Low Voltage Electrical Networks Research Articles

MAXIMIZING SELF-CONSUMPTION FROM PHOTOVOLTAICS

The present study refers to the maximization of self-consumption through the automation of a residential consumer that is or not fed from the low-voltage electrical network and from its own photovoltaic system. The level of self-consumption from photovoltaic sources in the residential sector is strictly dependent on the power installed in the own sources, as well as the load profile of the respective consumer. Two major directions are relevant regarding the possibility of increasing and optimizing self-consumption: the management of electrical energy storage systems (especially through the use of battery systems), respectively the implementation of load management systems, through the partial or total redistribution of their operation over time, but also through prioritization of critical consumers.

Testing the operation of protection devices against parallel arc breakdown and spark gaps in the event of a ground fault

Testing the operation of protection devices against parallel arc breakdown and spark gaps in the event of a ground faultTHE PURPOSE. Develop a laboratory rig for testing parallel arc fault and spark gap protection devices for tripping in the event of a ground fault. Conduct laboratory rig tests with subsequent development of requirements for the use of parallel arc fault and spark gap protection devices for tripping in the event of a ground fault.METHODS. Mathematical and statistical methods of analysis were used to achieve the stated objective. Laboratory tests of parallel arc fault and spark gap protection devices for different network parameters for correct tripping in the event of a ground fault.RESULTS. Laboratory tests of parallel arc fault and spark gap protection devices for correct tripping in the event of a ground fault were conducted with different network parameters. The oscilloscope recorded the shape of the voltage and current curve in the event of a ground fault and the tripping time of the devices. The tested devices demonstrated the ability to recognize and disconnect a ground fault. The tripping time of the devices varies, however, does not exceed the established requirements.CONCLUSION. A laboratory stand has been developed for testing parallel arc breakdown and spark gap protection devices for operation during a ground fault. This stand makes it possible to test devices for adequate operation during a ground fault with subsequent certification. The tests conducted demonstrate the need to develop mandatory requirements for the device to standardize their operating algorithm. Therefore, the use of this protection device can contribute to safer operation of low-voltage electrical networks by preventing emergency situations and reducing the risk of fires. This is an important technical aspect for improving the reliability and safety of power supply.

Detailed modeling of droop-controlled multi-energy systems under unbalanced operation

Considering the residential sector, greenhouse gas emissions can be effectively reduced by the widespread deployment of distributed renewable energy sources (DRESs) in low-voltage (LV) electrical networks (ENs). Through the electrification and the integration of different energy systems, the exploitation of the locally generated renewable energy can be further increased, acting also as an efficient countermeasure to the technical challenges in ENs posed by the intermittent nature of DRESs. This work deals with the modeling of multi-energy systems (MESs) consisting of unbalanced ENs and district heating networks (DHNs), formulated based on existing EN and DHN models. The developed model is enhanced by the incorporation of a thermal droop control scheme into the controllable sources of DHN, i.e., heat pumps (HPs). The validity of the proposed model is assessed via time-series simulations on a MES composed of a benchmark unbalanced LV EN and a real DHN. It is shown that the integrated droop control scheme can act as a means towards overvoltage mitigation, temperature control and reduced MES losses, improving the operational reliability and exploitation of the DRES potential. Therefore, the proposed model could be useful for system operators and decision makers for the efficient planning and operation of MESs.

Stability Study of Low Voltage Electrical Distribution Network: Audit and Improvement of DJEGBE Mini Solar Photovoltaic Power Plant in the Commune of OUESSE (Benin)

Stability Study of Low Voltage Electrical Distribution Network: Audit and Improvement of DJEGBE Mini Solar Photovoltaic Power Plant in the Commune of OUESSE (Benin)

Low voltage electric distribution network planning with demand control

Low voltage electric distribution network planning with demand control

Метод оптимизации размещения компенсирующих и симметрирующих устройств в электрических сетях низкого напряжения

The paper studies the optimization features of low-voltage electrical network modes for energy-efficient power transmission. The main features of these networks are the high values of the zero-sequence voltage unbalance factor and the mismatch of voltage values with the necessary requirements. Therefore, balancing the loads by phases and reactive power compensation are chosen as measures to improve the listed network parameters. One of the main factors for the effective solution of this problem is the determination of load balancing points and reactive power compensation, as well as the required power of the devices used. To solve the multicriteria problem of determining device connection points, an analysis of existing objective functions is carried out. As a result, a target function is proposed that includes costs, voltage losses, zero-sequence voltage asymmetry coefficient. When solving the optimization problem with the help of the proposed objective function, the voltage values and the voltage asymmetry factor at the consumer connection points will be within the required limits. The results of a study of the optimization function using the example of a model network are presented. The calculations are carried out in two stages: the search for sensor's nodes, then their study for optimality. All calculations are carried out in the MATLAB environment, taking into account voltage losses and power.

Study of the variation of operation of a low voltage electric network due to the integration of distributed energy resources—Steady state condition

Distributed energy resources (DERs) can significantly impact distribution networks, necessitating characterization studies to understand the technical consequences in various operating conditions. Existing literature primarily applies deterministic or probabilistic techniques for modeling and simulating networks and DERs, but lacks studies that integrate multiple DERs simultaneously. Additionally, assessing various indicators is necessary to determine the influence of DERs on network operation. Furthermore, resilience approaches often overlook DER integration as a disruptive event. To address these gaps, this work employs deterministic, probabilistic, and harmonic distortion analyses to characterize the impact of photovoltaic systems, storage units, and electric vehicles on a reference low voltage network. The study investigates how these DERs influence network operation at different time intervals throughout the day. By examining parameters and indicators (PaI) such as RMS values of voltages and currents, voltage unbalance, and harmonic distortions, the individual and collective effects of DERs are estimated. An adapted resilience evaluation technique groups the PaI values to generate a representative population of a single R indicator for each hour, allowing for quantification of network operation variations. Data for the analysis is obtained through PowerFactory-Python co-simulation, encompassing twenty operating scenarios.

Battery-Based Energy Storage System from Solar Panels Utilization for Worship House Applications in Carang Wulung Village

Due to the topography and hilly terrain in the area, there is still a hamlet in Carang Wulungvillage that does not have a low-voltage electricity network from PLN, namely Gondang Hamlet. As a result of this limitation, there is a place of worship (musala) in Gondang Hamlet that has not been adequately taken care of and is considered unfit when viewed from the availability of electricity. The community in this predominantly Muslim hamlet experiences lighting problems during congregational prayers at night until dawn. The lack of a power source for speakers also prevents the use of speakers to mark the prayer times. Based on this background, a battery-based energy storage system from solar panels was developed for this community service activity. The stages of community service activities carried out include surveying the needs for the installation of solar panel and battery installation systems, assembling several system components, testing the laboratory-scale system, installing the system that has been assembled and tested, and conducting socialization and training for residents on the use, operation, and maintenance of the solar panel system. The residents are happy that this community service activity has been carried out because they can worship comfortably at any time without relying on PLN as a source of electricity

Evaluation of additional electricity losses in electric networks using a meter

In this article, additional electricity losses are calculated using the voltage imbalance factor. There is also a method for predicting extra losses in the case of longitudinal and transverse asymmetry, as well as information on how to measure power quality indicators. It is suggested that home appliances be used to monitor a separate power system's power quality indicators. The findings of investigations on the condition of asymmetry conducted in operational low voltage electrical networks are presented, along with an illustration of how to calculate additional electricity losses in low-voltage networks. In this article for this purpose, the author developed a Malika device, which is fully capable to measure, store, analyze, and draw conclusions from the results of all electrical quality indicators.

A Device for Decreasing Loss in Electric Networks Containing Unbalanced Nonlinear Load

Matters concerned with controlling the operating modes of low-voltage electric networks are discussed. Thus, 0.4 kV electric networks are characterized by significant emission of additional current sequences generated by unbalanced nonlinear load. A versatile compensating device filtering additional power flows caused by unproductive fundamental and higher harmonic current components is proposed as a technical means minimizing the undesirable consequences of additional current load. A method and calculation software were developed, using which the operating mode of a 0.4 kV electric network section was studied with the possibility to incorporate a simulation model of the proposed device. The compensating device parameters are calculated proceeding from the unbalanced power consumption in the network section considered. By using the MATLAB software package, time diagrams visualizing the variation of the studied indicators have been obtained. The economic efficiency of the proposed versatile device for decreasing electric energy loss has been estimated.

Method of creation of power sources for home appliances under constraints of limited resources

The subject of study in this article is the voltage ranges, methods, and tools for prototyping independent sources of power supply and artificial lighting for home appliances with reuse of only widespread components. The goal is to improve the efficiency of the creation and use of independent power supply sources for home appliances. Task: to analyze the history of the development of voltage standards for households; analyze existing autonomous power sources and types of batteries; analyze different loads; find rational voltage ranges based on fundamental values; analyze charge control and balancing circuits for lithium-based batteries; propose the technique of prototyping independent sources of power supply based on reused lithium-ion (Li-ion) accumulators; provide an example of the practical application of the results of research. According to the tasks, the following results were obtained. The evolution of voltage standards of electrical supply networks is analyzed. Types of autonomous power supplies, including pure sine versions, are discussed. The analysis of batteries for autonomous power sources of different chemical compositions is performed. It is proposed to use the water analogy of current and area as an analogy of battery capacity for visual representation of electrical processes. Models of constant current consumption and constant power consumption are considered. It is proposed to reduce the internal resistance of the battery assembly by parallel connection of the reused lithium-ion accumulators. Correspondence of voltage ranges of sequential connection of lithium-ion cells to ensure compatibility with existing devices is investigated. Rational parameters of voltage ranges to ensure compatibility of lithium-ion and acid accumulators with the ability to charge directly from solar panels without a charge controller are found. Charge controllers, battery management systems (BMS), and battery balancing circuits are analyzed. A set of steps for reuse of lithium-ion accumulators for the creation of autonomous power sources is proposed. Conclusions. The main contribution of this research is the proposed method of creation of power supply and interior lighting based on the reuse of accumulators without additional components. The discovered and proposed magic numbers of 3, 5, 7, 9, 11 and 13 for series connection of lithium-ion cells allows to obtain the equivalent of standard voltage ranges of 12 V, 19 V, 27 V, 36 V, 42 V and 48 V. The proposed technique of adjusting the voltage of the passive balancer allows adding 4.5 % to the capacity of the battery assembly. The described solutions allow to build the completely scalable autonomous low-voltage electrical supply network with the ability to charge directly from solar panels without expensive charge controllers.

Expert System Integrating Rule-Based Reasoning to Voltage Control in Photovoltaic-Systems-Rich Low Voltage Electric Distribution Networks: A Review and Results of a Case Study

Nowadays, in low voltage electric distribution networks, the distribution network operators are encountering a high number of connected small-scale distributed generation units, mainly photovoltaic prosumers. The intermittent nature of the prosumers, together with the degree of uncertainty of the requested and injected powers associated with all end-users from low voltage electric distribution networks, can cause voltage variations that violate the allowable limits. In this context, this paper developed an efficient and resilient expert system integrating rule-based reasoning applied to the on-load tap changer-fitted transformer to improve the efficiency of the voltage control in the PV-rich LV EDNs. An in-depth analysis based on 75 scenarios, resulting from the combinations of three indicators—the penetration degree of the photovoltaic prosumers, the consumption evolution associated with the consumers, and the energy production of the photovoltaic systems—was performed to demonstrate the efficiency of the proposed expert system in a low voltage electric distribution network from a rural area belonging to a Romanian distribution network operator. The success rate of the expert system was 86.7% (65 out of 75 scenarios did not have voltage issues). All voltages were between the allowable limits in 100% of the time slots associated with the analysed period. For the other scenarios (representing 13.3%), voltages were inside the range [−10%, +10%] in at least 95% of the time slots.

A Hybrid Approach for Low-Voltage AC Series Arc Fault Detection

In a low-voltage electric distribution network, arc fault presents a high energy density electricity-discharging phenomenon between conductors, which is often caused by aging of electric facilities, loose contacts and terminals, or insulation failure due to internal and external destructions. A large amount of heat may be created during this discharging, which will further cause the risk of fire hazards to mitigate in the residential environment. Currently, many utility grid operators and electricity users are still devoted to seeking effective detection technology for arc fault protection. This paper proposes a hybrid approach that combines discrete wavelet transform (DWT), empirical mode decomposition (EMD), and dynamic time warping (DTW) methods for low-voltage AC series arc fault detection. In DWT, it uses time–frequency domain characteristics of the arc current signal to extract the occurrence of arc fault. In EMD, it decomposes the complex arc fault current signal into a finite intrinsic mode (IMF) signal; then, instantaneous amplitude of IMF signal is obtained by Hilbert–Huang transform (HHT) as a feature for arc fault identification. Firstly, the results of arc fault detections depend on the results from DWT and EMD. When both two methods detect different results, DTW method will be activated, using the similarity measurements between normal and arc fault current waveforms as an assistant measure to determine the occurrence of arc fault. The performance of the proposed approach is tested and validated using various electric appliances, and the results show that the proposed approach can effectively detect low-voltage AC series arc fault.

Probabilistic load forecasting for the low voltage network: Forecast fusion and daily peaks

Short-term forecasts of energy consumption are invaluable for the operation of energy systems, including low voltage electricity networks. However, network loads are challenging to predict when highly desegregated to small numbers of customers, which may be dominated by individual behaviours rather than the smooth profiles associated with aggregate consumption. Furthermore, distribution networks are challenged almost entirely by peak loads, and tasks such as scheduling storage and/or demand flexibility maybe be driven by predicted peak demand, a feature that is often poorly characterised by general-purpose forecasting methods. Here we propose an approach to predict the timing and level of daily peak demand, and a data fusion procedure for combining conventional and peak forecasts to produce a general-purpose probabilistic forecast with improved performance during peaks. The proposed approach is demonstrated using real smart meter data and a hypothetical low voltage network hierarchy comprising feeders, secondary and primary substations. Fusing state-of-the-art probabilistic load forecasts with peak forecasts is found to improve performance overall, particularly at smart-meter and feeder levels and during peak hours, where improvement in terms of CRPS exceeds 10%.

A method for determining arc breakdown in low-voltage electrical networks

In low voltage distribution networks, there is a high risk of fires caused by wiring faults that lead to short circuits. Arcing protection devices (ARCs) already exist, but experiments show that they also often do not disable such faults. The operation of most existing arc fault detection devices is based on the detection of high frequency current components and their comparison with load profiles. For the fast arc fault recognition low-frequency oscillations can be assessed, which serve as a marker of the arc fault presence in a LV distribution network. This method of arc fault recognition in LV networks is easier to implement practically. Using the windowed Fourier transform or Wavelet analysis, it is possible to determine the change in time of the harmonic components of the current, which will be a characteristic sign of the presence of an arc fault along with other signs.

Design and Simulation of Grid-Connected Photovoltaic Single-Phase Inverters

This paper focuses on a new control strategy for single-phase photovoltaic inverters connected to the electrical power distribution network. The inverter studied is single-phase H bridge, equipped with a robust control strategy by sinusoidal duty cycle modulation. This new control strategy offers the advantage over the control strategy. Most used control in its first approximation (PWM control technique): A low Hardware complexity; a variable modulation frequency/period; a topology of modulation with feedback. This inverter structure is further composed of the robust PI controllers, a boost chopper and an LCL filter. The low voltage electrical network to which this inverter is connected is materialized and simulated by a voltage source of characteristics 230V-15A-50Hz and synchronized to the latter by a phase-locked loop (PLL). In this article, the main components of the grid-connected PV power plant are modeled and simulated under Matlab/Simulink as well as the simulation of the global behavior of the entire network+PV inverter and the results obtained are presented.

CONSIDERATION OF THE CRITERION OF THE INFLUENCE OF ASYMMETRIC LOAD ON VOLTAGE DISTORTION IN A 10 kV NETWORK FOR RECOMMENDATIONS FOR REDUCING VOLTAGE ASYMMETRY

To date, there is a fairly large number of electrical equipment that is a source of asymmetric modes of operation in medium and low voltage electrical networks. This electrical equipment can create conductive low-frequency electromagnetic interference in electrical networks by the coefficient of voltage asymmetry in the reverse sequence. Studying the methodological basis of research on the theory of conductive low-frequency interference, it was found that when switching from one adjacent electrical network to another (for example, from a 0.4 kV network to a 10 kV network and vice versa) potential for conductive low-frequency interference decreases, i.e. the interference is partially suppressed by a certain amount. This amount is called the criterion determining the changes of the voltage asymmetry coefficient values in the reverse sequence in the transition of conductive low-frequency electromagnetic interference to the adjacent network. The purpose of this article is to develop a mathematical model for the study of network parameters affecting voltage asymmetry in the reverse sequence, which is reduced to a method for determining the value of the criterion for the effect of an asymmetric load on voltage distortion in a 10 kV network for recommendations for reducing voltage asymmetry. The article describes in detail the method of calculating this value and how it can be used to form recommendations for reducing voltage asymmetry. Scientific novelty of the study consists in the fact that an empirical mathematical model has been obtained that determines the criterion for the influence of an asymmetric load in a low-voltage network, the impact on which makes it possible to improve the electromagnetic situation in a 10 kV electrical network. This parameter can be taken into account when designing elements of electrical networks to determine the electromagnetic environment.

Planning of Low Voltage Electricity Distribution at Griya Arjuna Kejuden Housing

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.

The 0.38 kV electrical networks unbalancing operating modes optimization

The equipment 0.38 kV low-voltage electrical networks is not a satisfactory level. Such electric networks operating modes management is carrying out save energy measures and electricity supply improve efficiency in general largely allows. As a result, the electric energy supplied parameters obtaining actual nature information about to consumers through these electric networks is the developing the power transmission requirements measures basis comply. The article presents results current unbalancing modes objective studies in 0.38 kV an electrical network that feeds Irkutsk multi-storey residential building electric consumers. The analysis electric energy parameters, power quality indicators changes as well as electricity lo sses caused by the currents unbalance in the studied electric network are presented. The calculate parameters and using results of balancing device efficiency as well as its influence on the quality indicators studied and electrical energy loss in the studied electrical network are presented.

The 0.38 kV “Green Network” Operating Modes Simulation with Multi-Level Unbalanced Power Consumption

The article considers modeling, parameters calculation and analysis of the rural electric networks operating modes, containing power take-off units with multi-level unbalanced power consumption. At the same time, a low-voltage electrical network section fragment is considered as a certain cluster in the structure of an extensive and heterogeneous 0.38 kV network. The model is made for a certain “green network” cluster variant, containing several nodes of highly unbalancing power consumption with a balancing device (BD). Connecting options the BD in various power take-off nodes, including power supply buses, are considered. As a balancing technical means, a device is presented that has a minimum resistance to zero-sequence currents with its power automatically control in a zero-sequence currents function. The main criteria for assessing the currents and voltages unbalanced level are the zero-sequence voltage unbalance coefficient, which characterizes the power quality, as well as the power loss coefficient, which characterizes the increase in power and energy losses in the unbalanced mode. Based on the developed method, algorithm and computer program “Unbalance”, the calculation was made and the changes characteristics in the studied indicators were constructed using modern the Matlab graphics editor technologies. The analysis of the studied indicators was carried out, on the which basis the most appropriate node in the electrical network model was determined, where the functioning efficiency of the balancing device will be the greatest.