METHODS OF ADJUSTING FORMING LINES USING A LOW VOLTAGE THYRISTOR SWITCH

A method of adjusting the generating lines of a high-voltage pulse modulator with a thyristor switch at a charg-ing voltage of 150 V is given. The degree of pre-distortion is determined to obtain in the operating mode (60 kV) a voltage pulse with the required non-uniformity at the optimal value of the degaussing current of the trans-former. An element of fine tuning of forming lines at operating voltage is developed and applied.

Hardware Implementation of Automatic Power Factor Correction Unit For Industry

Power factor correction has always been challenging task. Most of electrical energy is wasted due to leading and lagging power factor. Thyristor switch modules are widely used in the rolling mills where more fluctuating load is available. The thyristor switch module with the reactor and capacitor is usedfor the compensating the reactive power in electrical power system. Automatic power factor correctionunit is required to keep unity power factor and optimize current consumption. Harmonics is reduced by connecting detuned reactor/inductor in series with capacitor and thyristor switched module. This paper shows design and hardware implementation of thyristorised automatic power factor correction unit for three phase circuit in an industry. The unit is flexible to maintain nearly unity power factor. The outcome is confirmed and acquired that the recommended circuit is perfect to produce improved output.

Use of a phase-shifting transformer for increasing the power transmission capacity, taking into account the mode of the adjacent network

In this research, we develop measures aimed at improving the efficiency of power systems by increasing their transmission capacity. To this end, a FACTS system based on the phase-shifting transformer with a thyristor switch developed at the Power Engineering Institute named after G.M. Krzhizhanovsky was used. The efficiency of the phaseshifting transformer under study for increasing the transmission capacity of power systems was determined by the maximum permissible cross-section flows of the Barnaul-Biysk node-2. The calculations were performed for normal and various post-accident schemes using the RastrWin3 software package. Such factors as the regulation of the taps of the phase-shifting transformer and various places of its installation were considered. For the section under consideration, the phase-shifting transformer increased the maximum permissible flow by 4–12%. The determining factor limiting the maximum permissible flow in the Barnaul-Biysk node-2 was found to be the current overload of the 110 kV lines of the adjacent network. The greatest effect of increasing the maximum permissible overflow was noted when the phase-shifting transformer was installed on the 220 kV line adjacent to the section, parallel to the 110 kV lines (which were overloaded when the mode became heavier), rather than on the 220 kV line included in the section. Similar calculations were performed for normal and post-accident schemes of an alternative option, which involved replacing wires and installing automatic equipment for limiting equipment overload on overloaded 110 kV lines. The obtained results show that the effect of increasing the transmission capacity for this option comprised 4%.

Increasing railway capacity with the installation of reactive power compensation

The article considers existing regulated installations of transverse capacitive compensation for increasing the capacity of sections of the traction network of 25 and 2×25 kV of Russian railways. Characteristics of a static reactive power generator based on bipolar IGBT transistors (manufactured by LLC NPP “RU-Engineering”, Naberezhnye Chelny), a switchable filtercompensating unit (manufactured by the Gorkovskaya Railway and the Nizhny Novgorod branch of SamGUPS), a three-stage switchable filter-compensating unit. To increase the capacity, all installations are switched on at the traction network sectioning posts. Long-term operation of the static reactive power generator and switchable filter-compensating unit have proven their operational efficiency. At the same time, the following upgrades are proposed: in a static reactive power generator it is proposed to reduce the installed power, replacing it with unregulated compensation, and in a switchable filter-compensating installation, it is proposed to switch in 400–500 V steps to normalize the traction mode of the electric rolling stock.It is shown that in terms of technical characteristics, a switchable filter-compensating installation with a thyristor switch is not inferior to a static generator of reactive power in terms of increasing the capacity, and in some respects it surpasses it. On the whole, in terms of payback period, a switchable filter-compensating installation surpasses a static generator of reactive power due to the high cost of the latter. The following options for using the considered installations are proposed. With the required power of transverse capacitive compensation units up to 5–6 MVAr, to increase the capacity, switchable filter-compensating units should be installed. Taking into account real loads, such a solution will be implemented at most sectioning posts. For installations with a capacity of more than 5–6 MVAr, the option of using a static reactive power generator of reduced power should be considered: at high loads, its efficiency will increase.

The switching principle of thyristor assistant arc extinguishing hybrid on-load tap-changer

Thyristor assistant arc extinguishing hybrid on-load tap-changer uses thyristor auxiliary mechanical switch which combines the advantages of mechanical switch and thyristor switch. The hybrid OLTC has high reliability, a relatively small amount of work needs to be maintained. It is a kind of very promising transformer OLTC. This project focus on the application of the hybrid OLTC in 110, 220kV transformer, introduces the auxiliary thyristor arc hybrid on-load tap-changer principle of passive trigger with odd block switch to even block as an example, describes the hybrid on-load tap-changer switching process, and the switching principle of simulation verification, on the basis of summarizing the characteristics of hybrid on-load tap-changer.

Study on switching principle of thyristor assisted arc extinguishing hybrid OLTC

Thyristor assisted arc extinguishing hybrid on load tap changer has the advantages of both mechanical switch and thyristor switch. It has strong ability to withstand overload, over-current and overvoltage, high reliability, small maintenance workload and frequent voltage regulation operation. It is a promising on load tap changer of transformer. This paper introduces the principle of passive trigger of thyristor module, gives the switching principle and process of thyristor assisted arc extinguishing hybrid on load tap changer, and analyses the characteristics of hybrid on load tap changer.

Analysis and Design of Three-Phase Buck Rectifier Employing UPS to Supply High Reliable DC Power

In the DC distribution system, to step down the DC voltage level from the AC grid voltage, the conventional topologies require multiple power conversion stages and bulky line-frequency transformers, which degrade their power density and cost-effectiveness. In addition, the conventional topologies suffer from a shoot-through problem resulting in their low system reliability. In this paper, to overcome the above issues, systematic design approaches of a three-phase buck rectifier with an uninterruptible power supply (UPS) and a protection algorithm are proposed to obtain the high reliability of the DC distribution system, which can deal with fault conditions and can regulate the output voltage level. It only requires a single stage of the three-phase buck rectifier. Also, a thyristor switch is added without any commutation circuits to cut off the output from the fault circuit. The shoot-through faults do not occur in the buck rectifier, leading to high reliability. A dual-active-bridge (DAB) DC-DC converter is applied as the UPS to supply the electric power from the battery when the buck rectifier is shut down under the fault conditions. Finally, the protection algorithm is proposed to detect the fault conditions and to regulate the output voltage level.

Моделирование пространственной динамики включения лазера-тиристора (λ=905 нм) на основе многопереходной гетероструктуры AlGaAs/InGaAs/GaAs

A 2D carrier transport model to be used in studying the spatial current dynamics in laser thyristors is presented. The model takes into account such features as optical feedback, impact ionization, and drift velocity saturation in strong electric fields. It is shown that there is current localization during laser-thyristor switch-on. A relationship is demonstrated between the distribution nonuniformity of the control current and its amplitude and position of the initial switch-on region. The time of laser-thyristor switch-on is 13 ns at a feed voltage of 26V, with a time of switch-on spreading over the entire 200-μm stripe width of ~65 ns. These parameters remain invariable irrespective of the switch-on spatial dynamics.