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Microgrids/nanogrids of prosumers must be able to adapt to new business opportunities related to energy trading. Therefore, highly accepted hierarchical control strategies should be modified to allow deliberate energy interchange among prosumers, even when the microgrid they are integrated in, operates islanded. This is the main contribution of this paper, as energy exchange between prosumers is rarely addressed when they are islanded from the main grid. This work proposes a comprehensive hierarchical control strategy for a multibus nanogrid of prosumers, each of them having photovoltaic generation, battery energy storage systems and loads, in such a way that different voltage and power setpoints for each prosumer allow such energy interchange. Power flow inside the nanogrid is controlled to guarantee the technical feasibility of the obtained setpoints. The proposed control strategy is defined and experimentally validated in both islanded and grid-connected modes, by means of a laboratory-scale prototype. In addition, a smooth transition between the two modes is demonstrated. An adequate capability of the power converters to follow setpoints is proved, with acceptable transient behavior.

Although there is a growing interest in developing fast charging methods to enhance the Electric Vehicles’ appeal, the main energy supply is still the single-phase outlet. While single-phase charging may be simpler than three-phase, there are challenges in the integration of the propulsion and charging systems without adding inductive grid filters. Such integration would bring benefits like the simplification and reduction of components, costs, volume or weight. This can be achieved by using the windings of the propulsion machine as grid filters, but the use of the electric motor as a grid inductive filter leads to the generation of pulsating torque during the charging state. This translates into vibration, noise and eventually, damage to the motor and other components of the system. In this work, the authors propose a control strategy that considerably reduces the peaks of pulsating torque generated in any rotor position while using the machine wingdings as filter. Simulation tests have been carried out to validate the control strategy, taking into account the system efficiency. Finally, experiments are conducted to prove that the reduction of the torque pulsation is achieved.

Integration of renewable energy sources, active role of consumers, and energy management systems is currently among research priorities in energy systems. This paper proposes an innovative coordinated energy scheduling for a microgrid of neighbor prosumers with different consumption patterns. All prosumers have photovoltaic generation systems, Li-ion batteries as energy storage systems, and regular household loads. A genetic algorithm is used to schedule each prosumer's battery charge/discharge, with the aim of reducing energy exchange losses by minimizing the power in the point of interconnection of the microgrid with the main grid, with several advantages compared to classical optimization objectives, and without worsening battery lifespan degradation. Individual and coordinated strategies are compared, and self-consumption and self-sufficiency of the prosumers’ set are evaluated with the aim of showing the advantage of coordination. The paper concludes that coordinated operation can contribute to improve the exploitation of energy resources in the prosumer microgrid, reducing the amount of energy interchanged with the distribution grid by approximately 13%, and, at the same time, avoiding increasing the battery cycling and consequent degradation.

This work is based in the cascade connection of several H-bridges as input side of a multiport smart transformer. This paper is focused on finding the best control strategy for this stage, turning from previous individual controllers to a centralized control. This control strategy must guarantee a stable voltage in the DC bus of the desired value, and achieve a unity power factor. In addition, it has been solved another problem derived from applying the control strategy, that was a distortion in the input current caused by a third harmonic component.

This article is about the cascade connection of several H-bridges as the input side of a multi-port Smart Transformer. The paper discusses its unipolar control strategy with two different modulation techniques by connecting different loads in each module or port. The operation of both techniques and the distribution of voltage and current is analyzed using co-simulation with PSIM and SIMULINK. The best technique is determined with the study from the harmonic and efficiency point of view.

In this article a power flow control strategy based on proportional-resonant current controller in a three-phase 3L-T-type qZSI connected to the grid to regulate the active power flow exchanged with the main grid is analyzed. This topology is quite promising in renewable energy application as the photovoltaic systems. The different components of the system are described and calculated as well as the control strategy, the current control loop based on αβ stationary reference frame and the special modulation method which includes alternating shoot-through states between upper and lower impedance networks. Simulation results illustrate and validate the proposed solution.

Since most power electronics used in photovoltaic (PV) inverters at commercial and industrial facilities exhibit behavior as non-linear loads from the grid side, these high-power demand installations are expected to have a major impact on the network&rsquo, s power quality. In an attempt to facilitate their integration into the distribution grid, this paper presents a comprehensive control strategy for Quasi-Z Source T-Type PV inverters inside a facility, which performs active and reactive power control, and harmonic and imbalance compensation at expenses of the spare inverter power capacity. Unlike other approaches, the one proposed here operates properly under distorted and unbalanced grid voltages. The electrical network structure inside a commercial and industrial facility is considered, analyzing the operation of the proposed strategy on three-phase PV inverters. The power topology used has voltage boosting ability, which eliminates the requirement for both an additional DC-DC converter and/or a step-up transformer commonly used in PV inverter systems. The proposed strategy performance is demonstrated on a 50 kW converter model under a disturbed grid environment and changing load conditions.

Smart transformers are considered a crucial part of future smart grids as they will operate as the energy router and be able to control the power flows from and to the microgrids since they are placed in the border. A multi-port transformer can integrate different energy resources, loads and energy storage systems, optimizing the power flows between these elements. Combining both concepts, a multi-port smart transformer is obtained that is able to integrate efficiently distributed and renewable energy resources, electric vehicle chargers, prosumers and energy storage in both AC and DC microgrids. Nevertheless, the operation of these transformers, composed of several modules connected in series to the high-voltage grid is not easy, mainly due to the different power consumed or generated by each module. In this paper this issue is analyzed and different operation strategies for coordinating the series-connected modules at the input side are studied by simulation. The paper will expose how it is possible to extend the proper operation of the system if a reactive power controller is implemented.

Smart grids aim to dramatically change residential area energy systems by creating active grid interaction. Specifically, renewable energies will play a key role when it comes to handling energy storage systems (ESS) at houses within a Smart Community. This paper presents a novel global control strategy for distributed micro-storage energy system. Each home receives the active and reactive power set- points from the Smart Community Energy Management System (SCEMS), providing energy resources to the community in function of the expected demand and production. Once SCEMS requirements are fulfilled, harmonic current components demanded by the household circuitry are injected according to the ESS available capacity. The proposed approach not only causes a local improvement in the power quality of the demanded current, but also contributes to the global power quality consumption of the community. Experimental tests are conducted using a prototype of the proposed ESS charger, validating the control strategies.

It is usual in literature that power sharing among grid-forming sources of an isolated microgrid obeys their energy rating, instead of economic agreements between stakeholders, and circulating energy among them is usually avoided. However, these energy interchanges make strong sense and classical power sharing methods must be reformulated in the context of prosumer-based microgrids. This paper proposes a secondary control method for a prosumer-based low-voltage nanogrid that allows for energy interchange between prosumers, where storage systems, together with PV generators, are the controllable grid-forming sources. A power flow technique adapted to islanded microgrids is used for secondary control algorithm and the whole hierarchical control strategy for the prosumer converter is simulated and validated. This hierarchical control consists of three stages: tertiary control plans the energy interchange among prosumers, secondary obtains different voltage and power setpoints for each of the grid-forming sources, and, finally, primary control guarantees stable voltage and frequency values within the nanogrid with droop rules. Inner control loops for the power converter are also defined to track setpoints and assure stable performance. Simulation tests are carried out, which prove the stability of the proposed methods and the accuracy of the setpoint tracking.

Based on the assumption that vehicles served by petrol stations will be replaced by Electric Vehicles (EV) in the future, EV public charging station facilities, with off-board fast chargers, will be progressively built. The power demand of these installations is expected to cause great impact on the grid, not only in terms of peak power demanded but also in terms of power quality, because most battery chargers behave as non-linear loads. This paper presents the proposal of a novel comprehensive global control strategy for the power electronic converters associated with bidirectional three-phase EV off-board fast chargers. The Charging Station facility Energy Management System (CS-EMS) sends to each individual fast charger the active and reactive power setpoints. Besides, in case the charger has available capacity, it is assigned to compensate a fraction of the harmonic current demanded by other loads at the charging facility. The proposed approach works well under distorted and unbalanced grid voltages. Its implementation results in improvement in the power quality of each fast charger, which contributes to improvement in the power quality at the charging station facility level, which can even provide ancillary services to the distribution network. Simulation tests are conducted, using a 100 kW power electronic converter model, under different load and grid conditions, to validate the effectiveness and the applicability of the proposed control strategy.

This paper studies an operation strategy for a single-phase grid-connected 3LT-type qZSI to regulate the active and reactive power flows. This topology is quite promising in photovoltaic system. The different elements are properly calculated, providing simulation results with a good concordance with the theoretical predictions.

In this paper a detailed analysis of a bidirectional buck boost converter used for charging/discharging a supercapacitor is carried out. The analysis takes into account conduction parameters of semiconductors and resistances of inductors, determining the variation of different performance indeces when the charge (and voltage) of supercapacitor varies.

The boost feature that characterizes Z-source and quasi-Z-source converters is usually achieved by means of a proper insertion of short-circuit states in the full DC-link. In this work, a novel pulse width modulation carrier-based strategy for a three-phase, three-level T-type, quasi-Z-source inverter is introduced, based on the addition of alternate short-circuits in the two halves of the DC-link bus. This technique achieves better performance, less electromagnetic interference, and lower harmonic distortion of the output line-to-line voltage compared to the traditional methods based on the full DC-link shoot-through. At the same time, generating the switching states is to easy implement. The proposed strategy permits the use of electronic devices with lower blocking voltage capability, thus improving converter reliability, size, and cost. The new method may be implemented in another multilevel inverter with an impedance-source network as well. A comprehensive simulation study is performed in order to validate the adopted method, with different inverter input voltages, which is taken as representative of a photovoltaic array. Comparisons are conducted with conventional strategy insertions using the same topology in order to show the improvements achieved.

El presente articulo presenta una guia de buenas practicas para el diseno, ejecucion y operacion de instalaciones que suministran energia electrica a infraestructuras criticas o a equipos cuyo funcionamiento sea esencial. El objetivo es disminuir el riesgo de interrupciones de suministro y/o minimizar su duracion, considerando tanto el caso de causa interna como el de externa a la propia instalacion. Este trabajo aporta una vision global, actualizada y basada en la experiencia practica profesional de los autores, recogiendo recomendaciones, tanto para la instalacion receptora como para los equipos de alimentacion propios, y comentando como afectan estas medidas a la fiabilidad de la instalacion. Palabras clave: Continuidad del suministro electrico, fiabilidad, infraestructuras criticas, suministro complementario, redundancia de instalaciones

grant number TEC2016-77632-C3-1-R (AEI/FEDER, UE). UID/EEA/00066/2013. Microgrids of prosumers are a trendy approach within the smart grid concept, as a way to increase distributed renewable energy penetration within power systems in an efficient and sustainable way. Single prosumer individual management has been previously discussed in literature, usually based on economic profit optimization. In this paper, two novel approaches are proposed: firstly, a different objective function, relative to the mismatch between generated and demanded power, is tested and compared to classical objective function based on energy price, by means of a genetic algorithm method; secondly, this optimization procedure is applied to batteries’ coordinated scheduling of all the prosumers composing a community, instead of single one, which better matches the microgrid concept. These approaches are tested on a microgrid with two household prosumers, in the context of Spanish regulation for self-consumption. Results show noticeably better performance of mismatch objective function and coordinated schedule, in terms of self-consumption and self-sufficiency rates, power and energy interchanges with the main grid, battery degradation and even economic benefits. published

TEC2016-77632-C3-1-R (AEI/FEDER, UE) Sem PDF conforme despacho. The proliferation of residential photovoltaic (PV) prosumers leads to detrimental impacts on the low-voltage (LV) distribution network operation such as reverse power flow, voltage fluctuations and voltage imbalances. This is due to the fact that the strategies for the PV inverters are usually designed to obtain the maximum energy from the panels. The most recent approach to these issues involves new inverter-based solutions. This paper proposes a novel comprehensive control strategy for the power electronic converters associated with PV installations to improve the operational performance of a four-wire LV distribution network. The objectives are to try to balance the currents demanded by consumers and to compensate the reactive power demanded by them at the expense of the remaining converters’ capacity. The strategy is implemented in each consumer installation, constituting a decentralized or distributed control and allowing its practical implementation based on local measurements. The algorithms were tested, in a yearly simulation horizon, on a typical Portuguese LV network to verify the impact of the high integration of the renewable energy sources in the network and the effectiveness and applicability of the proposed approach. publishersversion published

The upgrade of power systems in the last years due to the proliferation of distributed generation with renewable energy sources, active users and electric vehicles has become a challenge. In this new scenario, prosumers play an important role in order to buffer the consumption curve and, therefore, contributing to the grid requirements. Special attention is attracted by photovoltaic (PV) arrays integrated in residential buildings, because they can be complemented with energy storage systems (ESSs), such as batteries or ultracapacitors (UCs) or even a combination of both, with the aim to achieve that customers could manage their energy. The above reasons justify the need of an energy management system (EMS) that coordinates the operation of the energy storage devices in an optimized way, as they are expensive. In this paper, a comprehensive control system is proposed to exchange energy between the hybrid storage devices (batteries and UCs) of two dwells with PV installations in order to increase the availability of their ESSs and support the energy requirements during the most time possible, optimizing sizes and costs and avoiding saturation.

In recent years, power systems have experimented a great development as a consequence of the apparition of the distributed generation. Renewable energy sources, active users and electric vehicles play a fundamental role in power systems, which has supposed a new topic research. In this scenario, the figure of prosumer has gained relevance due to the multiple advantages that they can contribute to improve the behavior of power systems and to achieve energy and cost savings. In particular, special attention is focus on photovoltaic (PV) arrays integrated in residential buildings with energy storage systems (ESSs), such as batteries or ultracapacitors (UCs) or even a combination of both in a hybrid energy storage system (HESS). This paper presents an energy management strategy to exchange energy between the batteries and the UCs that form a HESS installed with a PV array in a prosumer dwell in order to maintain its UC bank available to support the energy requirements during the most time possible.

In this line, this chapter aims to provide an analysis of distributed microstorage energy systems at the residential level to contribute to smart grid goals. The chapter is organized in five sections as follows: first an overview of micro-storage technologies, including the state of the art, is presented. It will also be shown the advantages when using different ESS unified in a hybrid energy storage system (HESS), achieving best parameters for specific applications than the ESS operating individually. The second section is devoted to the suitable topologies for the bi-directional electronic converter responsible for the flux between the micro-storage energy system located at home and the grid by means of the smart community energy management system (SCEMS). Afterwards, in the third section control strategies for the ESMS of the microstorage device are proposed, following different compensation objectives from the set-points provided by the SCEMS. Furthermore, these strategies will ensure at all times safety and will improve the efficiency and lifetime of the ESS. In the fourth section, the attention is paid to the power interfaces for the integration of ESS into the grid to adapt the requirements of distributed microstorage system in a smart community with high penetration of photovoltaic systems.

This paper proposes a comparative analysis of control strategies for active power flow between a smart community grid and an energy storage unit located in a house of the community, which is connected to the grid by a bidirectional charger. These strategies are applied to the bidirectional DC/DC converter of the charger and include an improved precharge stage of the storage unit, based on the gain scheduling method. The gain-scheduled controller aims to extend the lifetime of the battery reducing the stress and peak current values. The control strategies are compared and validated by using an experimental prototype of the charger. Experimental results are included.

This paper aims to provide control strategies for distributed micro-storage energy systems at the residential level to contribute to smart grid goals. A simulation model of an energy storage system (ESS) charger has been implemented to test these proposed control strategies. The smart community energy management system (SCEMS), acting as an aggregator of resources in the community according to the expected demand and production, sends to each individual home the active and reactive power set-points. Besides, in case the ESS has available capacity, once the SCEMS requirements are satisfied, it is used to absorb the harmonic current components demanded by the household circuitry. It allows a local improvement in the power quality of the demanded current, and thus contributes to the global power quality consumption of the community. Simulation results showing the operation of a local ESS at a home in a Smart Community are presented to validate the proposed control strategies.

This paper presents a cooperating converter that interfaces a Low-Voltage Energy Storage System with the electrical grid. In this paper, Low-Voltage is consider a voltage that is much lower than the minimum DC voltage required for controlling properly the current of the grid connected inverter. Energy Storage Systems operating at Low-Voltage usually require in conventional applications the inclusion of a step down converter or transformer, the solution proposed in this paper avoids the inclusion of this transformer. The proposed solution is also able to fully discharge the Energy Storage System if supercapacitors are used. in comparison with other solutions where a minimum operative voltage should by maintained, producing that a residual energy to be always stored and reducing the storing capacity of the system. The correct performance of the proposed solution is validated by simulation.

This paper aims to provide control strategies for distributed micro-storage energy systems at the residential level to contribute to smart grid goals. The operation of local Energy Storage Systems (ESS) at homes in a Smart Community with distributed generation based of renewable energies is analyzed by simulation. Each individual home receive the active and reactive power set-points from the Smart Community Energy Management System (SCEMS), acting as an aggregator of resources in the community according to the expected demand and production. Besides, in case the ESS has got available capacity, once the SCEMS requirements are satisfied, it is used to inject the harmonic current components demanded by the household circuitry. It allows a local improvement in the power quality of the demanded current, and so contributes to the global power quality consumption of the community. Simulation results showing the operation of the local ESS are presented to validate the proposed control strategies.

Electric vehicles (EV) can be used as distributed energy storage devices to provide to the smart grid different regulation services. However, to have enough impact in the grid, the trend is to jointly manage a set of EV by means of a new stakeholder called aggregator. Knowing the availability, mobility habits, and the state of charge (SOC) of each EV battery, the aggregator performs the allocation of an active and/or reactive set-point to each EV within a time slot. This paper aims to propose reference charger currents for each EV from the individual set-point received by an aggregator. Control strategies for bidirectional active power control are compared under ideal and distorted source conditions. Besides, to contribute to reactive power support and voltage control in the bus where the set of EVs are connected, a reactive control strategy is proposed and validated by simulation. The proposed control strategies are applied to a Mode 2 single-phase EV battery charger connected to a single-phase grid. Simulation tests have been conducted using different control strategies and active/reactive set-points provided by the aggregator.

This contribution presents a smart power electronics injection system for grid-connected photovoltaic energy resources. The developed converter can not only inject the maximum active power as a typical inverter does, but also provide the active functions the Smart Grid scenario needs, including reactive power reference tracking for compensating purposes, node voltage regulation for helping the grid when there are undervoltages or overvoltages, grid harmonic distortion elimination due to non-linear loads and active power reference tracking with the addition of an energy storage system, based on ultracapacitors, for managing the discontinuities of the photovoltaic energy. The topology is composed by an inverter that interfaces the photovoltaic array with the grid and a bidirectional DC-DC converter for the energy storage. The control system is based on d-q current control theory guided by a reference power point tracking method. Simulation test bench has been developed with the objective of testing the control system.

A novel multiconverter conditioner topology and its control stage are proposed in this paper. It is formed by an active conditioner in parallel with a hybrid conditioner composed of an active filter in series with one or more passive filters. This topology allows the reduction of the inverter ratings, constituting an effective solution at high-power levels. Collaborative control strategies are developed for the new topology, which share the compensation objectives between the two converters. These control strategies and the tracking techniques are based on estimating the load current, achieving new algorithms with a reduction in the number of meters in the control stage. The conditioner operates properly in three-phase four-wire systems reducing the harmonic distortion and/or imbalance and attaining the unity displacement power factor. Experimental results are included for the testing of the topology and its control.

Nowadays the study of power quality is a critical issue due to the proliferation of “nonlinear” consumers connected to the grid, most of them electronic loads which produce voltage and current waveforms distortion, causing a worse operation of the power system and leading to higher losses. At present, “bad customers” of power energy are only penalized due to reactive power consumption. The measurement of this consumption is made by using conventional energy meters designed to operate under sinusoidal and balanced systems with parametres within the required limits. In this paper the experimental validation of these devices in low voltage power systems with harmonic distortion and imbalance is carried out. Finally, a new ratio is proposed for the electrical billing, to penalize at the same time the reactive power consumption, the harmonic pollution and the imbalance.

This paper presents a new topology for the power injection system that is based on the parallel association of two voltage source inverters. One operates using a quasi-square voltage waveform strategy, and the other operates with a pulsewidth-modulation (PWM)-based strategy. The aims of this topology are to inject the power from the photovoltaic generation system using the quasi-square inverter and to control the current quality using the PWM inverter. The proposal optimizes the system design, permitting the reduction of system losses and an increase of the energy injected into the grid.

This paper presents the control of one cell of a modular single-phase power electronics transformer with active functions for meeting the smart grid concept. In this way, the converter could be used not only as a conventional transformer but also for grid such as reactive power, harmonic elimination and energy storage. The topology of the cell is composed by a bidirectional converter with three stages: a half bridge in the input stage, a dual half bridge in the middle stage and a half bridge in the output stage. Volume, modularity, flexibility, functionalities and cost are better in comparison with the conventional transformer and also more suitable for the smart grid scenario. The control algorithms are based on the dq theory for single-phase systems. A bidirectional converter has been connected to the secondary side for providing energy storage capabilities. The cell plus energy storage converter has been simulated to determine the performance. The obtained results are depicted and discussed.

Proliferation of plug-in electric vehicles obviously involves an interesting potential of electric energy storage for purposes related to smart grids. Among other opportunities, the possibility of providing ancillary services to the distribution grids they are connected to is evaluated in this paper as an added advantage of this kind of vehicles. Issues like aggregation needs, incentives, coordination with the aggregation manager and generation of setpoints, as well as the charging/discharging constraints of PEV batteries depending on the task to be performed are addressed, as an overview of the most recent literature related to the subject.

This paper focuses on the implementation of power electronics algorithms in control platforms based on DSP-FPGA. Today's power electronics technology demands high power computation with high speed interfacing at the same time. The most popular configuration is a DSP for the former and a FPGA for the latter. The main goal of this work was to develop a generic control system for power electronics application, but it is explained for an active power electronic transformer, which will be an active player in the energy storage, management and production game in the smart grids. Thus, demands for the control system are high, so it is mandatory to have a reliable, fast and user friendly control algorithm basis. The control board (SH363) used in this work contains a SHARC ADSP21363 DSP and a CYCLONE II EP2C8F256I8N FPGA. FPGA as a system interface, critical and non-critical communications between DSP and FPGA, including synchronization, and DSP programming are detailed. Also, a PC interface has been developed for an easy debugging and future system management. The methods used to achieve the maximum loop control frequency and the issues found during the implementation are discussed. The performance of the control board of the active power electronic transformer is verified experimentally.

Nowadays in order to know in real time the level of charge existing in a distribution network, the installation of a remote infrastructure of operation and supervision is necessary, allowing an immediate view of its electrical state, both normal operation as well as in case of incident. The analysis of the state of the network provides useful data for the adequate planning of organised maintenance, which in turn also leads to better results and serves as a basis for establishing adequate objectives of substitution or growth of the network. Nevertheless, setting this type of operation and conservation structure up in low voltage levels of distribution requires high levels of investment with lengthy repayment periods, which cannot be met by all the distribution companies. This paper proposes a low cost, short-term method of assessment of the state of charge and voltages in the distribution network, which aids the carrying out of a specific directed maintenance which in turn lowers the incident rate and provides clear objectives for improvement plans based on preventive methods. The proposed method is based principally on the details of customer invoicing, making it the ideal solution where a system of invoicing by telemetry is being used.

A variation of the pulse width modulation (PWM) operating technique, which we call "adjustable carrier PWM," is analyzed. The technique is applied to an active filter in order to compensate the low harmonics present in a load current. The aim is to prove that the proposed technique performs better at minimizing the root mean square (RMS) tracking error between the reference and the real currents than the usual PWM techniques in active filtering. Four generating techniques were simulated and compared in terms of the total and individual harmonic distortion (THD and IHD) in the supply current. The proposed technique was tested against experiments.

In this paper a variation of the Pulse Width Modulation (PWM) operation technique, which we have called "of adjustable ramps", is analysed. This technique will be applied to an active filter in order to compensate the low harmonics content present in a load current. The aim is to prove that the proposed technique, whose objective is minimising the Root Mean Square (RMS) tracking error between the reference and the real currents, achieves a better performance than the usual PWM techniques in active filtering. Simulation results comparing several gen eration techniques will be presented. These techniques will be analysed in terms of the total and individual harmonic distortion (THD and IHDi) in the supply current.

In recent years, power quality has gained importance due to increasing pollution in the electric system as a consequence of the proliferation of non-linear loads connected to the grid. For this reason, research has been intensified on this issue to improve power quality; especially through simulation models development using software tools, which allow studying the possible causes and effects of disturbances on the electric system and testing solutions to mitigate these power quality events. This paper focuses on analyzing by simulation a possible cause, effect and solution of harmonic distortion, as an example of using cloud-based platforms in order to get the power quality requirements of the future Smart Grid.

The future of the grid includes distributed generation and smart grid technologies. Demand Side Management (DSM) systems will also be essential to achieve a high level of reliability and robustness in power systems. To do that, expanding the Advanced Metering Infrastructure (AMI) and Energy Management Systems (EMS) are necessary. The trend direction is towards the creation of energy resource hubs, such as the smart community concept. This paper presents a smart multiconverter system for residential/housing sector with a Hybrid Energy Storage System (HESS) consisting of supercapacitor and battery, and with local photovoltaic (PV) energy source integration. The device works as a distributed energy unit located in each house of the community, receiving active power set-points provided by a smart community EMS. This central EMS is responsible for managing the active energy flows between the electricity grid, renewable energy sources, storage equipment and loads existing in the community. The proposed multiconverter is responsible for complying with the reference active power set-points with proper power quality; guaranteeing that the local PV modules operate with a Maximum Power Point Tracking (MPPT) algorithm; and extending the lifetime of the battery thanks to a cooperative operation of the HESS. A simulation model has been developed in order to show the detailed operation of the system. Finally, a prototype of the multiconverter platform has been implemented and some experimental tests have been carried out to validate it.

Plug-in Electric Vehicles (PEVs) will remain connected to the grid a high percentage of their life-time. During these connections, idle-time will be considerably longer than battery charging time. This fact turns PEV idle-time into a suitable candidate to help in the distribution grid management by implementing active distribution grid functions, leading to the future Smart Grids. In this chapter, conventional ancillary services for distribution grids are presented, including their development in the new context of Distributed Energy Resources (DER), micro grids, smart grid and either in connected or isolated modes. Later, the coordination of the previously discussed services with PEVs is analyzed, mainly considering them as Energy Storage Systems. Then, the optimization problem is presented, empathizing the indexes and constriction that could be taken into account. From the optimization procedure, reference operation setpoints are generated for each individual PEV. Then, the coordination of charger operations for maximizing global impact on the whole distribution grid is developed. Control strategies are presented and analyzed in terms of their operation setpoints in normal and abnormal grid states, when they are expected to control active, reactive and harmonic power. Finally, some examples on how the described strategies can be used for controlling active, reactive and harmonic power using a PEV charger, when the PEV is following the given operation references, are discussed.

This paper analyzes the inductances used at the terminals of an Active Power Line Conditioner (APLC) based on a voltage source inverter (VSI) in some current correction topologies. The criteria to select the optimal inductances values are determined and a novel design criterion, named “control criterion”, is proposed. This novel method is applied to situations where there are sharp current variations as the case of a three phase rectifier feeding a resistive load. A parametrical analysis of the expressions obtained for the inductors is performed, obtaining the intervals of possible values of inductance that can meet the initial specifications. Finally a simulation is carried out to verify how the method presented reaches these specifications.

This paper presents the simulation of a new topology for the power injection system of a single-phase grid connected photovoltaic generation system that is based on the parallel association of two voltage source inverters: one is a 3 level neutral point clamped operated using a low switching frequency strategy and the other is a 2 level inverter which operates with a pulse width modulation based strategy. The aim of this topology is that multilevel inverter injects the power and the other inverter controls the current quality. The DC-link capacitor voltage balancing is solved by using the redundant states of the multilevel inverter. The proposal optimizes the system design, allowing high power injection, permitting reduction of system losses and an increase of the energy injected into the grid.

A single-phase power injection system for photovoltaic generation plants based in two collaborative inverters is presented in this paper. The first converter works as a quasi-square waveform inverter with the main objective of injecting the energy produced by the photovoltaic generation system. The second converter acts as an active power filter with the objective that the current that flows from or to the grid is sinusoidal. The presented power injection system will be able to achieve a sinusoidal current even when a non-linear load is connected to the same point of common coupling. The performance of the proposed system, including the maximum power point tracking algorithm, is evaluated through simulation.

A novel control strategy to extract the reference currents for a shunt active power filter is presented in this paper. The method is a modification of the fundamental voltage synchronization (FVS) and can be applied to single-phase and three-phase three-wire or four-wire systems. Under unbalanced and distorted mains, the load plus the conditioner will demand a balanced and sinusoidal current, with unity displacement power factor. The control stage uses an autoadjustable synchronous reference frame (ASRF) for the synchronization to the positive-sequence fundamental component of the voltage in three-phase utilities or to the fundamental component in single-phase utilities. Experimental results testing the performance of the control strategy in a laboratory prototype in three-phase and single-phase systems are included.

An autoadjustable synchronous reference frame for extracting the positive-sequence fundamental component of the voltage in the point of common coupling is proposed in this paper. It operates suitably under unbalanced and distorted input voltages, with no steady state error in amplitude, phase and frequency tracking. The dynamic response of the method in case of frequency or amplitude variations is good, achieving the steady state in only two cycles of the fundamental period. The method allows a simple adaptation for being used in single-phase systems too. Simulation and experimental results are presented to test the novel method.

A new topology for active power line conditioners is presented in this paper. It is based on the association of two electronic converters with the main objective of minimising the volume of the filtering inductors, what become more significant in high power applications. A control strategy for the two collaborative converters is proposed. power quality, active power line conditioner, power active filter.