results of a 100-W prototype are presented to verify the effectiveness of feedback communication and power transfer. Tuesday, September 20, 11:00AM-12:30PM Poster Session: Renewable and Sustainable Energy Applications Tuesday, September 20, 11:00AM-12:30PM, Room: Exhibit Hall, Chair: Euzeli Santos Jr., Rajendra Prasad Kandula
P1901 Power Balance Control and Circulating Current Suppression for MMC based EV Integration System Considering Users Requirement [#914] Meiqin Mao, Tinghuan Tao, Yong Ding, Liuchen Chang and Nikos Hatziargyriou, Hefei University of Technology, China; University of New Brunswick, Canada; National Technical University of Athens, Greece A modular multilevel converter MMC is a possible solution to integrate EV fleet into grid by embedding EVs into the DC link of each sub module of MMC. The charging discharging power differential control strategy considering EV users requirements in the same arm has been proposed in the previous work. However, it is also important that the balance among the power of three phase-units should be met up with meanwhile circulation current should be controlled to ensure the system operation stably. This paper proposes the control strategy of balancing power among three phase units for MMC Based EV fleet integrated into smart grid based on virtual SOC concept to realize the control objectives considering both EV users requirements and utility demands. In addition, a circulation current suppressor is designed for contributing to the power balance control. Detailed system structure and control scheme are presented and a MMC based EV integration system model is established in Matlab Simulink to verify that the power of three phase-units can be controlled differentially considering both EV users requirements and utility demands without affecting the output powers and currents waveforms of the system and the circulation current can be restrained P1902 Optimal Sizing of Energy Storage for PV Power Ramp Rate Regulation [#1438]
With increasing PV power penetration in the modern power grid, a cost-effective solution to address PV intermittency becomes more and more compelling. The ramp rate of PV power can reach 60\% of its rated capacity in just 30 seconds. Energy storage is a technically feasible solution to suppress the adverse impacts of injecting intermittent power output with such a high ramp rate into the grid, but its cost is very high. Therefore, to reduce the system cost of integrating PV and maximize the grid operation profit, optimal sizing of energy storage is necessary. In this paper, a method of optimizing energy storage size for controlling PV ramp rate is presented. The characteristics of PV ramp rate are first investigated. Based on the results, an energy dispatch model for controlling PV ramp rate with fast response energy storage is developed. The optimal size of energy storage which minimizes system operation cost to accommodate high PV penetration is subsequently determined. P1903 Model-Based Adaptive Control of a Hydraulic Wind Power System [#775]
In this paper a multiple model adaptive control (MMAC) strategy is used to mitigate the undesired effect of output power fluctuations in hydraulic wind power systems. This control structure is based on linear Kalman filters, probability block and PID controllers and aims to regulate the speed of generation unit. Nonlinearities and disturbances such as wind speed and valve position make the system work over a wide range of operating point which degrades the performance of the control loop. MMAC as an approach for these types of systems implemented and simulated to consider the control performance over the whole operating regimes. P1904 Sensorless speed control of a small wind turbine using the rectifier voltage ripple [#1004]
Grid-tied small wind turbines based on permanent magnet generators are usually operated using a basic converter topology based on a passive rectifier, a boost converter, and an H-bridge inverter. The rotor speed signal is rarely obtained from speed or position sensors in this kind of systems. Model-based estimators are rather used for this purpose relying on electrical magnitudes. Despite its complexity all models show inaccuracy under machine parameter change mainly due to temperature. A speed sensorless method is proposed in this paper based on the measurement of the rectifier voltage ripple. This method is insensitive to machine parameter change. The method will bring a significative improvement in the dynamic response of the small wind turbine system under unrated parameter operation. The proposed method is extended to detect the temperature of the electrical generator. Simulations will corroborate the validity of the proposed method. P1905 Maximum Power Point Tracking (MPPT) of Sensorless PMSG Wind Power System [#1335]
This paper investigates the modeling, simulation and implementation of sensorless maximum power point tracking (MPPT) of permanent magnet synchronous generator (PMSG) wind power system. A comprehensive portfolio of control schemes are discussed and verified by simulations and experiments. Both simulation and experimental results demonstrate a robust sensorless MPPT operation in the customized PMSG wind power system. P1906 Current/Voltage Sensor Fault Detection and Isolation in Wind Energy Conversion Systems Based on Power Balance [#1133]
This paper proposes a novel current/voltage sensor fault detection and isolation (FDI) method for wind energy conversion systems (WECSs) based on the power balance principle. The proposed method uses the sensor-measured signals to calculate the imbalanced power in the power converters of a WECS, which is then used as the indicator for sensor fault detection. The fault isolation process is started when a fault is detected and is achieved by generating and comparing the residuals between the estimated and measured signals, where the residuals are generated by a trigonometric function-based estimation algorithm. The proposed method does not require additional hardware or the information of generator parameters, is capable of detecting and isolating both machine-side and grid- side current/voltage sensor faults, and is not influenced by other types of faults in WECSs or power grids. The effectiveness of the proposed method is confirmed by simulation results in MATLAB/Simulink and experimental results for a 2.4-kW permanent-magnet synchronous generator-based WECS. P1907 Quasi-Z-Source-Based Multilevel Inverter for Single-Phase Photo Voltaic Applications [#1217]
The use of multilevel inverters in Photovoltaic (PV) applications have attracted major attentions in both industry and academic research. This paper presents a PV system based on a single-phase Quasi-Z-Source (QZS) multilevel inverter with a great reduction in number of switches. The introduced inverter is based on a Multilevel DC link (MLDCL) structure and an H-bridge inverter. The MLDCL consists of cascaded half-bridge units with each unit having a PV cell and two switches as the main components. To regulate the PV voltage, a QZS network is considered in each unit in order to reach the desired level of voltage and the system would be able to perform in a wider range of PV output voltage in a more reliable and efficient system. A detailed analysis is applied to 180 W single phase stand-alone PV system with three cascaded half-bridge QZS networks and a 60 Hz H-bridge. Each QZS module in the proposed structure has the advantage of having an independent control scheme, using which each unit can effectively achieve the distributed maximum power point (MPP). The system is simulated to verify the proposed concept and theoretical analysis using Matlab/Simulink. The feasibility of the proposed topology is also confirmed through the experiment on a 60 W system. P1908 Dual Buck Based Power Decoupling Circuit for Single Phase Inverter/Rectifier [#840]
Single phase rectifiers and inverters are inherently subject to double-line frequency ripple power, at both the ac and dc sides, which has adverse effects on the overall system performance. Normally a bulky capacitor is placed at the dc side of the circuit to prevent this ripple power ripple from reaching the dc source. This approach results in low power density and reliability issues. As a result, active power decoupling methods have been proposed such that the total capacitance required can be orders of magnitude smaller. This paper proposed a new power decoupling circuit, which is composed of two separate buck converters operating in each half cycle and two split dc-link capacitors. The dc link capacitors can be used to store ripple power while supporting transient power to the main output. The capacitance needed is reduced largely by allowing high voltage fluctuation on capacitors, while the dc link voltage can be controlled with small fluctuation. The dc link capacitors can be fully charged and discharged with full energy utilization. The added power decoupling module does not need dead time, and totally eliminates the shoot through concerns, which could enhance the system reliability. Another advantage of the proposed power decoupling method is that its control is independent with that of the main power stage. Modulation and control strategy are proposed for the power decoupling circuit. The operating principles together with parameters design are discussed in detail. Both simulation and experimental results prove the effectiveness of this method. Poster Session: Smart Grid & Utility Applications Tuesday, September 20, 11:00AM-12:30PM, Room: Exhibit Hall, Chair: Johan Enslin, Euzeli Santos Jr. P2101 Design and Development of a True Decentralized Control Architecture for Microgrid [#1126] Abedalsalam Bani-Ahmed, Adel Nasiri and Hosseini Hossein, UW-Milwaukee, United States Emerging smart grid concept compels microgrids to adopt decentralized methods.Centralized methods of operation are more susceptible to failure due to single point of failure held by the single controller. Decentralized microgrid control architecture is proposed, improving system reliability and avoiding control command transmission over the network. Delays in communications are unpredictable, uncertainty of data exchange delays leads to inaccurate modeling. As a solution, Hardware-in-The-Loop platform is developed using real physical communication links and network components, and applying the concept of decentralization dynamically over a network of real-time controllers. The proposed system insures reliable data exchange between controllers and microgrid components. Case study is adopted for testing purposes. Results proves the robustness of the architecture as long as the properties of a true decentralized system is maintained. P2102 Modeling and Control of a Synchronous Generator in an AC Microgrid Environment [#1127]
An AC microgrid system model is created to assess transient and steady state stability during periods of separation from the grid. A secondary control is constructed to dispatch energy sources according to user selected setpoints and participation factors. Two sources, an energy storage device and synchronous generator, are controlled to share active and reactive load burdens. A system load models the difference between solar and wind powered generation and load. First order differential equations are written to describe the system, and implemented in Simulink. The model components carry a high level of detail to capture all relevant modes. Systems include an eight state salient pole synchronous machine, AC8B regulator, prime mover, equivalent PI cable, RL microgrid load, ideal battery and basic inverter model, and a detailed LCL filter at the inverter output. A detailed model of the inverter primary control is included, and a secondary level control which distributes the power error according to user defined participation factors is proposed. P2103 State Estimation of Power Systems with Interphase Power Controllers Using the WLS Algorithm [#109]
Traditional state estimation methods are not well suited for power systems with FACTS devices. A novel approach to state estimation of systems with interphase power controllers (IPC) is proposed. The extension of the conventional model of the system necessitates the use of constraints accounting for limits associated with the IPC operation and ratings. Results of tests on the IEEE 14 bus system using the weighted least-square method, have confirmed validity of the proposed approach. P2104 A Novel T-Type Half-Bridge Cell for Modular Multilevel Converter with DC Fault Blocking Capability [#368]
The Modular Multilevel Converter (MMC) is very suitable for high-power applications such as High-Voltage Direct Current (HVDC) transmission system. However, the DC fault vulnerability seriously constrains the conventional Half-Bridge based submodule (HBSM) of MMC, while the Full-Bridge based SM (FBSM) and Clamp Double based SM (CDSM) with DC fault blocking capability greatly increase the costs. This paper presents a novel T- Type Half-Bridge based SM (T2HBSM) topology that is capable of blocking DC fault current and separating the AC grid from the DC fault point instantly, and it can rebuild the DC link voltage to get the MMC-HVDC back to normal immediately after the fault is clear. More significantly, the proposed T2HBSM topology saves one diode and utilizes the same number of switches in comparison with the CDSM. The simulation results in PSCAD/EMTDC demonstrate the feasibility of the proposed T2HBSM topology. P2105 A Distributed Control Method for Power Module Voltage Balancing of Modular Multilevel Converters [#376]
This paper focuses on the distributed control method of the power module (PM) capacitor voltage balancing in modular multilevel converters (MMCs). The large number of PMs imposes great computational challenge on the capacitor voltage balancing in MMC based high voltage direct current (HVDC) transmission system. In this paper, a distributed voltage balancing method is proposed to reduce the computational load of control strategy of MMCs with hundreds of PMs per arm. With this method, all PMs in one arm of MMC are grouped first. The PMs in each group is balanced independently by voltage sorting and arm current polarity. The sorting all the PM voltages in this arm is avoided. Meanwhile, a close-loop control strategy is also introduced to balance the average PM voltage of each group dynamically. This paper proposed a distributed capacitor voltage balancing method for MMCs. This method divided PMs in each arm of MMC into several groups, calculates the reference number of each group and adjusts the reference number through a close-loop control in real-time. The proposed method avoided sorting of all the PM capacitor voltages and reduced the load of computation, which improved the computational speed of the MMC control system. The effectiveness of the control scheme is demonstrated by computer simulation results on a 700 kV 1000 MW MMC based HVDC system. P2106 Control Method of Single-phase Inverter Based Grounding System in Distribution Networks [#602]
The asymmetry of the inherent distributed capacitances causes the rise of neutral-to- ground voltage in ungrounded system or high resistance grounded system. Overvoltage may occur in resonant grounded system if Petersen coil is resonant with the distributed capacitances. Thus, the restraint of neutral-to-ground voltage is critical for the safety of distribution networks. An active grounding system based on single- phase inverter is proposed to achieve this objective. Relationship between output current of the system and neutral-to-ground voltage is derived to explain the principle of neutral-to-ground voltage compensation. Then, a current control method consisting of proportional resonant (PR) and proportional integral (PI) with capacitive current feedback is then proposed to guarantee sufficient output current accuracy and stability margin subjecting to large range of load change. The performance of the control method is presented in detail. Experimental results prove the effectiveness and novelty of the proposed grounding system and control method. Poster Session: Transportation Electrification Applications Tuesday, September 20, 11:00AM-12:30PM, Room: Exhibit Hall, Chair: Jin Wang, Yaosuo "Sonny" Xue P2301 A Novel Energy Balanced Variable Frequency Control for Input-Series-Output-Parallel Modular EV Fast Charging Stations [#57] Qi Tian, Hua Bai, Huang Alex, Teng Hui and Lu Juncheng, North Carolina State University, United States; Kettering University, United States At present time, the most common electrical vehicle (EV) chargers employ a two-stage design, i.e., a front-end AC/DC stage + an isolated DC/DC converter. In this paper, an isolated dual-active-bridge (DAB) based single- stage AC/DC converter was proposed, which has the power-factor-correction (PFC) and zero-voltage-switching (ZVS) functions over the full-load range. By reducing one power stage and eliminating the large DC link capacitor, a high efficiency and high power density are achieved. Such topology can be used as a modular building block to scale up to 50kW by serial connecting the input terminals and paralleling output terminals. A novel energy-balanced variable switching frequency control for such input-series-output-parallel (ISPO) modular designed is proposed. A single-phase d-q transformation is implemented to achieve zero steady-state error. Simulation analysis and experimental validation are presented.
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