Bruno W. França

An Improved iUPQC Controller to Provide Additional Grid-Voltage Regulation as a STATCOM

This paper presents an improved controller for the dual topology of the unified power quality conditioner (iUPQC) extending its applicability in power-quality compensation, as well as in microgrid applications. By using this controller, beyond the conventional UPQC power quality features, including voltage sag/swell compensation, the iUPQC will also provide reactive power support to regulate not only the load-bus voltage but also the voltage at the grid-side bus. In other words, the iUPQC will work as a static synchronous compensator (STATCOM) at the grid side, while providing also the conventional UPQC compensations at the load or microgrid side. Experimental results are provided to verify the new functionality of the equipment.

Comparisons between the UPQC and its dual topology (iUPQC) in dynamic response and steady-state

In this paper the Unified Power Quality conditioner is studied with conventional operation mode (UPQC) and with its dual topology (iUPQC). The iUPQC is presented as solution to improve the dynamic response in power quality disturbance mitigation. Comparisons in steady-state and dynamic response are provided. Simulations and experimental results are shown to verify the iUPQC behavior for power quality safety and several load change issues.

Hardware-in-the-loop evaluation of DSP-controlled converters

Translation of power electronic circuit designs from simulations into actual hardware can give rise to difficulties, regarding the implementation of control functions with embedded controllers. This task is even more difficult when the power converter must operate connected to the grid. A design framework is described in this paper, which is suitable for testing and debugging software implementations of control algorithms for such applications, under nearly ¿real¿ conditions, while avoiding risks of damage to actual hardware. An example of application is given, along with experimental results.

Comparison between alpha-beta and DQ-PI controller applied to IUPQC operation

The iUPQC is a dual approach of the well-known UPQC, which uses the series compensator as sinusoidal current source and the shunt compensator as sinusoidal voltage source. In this way, the control references outputs are sinusoidal signals at the fundamental frequency. This paper compares two different controllers for the PWM reference signal generations, using α-β and d-q reference frame, respectively. Experimental results using both controllers are presented as well.

A synchronverter to damp electromechanical oscillations in the Brazilian transmission grid

Nowadays a SVC at the Bom Jesus da Lapa (BJL) substation (250 MVAr) is utilized to control voltage at the Southeast/Northeast interconnection. This paper has two purposes. One is to show the technical possibility to substitute the Static VAR Compensator (SVC) by a synchronverter. Secondly, that the synchronverter mitigates electromechanical oscillations. A control strategy is utilized to damp the North/South mode in the same way as a Power System Stabilizer (PSS), based on the power flow on a transmission line at a distance of more than 1000 km.

A novel topology for fuel cell stack generation with flywheel energy storage system and Z-source converter

Nowadays fuel cell stack and other alternative energy sources use batteries to store energy. However, the battery cannot be quickly charged or discharged because of low rate chemical reaction. In this way, a flywheel energy storage system (FESS) has been widely employed to provide dynamic storage and supply energy. Here, the FESS feeds mechanically a permanent magnetic synchronous machine (PMSM), which will supply the power load. Although the fuel cell is a clean, silent and efficient generator, it has a low output voltage. In order to solve this problem the Z-source converter can be applied as boost and as dc-to-ac power converter, reducing the number of switching. This paper proposes a system composed by PMSM and flywheel with PEM fuel cell stack and Z-Source converter. The simulation results of proposed system will be provided at PSCAD/EMTDC environment and advantages of FESS and PMSM, as well.

Three-wire investigation of a hybrid power filter with four-switch structure applied to the attenuation of 5 th and 7 th harmonics with reduced inverter power rating

This paper studies a hybrid filter formed by a single tuned LC filter per phase and a small-rated three-phase active filter, which are directly connected in series without any matching transformer. The required rating of the active filter is much smaller than that of a conventional standalone active filter would be and it comprises a four-switch H-bridge inverter connected to the three-wire system. The analytical procedure is verified by simulation results to confirm the effectiveness of the proposed control scheme.

A new control method of Z-source converter with PEM fuel cell in PSCAD/EMTDC environment

This paper proposes a generalized model of Proton exchange membrane fuel cell (PEMFC) with Z-source converter design in PSCAD/EMTDC simulator. The fuel cell model considers the chemical and electrical parameters, and it is composed by five inputs and one electrical output. In the other words, the user needs to filled up five parameters of fuel cell to obtain the dc voltage output, which feeds Z-source converter. Although the Z-Source concept can be applied to all power conversion (dc to ac, ac to dc, ac to ac and dc to dc), this paper analyses its capability to dc-ac power conversion and boosting voltage, this is an extremely attractive quality particularly for fuel cell power which has low output voltage. A new Z-Source voltage control is also proposed based on anti-wind up control technique. Simulations results of PEM fuel cell/Z-source converter system are presented and polarization curves as well.

A novel predictive controller and experimenntal analysis of a power electronic load

In this paper is proposed a novel predictive controller to improve the Power Electronic Load (PEL) dynamic. Moreover, details of the developed three-phase PEL prototype (25 kVA) are provided with capability of burn-in-test series, shunt and series-shunt power conditioners. In order to validate the load emulation effectiveness and dynamic improvement, experimental results and a power flow analysis are provided.

Robust positive-sequence detector algorithm

This paper discusses a new PLL (Phase-Locked-Loop) approach for detection of the fundamental positive-sequence component of three-phase systems. Details about this three-phase PLL structure are provided. The positive sequence detector presented computes inner-products between the input and a locally generated version of the fundamental frequency. The inner-products are used to estimate the phase-angle, frequency and amplitude of the fundamental component. In order to validate the effectiveness of the detection algorithm here discussed, simulations using PSCAD/EMTDC under conditions that are similar to the ones encountered in practical digital implementations are presented, for disturbances and unbalance. The digital implementation of this positive-sequence detector has a fast dynamic response and robust performance under distortion and/or faulty conditions when implemented using a high sampling rate and floating-point precision. For embedding such an algorithm (for example in a DSP) reducing its computational complexity is welcomed. This reduction can be approached in several ways: using fixed-point arithmetic, reducing the sampling rate or avoiding some computations. The impact of down-sampling in the inner products carried out by the algorithm (what reduces the overall computational complexity) in the performance of the algorithm is analyzed. Experimental results using a fixed-point DSP are presented as well.