Low Voltage Distribution Networks Research Articles

The Joint Application of Photovoltaic Generation and Distributed or Concentrated Energy Storage Systems in A Low Voltage Distribution Network: A Case Study

The Joint Application of Photovoltaic Generation and Distributed or Concentrated Energy Storage Systems in A Low Voltage Distribution Network: A Case Study

Model-Less Non-Technical Loss Detection Using Smart Meter Data

This paper proposes a novel method for estimating non-technical losses (NTL), typically due to electricity theft caused by bypassed meters in low-voltage distribution networks. First, the voltage sensitivity coefficients are estimated by a weighted least squares based approach using the residuals obtained from an ordinary least squares-based approach. Then, the voltage measurements of smart meters and the estimated sensitivity coefficients are used to estimate the actual consumption of customers. The differences between the measured and the estimated consumption values are compared against a threshold and customers whose differences exceed the threshold are flagged as fraudulent customers. The performance of the algorithm is evaluated on the IEEE European Low Voltage (LV) network in various case studies, and on large randomly generated distribution networks. The results exhibit the capability of the proposed algorithm in correctly identifying fraudulent meters, together with their actual consumption values.

Study on Single-phase Ground Fault Localisation in Distribution Networks Based on Transient Travelling Waves

China's low and medium voltage distribution networks are mostly grounded by small currents, and single-phase grounding faults are frequent and their fault characteristics are weak, so that the traditional fault localization schemes may fail. In order to effectively solve the problem of single-phase grounding fault localization in distribution networks, the traveling wave localization technology is applied in distribution networks, which is expected to realize fast and accurate fault localization in distribution networks. Firstly, the paper analyzes the characteristics of traveling wave signals in distribution networks and those in transmission networks, and proves the feasibility of the traveling wave localization method applied to distribution networks. Secondly, the transient electrical quantities after a single-phase ground fault occurs in the distribution network are characterized, and it is concluded that in the fault transient process, nonlinear and nonsmooth signals appear in the faulted and non-faulted lines, and effective information is extracted for fault localization using the traveling wave method. Finally, in the case of abnormal traveling wave data during fault localization, single-end localization is carried out using the initial wave head arrival moment and reflection wave arrival moment of the traveling wave signal of the side branch to ensure accurate localization, and simulation verification is carried out using PSCAD/EMPDC.

Traceability analysis for low-voltage distribution network abnormal line loss using a data-driven power flow model

The abnormal behavior of end-users is one of the main causes of abnormal line loss in distribution networks. The integration of a large amount of distributed renewable energy into a low-voltage distribution network (LVDN) complicates line loss analysis. Traceability analysis for abnormal line loss aims to identify the specific end-user responsible for the anomaly in line loss. This paper proposes, for LVDNs with incomplete topology and line parameters, a practical traceability analysis approach using a data-driven power flow model. A data-driven power flow model based on a neural network is first established to capture the power flow mapping relationship without topology and line parameter information. A backpropagation algorithm is then presented to correct the actual power consumption data according to the measured voltage data. By comparing actual power consumption data with measured power data, users with abnormal behavior can be accurately identified and tracked. Finally, the effectiveness of the proposed approach is verified by actual data.

Management of electric vehicle charging stations in low-voltage distribution networks integrated with wind turbine–battery energy storage systems using metaheuristic optimization

This study investigates the IEEE 69-bus distribution network with three wind turbines (WTs) connected at the same buses of three battery energy storage systems (BESSs), with three 20- or 30-outlet electric vehicle charging stations (EVCSs) for charging electric vehicles (EVs). The honey badger algorithm (HBA) is adopted to minimize daily energy loss. The HBA determines the best size and position for three WT-BESS buses and three EVCS buses. The HBA calculates BESS size and operation mode to minimize daily energy loss. The demand of EVCSs varies throughout the day depending on the random choice of the number and state of charge of EVs entering the station. This results in the active and reactive energy losses and utility input energy decreasing by 63.5%, 60.6% and 59.6%, respectively, and the minimum voltage increasing from 0.9256 to 0.9839 pu. The network voltage profile and stability are also improved.

Planning Method of Low-Voltage Distribution Network Applicable to the Access of Multiple Flexible Entities

Since the establishment of the goal of “peak carbon and carbon neutrality”, various types of emerging loads have been developing rapidly. However, the application scenarios and working principles of various loads are different, and there is no clear standard for distribution network requirements. Thus, the existing low-voltage distribution network planning methods do not take emerging loads into account. Therefore, this paper proposes a low-voltage distribution network planning method that is applicable to the access of multiple flexible subjects. Firstly, the operational characteristics of flexible resources on the power side, user side, and energy storage side are analyzed and studied. Secondly, the low-voltage distribution network planning method applicable to the access of multiple flexible subjects is studied. Finally, the low-voltage distribution network of Song Yang County, Lishui City, is selected for the empirical application.

Research on Daily Load Curve Classification Based on Improved Fuzzy C-means Clustering Algorithm

For the problem of severe unpredictability and three-phase unbalance of user demand in low-voltage distribution networks, a daily load curve clustering technique integrating the sparrow search algorithm (SSA) and the fuzzy C-mean clustering algorithm (FCM) is presented. The initial load data set is pre-processed to lessen the interference of classification results. The load characteristic index of the daily load curve is removed to produce a reduced dimensional data set. The clustering validity index is introduced to solve the optimal number of clusters, and the early warning mechanism of the sparrow search algorithm is adopted to improve the global search capability. These improvements are made to improve the sensitivity of the initial clustering center of the FCM algorithm and the problem of local optimum in the process of finding the optimum. The simulation used to validate the revised clustering algorithm’s accuracy and efficacy for daily load categorization is a reference for resolving the three-phase load unbalance issue.

PV Inverter-Based Fair Power Quality Control

Low voltage distribution networks incorporating solar photovoltaic (PV) panels experience overvoltage and voltage unbalance during periods of low load and high PV generation. Resolving overvoltage by active power curtailment (APC) is an effective and cost-efficient solution. However, current APC techniques result in excessive and unfair power curtailment for prosumers at the sensitive parts of the grid that might induce neutral current. In this work, an analytical approach for fair APC and Reactive Power Control is presented for voltage regulation along with neutral current compensation. The desired power quality is maintained by controlling each phase of the PV inverter independently. The proposed algorithm regulates the voltage at the point of common coupling (PCC) within grid limits, eliminates neutral current, and reduces the grid unbalance. Furthermore, the results demonstrate that reducing the neutral current reduces the voltage at the PCC and consequently decreases the power curtailment required for overvoltage regulation.

Line loss calculation model of low-voltage distribution network under harmonic and three-phase unbalance disturbances and its experimental validation

With the grid integration of distributed power sources and traction loads, the power quality problem of the power system has become more and more serious, aggravating the distribution network line losses, so it is important to study the calculation model of distribution network line loss under power quality disturbance in order to find loss reduction measures. This paper first theoretically derives the calculation model of line loss of low-voltage distribution network under separate disturbance of 2 common power quality problems, namely, harmonics and three-phase unbalance. Then, using the composite power quality disturbance decoupling method, the calculation model of line loss of low-voltage distribution network under the disturbance of harmonics and three-phase unbalance is derived, which improves the accuracy of line loss calculations. Finally, experiments are conducted for each part by Matlab/Simulink simulation tool to verify the correctness of the theoretical derivation.

A study of the impact of voltage sag on sensitive loads at low-voltage distribution areas

Under the background of the dual carbon goal and the new power system, the power system becomes more complex and diverse, and voltage sag events caused by short-circuit faults, overloads, switching operations, large motor starting, and distributed generation access are more frequent. On the other hand, with the increasing sensitivity of low-voltage distribution network electrical equipment to power quality, especially for precision process control equipment using computers, power electronics, and automation technology, new energy generating units, and electric vehicle charging facilities, voltage sag accidents will cause difficult-to-estimate losses in equipment production and operation, and frequent voltage sag events have become one of the main power quality problems affecting reliable power supply and normal equipment operation. To address this problem, this paper analyzes the impact of voltage sag on low-voltage substation loads from a mechanism perspective, establishes a voltage sag tolerance curve for electronic appliances through experimental research, and simulates and verifies the effectiveness and correctness of the method in this paper using a 3 MW-rated induction generator connected to the distribution network as an example.

Research on the overvoltage suppression strategy of single-phase photovoltaic grid-connected systems based on FCS-MPDPC

For the overvoltage problem brought by the access of high-penetration photovoltaic power plants to the low-voltage distribution network, this paper chooses to deal with it by using the reactive power regulation capability of photovoltaic power plant inverters, which reduces the equipment investment in distribution line voltage regulation. Based on the reactive power regulation theory of the inverter, a finite set model predictive direct power control method is proposed by constructing a virtual voltage vector, taking a single-phase cascaded 2H bridge grid-connected inverter as an example, to realize independent control of active and reactive power. By setting different power reference values, the inverter can be made to have two functions: grid-connected per-unit power factor and reactive power control during overvoltage. Finally, the two modes of inverter operation are verified by Simulink simulation, and the verification by example shows that the method can limit the grid-connected voltage deviation to within 7% and meet the requirements of grid-connected regulations.

Cloud Server-Assisted Remote Monitoring and Core Device Fault Identification for Dynamically Tuned Passive Power Filters

Reliability and safety are crucial for the operation of a dynamically tuned passive power filter (DTPPF). Safe performance of DTTPFs implies complete normal filtering without failure within a specified period. To prevent potential disaster or economic loss, it is desirable to achieve early warning of any core device faults in a DTPPF based on its running state and to optimize its harmonic mitigation performance. In this paper, we explore effective methods for identifying core device faults in DTPPFs. First, we summarize the characteristic parameters of faults, running state parameters, parameters required for fault monitoring, and fault type parameters. Then, a cloud server-assisted remote monitoring and fault identification system for DTPPF is proposed, which consists of monitoring system’s architecture and cloud servers’ software architecture as well as software design of the back-end service layer and functional design of the front-end application layer. Our experiments demonstrate that the proposed system can monitor the real-time operational status of the DTPPF, enabling remote diagnosis and identification of core device faults. Moreover, it is user-friendly, as it is capable of optimizing equipment maintenance schedules and utilizing manufacturers’ service capacities. Therefore, this research provides a theoretical foundation for harmonic mitigation in low-voltage distribution networks and is valuable for practical engineering applications in industrial power grids.

SISTEM KONTROL DAN MONITORING ALIRAN DAYA LISTRIK PADA JARINGAN DISTRIBUSI TEGANGAN RENDAH MENGGUNAKAN MIKROKONTROLER BERBASIS IOT

To meet the needs of small or large scale electricity supply, the use of electrical energy generally uses 1 phase electricity and 3 phase electricity which is used to operate electrical equipment. To be able to find out the voltage, current, and electrical power of the low-voltage distribution network, manual checks are carried out on each R, S, T phase which is on the low-voltage distribution panel. When a 3-phase power failure occurs, it is often difficult to identify which phase is failingSo that in this case it is considered less efficient, for this research is expected to overcome the problems that have been identified. So a tool is made that can monitor failures in the R, S, and T phases which functions as safety when a failure occurs and can display a notification in which phase a failure occurs.In this study, the PZEM-004T sensor, Wemos D1 mini-module, and Android Studio are used which can allow for remote monitoring using electronic devices that have installed applications that have been created. when an error occurs, the "reset" button on the monitoring application is used to reset the protection to restore the device. The current difference in the avometer is 1.48A and the sensor is 1.46A and the current flowing to the load is written 1.88A. The contactor works when the relay receives a command from the Arduino nano with a fast time: 1.60 seconds on the first try, 1.72 seconds on the second experiment, and 1.68 seconds on the third experiment.

A thorough comparison of optimization-based and stochastic methods for determining hosting capacity of low voltage distribution network

A thorough comparison of optimization-based and stochastic methods for determining hosting capacity of low voltage distribution network

AC Network-Constrained Peer-to-Peer Electricity Market Model in Low-voltage Power Distribution Networks

The rapid growth of Distributed Energy Resources (DERs) and demand response in modern power grids calls for decentralized electricity trading mechanisms to effectively induce and coordinate responses from massive DERs and load entities. This paper proposes a fully decentralized peer-to-peer (P2P) distribution electricity trading mechanism backboned by a modified version of Alternating Direction Method of Multipliers (ADMM). Comparing with the state-of-the-art P2P electricity markets, the proposed electricity trading mechanism comprehensively incorporates power network constraints formulated by an alternating current power flow model. In the proposed method, nodal voltages are designed as the only public variables shared among participants. Privacy of each participant is thus sufficiently preserved without exposing the bid data to the others. Meanwhile, the proposed P2P method can also ensure the global optimality of social welfare in electricity transactions. Comprehensive case studies are carried out using the IEEE 33-node distribution system to demonstrate the feasibility and efficiency of proposed P2P electricity trading mechanism. The results indicate that the proposed model can efficiently integrates network constraints in the market clearing process while maintaining computational performance, ensuring stable convergence regardless of distribution system congestion. The proposed P2P electricity market can achieve global maximization of social welfare, with a relative difference of no more than 5.0% compared to the conventional centralized market. Even in worst-case scenarios, the relative difference remains within 7.32%. Meanwhile, the method accurately accounts for network losses, guaranteeing the feasibility of trading plans within the physical network.© 2017 Elsevier Inc. All rights reserved.

Connection of photovoltaic sources to the low voltage distribution network vs. risk of overloading the transformer station. Part 2: Simulation analysis

Connection of photovoltaic sources to the low voltage distribution network vs. risk of overloading the transformer station. Part 2: Simulation analysis

Connection of photovoltaic sources to the low voltage distribution network vs. risk of overloading the transformer station. Part 1: Characteristics of the existing state

Connection of photovoltaic sources to the low voltage distribution network vs. risk of overloading the transformer station. Part 1: Characteristics of the existing state

PV Hosting Capacity in LV Networks by Combining Customer Voltage Sensitivity and Reliability Analysis

This paper investigates voltage regulation in low voltage (LV) networks under different loading conditions of a supply network, with increased levels of distributed generation, and in particular with a diverse range of locational solar photovoltaic (PV) penetration. This topic has been researched extensively, with beneficial impacts expected up to a certain point when reverse power flows begin to negatively impact customers connected to the distribution system. In this paper, a voltage-based approach that utilizes novel voltage-based reliability indices is proposed to analyse the risk and reliability of the LV supply feeder, as well as its PV hosting capacity. The proposed indices are directly comparable to results from a probabilistic reliability assessment. The operation of the network is simulated for different PV scenarios to investigate the impacts of increased PV penetration, the location of PV on the feeder, and loading conditions of the MV supply network on the reliability results. It can be seen that all reliability indices improve with increased PV penetration levels when the supply network is heavily loaded and conversely deteriorate when the supply network is lightly loaded. Moreover, bus voltages improve when an on-load tap changer is fitted at the secondary trans-former which leads to better reliability performance as the occurrence and duration of low voltage violations are reduced in all PV scenarios. The approach in this paper is opposed to the conventional reliability assessment, which considers sustained interruptions to customers caused by failure of network components, and thus contributes to a comprehensive analysis of quality of service by considering transient events (i.e., voltage related) in the LV distribution network.

Operational failure mechanisms of electromagnetic potential transformer

In response to the problem of transformers blowing up or even burning up together with detuning devices in recent years, an assessment method based on the equivalent of transformer winding currents is proposed for potential transformers (Potential Transformer, PT) in low and medium voltage distribution networks. Firstly, the damage mechanism of potential transformers is analyzed and the thermal breakdown is identified as the main cause of damage to the winding insulation. At the same time, the winding currents under different faults are analyzed theoretically to identify the characteristics of various fault currents. Secondly, an operational failure indicator based on thermal equivalence, i.e. the fault current threshold indicator, is proposed in conjunction with the general voltage transformer specification. Finally, the proposed indicator is verified by means of ATP simulation software and combined with simulation tests. The results show that the proposed index can accurately reflect the winding failure of potential transformers, and the research results can provide a reference for the selection of potential transformers and the prevention of insulation breakdown.

Efficient voltage control of low voltage distribution networks using integrated optimized energy management of networked residential multi-energy microgrids

The optimal energy management system (EMS) of individual and networked residential microgrids and multi-energy microgrids (MEMGs) has received a great deal of attention. Several solutions have been studied to mitigate voltage limit violations due to the increasing penetration level of distributed generation resources (DGRs) and other issues. However, a research gap exists in developing a voltage control-oriented EMS for networked MEMGs (NMEMGs) to overcome the under/over voltage concerns. This paper aims to respond to this research gap by proposing a new voltage control-oriented EMS instead of conventional solutions, e.g., on-load tap changers (OLTCs) and limiting/curtailing output power of DGRs. The simultaneous management of the electrical and thermal supply/demand sides empowers the proposed method from the viewpoint of cost reduction and satisfaction of voltage constraints. Another contribution of this research is using the concept of sensitivity matrix information to calculate/control the voltage of NMEMGs, which is adequately fast and accurate. The voltage control of NMEMGs based on the flexibility of controllable residential thermal/electrical loads and appliances is one of the major advantages of this study. Moreover, the emission costs are considered in the proposed framework. The comparative test results illustrate that significant voltage constraint violations appear if the voltage limits are not considered. On the other hand, obtained results show that less than a 12% increase in the operation cost of some MGs/MEMGs has appeared due to additional constraints of the introduced voltage control-oriented EMS, while all voltage constraints are satisfied.