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This paper presents a new control strategy for Modular Multilevel Matrix converters where the output frequency is higher then the input frequency. In operating points when ωout ≥ ωin the energy pulsation in the converter cells are dominated by the second harmonic of the input frequency. These energy pulsations can be identified and compensated by inducing additional currents. The results are verified...
In this paper, a new control method for capacitive link universal power converters is proposed to eliminate the need for measuring the output and input voltages. Capacitive link universal converters are a new class of power converters that offer high power density and reliability, and are capable of transferring power between any type of source and load, dc or ac, with any number of phases, emerges...
This paper describes a method to provide LV four-wire three-phase power converters with the capability of correcting unbalance as an ancillary service to the main role that they play in the distribution system (distributed generator, energy storage system, drive, etc). Typically, dedicated grid/load current sensors are needed to effectively comply with unbalance compensation tasks, increasing system...
In this article an energy management strategy for a Modular Multilevel Converter is proposed, this converter is operating as a direct frequency changer. It is connected in three-phase configuration and the developed control strategy depends only on measurements made at the converter site without using neutral wire parameters information, which is convenient for high power applications. Developments...
This paper presents the analysis of an AC-AC converter used in partial discharge test. In this paper, the analysis of the frequency converter is separated into two parts. Firstly, the converter models are simulated by a circuit simulation program for comparing noise signals generated by the 2-level SFC and 5-level SFC. The frequency of the converter was set to be 200 Hz. With the help of the simulator,...
Although existing standards such as IEC62684 and EN 301 489-34 limit the line frequency common mode (CM) voltages at the output of AC/DC converters, the mechanism and characteristics of line frequency CM voltages at the outputs of AC/DC converters are unclear and the technique to reduce it is not well investigated and developed. In this paper, the line frequency CM voltages at the outputs of AC/DC...
This paper proposes a frequency-offset method to determine a conversion coefficient of an extremely low-frequency magnetic field (ELF-MF) detector to measure the strength of a power-line magnetic field, which is caused by electricity operating at 60 or 50 Hz. Using the frequency-offset method, the conversion coefficient can be determined in spite of interference caused by ambient noise. The frequency-offset...
Increased penetration of offshore wind power plants (OWPPs) demands frequency control services from them. Overloading the wind turbine, for few seconds after the under frequency event, to utilize its kinetic energy seems promising option for fast primary frequency control. Two methods of overloading the wind turbine (WT), with and without considering the impact of WT dynamics and variation of WT output...
This paper proposes a novel control scheme for frequency support among asynchronous AC areas through HVDC grids. It is based on local controllers, each acting on a voltage source converter, using locally available measurements only, and supporting frequency of the adjacent AC area after a significant disturbance. The controller is combined with the existing DC voltage droop technique and is inspired...
This paper proposes a novel method that uses two phase-locked signal generators to evaluate wideband voltage dividers that have wide voltage ratio ranges, including atypical ratios like 1/101. These voltage dividers are intended to be fabricated by applying the Hamon principle. Verification of the proposed method was carried out using standard inductive voltage dividers calibrated using Thompson’s...
The modern locomotives, which are in exploitation in the railway network in Bulgaria, are equipped with electronic devices for registration of analogue and digital running parameters (i.e. the so-called “black boxes” or “recording devices”). Such systems are the Hasler TEL 1000 and the DSK type from KWR. The registration devices used in the older locomotives are not digital, but mechanical. Since...
Power conversion equipment, such as power conditioning systems (PCSs), is known to generate conducted disturbance in a broad frequency range. Recently, the power capacity of the equipment has become larger because of the efficient use of them, and the conducted disturbances occur in the frequency range from 2 kHz to 9 kHz, where no measurement method and limit levels are regulated. In this paper,...
The development of measuring converters with a direct voltage-to-frequency conversion represents significant interest. This paper describes the possibility of using acoustoelectric effect for the development voltage-to-frequency converters. The first part of this paper deals with the theory of the acoustoelectric effect. In the second part the design and the realization of the voltage-to-frequency...
This paper proposes and demonstrates a novel dualband rectifier at 2.45 GHz and 5.8 GHz. The proposed rectifier employs a microstrip spurline notch filter to realize dual-band high RF-DC conversion efficiency. The control of reflected signals from the output filter to maximize the voltage swing at the diode, and use of the spurline notch filter provide high-level conversion efficiencies at both operating...
The article discusses assessing the reconstruction accuracy of a signal in systems using converters with a frequency output. A Voltage-to-Frequency Converter VFC working in a dynamic state was considered. The frequency signal obtained in this manner is particularly disadvantageous from a dynamic perspective, as digital frequency processing is always a measurement of its mean value. Therefore, in dynamic...
A frequency-to-voltage converter (FVC) is designed for directly converting an input radio-frequency to a dc output voltage over a wide microwave frequency range. The proposed circuit consists of a limiting amplifier (LA) for converting input frequency to correspond ac magnitude and a power detector for ac magnitude to dc voltage conversion. Consequently, the circuit converts the signal frequency of...
The interlinking converter in an AC/DC hybrid micro-grid plays a crucial role in the stable operation and power allocation of power system. A bidirectional droop control method for the converter is proposed, which measures the power demand degree of AC sub-grid and DC sub-grid according to AC bus frequency and DC bus voltage respectively, and determines the direction and magnitude of the converter...
Causes of measurement uncertainties might be numerous and as the rule, not all of them can be considered. Two basic types of measurement uncertainty are the type A and the type B. Measurement uncertainty of type A is determined only by method of statistical data processing. A result of this is that measurement uncertainty of type A exists only in case of a measurement repeated several times. Measurement...
The design and measurements of a CMOS pseudodifferential voltage-controlled ring-oscillator (VCRO) are presented. It is aimed to act as time interpolator for arrayable picosecond time-to-digital convertors (TDC). This design is incorporated into a 64×64 array of TDCs for time-of-flight (ToF) measurement. It has been fabricated in a 0.18μ™ standard CMOS technology. Small occupation area of 28×29μm2...
The response time of high voltage impulse dividers is very important parameter which determine their maximal frequency. This parameter has to be tested by measurement in high voltage laboratories. Usually, the step voltage method is used to determine normalized step response and the experimental response time is calculated. Another method is the direct measurement of voltage divider frequency characteristics...
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