Transitional Reactances of Capacitor at Switching Processes

2020

In switched capacitor circuits, it is quite common to use MOSFET switches, integrated capacitors (IC) and non-overlapping clocks for carrying out switching operations. MOSFET switches are far from ideal switches mainly when they are operated with small operating voltages. Some investigations have been carried out on the performance of switched capacitor resistors (SCRs) with the switches operated under varied conditions. Further, an attempt has been made to find out how closely SCR represents conventional resistors. It has been found that the SCRs with ideal components satisfy the properties of series and parallel connected conventional resistors. Further, the energy dissipation in SCR is the same as that in conventional resistors when operated under fixed voltage difference. FET based SCRs exhibit higher resistance values, compared to SCRs with ideal switches depending on the operating conditions. When SCRs are loaded with conventional resistors or capacitors, their output is entir...

Advances in Power Electronics, 2012

This paper addresses the switching transients in multibranch thyristor-switched capacitors (TSCs). The current transients following the addition of a branch to a group of already connected ones are analyzed. Expressions for both its fundamental and its oscillatory components are given in terms of the power network voltage, frequency, short-circuit level, and the switching angle. The relations include also the compensator parameters such as its total reactive power rating, total number of branches, the number of already connected branches, and the initial voltage on the capacitor involved in the switching transient. An expression for the distortion of the supply current is also given. A minimization procedure is presented for identifying the optimal switching angle leading to the least magnitude of the oscillatory current. Switching when the instantaneous supply voltage is equal to the initial voltage will result in the least oscillatory current only in the two special cases of a single-branch compensator, or in the switching of the first branch of a multi-branch TSC. The effect of both the total number of branches and the branch switching steps on the oscillatory current and on the optimal switching angle is also discussed. The advantage of the suggested procedure is demonstrated by investigating several case studies.

International Journal of Power Electronics and Drive System (IJPEDS), 2019

The paper derives closed form expressions for transient and steady-state operation of a DC-DC converter with single switched capacitor. To this end, the result of each switching is considered as a point in the iterative process, and the function between the points is reconstructed. As opposed to the commonly accepted approach, when each of the topologies is approximated by a first order circuit, the proposed analysis is carried out for second order circuits. This allows obtaining the waveform of output voltage ripple and paves the way to more accurate calculation of equivalent resistance. The obtained analytical expressions were verified by simulations and an excellent agreement between the results was found.

2000

The permanently installed syncronously switching •vacuum breaker. • •. .. .. .. . 45 24. An oscillographic record of bus voltages and phase currents during a single bank energization of the prototype installation. • • • • • 47 25. A plot illustrating the effects of ambient temperature on the timing accuracy ofthe switch during its first 2 years in service. • • • • • • • • • 48 26. Computer plot of the bus voltage as a function of time for the "single bank" case. Energization 4.17 ms from voltage zero • • • • • 56 27. Computer plot of the capcitor current as a function of time for the "single bank" case. Energization 4.17 ms from voltage zero •• 57 28. Computer plot of the bus voltage as a function of time for the "single bank" case. Energization 3.0 ms from voltage zero. 58 29. Computer plot of the capacitor current as a function of time for the "single bank" case. Energization 3.0 ms from voltage zero •. .. .. a a a 59 30. Computer plot of the bus voltage as a function of time for th "single bank" case. Energization

7th Vienna International Conference on Mathematical Modelling, 2012

This paper presents the results of experimental and simulated investigations of electromagnetic transient phenomena during energizing of industry capacitor banks. Experimental and simulated investigations based on the electrical network model having the nominal voltage of 6 kV are carried out. In addition, sensitive analyses of characteristic impact factors are performed. It is shown how capacitor banks switching transients influence a degradation of the power quality in electrical distribution system.

Journal of Advanced Computer Science & Technology, 2014

This paper presents a new and a modern method for study the inductive-capacitive circuits which are connected to an AC power source, using modern methods based on digital technology and software used in engineering applications. The capacitive circuits which are switched on an AC power source at the initial moment are presented below. We can determine the capacitor current variation forms, the capacitor voltage in a transient regime by using virtual mediums, in two different regimes: the oscillating regime and the-periodic regime. Each presented case contains an analytical presentation of the phenomenon, but it also contains the diagrams of current and voltage capacitors. The diagrams were obtained by two methods, which use MATLAB package. These diagrams are compared with experimental measurements obtained with a data-acquisition system produced by National Instruments using LABVIEW software.

The contribution of the rise and fall times of switches to the losses of Switched Capacitors Converters was evaluated by an approximate analysis applying the equivalent resistance concept. It was found that switch turn-on and turn-off durations increase the equivalent resistance of the converter and, consequently, the losses, except in the case of complete charge/discharge of the flying capacitors within the switching phase. Loss increase is related to the fact that during the current rise/fall state, the instantaneous losses are much higher than when the switch is in a constant 'on' state. Theoretical predictions were validated by full circuit simulations and experimental results. The present study integrates the switching losses into the generic equivalent resistance loss model, enabling the calculation and/or simulation of the total losses in switched capacitor converters.

Measurement Techniques, 1981

MATEC Web of Conferences

The power factor improvement has a great concern in the distribution system due to large motor installed in industrial system. The capacitor bank was installed to improve the power factor in the distribution system. Due to frequently capacitor bank switching has create transient phenomena in the distribution system and their effects the power quality. The aims of this research to study and simulate the effects of capacitor bank switching in the distribution system. The simulation has been conduct with PSIM software by modelled the system which contain of supply, load and three capacitor bank. The simulation was conducted with two conditions which are single bank and bank to bank switching. For single bank switching peak voltage of phase R reached about 60.9 kV and peak inrush current is reached about 6.7 kA. While for bank to bank switching the peak voltage of phase R reached as high as 59 kV and the peak inrush current is almost 8.2 kA.

Transitional processes at switching-off high-voltage capacitor banks by circuit-breakers with pre-insertion resistors are considered in the paper. Capacitor banks switching-off process by circuit-breakers with PIR was studied from the point of view improving electromagnetic environment via reducing switching currents by pre-insertion resistors. It is shown in the paper that appropriate resistances and pre-insertion times provides both reducing switching currents and stable operation of resistor.