scholarly journals Allocation of steady-state areas of total electrical load schedules of 10/0.4 kv transformer substations located in residential areas

2021 ◽  
pp. 11-19
Author(s):  
Oksana Dovgalyuk ◽  
Iryna Shcherbak ◽  
Yuliia Kovalova ◽  
Volodymyr Korobka
Keyword(s):  
Autocorrelation Function ◽  
Reactive Power ◽  
Distribution Networks ◽  
Voltage Regulation ◽  
Electrical Network ◽  
Electrical Load ◽  
Residential Areas ◽  
Total Load ◽  
Load Variation ◽  
Wide Range

Improving the efficiency of regulating the parameters of distribution network modes is an actual task for the energy sector, requiring a detailed analysis of the nature of the total electrical load graphs of 10/0.4 kV transformer substations. The complexity of the problem in consideration is due to the fact that the load variation of transformer substations 10/0.4 kV in residential areas occurs randomly, due to the significant number, wide range and probabilistic nature of the operating modes of connected consumers, and the lack of deterministic links between consumers of electricity. The investigated function of total load of transformer substations 10/0.4 kV on a daily interval is non-stationary, in this connection there was a necessity of allocation of stationarity areas for adjusting the process of regulation of parameters of electrical network modes. In order to solve this problem, total load graphs for 10/0.4 kV transformer substations located in a residential area were constructed based on experimental measurements of active and reactive loads. The use of these dependencies made it possible to analyse the distribution law for the active and reactive power of the total load of 10/0.4 kV transformer substations, which change in time is stochastic characterised. The use of probabilistic-statistical modelling was justified to reliably describe the load variation process of 10/0.4 kV transformer substations. The hypothesis of a normal law distribution of the functions under consideration was confirmed and parametric tests were performed. Fisher's F-criterion was used to confirm the hypothesis of variance constancy, and Student's t-criterion was used to confirm the hypothesis of mathematical expectation constancy. Using the fact of constancy of dispersions and expectations of investigated mode parameters, autocorrelation coefficients of investigated random functions were determined and autocorrelation function graphs were plotted. In order to approximate the functions under investigation, the autocorrelation function coefficients were determined using the least-squares method, and an analysis of the attenuation of the autocorrelation function was carried out. The calculations carried out have highlighted the areas of stationarity on the total load curves of the 10/0.4 kV transformer substations. These stationarity plots can be used for further modelling of load graphs and the formation of control actions to adjust the load of consumer regulators in order to equalise the overall electrical load graph, as well as for voltage regulation facilities, which will contribute to the required modes of operation of the electricity distribution networks.

scholarly journals ANALYSIS OF ELECTRICAL LOAD SCHEDULES OF 10/0.4 KV TRANSFORMER SUBSTATIONS OF RESIDENTIAL AREAS FOR THE IDENTIFICATION OF STATIONARITY PLOTS

2021 ◽  
pp. 96-101
Author(s):  
Iryna Shcherbak ◽  
Yuliia Kovalova ◽  
Volodymyr Korobka
Keyword(s):  
Autocorrelation Function ◽  
Mathematical Expectation ◽  
Reactive Power ◽  
Least Squares Method ◽  
Electrical Load ◽  
Residential Areas ◽  
Distribution Law ◽  
Random Load ◽  
Constant Variance ◽  
Student’S T

It is proposed on the electrical load graphs of transformer substations 10/0.4 kV in residential areas to allocate the stationarity areas for further modelling of load schedules and the implementation of controlling influences on the modes of consumers-regulators in order to align the overall graph of the electrical load. The relevance and complexity of the problem under consideration is caused by the fact that the load variation of transformer substations 10/0.4 kV in residential areas occurs randomly. This is due to the significant number, nomenclature and diversity of types of connected consumers, as well as the lack of deterministic connections between consumers of electricity, in addition, the random load function in the daily interval is non-stationary. In this regard, there was a need to develop the stages of selecting the areas of stationarity on the electrical load graphs of transformer substations 10/0.4 kV of residential areas. A measurement of the load graphs of 10/0,4 kV transformer substations is carried out, according to the results of which the distribution law of active and reactive power measurements is investigated. After confirming the hypothesis of normal distribution law, parametric tests are performed. Fisher's F-criterion is used to confirm the hypothesis of a constant variance, and Student's t-criterion is used to confirm the hypothesis of a constant mathematical expectation. The next stage, based on constancy of the variance and mathematical expectation, is the determination of autocorrelation coefficients of the studied random function and plotting of the autocorrelation function. To approximate the function the autocorrelation coefficients are determined by the least squares method and the autocorrelation function attenuation analysis is performed. The implementation of the defined stages allows to identify the areas of stationarity on the load graphs of transformer substations 10/0.4 kV. For a reliable description of the process of changing the load of transformer substations 10/0.4 kV the use of probabilistic-statistical method of modelling is justified that takes into account the stochastic nature of the load changes on the selected areas of stationarity.

scholarly journals Using Energy Storage Inverters of Prosumer Installations for Voltage Control in Low-Voltage Distribution Networks

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1121
Author(s):  
Rozmysław Mieński ◽  
Przemysław Urbanek ◽  
Irena Wasiak
Keyword(s):  
Energy Storage ◽  
Control Strategy ◽  
Reactive Power ◽  
Low Voltage ◽  
Storage System ◽  
Distribution Networks ◽  
Energy Storage System ◽  
Voltage Regulation ◽  
Active Power ◽  
Total Power

The paper includes the analysis of the operation of low-voltage prosumer installation consisting of receivers and electricity sources and equipped with a 3-phase energy storage system. The aim of the storage application is the management of active power within the installation to decrease the total power exchanged with the supplying network and thus reduce energy costs borne by the prosumer. A solution for the effective implementation of the storage system is presented. Apart from the active power management performed according to the prosumer’s needs, the storage inverter provides the ancillary service of voltage regulation in the network according to the requirements of the network operator. A control strategy involving algorithms for voltage regulation without prejudice to the prosumer’s interest is described in the paper. Reactive power is used first as a control signal and if the required voltage effect cannot be reached, then the active power in the controlled phase is additionally changed and the Energy Storage System (ESS) loading is redistributed in phases in such a way that the total active power set by the prosumer program remains unchanged. The efficiency of the control strategy was tested by means of a simulation model in the PSCAD/EMTDC program. The results of the simulations are presented.

scholarly journals Hardware solutions for energy-efficient control technologies of distribution network objects based on power semiconductor devices

2021 ◽  
Vol 24 (1) ◽  
pp. 91-96
Author(s):  
V. N. Krysanov ◽  
◽  
V. L. Burkovskii ◽  
I. A. Khaychenko ◽  
◽  
...  
Keyword(s):  
Reactive Power ◽  
Short Circuit ◽  
Distribution Networks ◽  
Voltage Transformer ◽  
Industrial Facilities ◽  
Power Semiconductor ◽  
Wide Range ◽  
Electric Power Sector ◽  
Power Part ◽  
Control Technologies

The article considers topical issues in development of energysaving technologies to optimize the control of distribution networks according to the criterion of minimum power losses. The technology consists in introducing new hardware to control the modes based on static devices. Based on the analysis of the existing hardware created to control the modes of distributio networks, the developed circuitry solutions of the power part and the control system of the multifunctional thyristor voltage transformer and hybrid thyristor capacitor are proposed. Their main technical characteristics and ways to reduce voltage asymmetry, limiting short circuit currents and regulating reactive power are det ermined. The use of software and hardware solutions was recommended for a wide range of energy conservation tasks, both in the electric power sector and at the level of industrial facilities

scholarly journals Power factor control of PV generators in local distribution networks using fuzzy logic concept

2018 ◽  
Vol 7 (2.28) ◽  
pp. 362
Author(s):  
Raed A. Shalwala
Keyword(s):  
Fuzzy Logic ◽  
Control System ◽  
Power Factor ◽  
Fuzzy Logic Control ◽  
Reactive Power ◽  
Distribution Network ◽  
Voltage Control ◽  
Distribution Networks ◽  
Voltage Regulation ◽  
Logic Control

One of the most important operational requirements for any electrical power network for both distribution and transmission level is voltage control. Many studies have been carried out to improve or develop new voltage control techniques to facilitate safe connection of distributed generation. In Saudi Arabia, due to environmental, economic and development perspectives, a wide integration of photovoltaic (PV) genera-tion in distribution network is expected in the near future. This development in the network may cause voltage regulation problems due to the interaction with the existing conventional control system. In a previous paper, a control system has been described using a fuzzy logic control to set the on-line tap changer for the primary substation. In this paper a new control system is proposed for controlling the power factor of individual PV invertors based on observed correlation between net active and reactive power at each connection. A fuzzy logic control has been designed to alter the power factor for the remote invertors from the secondary substation to keep the feeder voltage within the permissible limits. In order to confirm the validity of the proposed method, simulations are carried out for a realistic distribution network with real data for load and solar radiation. Results showing the performance of the new control method are presented and discussed.  

scholarly journals Capacitor Siting and Sizing using Cost Minimization & Monty Carlo Simulations for RDS

2019 ◽  
Vol 8 (3) ◽  
pp. 2482-2489
Keyword(s):  
Reactive Power ◽  
Cost Minimization ◽  
Minimum Cost ◽  
Distribution Networks ◽  
Voltage Regulation ◽  
System Capacity ◽  
Design Stage ◽  
Loss Reduction ◽  
Minimization Algorithm ◽  
Optimal Value

Capacitors are widely used in distribution networks for energy loss reduction, reactive power compensation, voltage regulation, and for system capacity release. However, it’s important that the system is designed initially, and capacitors are applied in correct magnitude and at right node to achieve best results. The most important task for distribution engineer is to efficiently simulate the system at design stage and later apply optimum capacitance injection. The work presented in this paper proposes a cost minimization algorithm using a unique mathematical model along with Monty carlo simulation to choose optimal value of capacitors, both fixed and switching based on total minimum cost algorithm.

scholarly journals Analysis of the number of switches of on-load tap changer of a power transformer for field substation, taking into account discrete time and voltage level sampling

2020 ◽  
Vol 220 ◽  
pp. 01056
Author(s):  
T.V. Tabachnikova ◽  
L.V. Shvetskova ◽  
A.V. Yumalin
Keyword(s):  
Smart Grids ◽  
Oil And Gas ◽  
Reactive Power ◽  
Power Transformer ◽  
Voltage Regulation ◽  
Electrical Network ◽  
Universal Method ◽  
Voltage Level ◽  
Tap Changer ◽  
Load Tap Changer

The introduction of “smart grids” technologies poses the problems of multi-criteria determination of the optimum voltage in the main substation of the object under study. In this study the busbar sections of the field substation of the oil and gas company is considered as the main substation. This paper studies regulation of voltage level in an electrical network using on-load tap changer (OLTC) of a power transformer for field substation of an oil and gas enterprise. Considered are approaches for voltage regulation taking into account the development of smart grid technologies. The authors have developed a universal method for determining the optimal voltage level on the busbar sections of a field substation, which allows for selection of the optimum voltage in accordance with certain parameters: loss of active, reactive power, voltage, electricity consumption, specific consumption or efficiency factor of artificial oil lift. The actual daily graphs of consumption of active, reactive power and voltage level at one of the field substations of PJSC Tatneft were studied. The operation mode of on-load tap-changer drive of the field transformer was modeled, taking into account the calculated optimal values of voltage and the dead zone. The paper presents the results of study of automatic voltage regulation on busbar sections of a field substation, taking into account the constraints for tap changer switches of a power transformer.

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