Design of a Modified-Bridge Circuit with a Master-Slave Input Supply Mechanism for Ozone-Driven System Applications

This study proposes a design of a modified-bridge circuit with a master–slave input supply mechanism for ozone-driven system applications. Because the single-source supply design is becoming the mainstream choice in the existing ozone-driven systems, the input supply reliability of the ozone-driven system is crucial. Therefore, this proposed design involves a modified-bridge circuit combined with inductors and transistors, which can be augmented with the energy storage device as a backup source to improve the reliability of the input supply for the ozone-driven system. In addition, considering that the original source directly connected to DC BUS can re-charge the energy storage device, the energy recycling operation mode is designed in this proposed system to extend the duration of the energy storage device, which improves the supply reliability of the ozone-driven system further. To validate this proposed system, both model formulation and hardware realization are assessed through different test scenarios. Experimental outcomes of these tests confirm the practicality of the proposed design.

A method of testing relay protection and automation involving exposure to cascading effects for improved power supply reliability and electric power system stability

The Aim of the paper is to show that improved power supply reliability and electric power system stability are achieved by applying new methods of testing relay protection and automation (RPaA). Major cascading failures in electric power systems are caused by cascading effects, i.e., effects involving several successive effects of various nature. Cascading effects allow extending the functionality while testing RP&A and taking into account the time factor in the context of effects of various nature. Method. A method is proposed for testing relay protection and automation taking into account the cascading effect that is used in the process of development, calibration and installation of protection devices for operation in predefined modes for the purpose of improved power supply reliability and unfailing stability of electric power systems. Result. Intermittent cascading effects do not allow the relay protection and automation recover the electric power system from the post-emergency mode, thus reducing the dynamic stability to the critical level. The diagram of relay protection and automation exposure allows taking into consideration the environmental effects in the process of testing the relay protection and automation. Conclusion. The proposed method of cascading exposure as part of testing relay protection and automation can be used in the process of development, calibration and installation of electric power systems protection and will enable improved stability of electric power systems and reliability of power supply.

Allocation of 0.4 kV PTL Sectionalizing Units under Criteria of Sensitivity Limits and Power Supply Reliability

Sectionalizing 0.4 kV power transmission lines (PTL) improves power supply reliability and reduces electricity undersupply through the prevention of energy disconnection of consumers in the event of a short circuit in the power line behind the sectionalizing unit (SU). This research examines the impact of sectionalizing on power supply reliability and reviews the literature on sectionalizing unit allocation strategies in electrical networks. This paper describes the experience of the use of sectionalizing units with listing strengths and weaknesses of adopted technical solutions and describes the new structure of sectionalizing units. A new methodology is proposed, whereby there are two criteria for allocating SU in 0.4 kV power transmission lines. The first criterion is the sensitivity limits against single-phase short circuits used for calculating the maximum distance at which SU can be installed. The second criterion is power supply reliability improvement, evaluating the cost-effectiveness of installing sectionalizing equipment by reducing power supply outage time. The established methodology was put to the test on an actual electrical system (Mezenka village, Orel area, Russia), which demonstrated that the installation of a sectionalizing unit paid off.

Interval Reliability Evaluation of a Hybrid Energy Generation System With Energy Storage

To deal with the uncertainties of wind power and load residing in the power supply reliability model, an interval reliability evaluation method is proposed by combining the wind power generation and energy storage system (ESS). Firstly, the interval power supply reliability evaluation model, which belongs to an interval mixed integer program (IMIP), is established based on the interval variables. Secondly, the IMIP model is transformed into the deterministic optimization model under two extreme circumstances by utilizing the possibility degree theory of interval numbers. The maximum power supply probability, considering the wind power interval to meet the load demand interval, is sought by optimizing outputs of the ESS and generators, i.e., the upper boundary of the load shedding is the smallest. Finally, the states of wind turbines and generators are generated based on sequential Monte Carlo simulation, and the reliability of the hybrid energy generation system is evaluated by calculating the loss of load expectation, expected energy not supplied, and maximum power supply probability, which provides a basis for establishing interval optimal allocation model of energy storage. IEEE RTS-24 test system is utilized to verify the performance of the proposed method, and the model is solved by the CPLEX 12.7 solver. The simulation results demonstrate the effectiveness and applicability of the proposed method.

Water Supply Reliability of Agricultural Reservoirs under Varying Climate and Rice Farming Practices

Technological development and climate change dictate farming practices, which can directly affect irrigation water requirement and supply. In this article, the water supply reliability (WSR) of 62 major Korean agricultural reservoirs was comprehensively evaluated for varying climate and farming practices. Field surveys identified the recent divergence from standard rice farming practices and a 45-year daily weather data set (1973–2017) was examined to understand the phenomenon of climate change. Effective rainfall increments mitigated the imminent surges in rice irrigation water requirements driven by warming-led accelerated crop evapotranspiration rates; therefore, climate change marginally influenced the WSR of selected reservoirs. The transplanting period and associated water consumption were the primary deviations from standard rice farming practices. A significantly prolonged transplanting period seriously compromised the WSR of agricultural reservoirs and the maximum number of unsafe reservoirs was detected for a 24-day increase in the transplanting period. A watershed/irrigated area ratio of less than 2.5 was the lower threshold below which all the reservoirs had unsafe WSR regardless of the climate change and/or farming practices. Recent variations in farming practices were the primary cause of reservoir failure in maintaining the WSR.