Medium Voltage Switching Optimization Using Time-Based Load Variation Study For Underground Electrical Network With High Current Flow

The Digitalization of the power supply system and the introduction of sources of distributed generation based on renewable energy create new conditions for improving the efficiency of transport and distribution of electric energy. In normal operation, the 35/10 (6) kV distribution electric networks of railways have an open-ended structure and are partitioned in such a way as to be able to connect a group of substations to another power source in emergency or repair modes. Existing technologies for managing modes in these electrical networks do not imply the possibility of changing their topology to ensure the tasks of reducing overload and electricity losses in the pace of processes of change in demand for electricity in normal modes. As a rule, at present, the task of reconfiguring the electrical network arises when normal conditions are restored after accidents, when lines are overloaded, and if necessary, electrical equipment needs to be repaired according to the n-1 criterion, while optimizing the modes. The most important task of increasing the transmission capacity of distribution grids can be solved by reconfiguring them at the pace of changing the demand for electricity in normal conditions, without resorting to expensive reconstruction and increasing the installed capacity of electrical installations and lines. An algorithm for reconfiguring the electrical network has been developed to increase its capacity based on solving problems of optimizing normal modes (static reconfiguration) and minimizing power consumption without calculating steady-state modes in the pace of electricity demand changes (dynamic reconfiguration).To ensure the admissibility of the modes of distribution electric networks, approaches to managing the supply of active (based on renewable sources) and reactive capacities and the demand of active consumers have been proposed. There are the results of the implementation of dynamic reconfiguration for the test circuitry without taking into account the power supply and demand management of active consumers, indicating the validity of the proposed approaches to improving the capacity of the electrical network

The article presents an algorithm of voltage coordinated management in distributive electric railway networks using the sources of the reactive capacity based on the agent approach. Voltage management in the electric network is implemented by the managing system coordinated between all local regulators inside the controlled zone. The authors present an approach to the coordination of the local regulators operation based on their possibilities ranking by the type of the action to achieve the global management purpose. By means of operational voltage management in the electric network it is proposed to use the linearization of the management task from behind the almost linear dependence of the comparative powers growth on the loads of separate units as a matrix of the sensitivity. The authors conducted the simulation and mathematical modeling of the implementation of the proposed algorithm in the distributive electric railways network and there.

RELEVANCE. An urgent task is to improve the reliability and quality of power supply. Very often, failures in operation are caused by damage to overhead and cable lines. Traditionally, a fairly large number of violations occur in the share of electrical distribution networks. For the reliable functioning of power systems and uninterrupted power supply to consumers, it is necessary to identify and eliminate faults in a short time to minimize damage. Thus, a method for efficient, accurate and reliable fault location is needed for both utility companies and consumers. To solve this problem, it is necessary to quickly obtain information about the state of the distribution eclectic network. THE PURPOSE. Reducing the time to search for a fault location in electrical networks, reducing damage from downtime for undersupply of electricity by analyzing existing methods for determining the location of faults on a power transmission line and developing a method for its prompt detection in electrical networks. METHODS. The basis of this method is a preliminary theoretical calculation of short-circuit currents in various sections of a power line. Based on the values obtained as a result of the calculation, the measured values of the short-circuit currents are compared with these values, on the basis of which the location of the line damage is determined. An algorithm for searching the left and right boundaries of the short-circuit current value in an ordered array of statistical data has been developed. RESULTS. A method for quickly determining the location of a short circuit is proposed, which is based on the use of a data array of theoretically calculated short circuit currents. The presented algorithm is able to accurately determine the coordinates of the short circuit in electrical networks. CONCLUSION. The proposed method for determining the location of damage to the power line allows you to increase the efficiency of determining the point of a short circuit and thereby reduce the time to eliminate the accident, and therefore, economic losses from undersupply of electricity.The basis of this method is a preliminary theoretical calculation of short-circuit currents in various sections of a power line. Due to the subsequent comparison of the measured values of short-circuit currents with the values of the calculated values, the location of the damage to the power line is determined. The presented algorithm is designed to accurately determine thecoordinates of the short circuit location, which can significantly reduce the search time and improve the accuracy of determining the fault location in the range from 100 to 150 m, regardless of the length of the power line, which significantly reduces the time to search for damage at the same time as solving the problem of reducing downtime , as well as minimizing damage both for guaranteeing suppliers represented by electric grid companies, and for consumers represented by industrial and agricultural enterprises.

The utilisation of gas-fired generators (GFGs) has expanded in recent decades, increasing the link between electricity and natural gas network (NGN). As a result, regardless of interconnectedness, planning any particular system rises the total cost of the entire system. An effective expansion planning optimization model for an integrated NGN and electrical distribution networks is presented in this paper. To be more specific, the suggested model's objectives are to determine which and where candidate pipes, compressors, and electrical lines should be constructed in order to obtain the lowest feasible investment cost while fulfilling future energy demands. Furthermore, the proposed model uses a scenario Tree to account for the stochastic and intermittent characteristics of wind and solar power supply including load demand. GAMS and the CPLEX solver are used to deduce a new model stated by a mixed-integer nonlinear stochastic profile. On a modified 16bus UK generic electricity distribution system (UKGDS) and a modified Belgian 20-node NG distribution scheme, the success of the suggested model is validated. Numerical results shows a 10% reduction cost when both integrated networks are plan simultaneously as compared to the traditional method in which natural gas and electricity networks are plan separately.

Underground power cables are usually used to transfer electric power from distribution stations to the consumer, especially in densely populated areas in which the overhead lines cannot be used. During the process of energy transfer occurring some phenomena such as high temperature of the cable as a result of the losses, as well as the formation of electromagnetic fields around the cable. The aim of this research is to investigate the levels of electromagnetic fields generated by 11kv underground power cable. Research has been conducted in two ways, mathematical calculations and practical measurements. Results show that the mathematical calculations and practical measurements are approximately identical. The safe and unsafe zones from the underground power cable have been determined by comparison of these results with reference values established by the World Health Organization. These results may consider as an important data for the categorization of underground distribution power cables as well as individual sources of EMF to reduce exposure to such fields in order to avoid its negative health effects on human health.

In a low-voltage power distribution system, there are often disturbances that result in disruption of electricity distribution to customers, resulting in losses for customers and PLN. The problem that often occurs is the occurrence of voltage drops and power losses so that in planning the construction of a low-voltage electric power distribution network, it is necessary to anticipate the occurrence of these problems. This research is expected to be used as a lesson for the creation of a low-voltage electric power distribution network with suitable and environmentally friendly construction and with low investment costs. collected data by visiting the location to conduct a survey and obtain accurate data related to the state of the research location. The stages in planning the Low Voltage Electricity Distribution Network begin with a field survey to obtain the required data. The installed power for each unit is 1.300 VA, so the total installed power is 122,200 VA and the spare power is 5% of the installed power so that the total installed power is 128.310 VA. during peak load times it is estimated that power consumption will only absorb 80% or 97,760VA. The required substation is a Portal Type Pole with a transformator capacity is 160kVA. The total breakdown of the electricity distribution network budget at the Griya Arjuna Kejuden is IDR 382,333,141.

Underground electrical conductors, both medium-and high-voltage, play a crucial role in energy infrastructure. However, they present a maintenance challenge due to their difficult access. Unlike overhead installations, these cables remain hidden, making it harder to obtain key parameters, such as their temperature or structural condition, in a simple manner. Current temperature measurement methods, including fiber-optic-based systems (DTS and LTS), involve high costs that limit their feasibility in medium-voltage networks, where more economically accessible alternatives are required. This study introduces an alternative system for monitoring the temperature of underground cables using NTC thermistors. Its design allows for reducing the number of connection conductors for sensors to just four regardless of the number of measurement points. The implemented measurement technique is based on the sequential activation of sensors and the integration of the recorded current to achieve an accurate thermal assessment. The tests conducted validate that this proposal represents an efficient, cost-effective, and highly scalable solution for implementation in electrical distribution networks.

The reliable operation of electricity transport and distribution networks plays a crucial role in modern societies. However, too often, when a fault occurs in electricity networks, such as a transmission line drop, loss of generation, or any other important failure, voltages start to decay, potentially leading to complete blackouts with dramatic consequences. Thus, techniques are required that improve the power grid operation in case of emergencies. In this chapter, to achieve this aim, an approach is presented that uses an adaptive predictive control scheme. Electric power transmission networks are hereby considered as large-scale interconnected dynamical systems. First, voltage instability issues are illustrated on a 9-bus benchmark system. Then, the details of the proposed approach are discussed: the power network modeling and the construction of a hybrid prediction model (i.e., including both continuous and discrete dynamics), and the formulation and the resolution of the adaptive predictive control problem. In simulation studies on the 9-bus benchmark system the performance of the proposed approach is illustrated in various emergency voltage control cases.

Analysis has been performed of the operation of electric distribution networks of ten branches of Oblkommunenergo (OKE) of Irkutsk Region [1]. Based on the data on the operation of these networks published in public media, algorithms and computer programs for the Matlab graphic editor are compiled, which are used for plotting time diagrams that characterize the operation of the electrical networks under consideration. The balance changes are shown in the transmission of electric energy into the OKE networks and from the OKE networks directly to consumers (high, medium and low voltage networks). The number of failures, the power supply interruption time and the amount of electricity undersupplied in each month of the year for each of the branches are considered. The months of the year are determined, in which the greatest and least damage occurs to the electrical networks of the OKE branches. Data are presented on the dynamics of annual wear of electric networks, planned activities and their annual implementation. The level of reliability is considered according to the established indicators of the average duration of interruptions in the transmission of electric energy in each calculated regulation period. It is shown that the combination of the main causes of failures largely depends on the natural-climatic and terrain specifics of the regions through which the routes of electric networks pass. As an example, data on the causes of failure in the electrical networks of one of the OKE branches are considered. The most and least damaged electrical networks of the considered OKE branches have been established. In conclusion, findings are formulated and recommendations are presented on minimizing outages based on the main types of failure causes for the purpose of increasing the operational reliability of the electrical networks under consideration.

A new procedure for determination of insulators contamination in electrical distribution networks

Towards full electrification of local public transport: A tool to guide strategies for implementing the electric charging network

The added generating units in the electrical distribution network would affect the currents and voltages during fault conditions. Subsequently, these fault currents and voltages will influence the operation of relay protection units, circuit breakers, and safety measures at the inter-connection point with the utility. It is necessary to calculate those currents and voltages to select new protective devices or to re-tune the settings of the existing units. The chapter addresses fault conditions in electrical distribution networks that includes two types of distributed generators: induction generators—this subchapter addresses the short-circuit phenomenon and offers a modified way, as compared with the IEEE Standard, to assess the circuit breaker ratings; and single-phase synchronous generators—this subchapter summarizes the symmetrical component mathematical tool and offers a way of applying it when a three-phase system employs single-phase distributed generators.

This paper develops a computationally efficient algorithm which speeds up the probabilistic power flow (PPF) problem by exploiting the inherently low-rank nature of the voltage profile in electrical power distribution networks. The algorithm is accordingly termed the Accelerated-PPF (APPF), since it can accelerate “any” sampling-based PPF solver. As the APPF runs, it concurrently generates a low-dimensional subspace of orthonormalized solution vectors. This subspace is used to construct and update a reduced order model (ROM) of the full nonlinear system, resulting in a highly efficient simulation for future voltage profiles. When constructing and updating the subspace, the power flow problem must still be solved on the full nonlinear system. In order to accelerate the computation of these solutions, a Neumann expansion of a modified power flow Jacobian is implemented. Applicable when load bus injections are small, this Neumann expansion allows for a considerable speed up of Jacobian system solves during the standard Newton iterations. APPF test results, from experiments run on the full IEEE 8500-node test feeder, are finally presented.

Due to the advancements in the smart grid technologies, smart mechanisms are required within the Energy Management System (EMS) environments for microgrids. One of the functionalities of EMS is to ensure grid stability. In order to test and validate new mechanisms, appropriate simulation tools exist. Most of the existing validation strategies include modeling the target system in simulation environment and then deploying the mechanism in the real environment. When the validated mechanisms are implemented in real environment, they often do not work as intended and require modification due to the implementation difference within the EMS controller. An EMS should be able to communicate with the simulated model, inject faults in the simulated model and able to perform various control actions. In this paper, we propose a software-in-loop approach, where the grid stability mechanisms are implemented in the EMS, which is deployed in the real environment. EMS must operate exactly the way it does in the simulation environment. For such a capability, the simulation platform should be able to communicate with the EMS. In this work, we consider a 13-node radial distribution grid with one solar panel as a generation unit. The 13-node distribution grid has been modeled using Apros simulation software. SMG2.0, a software application for microgrid is used to monitor, inject electrical faults and trigger recovery mechanisms in the Apros model. A communication architecture called ICT gateway has been developed between Apros and the EMS (SMG2.0). Two fault scenarios (line-breakage and under-voltage) are considered as the fault injection scenarios to evaluate the performance of the communication architecture. When the SMG2.0 detects a line fault, it triggers network reconfiguration as the recovery strategy for the line-breakage scenario in the simulation environment. This approach not only helps in designing fault handling strategies in the electrical network but also helps in designing an effective software application targeted to control the physical entities.

Harmonics are one of the key power quality issues on the front burner in the power system. Advancements in solid-state technology in recent times have resulted in the proliferation of non-linear loads which are the main sources of harmonics. Harmonics penetration in power system networks is detrimental to effective system operation and can result in frequent failures and damage to electrical equipment. This, therefore, creates the need for harmonic mitigation in power system networks for power quality enhancement. This work examined the impact of a shunt passive filter (SPF) in minimizing harmonic distortion on an electrical distribution network considering the power network layout of 7-Up Industry Plc as a case study. The indices for quantifying the level of harmonic distortion and shunt passive filter design for harmonic mitigation in power networks were respectively analysed and presented. The considered 7-Up Industry Plc power network was modelled and simulated with and without SPF in MATLAB/Simulink software environment R2020a. The voltage and current total harmonic distortion, VTHD and ITHD, from the two system states, were evaluated. The observed voltage and current waveforms from the simulation of the test network without any filter applied were distorted, signifying the harmonics’ presence. The estimated VTHD and ITHD values with no filter used were 6.084 and 19.79 % respectively. SPF application on the test network mitigated the VTHD and ITHD to 0.7802 and 2.448 %, giving an improvement of 5.304 and 17.342 % respectively in the minimization of voltage and current total harmonic distortion compared to the no filter case. This study established that a shunt passive filter is suitable for power quality enhancement in an electrical distribution network. Keywords: Electrical distribution network, harmonics, non-linear load, power quality, shunt passive filter, total harmonic distortion