Dariusz Zieliński

Synchronization of voltage frequency converters with the grid in the presence of notching

Purpose – In the dispersed generation system, power electronic converters allow for coupling between energy sources and the power grid. The requirements of Transmission System Operators are difficult to meet when the share of distributed energy sources of the total energy balance increases. These requirements allow to increase penetration of distributed generation sources without compromising power system stability and reliability. Therefore, in addition to control of active or reactive power, as well as voltage and frequency stabilization, the modern power electronic converters should support power grid in dynamic states or in the presence of nonlinear distortions. The paper aims to discuss these issues. Design/methodology/approach – The research methodology used in this paper is based on three steps: Mathematical modelling and simulation studies, Experiments on laboratory test stand, Analyzing obtained results, evaluating them and formulating the conclusions. Findings – The authors identified two algori...

The impact of converter's synchronization during FRT voltage recovery in two-phase short circuits

This article aims to examine the impact of synchronisation methods on transient phenomena occurring during a short-term voltage sag. The study was conducted for several synchronisation algorithms during interference from a short-term two-phase short-circuit. The research results show that in a state of transition of reduced and unbalanced voltage the best inverter results are obtained for fast-synchronisation algorithms which generate a synchronisation signal adequate to the voltage distortion. In contrast, the greatest threat turned out to be big oscillations of active power during work with advanced, time-consuming synchronisation algorithms. These oscillations adversely affect the mechanical components, particularly on the drive train system of a wind power plant if the plant uses the Fault Ride Through procedure.

Comparison of main control strategies for DC/DC stage of bidirectional vehicle charger

This paper presents comparison of two control algorithms for DC/DC converters in vehicle chargers. It presents operation in phase-shifting algorithm and resonant LLC algorithm, their implementation, and test results.

COLD STORAGE-SUPPORTED AIR CONDITIONING SYSTEM IN URBAN TRANSPORT VEHICLES

A bottleneck for the development of public transport vehicles is their electricity supply. Electric buses are almost exclusively equipped with electrochemical batteries, while nearly 40% of the energy is used in the processes of air conditioning. For this reason, we developed and built a demonstration system for storing thermal energy in public transport vehicles. The most important effects are: significant reduction of financial expenses and of the total weight of all batteries with the same amount of stored energy.