Abstract. This paper deals with a medium-voltage distribution network. The feeders in the open-loop arrangement are changed to the closed-loop arrangement with the aim to improve reliability of the power supply. The paper focuses on the analysis of transient and steady-state operation in the closed-loop that is established by connecting feeders supplied from two different transformers located in the same transformer substation. The transformers are equipped with the tap changers that can change the amplitude of the 20 kV voltages in steps whilst the phase cannot be changed. The possibilities to control the active and reactive power at both ends of the medium-voltage loop are discussed for the case when only the voltage amplitude can be changed and for the case when the voltage amplitude and phase angle can be changed. A simple algorithm for closed-loop active and reactive control is applied. The results of simulations and field testing performed in a 20 kV network are presented.

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A resistance-grounded distribution system has a critical element that is often forgotten -the neutral-grounding resistor (NGR). Because NGR's are subject to failures [1] related to thermal overload, lightning, storms, extended service life, manufacturing faults, vibration, corrosion, and improper specification or installation, the proper monitoring of NGR health is important as all other protections to preserve distribution system in safe state.

Abstract. This paper deals with the power losses and power quality in the medium-voltage distribution network considering feeders in the open-and closed-loop arrangements. The feeders in the open-loop arrangement are changed to the closed-loop arrangement with the aim to improve reliability of the power supply. Apart from that the power quality could be increased, while power losses could be decreased. In the case study the feeders supply loads, while in some cases loads are replaced with the renewable source of energy.

Warpage is one of the most challenging defects occurring in plastic injection moulded parts. Various approaches to overcome this issue have been proposed in the literature, but they all provide only partial solutions to the problem. This paper proposes a new method for the compensation and minimisation of warpage. The method is based on Mould Cavity (MC) correction. In contrast to other similar methods, here the MC correction is accomplished through a direct comparison of the local deviations of the warped part's geometry to the desired geometry of the part. Modifying the MC shape accordingly yields parts with a lower shape discrepancy from the desired geometry compared to the nonadjusted shape. The key novelty of the paper is the development of software that iteratively adjusts the MC shape to minimise local deviations. In every iteration, the warped part is compared to the desired geometry and the MC geometry is adjusted accordingly. A curved thin-walled plate part case study demonstrates the method's capabilities. We show that the maximum warpage value of 0.005 mm (0.7% of the initial maximum warpage) was reached after three iterations of MC geometry correction and remained stable afterwards.