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In this paper, a comprehensive behavioral efficiency model of an electric motor drive system is proposed. The proposed model includes all possible motor drive losses without ignoring, approximating or assuming any of the inverter or machine losses, which are usually done for other efficiency models, hence the model is comprehensive. The input (DC electrical) and the output (mechanical) power of the...
Photovoltaic power plants (PV) are equipped with anti-islanding algorithms, embedded in the converters controller, to avoid the island operation. However, the current trends in the development of the future electrical networks evidence that it is technically feasible and economically advantageous to keep feeding islanded systems under these situations, without cutting the power supply to the loads...
This paper proposes a new method to suppress frequency variations of power system with large amount of wind power installed by using the kinetic energy of the wind power generators. In recent years, environmental problems have been becoming serious and wind power generation with less environmental impacts has attracted much attention and introduced. Since wind power generation is an unstable power...
Brushless Doubly-Fed Induction Generator (BDFIG) is potential for power generation applications for its high reliability and low maintenance-cost. There are two operation modes for BDFIG: grid-tied and stand-alone modes. The grid-tied mode usually uses the power winding (PW) synchronous and orientation frame since PW is connected to the grid; however in stand-alone mode, the PW is connected to the...
In this paper, a new common inductor current sharing method is proposed for multi-phase LLC resonant converter for high power application. Automatic current sharing is achieved by using a common resonant inductor for all the LLC resonant stages, by connecting the resonant inductors in each phase in parallel. The proposed method can automatically share the load current without any additional circuit...
This paper presents the application of a Delta-Connected Cascaded H-Bridge Converter in unbalanced load compensation. The compensation includes positive sequence reactive power current and negative sequence current compensation. The controller designed based on the detail power flow analysis which can achieve dc capacitor voltage balancing control by zero sequence current injection even when compensating...
In most modern power electronics systems constant power loads (CPL) exist, which could have a severe influence on system stability. Conventionally two modelling tools for a system qualitative study are considered — generalized state-space averaging (GSSA) and DQ modelling methods. In this paper their strict mathematical equivalence in the balanced three-phase system is shown and areas of GSSA application...
Portable AC generators directly driving isolated AC loads require tight voltage regulation, good voltage waveform quality and high efficiency. This paper compares the performance of a 4-pole, 16 kW, three-phase interior permanent-magnet generator with a single-phase resistive load when operating with both star and delta winding connections. The results of analytical and finite-element simulations...
In this paper, a hybrid mode control (HMC) is proposed to increase performance of light load operation without an extra hardware for a three phase PWM converter (TPPC). The proposed algorithm changes an operation mode of the TPPC to 3-phase or 2-phase according to the load condition. To select optimal mode change point, performance of TPPC is analyzed. The validity of the proposed algorithm is verified...
Droop control is a widely used technique for load sharing in DC microgrids (MGs); however, its performance is affected significantly by the voltage drops over coupling line impedances causing load sharing errors and voltage degradation across MG bus. Therefore, the locations of the sources in the MG and loading conditions (LCs) have considerable effect on load sharing accuracy and voltage regulation...
The interactions of more and more power electronics-interfaced power systems can worsen the power quality and the system stability in distribution networks. System stability can be addressed analyzing the source and load impedances at the interaction section and well-established approaches exist for DC and three-phase AC networks. Some papers focus also on single-phase AC systems, whose study is generally...
Utilities implementing grid modernization programs, or facing challenges of increased level of renewable integration, are seeking tools that can provide distributed and dynamic volt-VAR control. This paper presents a distributed autonomous volt-VAR control approach that uses a large number of small rated VAR injection sources to convert a distribution feeder into a dynamically controllable VAR source...
In this paper, we present an unstable phenomenon in cascaded systems that the source converter might become unstable after connected with the load converter though it can work stably individually. However, by staggering the switches' turn-on time between the source converter and load converter, it can become stable. Analysis in this paper shows that the essential reason for this phenomenon is that...
This paper proposes a methodology to model and control a three phase voltage source inverter (VSI) with LCL filter intended for distributed generation in microgrid scenario. Thus, the inverter should be able to operate in both grid-connected and islanded modes with a smooth transition between them. The strategy is to split the control input into two components. The first component is generated to...
Modular multilevel converter (MMC) is a promising topology for medium and high power applications. The MMC system consists a large number of sub-modules (SMs), which take long time to simulate. In a real-time simulator, the MMC model is optimized to have a fast simulation speed for real-time applications, such as hardware-in-the-loop (HIL) tests. The methodology to evaluate model fidelity is important...
This paper provides a comprehensive study on the life test method of the retired xEV(PHEV/HEV/EV) battery pack for smart house energy storage applications. First, the paper proposes a detailed model for a energy management system supported smart house. By utilizing historical household load data and Photo Voltaic (PV) panel power generation data, a 96-hour close-to-real mission profile of the battery...
Resonant converters have gained popularity for a variety of applications due to their ability to provide soft switching conditions and high power density. Controlling these converters is complex because of their non-linear behavior and high frequency resonant tank. Controllers are often designed by using small-signal models, which are limited to operating around a quiescent point. However, the small-signal...
In this paper the effect of parasitic elements of the load connected to a power converter are considered. For the case of a high switching speed converter the equivalent parallel capacitance of the load or line inductance will cause a potentially large current overshoot, which will in turn lead to increased switching losses. This paper considers the relation between the operating conditions of the...
Advances in switching power electronic converter technology have brought about a resurgence of interest in the use of DC power distribution systems for a variety of applications. However, the notional power electronic based DC distribution system is a complex and extensively interconnected system consisting of multiple power converters. As a result, a number of system-level challenges related to stability...
The thermal dynamics of power device, referred as “thermal cycling”, are closely related to the reliability as well as the cost of the power electronics converter. However, the device loading is disturbed by many factors of the converter system which present at various times-constants from micro-seconds to years, thereby the complete loading conditions of power device are still challenge to be predicted...
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