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Battery energy storage systems (BESSs) are known as a potential solution to integrate renewables and electric vehicle (EV) charging in the power system. This article compares the direct grid installation of ultra-fast chargers (UFCs) with a hybrid system inclusive of a reconfigurable BESS, a photovoltaic (PV) unit, two UFCs and a grid connection. The hybrid system is simulated with an optimization model, which reveals that the overall efficiency of the system plays a major role in determining the power grid exchange. Results show that the hybrid system can increase the local PV consumption while reducing the grid impact of EV charging. Based on yearly results, the hybrid system shows potential for further improving the utilization of the BESS and unlocking new revenue streams.

The difficulty of controlling the charging of electric buses (EBs) and their effects on network demand are discussed in this study. The solutions suggest a call for worldwide, complex infrastructures that manage EVs and EBs equally. Additionally, the Distribution Network (DN) must be prepared for an increased prevalence of reverse power flow caused by widespread distributed renewable generation. This paper focuses exclusively on EBs since they have higher capacity and predictable charging patterns, which makes them more significant for the DN in the context of a transition to complete vehicle electrification and technologies that are mature enough to be hosted. The proposed algorithm employs the Day-Ahead Energy Market (DAEM) in the Smart Charging (SC) to forecast the network operating circumstances. Additionally, the technique makes it possible to facilitate distributed photovoltaic (PV) generation, allowing network demand to be referenced depending on net demand. It also identifies an appropriate individual charger current per vehicle and per-time-step with load-levelling or peak-shaving as its primary goal. The final real demand demonstrates that a coarse correction of the demand is possible. According to the analysis of the DN voltage profile and associated line losses, the ideal node position location of the CS is dependent on PV penetration.

Continuously changing electricity demand and intermittent renewable energy sources pose challenges to the operation of power systems. An alternative to reinforcing the grid infrastructure is to deploy and manage distributed energy storage systems. In this work, a micro-energy market is proposed for smart domestic energy trading in the low-voltage distribution systems in the context of high penetration of photovoltaic systems and battery energy storage systems. In addition, a micro-balancing market is proposed to address the congestions due to unforeseen energy imbalance. Centralised and decentralised management strategies are simulated in real time, based on generation and demand forecasts. In addition, electric vehicles are also simulated as potential storage solutions to improve grid operation. A techno-economic evaluation informs key stakeholders, in particular grid operators on strategies for a sustainable implementation of the proposed strategies. The results show that the micro-energy market reduces the energy cost for all grid users by 4.1–20.2%, depending on their configuration. In addition, voltage deviation, peak electricity demand and reverse power flow have been reduced by 12.8%, 7.7% and 85.6% respectively, with the proposed management strategies. The micro-balancing market has been demonstrated to keep the voltage profile and thermal characteristic within the set limit in case of contingency.

Multi-Energy Microgrids (MEMGs) offer great opportunities for enhancing energy systems efficiency and penetration of renewable energy sources (RESs). By coupling traditionally independent electrical and thermal networks with binding components such as Combined Heat and Power (CHP) units, system operators can benefit from higher energy utilization efficiency. However, MEMGs' operation is severely compromised by uncertainties existing in RES generation and electric loads, which can never be perfectly predicted. This affects considerably the MEMG day-ahead dispatch and poses major challenges on how to maintain reliable operating conditions. This work proposes a coordinated dispatch strategy to minimize the operating costs of a network-constrained MEMG consisting of combined electrical and thermal distribution networks when multiple uncertain parameters are considered. To capture uncertainty variability, the operation method was modeled as a stochastic programming problem. Moreover, the Monte Carlo sampling technique was used to generate a large number of random scenarios. The proposed stochastic operation method was tested on a 14-bus system to find the optimal day-ahead scheduling operation. A feasibility check of the stochastic and deterministic methods was then carried out based on a new set of uncertainties realizations. Results indicated the proposed operation model to minimize the operating costs and guarantee strong robustness against uncertainties' realizations.

A multi-phase losses allocation method is proposed to provide explicit information about losses allocated to the neutral conductor. This information from the proposed methodology can be utilized by distribution system operators in the identification of highly unbalanced nodes in a network and consequently, allows them to implement suitable unbalance compensation schemes at these nodes in order to improve network balancing. The newly developed approach, based upon neutral losses allocation factors, reduces the unbalance in a network by switching single-phase loads across phases of highly unbalanced nodes. Two-phase switching algorithms, based upon individual and combined load commutation, are proposed to achieve this objective. The developed technique is implemented on a real LV Italian distribution network by adopting real customer’s power profiles. Results indicate a significant improvement in network balancing and losses reduction, which clearly represent the positive active role that neutral losses allocation factors can play in the assessment and management of distribution networks.

The continuous increase of Renewable Energy Sources (RESs) connected to distribution networks requires a careful review of the current regulatory framework to enable the provision of Ancillary Services (ASs) by these small-scale units. One of the envisaged options for coordinating Transmission System Operators (TSOs) and Distribution System Operators (DSOs) is the agreement and regulation of a scheduled power profile at the Primary Substation (PS). This means assigning the balancing responsibility to DSOs and, consequently, reducing the unpredictability of the power exchanges with the upstream transmission grid. The paper proposes a novel procedure for the management of Distributed Energy Storages (DESs) in order to provide ASs to both the DSO (local regulation of distribution network and congestion management) and the TSO (control of the power profile at the PS). The methodology, based on a sliding time window approach, evaluates the actual availability of each storage unit in providing ASs, assigns a scheduled profile and corrects it during the real-time operation. In addition, for each DES, the scheduled State of Charge (SoC) is restored in accordance with network constraints. Simulations on a realistic case study network are carried out considering randomly perturbed power profiles for both loads and generators. Benefits associated with storage coordination (power exchange management at the PS and support to DSO in voltage regulation and congestion resolution) are evaluated and discussed.

The aim of this paper is to develop a control function that is able to manage, in the on-line environment, the active power output of a microturbine so as to compensate the unavoidable microgrid power imbalances caused by forecasting errors and unforeseen events. A central controller based on a Proportional-Integral-Derivative (PID) control loop evaluates the optimal control actions to be sent to the local controller of the microturbine inverter. In order to test the ability of the proposed controller to follow any change in the load demand of the microgrid, experimental tests have been performed on the microturbine connected at the experimental microgrid of the Polytechnic University of Bari, Italy.

The paper discusses preliminary results of an extensive survey of residential load users in an urban area. This work is part of a wider collaboration between University of Padova and AGSM aiming to analyze the Medium and Low Voltage electrical distribution network, i.e. to characterize existing loads and to define realistic future scenarios considering new resources satisfying sustainable energy policies, e.g., an increased penetration of electricity in final energy uses and the electrical mobility. The first part of the study focused on residential end-users, which represent the customer category with the highest diffusion in LV grids, with the aim of characterizing the actual utilization degree of the existing electrical infrastructure and providing a suitable estimate of end-users’ energy consumption growth trend for network planning purposes.

A novel optimal PhotoVoltaic (PV) inverter dispatch scheme is proposed in this paper which combines the active power curtailment and reactive power control schemes in order to simultaneously determine the optimal active and reactive power set points of residential PVs. The non-convexity of resultant AC optimal power flow model, caused by the inherent power balance constraints and selective inclusion of PV systems through binary variables, is handled by leveraging the cheap semi-definiteprogramming and sparsity-promoting-regularization approaches. The application of proposed methodology on a low-voltage test distribution network shows that recurrent technical issues of these networks such as voltage rise and voltage unbalance can be successfully mitigated as well as significant reduction in active power losses can also be achieved.

The diffusion of distributed energy resources in distribution networks requires new approaches to exploit the users&rsquo, capabilities of providing ancillary services. Of particular interest will be the coordination of microgrids operating as an aggregate of demand and supply units. This work reports a model predictive control (MPC) application in microgrids for the efficient energy management of energy storage systems and photovoltaic units. The MPC minimizes the economic cost of aggregate prosumers into a prediction horizon by forecasting generation and absorption profiles. The MPC is compared in realistic conditions with a heuristic strategy that acts in a instant manner, without taking into account signals prediction. The work aims at investigating the effect that different types of energy tariffs have in enhancing the end-users&rsquo, flexibility, based on three examples of currently applied tariffs, comparing the two storage control modes. The MPC always achieves a better solution than the heuristic approach in all considered scenarios from the cost minimization point of view, with an improvement that is amplified by increasing the energy price variations between peak and off-peak periods. Furthermore, the MPC approach provides a cost saving when compared to the case considering a microgrid endowed with only photovoltaic units, in which no storage is installed. Findings in this work confirm that storage units better perform when some knowledge of future demand and supply trends is provided, ensuring an economic cost saving and an important service for the overall community.

With the increase of the distributed generation, the development of distribution networks able to operate detached from the bulk grid has become possible. However, these islanded distribution networks lead to several issues to be dealt with, including the stability, the efficient generation profile scheduling and the procurement of balancing services. This paper proposes an optimal network management scheme capable of obtaining the power profiles of all users connected to the network for a given time frame. This scheme, based on a double negotiation phase, aims to minimize the social cost for the coverage of the overall demand, keeping the network within its technical operating limits. The impact of Multi-Energy Storage Systems (MESS) in the cost of providing these services is assessed by considering the technical limits of the specific users. Finally, the proposed control scheme has been tested on four different scenarios, with increasing MESS penetration level, demonstrating to be able to reduce the social cost associated with the re-dispatching by exploiting the services offered by the Battery and Thermal Energy Storage Systems.

A novel Optimal Power Flow (OPF) model, based on Semi-Definite Programming approach, for multi-phase active Distribution Networks (DNs) equipped with neutral conductor(s) and both wye- and delta-connected loads/Distributed Generators (DGs) is proposed in this paper. The coupled power injection across phase-neutral and phase-phase conductors is decoupled by modelling of a shunt load/DG through a correction current injection approach and, consequently, explicit power injections are obtained for each conductor of a node. Furthermore, the complete ZIP load representation is considered in the OPF model and two approximations, based on the first-order Taylor series and approximation of the first-order Taylor series, are introduced for the modelling of constant current component of a ZIP load in terms of an optimization variable. Simulations are carried out on several medium and low voltage active DNs under various parameters of the ZIP models for the minimization of either slack-bus power or network losses objective functions. It is successfully demonstrated that the proposed relaxation recovers the global optimal solution of the original OPF problem for both load types (wye and delta) under various combinations of ZIP parameters in the case of lightly or moderately unbalanced DNs, whereas in the case of highly unbalanced DNs, a rank-2 solution is obtained when constant current component dominates the other load components. Furthermore, the impact of unrealistic assumption of Kron reduction approach on the quality of the proposed relaxation for a single or multiple point grounded DNs is also discussed. From a computational point of view, the proposed methodology can be realized on a real-time basis for small DNs. However, for medium and large DNs, the incorporation of additional sparsity exploitation or distributed algorithm techniques are required for its real-time implementation.

Passive distribution networks are rapidly transforming to active networks due to ever growing penetration of mainly renewable distributed energy resources. The integration of these resources has positive impact from environmental perspective but their penetration has raised serious issues on secure and reliable operation of a network, owing to their intermittent and not dispatchable output. To maintain an optimal operation of a network, extensive research studies have been carried out under the theme of network management. This paper discusses the concept of losses management, which falls under the same theme, in active distribution networks. The methods related to modelling of such systems and end-users, numerical tools required for system analysis, active network management schemes for losses minimization and fair losses allocation to passive and active consumers are reported and investigated. Therefore, the aim of this paper is to provide a concise yet comprehensive comparison of the most recently proposed losses management approaches and strategies.

Under emergency conditions, portions of medium-voltage (MV) networks can be locally supplied for a significantly long time period by moveable generating units connected to the low-voltage (LV) side of a standard distribution transformer, which in this case operates as a step-up transformer. It is, therefore, necessary to ensure a proper operation which must include the detection of any possible faulty condition. When the MV network portion is operated with isolated neutral (as it is usually the case), a reliability issue arises for earth faults detection by the protection system, due to the negligible capacitive fault current values. In this work, possible detection methods are identified through analytical and numerical simulations and two promising solutions are proposed, i.e. the intentional earthing of one phase conductor and the connection of a suitable neutral forming transformer with earthed neutral terminal, both operated at the MV side of the MV/LV transformer.

The growth of distributed energy resources (DER) connected at distribution network level and the current legislation concerning the participation of DER to the energy and ancillary services markets, are a huge opportunity to get flexibility services from these resources but at the same time a great challenge from the technical point of view. According to the latest indications from EU Directives, demand response and generation flexibility are encouraged in order to meet network balancing needs, but a new actor is required: the aggregator. This new participant has the duty to aggregate consumption and generation in order to offer flexibility products in the ancillary services market, while ensuring the technical feasibility and assuring revenues for its clients and itself. This work focuses on the structure and the business model of aggregators and discusses the technical implication that such role has on the distribution network.

Optimal power flow problem for low-voltage radial distribution networks including neutral conductor is considered in this paper. The standard semi-definite programming based relaxation, initially proposed for three-phase networks, is extended to such multi-phase networks by taking into account the coupled phase-neutral power injections. An approach based upon correction current injection is utilized which incorporates the network loads into the system admittance matrix by representing them through constant admittances. Furthermore, the impact of neutral-ground impedance has also been taken into account. Simulations are carried out on real low-voltage unbalanced distribution networks for minimization of slack-bus power injection and power losses objective functions. It has been shown that the proposed approach is numerically exact under a large range of the value of neutral-ground impedance and can be successfully solved by a generic optimization solver such as MOSEK. The exactness of the proposed scheme has also been verified for the time-varying load and generation profiles, whereas the accuracy of the recovered solution is also confirmed by root-mean-square-error parameter.

The main goal of this paper is to get a simplified equivalent dynamic model of a co-generator when it is operated in the grid-connected mode. The gas-fueled co-generator installed at the PrInCE Lab microgrid is adopted and modelled in the real-time as a dynamic model of the second order. Parameters of the proposed model are derived through an input-output identification methodology based on the Lyapunov Theorem applied to the Sensitivity Theory (LTST). The correctness of proposed model has been tested experimentally.

The urban development of our cities has often made overhead power lines, almost always pre-existing, closely affected by the presence of new infrastructure and residential homes. The following questions arise from this aspect: “Is it possible to think of new overhead power lines arrangements, built with innovative solutions, with lower environmental impact compared to traditional solutions?” Further “were all this possible, what would the specific features and problems of these solutions be? And finally, as regards the magnetic field emission, “what would the performance of these overhead line innovative solutions be like, compared to the underground cable solution?” The above questions stimulated the research and application feasibility of “low magnetic field” technical solutions, traditional and innovative, described in this paper.

In this paper, a resynchronization control strategy for a master-slave controlled microgrid has been developed. In the proposed control scheme only the generator acting as the master for the isolated microgrid is responsible for its resynchronization. The derived controller consists of two different control loops: active and passive. The first one consists in forcing the master unit to adjust its active and reactive power outputs to rapidly adapt the overall system frequency and voltage magnitude to the reference signal. On the contrary, the passive method waits that the two sets of voltage phasors at both microgrid and utility grid sides are synchronized before enabling the master unit to start the resynchronization process. Experimental tests have been performed on the PrInCE Lab microgrid built at the Polytechnic University of Bari, Italy, in order to prove the effectiveness of the proposed controller..

Semi-Definite Programming (SDP) and Second Order Cone Programming (SOCP) relaxations are state-of-the-art lift-and-project based techniques for solving the non-convex AC optimal power flow problem in multi-phase active distribution networks. A novel centralized Quadratic Convex (QC) relaxation for such networks, which is a significant departure from the liftand-project based approaches, is developed in this paper. The proposed scheme encloses the non-convex region, associated with the non-linear terms of power flow equations represented in the polar form, by appropriate convex envelopes. The envelopes for the trigonometric terms are based upon the first order Taylor series approximation and cosecant/secant functions, whereas bilinear terms are enclosed by McCormick envelopes. Furthermore, appropriate bounds on the lifted variables are also introduced and the trilinear function is enclosed by the recursive application of the McCormick envelope. The application of the proposed scheme on several test cases reveals that it outperforms SOCP in all the cases and is close to the SDP relaxation. Furthermore, it has also shown to have high computational efficiency as compared to the SDP approach due to the existence of mature solving technology for quadratically constrained problems.

Ground Potential Rise (GPR) evaluation under fault conditions is important for the evaluation of electrical safety risk to human beings who are present in and around electric installations. Current national and international standards recommend such evaluation is based on a set of ‘worst-case’ conditions that include a simplified fault current calculation procedure based on assuming a maximum value. Accordingly, this approach may lead to over-design of grounding systems in certain cases by overestimating individual risk. To address this and move towards a comprehensive probabilistic assessment of risk, a more detailed model of the electric network is required for fault current magnitude evaluation. This paper describes the application of the multi-conductor method to determine fault current distribution on transmission networks. First, a model of a portion of the UK transmission network is built and the fault current and its distribution among the phases, ground wire and ground is evaluated for three example fault positions. It is found that the position of the fault along the line, substation bus section status and proximity to generation affect greatly the current distribution. Then, a transmission model based on the national network is built, and the effects of system loading and generation on fault current magnitude were also considered. A complete frequency distribution of fault current magnitude is obtained and the results demonstrate the value of such description for the probabilistic assessment of human safety in grounding system design.

In many countries, in the last years, there has been a wide spread of Distributed Generation (DG) from renewable sources at MV and LV level. The distribution network is eventually changing from a passive structure to an active protagonist of a dynamic, low carbon and reliable energy market. On the other hand, this change could lead to a power quality depletion and to threats to the safety of the network itself. In this work, a concurrent control strategy is proposed to coordinate the prosumers with the aim of improving the reliability of the distribution network. The control scheme is based on an adaptive-area-based method and a multi-conductor Power Flow. In this way, it is possible to monitor the voltage unbalance among the phases while managing voltage and current magnitudes.

Many planning and operation studies that aim at fully assessing and optimizing the performance of the distribution grids, in response to the current trends, cannot ignore grid limitations. Modelling the distribution system, by including the electrical characteristics of the network (e.g., topology) and end user behaviors, has become complex, but essential, for all conventional and emerging actors/players of power systems (i.e., system and market operators, regulators, new market parties as service providers, aggregators, researchers, etc.). This paper deals with a methodology that, starting from publicly available open data on the energy consumption of a region or wider area, is capable to obtain reasonable load and generation profiles for the network supplied by each primary substation in the region/area. Furthermore, by combining these profiles with territorial and socio-economic information, the proposed methodology is able to model the network in terms of lines, conductors, loads and generators. The results of this procedure are the synthetic networks of the real distribution networks, that do not correspond exactly to the actual networks, but can characterize them in a realistic way. Such models can be used for all the kind of optimization studies that need to check the grid limitations. Results derived from Italian test cases are presented and discussed.

Losses allocation, being a purely economical problem, demands a fair allocation procedure that can distribute the losses in an impartial manner by avoiding cross-subsidies among end users. In view of this, a novel multi-phase losses allocation methodology is proposed, which fairly segregates the losses associated with cross-terms of phase-currents and also provides an explicit information about losses allocated to the neutral. The effect of phase loading on another phase is comprehensively taken into consideration while distributing losses among end users. Furthermore, allocation of neutral losses to each phase of a node is avoided as these losses exist in a system due to its inherent characteristics. Quadratic and geometric losses partitioning approaches have been utilized to determine the share of losses between phase currents of same and different nodes. The methodology is implemented on a modified IEEE 13-node test system in the presence of distributed generators and results show that the proposed scheme leads to a more fair penalization and reward of passive and active end users as compared to the resistive component based losses allocation method. In addition to this, concept of neutral losses allocation factor along with their possible application in the management of distribution network has also been discussed briefly.

The large penetration of distributed energy resources (DERs), especially photovoltaic (PV), in low-voltage (LV) distribution grids has raised the concern of unintentional islanding operations. The probability of unintentional islanding is increased mainly due to the newly introduced standards with extended frequency and voltage thresholds and the additional grid support functions, such as active and reactive power regulation using P/f and Q/V droop characteristics. Moreover, islanding operation due to faulty events at the medium-voltage (MV) distribution level may be dangerous in the presence of automatic reclosing procedure leading to out-of-phase reconnections. In this paper, an analysis of this phenomena is provided using simplified generator and load models. Simulation results based on MATLAB and DIgSILENT tools on a simplified LV distribution network are reported together with experimental results on a lab-scale prototype.

The significant growth of embedded generation in distribution systems is leading network operators to reconsider some of the prescriptions for losses minimization. Analyzing the operating conditions of small-scale generators connected to Low Voltage (LV) networks is becoming more and more important. Since LV customers are mostly single-phase connected, the time shifting between load and generation power profiles is likely to increase both voltage unbalance and power losses. Recently revised grid codes focus on the involvement of distributed generators in the network management, and this feature needs to be taken into account in the power losses evaluation. In this paper, some of the controls applicable to embedded generators are considered in a real case LV distribution system, and their effects on annual network losses, referring to real customers’ power profiles, are investigated.

A multi-phase losses allocation method is proposed which provides explicit information about losses allocated to the neutral. This information can be used by DSO in implementing suitable techniques for better management of Active Distribution Networks (ADNs). A new methodology, based upon Neutral Losses Allocation Factors (NLAFs), is proposed in this paper, which reduces the unbalance in a network by switching loads across phases of highly unbalanced nodes. The proposed technique is implemented on a real LV Italian distribution network by adopting real customer’s power profiles. The results show that a significant reduction in unbalance and network losses can be achieved by phase switching of the loads, which indicate that NLAFs can be used as a significant indicator for assessment and management of ADNs.

The deployment of Electric Vehicles (EVs) is continuously increasing on a global scale due to governmental commitments to ensure energy security, decarbonisation and address environmental concerns, by phasing out Internal Combustion Engine (ICE) vehicles. However, if charging is not appropriately controlled, massive EV penetration can lead to significant challenges for local distribution systems. In this context, this paper presents a new extensive tool, based on a Matlab/Simulink platform, to model distribution networks and analyse the impacts of charging of EVs, generation from local Renewable Energy Sources (RES) and the use of smart grid technologies to mitigate these impacts. The tool models the geographical locations of the distribution substations and the nodes where local loads, RES and EV charges may be connected. It allows the user to study the operational framework of current and future distribution networks and enables techno-economic assessment to be made. The modelling tool simulates the daily basis operation of any low-voltage (LV) distribution grid, considering the interaction with both consumers and local RES. This is done by evaluating key system performance measures, such as nodal voltages, line currents and transformer overloading. A user-friendly Graphical User Interface (GUI) facilitates the flexible management of the input parameters. The tool was applied to analyse an existing UK LV distribution network, to demonstrate the feasibility of smart charging and V2G (Vehicle to Grid) technology and the advantages over uncontrolled charging. This paper presents the outline of the modelling tool and the results of investigation of the different scenarios considered in this research.

In this paper, the dynamic model of a master-slave controlled microgrid suitable for transient stability assessments has been developed. The dynamic model has been derived for the PrInCE Lab experimental microgrid located at the Polytechnic University of Bari. This microgrid represents a hard test bed for dynamic stability studies since all its devices are interfaced through power converters, giving rise to an inertialess system. Dynamic models of the main microgrid energy sources have been developed within the DIgSILENT Power Factory software environment. Some ad-hoc experiments have been performed in order to fine tune the models' parameters and the microgrid model accuracy has been proven by several validation tests performed under different scenarios of load and generation.

In the last decades, strengthening the high voltage transmission system through the installation of new overhead power lines has become critical, especially in highly developed areas. Present laws concerning the human exposure to electric and magnetic fields introduce constraints to be considered in both new line construction and existing systems. In the paper, a technique for passive magnetic field mitigation in areas close to overhead power lines is introduced, fully modelled and discussed through a parametric analysis. The investigated solution, which basically consists in approaching line conductors along the span making use of rod insulators, is applicable on both existing and under-design overhead lines as an alternative to other mitigating actions. Making use of a 3-dimensional representation, the procedure computes both positions of phase conductors and forces acting on insulators, towers, conductors and compactors, with the aim of evaluating the additional mechanical stress introduced by the compactors. Finally, a real case study is reported to demonstrate and quantify the benefits in terms of ground magnetic field reduction achievable by applying the proposed solution, in comparison to a traditional configuration. Furthermore, using compactors to passively reduce the magnetic field is simple to be applied, minimally invasive and quite inexpensive as regards to alternative mitigating actions.

As the penetration of small scale generators increases in distribution networks, the controllability of these systems, especially at Low Voltage (LV) level, is becoming more and more important. Several research studies proposed the adoption of the On-Load-Tap-Changer at the Secondary Substation transformer to enhance the voltage control, thus several commercial products are now available. This paper investigates how this technology may influence the voltage management in LV networks, taking into account the possible voltage unbalance deriving from uneven distribution of loads and generators on the three phases and the reactive power provision by the latter. Several scenarios regarding the voltage control are applied to a case study network to simulate different tap changing controls and voltage monitoring strategies.

The proliferation of Distributed Energy Resources (DERs) in the Distribution Network (DN) has affected the optimal operation of the grid due to multiple technical issues such as voltage rise, reverse power flow, voltage unbalance, islanding etc. Therefore, optimal management of DERs is becoming a key research area to improve the system power quality. In this context, several active network management schemes have been proposed to mitigate the issues associated with DERs integration into the grid and ultimately reduce the network power losses. This paper provides a comprehensive review of these schemes along with a discussion on the network modelling and load profiling. Further, it also reports the possible future research areas in the field of losses management.

The increasing penetration of distributed generation has lead international authorities to integrate the rules for the connection of active end-users to distribution networks. Thus, power regulating functions aiming at supporting the voltage and frequency stability of the main grid have been recently introduced in European grid codes. In this paper, the consequences of adopting such regulating functions have been examined in detail. In particular, the risk of uncontrolled islanding on a Medium Voltage network with increasing amount of embedded generation connected to Low Voltage subsystems has been studied. Both existing regulating requirements, such as active and reactive power modulation according to locally measured frequency and voltage, and additional stabilizing functions, such as Inertia Emulation and Fast Voltage Support, have been investigated. Results of dynamic simulations, carried out making use of DIgSILENT PowerFactory 2016 software, demonstrate the interactions between stabilizing functions, generators protection systems and network automatic reclosing procedures.

As a consequence of the increasing penetration of distributed generation from renewable energy sources into power systems, international authorities have provided the rules for the connection of active end-users to distribution networks. Power regulating functions have been recently introduced in European grid codes aiming to support voltage and frequency stability. In this paper, the effects of the adoption of such regulating functions have been widely examined, emphasizing the risk of uncontrolled islanding on a Medium Voltage network as the amount of static generators connected to Low Voltage subsystems increases. The study investigates the performances of both existing regulating requirements, such as active and reactive power modulation according to local frequency and voltage, and the additional contribution of further stabilizing functions, such as Inertia Emulation and Fast Voltage Support. Furthermore, the interaction between power regulating rules, generators protection systems and automatic reclosing procedures applied by the Distribution System Operator to circuit breakers at sending end of Medium Voltage feeders, are investigated. The presented results, carried out making use of DIgSILENT PowerFactory software, well demonstrate the correlation between regulating functions applied to generators and the islanding phenomenon.