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This paper proposes a new type of voltage swell/sag compensator based on single-phase Z-source AC/AC converter. The proposed topology employs a pulse width modulation (PWM) Z-source AC/AC converter along with a transformer. A commutation strategy to drive the AC/AC converter is employed to realize snubberless operation. Circuit analysis is provided. Simulation and experimental results at 20% voltage...
In future grid codes wind farms will have to fulfill demanding fault ride through requirements. Among several grid faults the voltage swell is a critical event. Wind farms with doubly-fed induction generators will not be able to fulfill the new grid code requirements without additional fault mitigation equipment. In this publication the applicability of the dynamic voltage restorer and the static...
Power converters operated in unsymmetrical three-phase electrical systems will generally work asymmetrically. This introduces disadvantages for the operation of the electrical power system, such as non-characteristic harmonics in voltage and current. In this paper, a method is presented to control the behavior of electrical equipment based on line-commutated current converters using unsymmetrical...
The present paper addresses the control of doubly fed induction generators under unbalanced voltage sags considering the converter limits. A control strategy is proposed by choosing certain current reference values in the positive and negative sequences so that the torque and the DC voltage are kept stable during such unbalanced sags considering the converter limits.
Over the past decade, power quality (PQ) issues became increasingly important. The most cited PQ problems are voltage dips, harmonic distortion and transient phenomena. The tarification method which is mostly used, tarifies the instantaneous active power. When absorbing harmonic power, e.g. when using an active filter, the customer has to pay for this. To overcome this, a tarification method is proposed...
Mainly due to historical and convenience reasons, for power levels up to several kVA electric utilities provide power distribution typically uses 1-phase a.c. feeders, despite a 3-phase supply would be technically preferable permitting for instance to use more efficient and compact induction motors, 3-phase rectifiers providing lower output ripple etc. This paper deals with a simple converter able...
Configurations of combined series and shunt active filters, also known as unified power quality conditioners (UPQCs), are designed for simultaneous compensation of voltage and current harmonics and imbalances. Sometimes, compensation of voltage sag/swell is also included as additional functionality of the UPQC. Traditionally, the shunt active filter of the UPQC behaves as a controlled current source...
The present paper deals with the integration of electrical, control and mechanical models in a single platform to evaluate the response of wind turbines to different classes of voltages sags. Models of all the wind turbine parts are described and integrated in two different platforms. Mechanical and aerdynamics are modeled using GH Bladedcopy while electrical and control parts are modeled using Matlab...
One presents the main disturbances sources from the distribution substations used for urban electric transportation systems: transformers from substations; three-phase supplying line; converters from substations; contact line and path rails. Using a quality analyzer, numerical recordings are obtained representing the waveforms of voltages and currents in a substation for the transformation medium...
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