Evaluation of 20 kV Distribution Network Losses In Radial Distribution Systems Due to Distributed Generation Penetration

The installation of distributed generation with renewable energy becomes a solution when the demand for electricity is increasing and electricity generation with fossil energy is increasingly limited. There has been a change in power flow before and after the installation of distributed generation. However there can be a negative impact on the distribution network losses applicable to reactive power flows. There are cases where the distributed generation capacity is greater than the supplied load, resulting in distributed generation operating as a system voltage regulator and requiring reactive power, so that DG will absorb the reactive power from the system. The increasing demand for reactive power in DG also causes an increase in the current flowing in the network, and causes an increase in losses in the network, especially for the losses in reactive power.

Changes in Caregiver Personal Support Networks: Gender Differences and Effects on Health (CUIDAR-SE Study)

Technological changes have led to important advances in medical diagnoses and treatments that prolong the informal care process. Support from the personal network of informal caregivers is an undervalued resource and the changes that have occurred over time are unknown. The aim of this study was to analyze the changes in personal network support among informal caregivers and to examine the effect of these changes on self-perceived caregiver health, with a focus on differences between men and women and caregivers with high and low levels of burden We also investigated caregiver perceptions and explanations of changes to their support network (losses and additions and no change). Using a mixed-methods approach, data were obtained from 32 caregivers that were intentionally selected in Spain, who were interviewed twice with a one-year interval. In the quantitative phase, personal networks analysis was performed with Egonet software, which obtained data on the composition and functional content in social support from 1600 personal relationships (25 alters for each ego in the two waves). In the qualitative phase, semi-structured interviews were conducted in the two waves with a guide in order to explore the changes in informal support resources over time. The selected men with high levels of burden pointed out a loss of network support with more discouraging reports compared with the low-burden male caregivers. Furthermore, the selected women with low burden levels mentioned losses too; however, their reports were more positive. Women reported improved health, especially those with low burden scores in the first wave and those who did not lose support. Caregivers with a high initial burden and who lost support reported worse health, particularly men and women with a strong sense of duty toward care. Social support from personal networks is important for caregiver health and its effects are influenced by gender roles. Our findings could help by improving the relational and social capital of informal caregivers and adapting them to the new needs of formal home care systems.

Multi-Time-Scale Optimal Scheduling in Active Distribution Network with Voltage Stability Constraints

The uncertainty associated with loads and renewable-energy sources affects active distribution networks in terms of the operation and voltage stability on different time scales. To address this problem, a multi-time-scale voltage stability constrained optimal scheduling framework is proposed, which includes a day-ahead model with a coarse-grained time resolution and an intra-day model with a fine-grained time resolution. The day-ahead economic-scheduling model maps out a scheme to operate different types of devices with the aim of minimizing the network losses. Following the scheme, the intra-day corrective-adjustment model based on model predictive control is proposed to regulate the flexible devices, such as the energy storage systems and the photovoltaic converters. In particular, the proposed optimal scheduling framework embeds a voltage stability constraint which is constructed by using a novel index, defined based on the Distflow model Jacobian. As the index at each bus is a linear function of the locally measurable power flow variables, the proposed constraint does not introduce additional computational burdens. Simulation results demonstrate the necessity and effectiveness of the proposed multi-time-scale voltage stability constrained optimal scheduling model. The results also show that the variation trend of the proposed index is consistent with that of the commonly used voltage stability index.

Scheduling for Prosumer Microgrid with Considering Price Based Demand Response

Unit commitment (UC) is the scheduling of power unit operating outages to meet electricity needs at a certain time with the aim of obtaining a total economical generating cost. Differences in the characteristics of each generating unit and limitations result in different scheduling combinations based on equations, and for this research, the renewable energy penetration will also be considered. Firefly Algorithm (FA) is a method to determine load requests and complete renewable energy scheduling power by using unit commitment. FA is a simple but reliable algorithm that solves optimization problems. Firefly Algorithm (FA) method obtained maximum generating power of 81,329 MW with the total cost of 827,556 $ and network losses of 3.6696 Coefficient of operating costs.

Recovery strategy of multilayer network against cascading failure

Cascading failure phenomena widely exist in real-life circumstances, such as the blackouts in power networks and the collapse in computer networks. In this paper, we construct a cascading failure model on the multilayer network, taking into account the number of invalid neighbors of nodes, the failure frequency of nodes, the effect between layers, and the percolation process. To minimize network losses caused by the cascading process, we propose a recovery strategy, i.e. repairing some certain clusters formed by ineffective nodes and links. The recovery strategy is discussed in detail, like whether to add links to the network, how many links are needed at least to add, how many layers are demanded to restore, and how to choose the values of [Formula: see text] and restorable threshold [Formula: see text] to improve the network performance. Besides, we theoretically analyze the cascading failure model with recovery strategy by virtue of mean-field approximation and generating function techniques. The theoretical solutions are found to be consistent with experimental results simulated on the ER as well as BA networks. In addition, we also investigate the affecting factors of network robustness. The effects of failure threshold [Formula: see text], base number [Formula: see text], and threshold [Formula: see text] between layers on network behaviors depend on the values of average degree [Formula: see text] and recovery proportion [Formula: see text]. These results may provide particular reference significance for maintaining system security, adjusting the network performance, and enhancing network robustness.

RESEARCH OF ENERGY LOSS IN A SOLAR POWER PLANT AT A TRACTION SUBSTATION

An analysis of losses in a solar power plant of direct current № 18 с. Zmiiv, Kharkivregion with all climatic conditions of this region. The energy efficiency indicators of inverters used in these solar power plants are analyzed. According to experimental data based on the softwarepackage PVsyst measured energy losses generated by a solar power plant. Connecting the SES to themains can improve the voltage levels at the system nodes, but it is necessary to provide a powerreserve in the system to cover the power deficit in the event of a sudden shutdown due to naturalfactors.To analyze the energy losses of solar energy, the software package PVsyst was used, whichallows you to analyze the parameters of electricity losses with the display of loss diagrams for theyear and the dependence of the amount of losses in electricity generation by solar panels. PVsystsoftware is used to calculate the output power, performance, and total loss of a station connected tothe network. Losses calculated by PVsyst software include two types: PV array loss and System loss.After analyzing research conducted in Ukraine and other European countries, it is possible toconclude that the impact of poor quality electricity on electrical equipment is quite significant, andthe study of the impact of unconventional generation sources on electricity quality indicators willidentify ways to reduce electricity losses and increase electricity life equipment. The efficiency ofsolar energy conversion is greatly reduced due to reflections from the surface of the photovoltaicsystem. Also due to the peculiarities of the construction of photovoltaic converters there is a decreasein the efficiency of solar panels with increasing temperature.

Adaptive Dragonfly Optimization Based Placement of Capacitor Banks for Voltage Stability Enhancement in Distribution Networks

The present day ever escalating power demand moves the operating point of the distribution networks in the vicinity of the voltage stability boundaries. Any small reactive power unbalance between the generation and demand may trigger voltage instability, which makes the voltage magnitude to fall slowly until a rapid change occurs. This paper presents an adaptive dragonfly optimization based method for placement of shunt capacitor banks with a view of improving the voltage stability besides enhancing the voltage profile and lowering the network losses. Simulation results on 33 and 69-node distribution networks exhibit the greater performances of the suggested algorithm.

A Coordinated Charging Scheduling of Electric Vehicles Considering Optimal Charging Time for Network Power Loss Minimization

Electric vehicles’ (EVs) technology is currently emerging as an alternative of traditional Internal Combustion Engine (ICE) vehicles. EVs have been treated as an efficient way for decreasing the production of harmful greenhouse gasses and saving the depleting natural oil reserve. The modern power system tends to be more sustainable with the support of electric vehicles (EVs). However, there have been serious concerns about the network’s safe and reliable operation due to the increasing penetration of EVs into the electric grid. Random or uncoordinated charging activities cause performance degradations and overloading of the network asset. This paper proposes an Optimal Charging Starting Time (OCST)-based coordinated charging algorithm for unplanned EVs’ arrival in a low voltage residential distribution network to minimize the network power losses. A time-of-use (ToU) tariff scheme is used to make the charging course more cost effective. The concept of OCST takes the departure time of EVs into account and schedules the overnight charging event in such a way that minimum network losses are obtained, and EV customers take more advantages of cost-effective tariff zones of ToU scheme. An optimal solution is obtained by employing Binary Evolutionary Programming (BEP). The proposed algorithm is tested on IEEE-31 bus distribution system connected to numerous low voltage residential feeders populated with different EVs’ penetration levels. The results obtained from the coordinated EV charging without OCST are compared with those employing the concept of OCST. The results verify that incorporation of OCST can significantly reduce network power losses, improve system voltage profile and can give more benefits to the EV customers by accommodating them into low-tariff zones.

Enhancement of a District Heating Substation as Part of a Low-Investment Optimization Strategy for District Heating Systems

In an ongoing project, low-investment measures for the optimization of district heating systems are analyzed. The optimization strategies are collected in a catalog, which is the core of a guideline. The application of this guideline is demonstrated using two concrete district heating networks as examples. In this study, the improvement of an analog controlled district heating substation by an electronic controller is investigated. High supply temperatures and heat losses are often a challenge in district heating networks. The district heating substations have a major influence on the network return temperatures. The comparison of the two substation setups with analog and electronic controllers is carried out by laboratory measurement. It can be shown that the return temperatures can be reduced by an average of 20 K in winter and transition, as well as 16 K in summer. The district heating network losses are calculated for one of both specific district heating networks. They are calculated from the ratio of network losses to generated energy. The generated energy is the sum of network losses and consumer demand. The thermal losses of the network can be reduced by 3%. The volume flow in the heating network can be reduced to a quarter. Therefore, the pumping energy requirement drops sharply since these changes cubically affect the volume flow.

BIBC Matrix Modification for Network Topology Changes: Reconfiguration Problem Implementation

The topology of a distribution network can be represented by a bus injection to branch current (BIBC) matrix. It has been introduced and used for load flow analysis of distribution networks. In this paper, a method for BIBC matrix modification is developed to use in applications which require a topology change representation. Proposed method that reflects the changes in configuration in the system BIBC matrix is implemented in distribution network reconfiguration problem. With providing potential solutions for network operational and planning requirements such as necessitate changes in configurations to transfer the loads to a different substation, ease the loading of equipment, conduct planned maintenance and reduce network losses during the normal operation with renewables, storage and other uprising technologies, reconfiguration may also be useful for emergencies, accidents, attacks and weather-related disasters. The BIBC modification process provides the knowledge of possible switches to open and the direction of power flow without any need to further radiality or continuity check. The proposed method needs only initial network topology information that makes it suitable to apply on any distribution network and to use with any search method or heuristic/meta-heuristic optimization algorithm. Efficiency of the method is investigated on systems with voltage dependent and time varying loads.