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In this paper a new voltage measurement technique for modular multilevel converter (MMC) capacitors is proposed. While all the capacitors voltages should be known for closed loop control of MMCs, only the arms voltages are measured employing the proposed method. Therefore, the number of voltage sensors reduced dramatically to one per arm. The capacitors voltage quantities are updated continuously...
Power quality has always been an important issue to electric power utilities, and it is gaining important awareness among consumers, who are beginning to understand the importance of having power quality. In this paper, a b-learning methodology for a power quality course is applied. A virtual environment which allows the execution of complementary experimental exercises for teaching how the power...
The increased interest in research and development of renewable energy solutions is based on the growing shortage of fossil fuels and the concerns about the global climate. Open water waves are one of the natural phenomena of our environment that have attracted attention for a long time. A huge source of potential energy resources is hidden in the oceans. The investment in the renewable energy technology...
This paper presents a Two-Switch Forward Converter (2SFC) designed to charge small arrays of battery cells. Such battery charger can be used to analyze the influence of different charge profiles on batteries and on their indicators, like in State Of Health (SOH) and State Of Charge (SOC) ones, beyond of in active balancing studies. The main design steps for the 2SFC will be presented along with the...
In recent years, power electronics utilization in modern devices has experienced a large growth due to several applications. For this reason, undergraduate laboratory courses in this field should have modern equipment for measurement and analysis of electrical signals. With this, students will have the opportunity to understand theoretical concepts in practice. However, commercial equipment of this...
This paper introduces a sensorless current-sharing strategy for two-phase input-parallel output-parallel (IPOP) DC-DC converters. A dual active bridge (DAB) DC-DC converter is chosen as the basic DC-DC converter. With this strategy, the parameter mismatches between phases are estimated by perturbing the duty cycle in one phase and measuring the changes of duty cycles in both phases. Then the duty...
The aim of this paper is to propose the application of the DC-link current sensors of the back-to-back converters for operation of a doubly-fed induction generator (DFIG). The operation of the DFIG is first discussed. The measured DC-link currents are used reconstruct the AC current waveforms for operation of the DFIG under different operating modes. The feasibility of the proposed application is...
This paper proposes a hardware implementation of new method for speed sensorless control of surface mounted (SM) permanent magnet synchronous motor (PMSM) drive. It adopts combination of the DC link measurement and the modified model reference adaptive scheme (MRAS) to estimate rotor speed and position. A 16-bit dsPIC33EP256MC506 DSC is used to implement the proposed estimation algorithm and the control...
In this paper the external stray flux around a motor has been investigated as a possible new diagnostic instrument to detect generalized roughness. This very common bearing fault has been slightly considered in the literature so far. Stray flux was measured by two probes, one commercially available and one realized in laboratory; the diagnostic content of both signals has been compared also with the...
This paper describes a crosstalk calibration and cancellation technique to achieve high precision power measurement using general single-ended analog to digital converter (ADC). Two crosstalk scenarios, in-phase and out-of-phase with the interfering source in multiple signal channels are discussed. Systematic approaches to characterize crosstalk effects are discussed. A calibration procedure to obtain...
Condition monitoring is gaining more and more importance in the past few years. As inverter fed operation puts additional stress on the machine's insulation system a breakdown of a drive system associated with costly outage of industrial processes or production plants is getting more likely. To enable a monitoring of the insulation system health state before an actual short circuit and breakdown occurs...
This paper shows a current measurement technique, which combines approaches for synchronized inverter current measurement with an advanced system of digital transmission and filtering of current measurement values. The measurement technique gives a significant increase in performance, accuracy and robustness compared to classical measuring with sampled A/D conversion or not synchronized techniques...
The paper presents an example of conformity assessment of novel distributed measurement system for monitoring the operation of MV power networks. The system is at prototype stage and it is made by Low Power Instrument Transformers featuring high accuracy, power quality bandwidth and allowing protection operation functions. The sensors are connected to a new Intelligent Electronic Device (IED), which...
For the determination of power losses in highvoltage direct current (HVDC) modular multilevel converters (MMC) the standards IEC 62751-1 and IEC 62751-2 demand component measurements with a sufficient uncertainty. Transient loss measurements on multilevel converter modules – so called submodules (SM) – are challenging, especially if they have to be done precisely. Measurement methods and results are...
The ability to monitor power and energy accurately and efficiently is becoming increasingly important in all areas of computing. In this paper, we introduce WattProf, a portable and flexible power monitoring platform that allows for fine-grained monitoring of power and energy consumption in various hardware components of HPC clusters. The WattProf system consist of a programmable monitoring PCIe expansion...
This work aimed to investigate which pulses (M-components and/or subsequent return stroke) of the upward lightning are detected by BrasilDAT lightning location network. It was found that, these pulses are similar to downward lightning pulses and therefore, they were well detected by the network. This report is based on a set of 29 upward lightning and 16 downward lightning whose strike points are...
We report simultaneous measurements of vertical electric fields and currents associated with positive flashes to the Säntis tower. The fields were measured at a distance of 14.7 km from the tower. All the data correspond to type-2 positive flashes characterized by currents with relatively slow rising portion on which oscillatory pulse trains, inferred to be due to an upward negative stepped leader,...
The application of Rogowski sensors in protection and control equipment has many benefits compared to traditional instrument transformers. However, the signal levels of these sensors are small compared to possible disturbances, which raises questions regarding the immunity of such applications to switching transients. This contribution investigates a protection application with Rogowski sensors from...
Spectrum measurements are a crucial element of compliance enforcement in dynamic spectrum access (DSA) networks and for emerging interference limit policies such as harm claim thresholds. Such measurements should provide better spatio-temporal resolution than traditional compliance enforcement approaches for characterisation of spectrum usage. Using current techniques, even in distributed monitoring...
Single-core Cross-linked Polyethylene (XLPE) cables are commonly used to transmit 3-phase power in long distance transmission and distribution lines. Cross bonding of metal sheaths across phases limits induced currents. Assessing cable condition allows asset managers to prevent failure. On-line monitoring of Dielectric Loss (DL) indicates the general state of the cable insulation. In practice, DL...
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