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Integrating renewable energy sources and distributed energy resources (DERs) in the Malaysian low voltage distribution network has introduced voltage stability challenges, particularly voltage rises, leading to detrimental impacts on network performance. This paper presents a novel reactive power control strategy for addressing these challenges. Unlike conventional methods with fixed reactive power references, the proposed technique dynamically adjusts the reactive power reference in real time, considering voltage and active power injection. It calculates the rate of change in reactive power reference (ΔQ) per second by analyzing Volt-VAR and Watt-VAR components and updates the reference accordingly. Simulations conducted on a low voltage distribution network in Taman Impian Putra, Malaysia, showcase the adverse effects of high photovoltaic (PV) penetration on voltage stability and highlight the success of the proposed strategy in mitigating voltage rise. The technique effectively reduces average voltage, maintains voltage regulation during high sun irradiance and low load demand periods, and surpasses the adaptability of existing methods dependent on PV active injection or network voltage alone. The proposed strategy ensures accurate control and efficiently addresses dynamic network changes by accounting for both PV active power injection and network voltage. This approach offers enhanced voltage regulation, adaptability to varying network conditions, and reduced losses, making it a promising solution for mitigating voltage rise in the Malaysian low voltage distribution network. The simulations, validated using MATLAB Simulation and OpenDSS, confirm the strategy’s efficacy and potential for real-world implementation. [ABSTRACT FROM AUTHOR]

This article presents the issue of the impact of the operation of prosumer installations on the operation of the distribution network. The emergence of a very large number of distributed generation units in electric distribution networks (in particular, photovoltaic installations in low-voltage grids) can be associated with both positive and negative consequences. Positive consequences can include, among others, the environmental aspect of electricity generation. Negative consequences, on the other hand, can include technical problems of power grid operation, manifested, for example, in changes that can be observed in steady states, in the values of such parameters of grid operation as voltage level, values of branch currents, or power and energy losses. The issue discussed will be illustrated by a calculation example considering, among other things, the size and location of the prosumer installation. [ABSTRACT FROM AUTHOR]

Local Electricity Market (LEM) appears as a promising consumer-centric market-based approach that extends the self-consumption method, widely implemented in residential households, to collective self-consumption in the local energy communities, enabled through peer-to-peer (P2P) transactions. To facilitate the integration of LEM in the wholesale electricity market (WEM), it is paramount to comprehend the synergy of retail electricity pricing on the LEM operation hosted in the low-voltage distribution network (LVDN). The paper presents a co-simulation framework consisting of a local electricity market model coupled with a three-phase distribution network simulator to perform a holistic case study for a smart energy community in Ireland. The novel contribution of the work is to explore the potential of local electricity trading in the presence of residential energy storage (ES), under different retail pricing schemes existent in Ireland, by evaluating economic benefits to the energy community and network performance of three-phase LVDN. Extensive simulation studies indicate that the presence of residential ES significantly boosts P2P transactions under static time-of-use (SToU) pricing. These P2P transactions are primarily contributed by energy arbitrage (among customers in LEM) in the winter and surplus PV-generated electricity in the summer. On the other hand, the scheduling of ES under SToU pricing deteriorates the network performance of LVDN in winter, showing the highest active power loss and under-voltage scenario among all the cases. Another unique aspect of LVDN is the voltage unbalance studied and found to be highly correlated with ES operation under SToU pricing. Recommendations have been made to the relevant stakeholders and market actors, identifying key aspects necessary to roll out the LEM under retail electricity pricing schemes.

Copyright of Journal of Nanchang University (Engineering & Technology) is the property of Nanchang University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to further improve the loss reduction effect of low-voltage distribution network, an auxiliary decision-making method of low-voltage distribution network loss reduction based on plant information real-time database was proposed. Through PI real-time database, the line losses of three-phase line and neutral line in low-voltage distribution network were calculated, and it was judged that unbalanced load of neutral line can easily lead to large loss. Taking temperature as the main factor affecting the loss of low-voltage distribution network, by increasing the proportion of low-energy-consuming transformers, increasing the cross-sectional area of conductors and optimizing the operation mode of distribution network, the loss reduction decision of distribution network was completed. The test results in a trunk-type low-voltage distribution network in a city show that the proposed method can effectively improve the unbalanced load of distribution lines. Compared with the loss of each phase line and center line before loss reduction, the loss value after loss reduction shows a significant downward trend, and the bus loss rate of the proposed method is relatively low. The line loss of each phase is controlled within 2%. [ABSTRACT FROM AUTHOR]

With the large number of renewable energy power sources such as wind power and photovoltaic power connected to the grid, the power system is becoming more electronic. The fault characteristics of renewable energy power sources and synchronous generators are obviously different, mainly manifested as the characteristics of short circuit current amplitude limitation and frequency offset, etc. The traditional protection based on the fault characteristics of synchronous generators may have adaptability problems. For a high proportion of renewable energy system, the short circuit current in the low voltage distribution network is greatly affected by the operation state of the renewable energy power sources after the short circuit fault occurs, which leads to the difficulty of the traditional three-stage overcurrent protection setting and coordination. In order to ensure the safe and stable operation of the system, this paper proposes a new backup protection method for low voltage distribution network. This method uses the information of the electric parameters on the high voltage side and low voltage side of the transformer. Firstly, the modulus sum of the voltage sampling value, the equivalent distance between the fault point and the protection installation place, and the modulus sum of the current sampling value are calculated. Secondly, the direction is judged by the criterion of the voltage direction element and the criterion of the distance protection element based on the multi-interval information. Finally, the maximum current branch of the low voltage distribution network is selected as the fault branch by the overcurrent element based on multi-interval information, so as to trigger the circuit breaker trip and isolate the fault. The low voltage distribution network model of the high proportion of renewable energy system is built on the PSCAD/EMTDC electromagnetic simulation platform. The simulation results show that the proposed protection method can reliably achieve fault removal by using multi-interval information, and has strong adaptability to the high proportion of renewable energy system.

The increased penetration of smart meters in the low voltage distribution network provides valuable insights that distribution network operators can leverage to produce detailed analytics for decision making. This includes enhanced network observability that can support network planning, phase balancing and planned outage management. In this paper, we propose three unsupervised learning algorithms to model the problem of identifying the transformer–customer connectivity relation at the low voltage network using smart meter voltage measurements of residential units as a classification problem. The algorithms are tested on real-world smart meter datasets and can detect the correct transformer–customer connectivity with 95% to 100% accuracy. This allows distribution network operators to effectively detect inconsistencies between customer data reports and actual physical connection of residential units to distribution transformers to comply with legal regulations.

This article presents the issue of the impact of the operation of prosumer installations on the operation of the distribution network. The emergence of a very large number of distributed generation units in electric distribution networks (in particular, photovoltaic installations in low-voltage grids) can be associated with both positive and negative consequences. Positive consequences can include, among others, the environmental aspect of electricity generation. Negative consequences, on the other hand, can include technical problems of power grid operation, manifested, for example, in changes that can be observed in steady states, in the values of such parameters of grid operation as voltage level, values of branch currents, or power and energy losses. The issue discussed will be illustrated by a calculation example considering, among other things, the size and location of the prosumer installation.

Copyright of Electric Power is the property of Electric Power Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electric Power is the property of Electric Power Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research investigated the increases of the voltage profile on the Provincial Electricity Authority (PEA)'s low voltage (LV) network due to the solar photovoltaic (PV) penetration. This study proposed the solution to maintain the voltage profile within the PEA's standard limitation by using battery energy storage system (BESS) application. The algorithm using bisection method to figure out the optimal size and location of BESS was examined and simulated in different scenarios such as summer/winter and weekend/weekday behaviors. Furthermore, the allocation of a battery in various locations was also considered. DIgSILENT power factory with DPL script and Python are the tools used to cover diverse scenario cases. The results showed that the best practice of how to implement BESS to solve the voltage rise problem was the BESS installation at the distribution transformer and the BESS installation separately at the end of each feeder near the loads. However, the optimal size of BESS installation at the distribution transformer was almost double that of installation at the end of each feeder. [ABSTRACT FROM AUTHOR]

A record amount of renewable energy has been added to global electricity generation in recent years. Among the renewable energy sources, solar photovoltaic (PV) is the most popular energy source integrated into low voltage distribution networks. However, the voltage limits and current-carrying capacity of the conductors become a barrier to maximizing the PV-hosting capacity in low voltage distribution networks. This paper presents an optimization approach to maximize the PV-hosting capacity in order to fully utilize the existing low voltage distribution network assets. To achieve the maximum PV-hosting capacity of the network, a novel method based on the dynamic line rating of the low voltage distribution network, the coordinated operation of voltage control methods and the PV re-phasing technique was introduced and validated using a case study. The results show that the proposed methodology can enhance the PV-hosting capacity by 53.5% when compared to existing practices. [ABSTRACT FROM AUTHOR]

With the continuous construction of new power system, large-scale access of distributed generation to low-voltage distribution network is an important development direction of energy in China. Therefore, rapid and accurate determination of fault location under power grid fault conditions is very important to improve the utilization rate of new energy and improve the reliability of low-voltage distribution network. Then, the current fault location research mainly focuses on the transmission network and medium and high distribution network, but there is little research on the low-voltage four wire distribution system, especially the scenario of distributed generation connected to the low-voltage four wire distribution system. In view of this, this paper proposes a fault location method based on impedance ranging for four wire distribution system, and gives a detailed calculation method and its acquisition method. This method overcomes the problem that most fault location methods are difficult to apply in low-voltage distribution network. The physical concept is clear and can well meet the actual operation requirements of distribution network. Finally, the proposed algorithm is verified and the simulation results show that the algorithm has good performance. The research results of this paper will help to improve the fault location level of low-voltage four wire distribution system. [ABSTRACT FROM AUTHOR]

Most existing voltage optimization approaches of low voltage distribution networks (LVDNs) assume users follow the regulations unconditionally, which is not always true. To tackle this, we propose a real-time peer to peer flexibility trading scheme for LVDNs. Besides distributed optimization, our scheme offers a way to let users trade their flexibility, in case some users do not want to follow the system regulations at some point. The scheme consists of flexibility allocation and trading. Player compatibility equilibrium and Bernoulli trials are employed to approximate the Pareto optimum in flexibility allocation, while consensus and voltage reference are used to provide real-time offers for flexibility trading. The proposed scheme is computationally tractable and can work with limited communication in a decentralized manner. All the user data is used locally so that privacy is well protected. A network based on a real Belgian semiurban LVDN is employed to validate the proposed scheme with three different scenarios. Besides, the flexibility allocation is benchmarked with a centralized ACOPF algorithm. The case studies result clearly prove the effectiveness and robustness of the proposed scheme. [ABSTRACT FROM AUTHOR]

This research investigated the increases of the voltage profile on the Provincial Electricity Authority (PEA)’s low voltage (LV) network due to the solar photovoltaic (PV) penetration. This study proposed the solution to maintain the voltage profile within the PEA’s standard limitation by using battery energy storage system (BESS) application. The algorithm using bisection method to figure out the optimal size and location of BESS was examined and simulated in different scenarios such as summer/winter and weekend/weekday behaviors. Furthermore, the allocation of a battery in various locations was also considered. DIgSILENT power factory with DPL script and Python are the tools used to cover diverse scenario cases. The results showed that the best practice of how to implement BESS to solve the voltage rise problem was the BESS installation at the distribution transformer and the BESS installation separately at the end of each feeder near the loads. However, the optimal size of BESS installation at the distribution transformer was almost double that of installation at the end of each feeder.

In many countries distributed energy resources (DER) (e.g. photovoltaics, batteries, wind turbines, electric vehicles, electric heat pumps, air-conditioning units and smart domestic appliances) are part of the 'Green Deal' to deliver a climate neutral society. Policy roadmaps, despite providing a framework and penetration targets for DER, often lack the network planning strategies needed to transition from passive to active distribution networks. Currently, DER's dynamic performance parameters and location identification techniques are not fully standardised. In fact, it can be very ad hoc. Standardised distributed load modelling and non-intrusive load monitoring (NILM) for equipment manufacturers, installers and network operators is critical to low and medium voltage network management in order to facilitate better balancing, flexibility and electricity trading across and within the power system for mass DER deployment. The aim of this paper is to fill this load modelling and NILM knowledge gap for DERto inform the 'Green Deal' transition and support standardisation. In the paper, existing load modelling techniques and NILM methodologies are critically examined to inform and guide research activity, equipment development and regulator thinking, as well as network operators. Seven key findings that need urgent attention are identified to support a smooth power system reconfiguration. [Display omitted] • A thorough review of existing monitoring and modelling methods for DER on distribution networks is provided. • Efficacies between 65% and 95% for conventional load identification exist. • Increasing DER penetrations are creating technological challenges in distribution networks. • Optimum DER integration in low voltage networks is vital for electric networks reliability. • Seven aspects to enable massification of DER on distribution networks are established. [ABSTRACT FROM AUTHOR]

Summary: This paper presents an overview of the impact of high penetration of photovoltaic (PV) systems in low‐voltage distribution networks (LVDNs). High integration of solar PVs in the LVDNs has severe implications on the system parameters, efficiency, and stability. This paper also introduces the methods that have been driven to overcome these effects to preserve the steady‐state conditions in the system during excessive penetration of PV generation units. A comparison between the contributions and shortcomings of the most recent researches for overvoltage mitigation strategies has been driven. Also, it includes comparing different overvoltage mitigation methods to handle the impact of the overvoltage under high penetration of PV units in the LVDNs. Besides, it presents a comparison between overvoltage mitigation methods based on their pros and cons. [ABSTRACT FROM AUTHOR]

A record amount of renewable energy has been added to global electricity generation in recent years. Among the renewable energy sources, solar photovoltaic (PV) is the most popular energy source integrated into low voltage distribution networks. However, the voltage limits and current-carrying capacity of the conductors become a barrier to maximizing the PV-hosting capacity in low voltage distribution networks. This paper presents an optimization approach to maximize the PV-hosting capacity in order to fully utilize the existing low voltage distribution network assets. To achieve the maximum PV-hosting capacity of the network, a novel method based on the dynamic line rating of the low voltage distribution network, the coordinated operation of voltage control methods and the PV re-phasing technique was introduced and validated using a case study. The results show that the proposed methodology can enhance the PV-hosting capacity by 53.5% when compared to existing practices.

The use of photovoltaic reactive power and energy storage active power can solve the problems of voltage violation, network loss, and three-phase unbalance caused by photovoltaic connection to low-voltage distribution networks. However, the three-phase four-wire structure of the low-voltage distribution network brings difficulties to power flow calculation. In order to achieve photovoltaic utilization through optimal power flow, a photovoltaic-energy storage collaborative control method for low-voltage distribution networks based on the optimal power flow of a three-phase four-wire system is proposed. Considering the amplitude and phase angle of voltage and current, a three-phase four-wire node admittance matrix was used to establish the network topology of the low-voltage distribution network. Also, to minimize the network loss, the three-phase unbalance and voltage deviation. a multi-objective optimization model based on three-phase four-wire network topology was established considering the voltage constraints, reverse power flow constraints and neutral line current constraints. Through improving the node admittance matrix and model convexity, the complexity of solving the problem is reduced. The CPLEX algorithm package was used to solve the problem. Based on a 21-bus three-phase four-wire low-voltage distribution network, a 24-h multi-period simulation was undertaken to verify the feasibility and effectiveness of the proposed scheme.

Bidirectional isolated dual active bridge is a vital component for low voltage distribution network. Conventionally dual active bridge is operated using single phase shift control technique. At unity voltage conversion ratio, it operates efficiently, but when voltage conversion ratio differs from unity, its efficiency decreases and current stress increases due to more reactive power. Moreover, voltage obtained at primary side of high frequency transformer is of 2‐level only, which increases voltage stress across switching devices. Furthermore, it has only one degree of freedom, which confines its ability to regulate power flow. In this paper, a transistor clamped dual active bridge DC‐DC converter is proposed with three degrees of freedom, which improves its ability to regulate power flow, and because of incorporation of 5‐level voltage on primary side of high frequency transformer, current stress in switches decreases significantly. It also leads to reduction in voltage stress across switching devices. Modeling of the proposed converter has been carried out to obtain power flow equation. In addition to the phase shift control, proposed converter has two more control parameter, which enhances the power flow controllability of the converter. It has higher efficiency as compared to conventional 2‐level DAB. Performance of the proposed converter is validated via simulation and experimentation on developed laboratory prototype. [ABSTRACT FROM AUTHOR]

Summary: Due to the rising renewable penetration rate, modern low voltage distribution network (LVDN) calls for active control with tractable computation and limited communication. To tackle this, the paper proposes a novel stochastic distributed optimization approach. The computation of optimum is completely decentralized, with a global broadcast signal is used as public reference in order to guarantee the consistency among individual shapeable energy resources. The proposed approach employs Bernoulli trials to imitate the searching process in classical gradient descent approach, and player compatible relationship is employed to play the role of gradients to indicate the direction of the search. Working in a model‐free manner without relying on iterations, the proposed approach offers an approximate optimization to minimize the accumulated compensation of reshaping/deferring the shapeable energy resources in a given LVDN while respecting the system constraints. A 103 nodes test network based on a realistic Belgian semi‐urban distribution network is used for validation. With two different profiles and a special case of communication failure, the proposed approach is validated and benchmarked with a classical AC optimal power flow algorithm. The results prove that the proposed approach is able to deliver a good approximation to the theoretical optimum with reasonable gap. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) system installation has encouraged to be further expedited to minimize climate change and thus, rooftop solar PV systems have been sparkled in every corner of the world. However, due to technological constraints linked to voltage and currents, the PV hosting capacity has been substantially constrained. Therefore, this paper proposes a competent approach to maximize PV hosting capacity in a low voltage distribution network based on voltage control and dynamic line rating of the cables. Coordinated voltage control is applied with an on-load tap changing transformer, and reactive power compensation and active power curtailment of PV inverters. A case study with probabilistic and deterministic assessments is carried out on a real Sri Lankan network to show how the PV hosting capacity is constrained. The findings revealed the capability of integrated voltage control schemes and dynamic line rating in maximizing hosting capacity. The study is expanded by incorporating the PV rephasing approach in conjunction with the aforementioned control techniques, and the effectiveness of PV-rephasing is clearly demonstrated. When compared to voltage control and conductor static rating, the combined rephasing, voltage control, and DLR yielded a 60% increase in PV hosting capacity.

Integration of rooftop photovoltaic (PV) systems in a three‐phase four‐wire distribution network cause voltage‐violations namely voltage‐rise and voltage unbalance. This study investigates the factors that affect both the voltage‐rise and voltage unbalance in low voltage distribution network integrated with the rooftop PV systems. The concerning factors are classified into active factors such as; loads active powers, PV active powers, and bus reactive powers, and passive factors such as; numbers of feeder buses and neutral‐grounded resistances. The study also determines the factors conditions at which the highest values of both voltage‐rise and voltage unbalance occurred. Moreover, the most and least significant effects of individual factors on both voltage‐rise and voltage unbalance are studied. The studied system is simulated and implemented in MATLAB software environment and the feeder loads are modelled based on Back–Forward Sweep method. The simulation results identify that the conditions of the worst voltage‐rise and voltage unbalance cases depend on the collective influence of the studied factors. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chongqing University of Posts & Telecommunications (Natural Science Edition) is the property of Chongqing University of Posts & Telecommunications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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.

Highlights • Proposing a new combined control scheme for voltage quality improvement in residential network. • Studying the effect of local, central, and combinational voltage controls on voltage quality. • Employing measured data and actual characteristics of DERs to achieve reliable results. • Simulations with 1-min resolution for better presentation of voltage control schemes effects. Abstract In this paper, a combined voltage control scheme is presented for improving the voltage profile, fluctuations, and imbalance of balanced and unbalanced residential distribution networks with a high penetration level (100% penetration level) of rooftop photovoltaic-wind turbine hybrid generation systems (PVWHSs) and electric vehicles (EVs). The combined control scheme includes both local and central control methods. Local controls in the inverter of EVs and PVWHSs of homes try to maintain their point of connection (POC) voltage within the acceptable range. Then the central controller does a complementary action for voltage improvement, by remotely controlling a battery energy storage (BES) and the network on-load tap changer (OLTC). The proposed control scheme is tested in DIgSILENT PowerFactory15.1.7 environment based on the weather and daily load data (wind speed, solar radiation, temperature, active and reactive power consumption of residential homes) during a year with a 1-min resolution in a three-phase four-wire network. The obtained results demonstrate the desired performance of the proposed scheme on voltage profile improvement, reducing voltage fluctuations, decreasing voltage imbalances of the phases and reduced number of tap operations, in the face of fast growth of distributed energy resources (DERs) penetration in the residential networks. [ABSTRACT FROM AUTHOR]

The energy transition poses a challenge for the electricity distribution network design as new energy technologies cause increasing and uncertain network loads. Traditional static load models cannot cope with the stochastic nature of this new technology adoption. Furthermore, traditional nonlinear power methods have difficulty evaluating very large networks with millions of cables, because they are computationally expensive. This paper proposes a method which uses copulas for modeling the uncertainty of technology adoption and load profiles, and combines it with a fast linear load flow model. The copulas are able to accurately model the stochastic behavior of solar irradiance, load measurements, and mobility data, converting them into electricity load profiles. The linear load flow model has better scalability and stability compared to traditional load flow models. The models are applied to a case study which uses a real-world dataset consisting of a realistic technology adoption scenario and a low-voltage network with millions of cables, which considers both voltage and current problems. Results show that risk profiles can be generated for all cables in the network, resulting in a valuable map for the district network operator as to where to focus their efforts.

This paper proposes a local control strategy applied in the soft open point (SOP) to suppress voltage fluctuation when adding a renewable energy source into the system. The mathematic model of the grid connected to SOP is established based on the characteristics of a low-voltage distribution network. Combined with the mathematic model and local voltage information, the local control strategy is proposed to optimize the active and reactive power distribution and consume the minimum apparent power of the converter. The local control strategy can effectively suppress the voltage fluctuation caused by renewable energy access, which was testified by MATLAB/Simulink simulation. In addition, the local control strategy can deduce the communication resource and increase the response speed compared to global optimization. This paper is meaningful for renewable energy source distribution and voltage balance in low-voltage distribution systems.

In view of the current three-phase unbalanced problems in the agricultural and urban networks, the operation characteristics and various indexes of the three-phase unbalance control in the radio distribution area are studied. Three kinds of common three-phase unbalance treatment schemes are proposed, including the phase switch type three-phase load automatic regulation device, the capacitive three-phase load automatic regulation device, and electronic three-phase load automatic regulation device. According to the different compensation principles, the three solutions compensate for the unbalanced three-phase current from the load side or the power side, and the purpose of load balancing compensation is achieved respectively. Through the detailed analysis of the working principle, the effect, the advantages and disadvantages and the application prospect of the three compensation devices, and the simulation of the compensation device, the validity and reliability of the three methods are proved, and the results can guide the related research and application work well. [ABSTRACT FROM AUTHOR]

Uneven load allocations and random load behaviors are two major causes for three-phase power imbalance. The former mainly cause systematic imbalance, which can be addressed by low-cost phase swapping; the latter contribute to random imbalance, which requires relatively costly demand-side managements. To reveal the maximum potential of phase swapping and the minimum need for demand-side managements, this paper first proposes a novel a priori judgment to classify any set of three-phase power series into one of four scenarios, depending on whether there is a definite maximum phase, a definite minimum phase, or both. Then, this paper proposes a new method to decompose three-phase power series into a systematic imbalance component and a random imbalance component as the closed-form solutions of quadratic optimization models that minimize random imbalance. A degree of power imbalance is calculated based on the systematic imbalance component to guide phase swapping. Case studies demonstrate that 72.8% of 782 low-voltage substations have systematic imbalance components. The degree of power imbalance results reveal the maximum need for phase swapping, and the random imbalance components reveal the minimum need for demand-side management, if the three phases are to be fully rebalanced. [ABSTRACT FROM PUBLISHER]

Adequately accounting for interactions between Low Carbon Technologies (LCTs) at the building level and the overarching energy system means capturing the granularity associated with decentralised heat and power supply in residential buildings. This paper combines dwelling/household archetypes (DHAs) combined with a mixed integer linear program to generate optimal (minimum cost) technology configurations and operation schedules for individual dwellings. These DHAs are scaled up to three socioeconomically differentiated neighbourhood clusters at the Output Area level in the UK. A synthetic distribution network generation and simulation assesses the required network upgrade costs for these clusters with different LCT penetration scenarios. Whilst the application here is to the United Kingdom (UK) setting, the method is largely based on freely available data and is therefore highly transferable to other contexts. The results show significant differences between the upgrade costs of the three analysed network types, and especially the semi-rural cluster has much higher costs. The employment of heat pumps together with photovoltaics (PV) has strong synergy effects, which can considerably reduce the network upgrade and carbon abatement costs if deployed in parallel. The determined CO 2 -abatement costs also suggest that decarbonisation measures with these two technologies should focus on semi-urban neighbourhoods due to the lower cost in comparison to the semi-rural case. This shows that such a socioeconomically differentiated approach to distribution network modelling can provide useful energy policy insights. [ABSTRACT FROM AUTHOR]

• A hierarchical scheduling framework and strategy of MV-LV distribution networks are proposed. • A schedulable domain model is presented. • The schedulable domains of 5G base stations and electrical vehicles are assessed. The rapid uptake of multi-new-flexible resources, such as 5G base stations and electric vehicles, is increasing network loss and peak-valley difference. This work proposes a collaborative control strategy to leverage multi-new-flexible resources in MV-LV distribution networks for power dispatching. Firstly, a bottom-up approach is adopted using a schedulable domain model to evaluate and aggregate the flexible capacity of multi-new-flexible resources. Then, an up-bottom strategy is adopted for power grid dispatching to improve the economy and security of the power grid. The proposed strategy is assessed using an IEEE-33 MV network and an 11-node LV network with multi-new-flexible resources. Results demonstrate that the proposed strategy effectively reduces network loss, peak-valley difference, and coordinates multi-new-flexible resources in MV-LV distribution networks. Comparative experiments prove that the proposed method can reduce the configuration cost of energy storage and computational complexity. [ABSTRACT FROM AUTHOR]

Line loss rate plays an essential role in evaluating the economic operation of power systems. However, in a low voltage (LV) distribution network, calculating line loss rate has become more cumbersome due to poor configuration of the measuring and detecting device, the difficulty in collecting operational data, and the excessive number of components and nodes. Most previous studies mainly focused on the approaches to calculate or predict line loss rate, but rarely involve the evaluation of the prediction results. In this paper, we propose an approach based on a gradient boosting decision tree (GBDT), to predict line loss rate. GBDT inherits the advantages of both statistical models and AI approaches, and can identify the complex and nonlinear relationship while computing the relative importance among variables. An empirical study on a data set in a city demonstrates that our proposed approach performs well in predicting line loss rate, given a large number of unlabeled examples. Experiments and analysis also confirmed the effectiveness of our proposed approach in anomaly detection and practical project management.

Many researchers in recent years have studied voltage deviation issues in distribution networks. Characterizing the impedance between consuming nodes in a network is the key to controlling the network voltage. Existing impedance estimation methods are faced with three challenges: time synchronized measurement, a generalization of the network model, and convergence of the optimization for objective functions. This paper extends an existing impedance estimation algorithm by introducing an enhanced particle swarm optimization (PSO). To overcome this method’s local optimum problem, we propose adaptive inertia weights. Also, our proposed method is based on a new general model for a low voltage distribution network with non-synchronized measurements. In the case study, the improved impedance estimation algorithm realizes better accuracy than the existing method.

This work explores the allocation question of battery energy storage systems (BESS) in distribution systems for their voltage mitigation support in integrating high penetration solar photovoltaics (PV). A genetic algorithm (GA)-based bi-level optimization method is developed that reduces the voltage fluctuations caused by PV penetration through deploying BESS among permitted nodes of a distribution system while accounting for their capital, land-of-use and installation costs using a qualitative cost model. The optimization problem considers BESS capacity and installation points in the distribution system as decision variables. Each BESS operation is determined using a linear programming (LP) routine that minimizes the daily coincident peak demand. A comprehensive validation study is carried out through exhaustive enumeration with the IEEE 8500-Node test feeder showing that the proposed method results in consistent decisions that appear to be globally optimal. Further sensitivity studies are conducted to showcase the behavior of the method under varying sizing costs, siting costs and PV penetrations. [ABSTRACT FROM AUTHOR]

Expansion of photovoltaic (PV) generation is increasing the challenge for network operators to keep voltages within operational limits. Voltage rise occurs in low voltage (LV) networks when distributed generators export, particularly at times of low demand. However, there is little work quantifying the scale of voltage issues and subsequently potential solutions across large numbers of real networks. In this paper, a method is presented to analyse a large quantity of geographically and topographically varying distribution networks. The impact of PV on voltages in 9163 real LV distribution networks is then quantified. One potential mitigation measure is increased network demand to reduce voltages. In this work, location algorithms are used to identify where increased demand, through energy storage, has the greatest effect on overvoltage. The study explores the impact on overvoltage of two modes of storage installation reflecting differing routes to adoption: purchase of storage by homeowners and purchase by network operators. These scenarios are compared with traditional re-conductoring in the 9163 networks. It is shown that to avoid violation of absolute voltage limits, storage should be installed at strategically important locations. Storage in homes reduces overvoltage, offering clear benefits to the network operator, but very wide deployment is required to completely remove the need for reinforcement.

Photovoltaic microgeneration (μG) located near the domestic consumers is expected to increase more in the future. Known issues regarding high μG penetration are voltage rise and reverse power flow. The concept of self‐consumption and storage is emerging as a way to improve network power supply quality and to facilitate the integration of small renewable energy sources in low voltage networks. This paper intends to give a further contribution by assessing the improvements provided by allowing domestic clients to consume and store the energy they produce. The tool at hand to study the situation is the unbalanced three‐phase load flow algorithm, based on the power summation technique, improved with the capability of explicitly compute the neutral voltages. The behaviour of a test radial distribution grid is assessed in different operating conditions, namely winter/summer, μG penetration level and μG operating mode. Voltage profile, active power flow in the service transformer and losses are monitored. The results suggest that self‐consumption with storage operating mode is a promising solution. Voltage excursions above normal grid voltage operating limits were not observed, the situation of reverse active power flow does not occur and the power losses are reduced. [ABSTRACT FROM AUTHOR]