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The four-level Hybrid Clamped Converter (4L-HCC) is emerging as a promising DC/AC converter topology for high-efficiency medium-voltage drives. However, without proper control, the voltage fluctuation of the DC-link capacitors will be excessive, resulting in distorted AC current and stability issue in low frequency operation. In reality, the distorted current makes it impractical for motor drive during...
The modular multilevel converter(MMC) is one of the most attractive converter topologies for high or medium voltage power system. In this paper, a combination of modular multilevel converter and dual active bridge(DAB) is discussed. The DAB assisted MMC(MMC-DAB) is capable of low frequency output with elimination of capacitor voltage fluctuations in submodules. This paper analyzes the MMC-DAB structure...
This paper proposes a new way based on FPGA to realize decoupled double synchronous reference frame software phase locked loop (DDSRF-SPLL) under unbalanced conditions. DDSRF-SPLL can lock in unbalanced grid voltage accurately as well as overcome the impact of the phase-locked loop on frequency performance in adopting the positive and negative sequence decoupling algorithm. When the frequency of three-phase...
The modular multilevel converter (MMC) mainly run at power frequency (50 or 60Hz) especially in the field of HVDC field. The disadvantage of cell capacitor voltage fluctuation at low frequency blocks the kind of convertor applied at AC motor drive. This paper uses a set of control novel scheme to restrain the fluctuation and make MMC to drive induction motor running from standstill to grid frequency.
This paper presents a nonlinear control strategy for single-phase universal active filters, using multiple reference frames. The control uses the concept of product demodulations and feedback linearization to circumvent realization problems of standard park transformation strategies and resonant controllers. However, similar to those, the present control allows achieving selective compensation and...
This paper describes an optimal design method for a current regulator and an output voltage regulator with a output capacitor in a boost-up chopper. In order to reduce the output capacitor and the boost-up reactor, high speed response of the current regulator and the output voltage regulator are required. In this paper, the current controller is designed based on dead-beat control with P, PI or IP...
In order to demonstrate the large-scale integration of wind power generation into small isolated island power systems, a test facility composed of two wind turbine generator systems (WTs) and a flywheel energy storage system (FESS) was introduced in a remote island in Okinawa prefecture, Japan in 2009. Since large-scale integration of wind energy may cause fluctuations in the frequency and voltage...
Wind power plant meets so many power quality issues when it is connected with strong grid. This paper proposes a new power quality conditioner to regulate the supply frequency, to control the power flow, to minimize the current harmonics, and to regulate the voltage for fixed speed induction generator type wind generator. The name of the proposed new power line conditioner is called as Universal Power...
The DC-bus voltage self-regulating of Hybrid Active Power Filter (HAPF) is not only critical to compensation performance, but also to the safe operation. Traditional controller, e.g. P or PI, has disadvantages for these applications. Regarding the popular shunt HAPF with passive and active filters in serial connected, this paper presents a novel controller for the DC-bus voltage self-maintaining....
Voltage sags and swells, voltage harmonics and voltage imbalances in power systems may affect sensitive loads causing production interruption or equipment damage. Now-a-days series voltage compensation using power electronics devices is a promising solution for these problems and the design, control and application of this type of devices have drawn much attention in the literature. Comprehensive...
Distributed power generation systems (DPGS) are based on the grid-converters as interface between the source and the grid. They require a control strategy is designed in order to guarantee system stability and reliability. The effect of converter outages should be properly studied as well as the effect of power quality disturbances. The aim of this paper is to provide a comprehensive analysis of these...
This paper describes the most recent German regulation on the integration of dispersed power generation into the medium and high voltage grid in terms of the latest grid codes. A special consideration is given to the advanced requirement on frequency control and dynamic voltage support. An overview on the status quo of certification regulations and implementation approaches in selected countries both...
In this paper, a new type of controller is proposed for series connected PV inverter for grid voltage compensation. The inverter operates during the day time as an active power compensator as well as load voltage regulator under grid voltage sag, swell or even under normal condition. The compensating voltage provided by the inverter is added vectorially in series with the grid voltage in such a way...
Dynamic voltage restorer (DVR) has been demonstrated to be a very effective mechanism to deal with key voltage-quality disturbances. Although the dynamic response requirement for voltage sag could be satisfied by a feedforward control strategy, the voltage-quality requirement and zero-error tracking need an advanced feedback control strategy. This paper proposes a d-q transformation and proportional-resonant...
From depletion of energy resources and consideration to natural environment, introduction of renewable energy facilities has been increasing annually. Moreover, introduction of photovoltaics has increased on the demand side. However, due to the fluctuating power from renewable energy sources, frequency and voltage fluctuations of power systems become problematic. At the same time, there has been a...
A novel voltage fluctuation and flicker generating main circuit topology is proposed in this paper, combined with passive and active to realize voltage fluctuation and flicker. The fundamental frequency power is supplied by system source and the other frequency fluctuation power is supplied by active components, so the capacitor of generator is easy to realize larger because of lower active loss....
From depletion of energy resources and consideration to natural environment, dispersed power system such as wind power generators are introduced. Moreover, all electrification in houses or residences and electric vehicles are increased in recent years. Again, introduction of photovoltaics has increased in demand side. However, due to the fluctuating power from renewable energy sources and loads, frequency...
This paper discusses the impact of balanced and unbalanced voltage dips on grid connected voltage source inverters, usually found in wind turbines. A Kalman filter synchronization method is used to provide an accurate and fast extraction of the voltage positive sequence under unbalanced voltage dips. Also, it minimize the transient effects due voltage-phase-jumps. In addition, two current controllers...
With a view to the integration in national power system of new power plants based on renewable energy sources, such as wind energy, this paper presents the technical requirements related to the connection of the wind power plants to the main grid. Grid connected wind turbines may cause power quality problems, such as voltage variation and flicker, and therefore, the connection of wind farms requires...
This paper is based on measurements obtained during a test of controlled islanding of part of the 50-kV grid in Southern Sweden. The purpose of the test was to verify operation of generator controls during islanding. The variations in voltage magnitude and frequency are shown as well as flicker severity and very-short variations. A number of performance indices have been calculated and compared with...
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