ABB Ltd

About: ABB Ltd is a company organization based out in Zurich, Switzerland. It is known for research contribution in the topics: Voltage & Signal. The organization has 6222 authors who have published 6852 publications receiving 83994 citations.

A method for on-line optimization of a fed-batch fermentation unit to maximize the product yield

Abstract: A method for on-line optimization of fed-batch fermentation unit containing bacteria and nutrients is disclosed. Parameters of the fermenter model used in optimization calculations are estimated periodically to reduce the mismatch between the plant and the calculated values. The updated fermenter model is used to calculate the optimum sugar feed rate to maximize the product yield. The method/fermenter model is implemented as a software program in a PC that can be interfaced to plant control systems for on-line deployment in an actual plant environment. An on-line optimization system is useful to the plant operating personnel, to maximize the product yield from the fed-batch fermenter unit.

Investigations on a unified controller for a practical hybrid multilevel power converter

Abstract: This paper is devoted to the investigation of a practically feasible and commercially viable hybrid multilevel power converter topology typically suitable for active rectifier or static reactive power compensation applications at distribution voltage levels. This system comprises a three-phase neutral point clamped (NPC) main inverter supported by three auxiliary single-phase H-bridge inverters fed from independent DC links. The main and auxiliary DC link voltages are configured in the ratio 3:1. A multilevel waveform is realized by adding the low-voltage, fast-switching auxiliary inverter outputs to the high-voltage, slow-switching main inverter output. A novel hybrid modulation scheme that incorporates stepped synthesis in conjunction with variable pulse width of the consecutive steps is described. In addition, the performance of a unified controller that enables the regulation of all the DC bus voltages is discussed.

Method for controlling harmonics and resonances in an inverter

Abstract: In a method based on the MPDTC algorithm for controlling an inverter of an electrical system, the harmonics and resonances in the inverter are damped by extracting frequency information from predicted data of the MPDTC algorithm and by damping harmonic distortion of the electrical system by reintroducing the extracted frequency information into a control loop of the inverter.

Addressing voltage stability related reliability challenges of San Francisco Bay Area with a comprehensive reactive analysis

Abstract: The paper presents the results of a comprehensive voltage stability study to identify reactive compensation requirements in the San Francisco Bay Area for the purpose of maintaining desired load-serving capability. The study focused on both steady-state and mid-term time-domain dynamic simulations. While conducting mid-term stability simulations, a significant amount of load sensitivity analysis was performed in order to assess the need for a prudent mix of dynamic VArs (e.g. an SVC) versus static devices (e.g. mechanically switched capacitor banks).

Direct current arc furnace

Abstract: A DC arc furnace having an electrically conductive hearth adapted to contain a melt, and at least one arcing electrode above the hearth and adapted to form a heating arc with the melt when the hearth and electrode are supplied with DC power; the hearth having a wear lining directly contacted by the melt and formed by refractory material through which electrical conductors extend from the bottom of the wear lining to its top. A metal plate under the wear lining electrically connects with the conductors and is supported by one or more electrically non-conductive layers of refractory. Power connection to the wear lining is via the plate and a connection with the periphery of the plate.