The consumers with building integrated photovoltaic (PV) systems have become prosumers, and their profit depends on network regulations, especially in the treatment of surplus electricity. Net-metering and feed-in tariff are the most common remuneration mechanisms for prosumers. Increasing the number of prosumers can cause various technical problems in the grid, therefore the distribution system operator sometimes imposes legal/regulatory and technical restrictions that are reflected in zero energy export. Integration of the energy storage systems can help with problems arising from these restrictions, but will make the initial investment significantly more expensive. This may negatively affect the profitability of investment. The main aim of this paper is analysis of different regulatory policies and their impact on building integrated PV system profitability. Two profitability metric factors were calculated for the purpose of better policy comparison. For the presented analysis, real data sets of a load demand and PV energy production were used. As an example, the integrated PV system installed at the Faculty of EE University of Sarajevo is analyzed.

Building integrated microgrids (BIMs) present a promising step towards a more efficient, decentralized and sustainable power system. Many buildings already have various renewable energy sources (RES) integrated, but the next step is adding energy storage (ES) systems, or proactive loads such as electric vehicles (EVs) to an already established system. However, ensuring the resilience of the system to accept these new elements presents a challenge in terms of stability, efficiency, and operational capability. This paper focuses on size optimized BIM simulated on Typhoon Hardware-in-the-Loop (HIL) platform using real measured load and PV production data. A rule-based energy management system (EMS) is proposed and its effective-ness is analyzed through testing resilience of the system under consideration. Performance analysis is conducted by adding an EV and assessing system response in several scenarios of load and EV use profiles. Through Typhoon HIL simulations the power profiles of system elements are analyzed, leading to conclusions on BIM performance.

Building integrated microgrids and building integrated photovoltaic systems (BIPV) are emerging as a promising avenue for seamlessly integrating small scale renewable energy sources (RES) into the grid. Challenges arise as new ideas are being explored and implemented in this area, and one of them is maximizing self-consumption and self-sufficiency, for any energy policy, but especially while adhering to zero energy export (ZEE) policy restrictions. As a solution to enhance the utilization of BIPV system this paper proposes a load management (LM) technique. By combining on-grid photovoltaic (PV) system with controllable loads, this paper demonstrates how proactive LM can increase self-consumption and self-sufficiency factors, as well as mitigate PV produced energy dumping due to ZEE restrictions. A case study in the wood sector's industrial building illustrates the efficiency of this approach, showcasing reduced reliance on grid power during sunny periods and increased self-sufficiency through strategic load scheduling. Real-world data analysis validates the effectiveness of LM in aligning PV generation with building energy demands, offering insights into its potential for broader adoption in the renewable energy sector.

Abstract Simulation of unsteady flow of SF6 gas in a simplified high-voltage circuit breaker model describing the nozzle, contacts and their nearest surrounding is presented. SF6 is considered as viscous, compressible, real gas described by Redlich-Kwong model. Heat transfer is taken into account due to the gas compressibility. The heat source, triggered by the electric arc between the contacts, was out of the scope of the current research, thus it was not included in the simulations presented. Turbulence, caused by the gas viscosity, is described using realizable k-ε model. In the simulation model, one of the contact sides – electrodes, is considered as moving at prescribed velocity. The part of the space ‘swept’ by the moving electrode is considered as the gas with imposed artificially increased viscosity in order to imitate the rigid body behaviour. Thus, no moving parts of the computational mesh are used in the model. The conservation equations of mass, momentum and energy, given in integral form, are solved using a finite-volume method on unstructured computational grids.

Abstract This paper describes the advantages of using data acquisition systems and software modelling tools to support the assessment and therefore redesign of the existing medium voltage switchgear. A 38kV/630A load break linear puffer (LP) will be used as an example for this study. In house testing was conducted to capture important design parameters of the switch such as displacement, velocity of mechanical parts and gas pressure using various sensors and three different measurement setups. The first setup, which is primarily intended for no-load measurements, consists of a DAQ system equipped with different types of sensors - two rotational encoders, three laser-based distance sensors, six pressure sensors, contact separation measurement, and a high-speed camera integrated and synchronized with the measurement system. The second and third setups, which are suitable both for no-load and on-load measurements, are based on state-of-the-art DAQ systems, which use three piezo-electric based pressure sensors, two fibre-optic based pressure sensors, three laser-based distance sensors and a high speed camera synchronized with the measurement system. The data acquired by the measurement systems is used in combination with an in-house developed simulation software HV CB Simulation, which enables simulating and predicting various variables of switching devices. Moreover, high speed camera videos analysed with both commercial and in-house developed image processing software, visualize and reveal many otherwise inaccessible occurrences. In addition to a comprehensive analysis of the proposed data acquisition and simulation setups, three design improvements in the linear puffer design - increase of the opening speed, removal of the flexible conductors and the length increase of the puffer cylinder - are presented and discussed in this paper.

Abstract The breaking capacity of a medium voltage (MV) rotary SF6 load break switch (LBS) can be improved by incorporating permanent magnets into the stationary contacts. The magnetic field is intended to blow the switching arc root towards a recessed space at the stationary contacts thereby preventing reignition of the arc after current zero. Making and breaking tests of load current 630 A were performed comparing the switching performance of load break switches equipped without a permanent magnet, with a ferrite and with a neodymium magnet. The impact of different polarity arrangements of the magnets in the three phases is also considered and analysed. In order to understand the arc behaviour caused by the effect of permanent magnet, arcing times and arc voltage were measured and evaluated. The results show that the arc voltage depends on the direction of the electromagnetic force, which is determined by the phase current direction but also by the polarity of the magnets. When the force is directed towards the recessed space at the stationary contacts, the arc voltage is notably higher than in the case where the arc is blown in the opposite direction. The higher arc voltage is a reliable indication that the length of the arc is increased, which significantly reduces the risk of both thermal and dielectric breakdowns after the first current zero. The consequences are noticed first in the reduction of the number of missed current zeroes and second in shorter minimum arcing times. An adverse arrangement of the magnet polarity in the three phases increases the number of missed current zeroes.

This paper describes the usage of voltage VAr control (VVC) in closed loop mode (CLVVC). The focus is the application in single feeder radial distribution systems, where the CLVVC is executed in combination with short term load forecast (STLF) and distribution system state estimation (DSSE). Although well-known benefits, this paper especially deals with pitfalls and drawbacks of implementing and using closed loop.

Abstract This paper presents the design and development of a distributed measurement system for measuring pressure in high voltage circuit breakers (HV CB) and other switching apparatuses, during no-load operations. Instead of using traditional pressure transducers which require significant installation space, additional data acquisition cards and often demand for complex wiring, an in-house solution of pressure measurement is proposed. The system consists of miniature sensors, accompanied with a suitable amplifier, microcontroller unit and communication module, which may be distributed inside the interrupter unit in convenient locations. Due to the fact that the measurement values are transmitted digitally, measurement noise is significantly reduced while the wiring of the system is additionally simplified. The proposed measurement system is tested using two different interrupters (HV CB and a load break switch). The experimental results have demonstrated that the developed system is applicable, accurate, cost-effective, flexible and simple to use.