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This paper proposes a new topological arrangement that consists in connecting the AC voltage source in series with two EIE Buck converters, one to operate in the positive half cycle and the other to operate in the negative half cycle. The control strategy is developed to achieve an AC output voltage within the limits set by standards in order to mitigate problems associated with Sags and Swells on...
This paper proposes an application of improved synchronous reference frame (ISRF)-based voltage sag detection in voltage sag compensation system. The ISRF-based voltage sag detection presents the fast detection time that is suitable to use in voltage sag compensation system. The proposed voltage sag compensation system consists of 1) ISRF-based voltage sag detector, 2) static transfer switches (STSs),...
Wind power generation is globally recognized as the most universal and reliable form of renewable energy. Korea is currently depending mostly on coal and petroleum to generate electrical power and is now trying to replace them with renewable energy such as offshore wind power generation. To make this possible, Korea has announced the National offshore power roadmap and is now in pursuit. However,...
This paper presents a discussion of the analysis of a static synchronous compensator (STAT-COM) device meant for compensating the unbalance produced by a single phase load and the design of its closed-loop control. The concept is tested experimentally using a small scale test platform.
Charging infrastructure for electric vehicles can impact significantly on distribution systems. Normal charging will be the usual way while fast charging has to be considered as a complement to this. Both charging processes represent a new load for distribution networks. The effect of both normal and fast charging are assesses. Management strategies are proposed for reducing the impact and the results...
This work proposes an operation strategy for a four-legs neutral point clamped converter (NPC) to be used in future bipolar dc distribution networks. The operation of the fourth leg with a three-level modulation is proposed to reduce the required inductance and switching losses. In addition, a proper control scheme based on a state space averaged model for the fourth NPC leg is introduced. This provides...
This paper describes a power conversion system that implements bidirectional power flow between the electric grid and a battery, based on a full bridge inverter associated with a dual active bridge. A method for power flow control based on the agreement between battery pack and low voltage grid requirements has been developed to allow the large penetration of both, electric vehicles (EV) and renewable...
The paper presents an analysis of the energy quality factors such as voltage and current spectra, THD, WTHD of any order, efficiency, for an energy storage system based on a diode-clamped multilevel VSC. The analysis technique includes two key parts: mathematical simulation and analytical research. The main advantages of the analysis technique are the possibility to apply it to any m-leg n-level converter...
Energy saving technology for electrical drives becomes high attention. Low harmonic drives reduce losses in the power supply. However, compare to the conventional drives, these have lower efficiency. In this paper the different kinds of adjustable speed low harmonic drives are compared. A new low harmonic drive with an integrated active filter is presented, which shows strengths of the harmonic mitigation...
In this paper three different implementations of the full-state feedback linear-quadratic (LQ) controller for a 3-phase 4-leg sine wave inverter are compared. The LQ controller is designed in stationary reference frames abc and αβγ as well as in a dq0 reference frame rotating with the fundamental output frequency, and is not cascaded with any inner controller. In the proposed control schemes integral...
The current harmonics can cause many problems for the electric power system, particularly the neutral conductor in the three-phase four-wire system. Active filter is known as the useful method for harmonic mitigation. Nevertheless, additional active filters increase system costs. In our work, the current harmonics will be only regulated to the specified values that should not be exceeded. We want...
An online harmonic estimation technique is proposed based on lifting wavelet transforms. The effectiveness of this technique is successfully verified in the paper through analyzing the current samples supplied to a practical building network which are unbalanced and corrupted with noise. Combining with a novel synchronization technique based on the energy operator principle, this scheme is applied...
Smart grids feature distributed energy resources interfaced to the grid by means of switching power converters. Synergistic control of these units can considerably increase the distribution efficiency and power quality by limiting the unbalance, reactive, and harmonic currents flowing through distribution lines. This can be achieved by a distributed control and communication architecture which implements...
Active power filters are often proposed as flexible solutions to tackle power quality problems in electric distribution systems. The need for tracking harmonic currents and voltages with these electronic devices exceeds the capabilities of conventional Proportional+Integral controllers and more sophisticated algorithms are sought. This paper presents a control method based on multiple reference frames...
The paper deals with the influence on the power quality of various new technologies of household appliances and measurement of their energy efficiency. Using a virtual power quality analyzer, which enables measurement of all power components according the newest power models and definitions, series of measurements were performed. Details of the measurement of harmonics generation by different domestic...
The presence of numerous power electronics converters on embedded networks, originates EMC issues. EMC modeling of power electronic converters is tricky due to modeling complexity. Indeed, on one side, EMC study needs the finest characterization of each element, thus, only a few numbers of converters plugged to the network can be described. On the other hand, a conventional network approach, representing...
A proposal to increase the existing residential LV grid voltage from 230 V to 300 V has been made in order to increase existing network capacity. A power-electronic AC-AC converter is then used to provide 230 V at each property. The equipment can also provide power-quality improvements to the network and load. Several constraints such as temperature rise at the converter location lead to a converter...
Efficiency is a fundamental UPS performance criterion. Remarkably, UPS efficiency in field applications may deviate from controlled laboratory conditions. This paper focuses on the impact of mains supply on double-conversion UPS efficiency. As the mains supply mostly affects the rectifier section, the results also provide a reference on the impact of mains supply on rectifier efficiency.
In this paper the impact of photovoltaic (PV) system connected to the medium voltage distribution gird using three-phase three-level inverter and step-up transformer will be investigated. The PV inverter is capable to control active and reactive power independently. The impact to the grid voltage profile of both active and reactive power regulation of the PV system will be examined. In order to simplify...
Because of the rapid increase of distributed generation, active voltage regulation becomes relevant for low voltage networks. In this paper, several power electronic voltage regulation approaches are presented and compared to each other through a Monte-Carlo-based network analysis. The focus of the investigation is on a series voltage regulator, for which simulation results and experimental results...
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