This paper presents a review of advanced control techniques for microgrids. covers decentralized, distributed, and hierarchical grid-connected islanded At first, decentralized microgrids are reviewed. Then, the recent developments in stability analysis controlled discussed. Finally, that mimic behavior mains grid is

The recently introduced proportional-resonant (PR) controllers and filters, their suitability for current/voltage control of grid-connected converters, are described. Using the PR controllers, converter reference tracking performance can be enhanced previously known shortcomings associated with conventional PI alleviated. These include steady-state errors in single-phase systems need synchronous d–q transformation three-phase systems. Based on similar theory, filters also used generating...

This paper proposes a hybrid ac/dc micro grid to reduce the processes of multiple dc-ac-dc or ac-dc-ac conversions in an individual ac dc grid. The consists both and networks connected together by multi-bidirectional converters. AC sources loads are network whereas tied network. Energy storage systems can be links. proposed operate grid-tied autonomous mode. coordination control algorithms for smooth power transfer between links stable system operation under various generation load...

This paper summarizes the main problems and solutions of power quality in microgrids, distributed-energy-storage systems, ac/dc hybrid microgrids. First, enhancement grid-interactive microgrids is presented. Then, cooperative control for enhance voltage harmonics unbalances reviewed. Afterward, use static synchronous compensator (STATCOM) grid-connected introduced order to improve sags/swells unbalances. Finally, coordinated distributed storage systems explained.

This paper investigates on power-sharing issues of an autonomous hybrid microgrid. Unlike existing microgrids which are purely ac, the microgrid studied here comprises dc and ac subgrids interconnected by power electronic interfaces. The main challenge is to manage flows among all sources distributed throughout two types subgrids, certainly tougher than previous efforts developed for only or wider scope control has not yet been investigated, would rely coordinated operation sources,...

The virtual impedance concept is increasingly used for the control of power electronic systems. Generally, loop can either be embedded as an additional degree freedom active stabilization and disturbance rejection, or employed a command reference generator converters to provide ancillary services. This paper presents overview virtual-impedance-based strategies voltage-source current-source converters. output shaping attained by impedances generalized first using impedance-based models....

This paper concentrates on the design, control, and implementation of an LCL-filter-based shunt active power filter (SAPF), which can effectively compensate for harmonic currents produced by nonlinear loads in a three-phase three-wire system. With LCL added at its output, proposed SAPF offers superior switching suppression using much reduced passive filtering elements. Its output thus have high slew rate tracking targeted reference closely. Smaller inductance also means smaller voltage drop...

Z-Source inverters have recently been proposed as an alternative power conversion concept they both voltage buck and boost capabilities. These use a unique impedance network, coupled between the source converter circuit, to provide properties, which cannot be achieved with conventional voltage-source current-source inverters. To facilitate understanding of Z-source inverter modulation, this paper presents detailed analysis, showing how various pulse-width modulation strategies can modified...

Multiloop control strategies have commonly been used to power inverters of both the voltage-source and current-source topologies for conversion applications including uninterruptible supplies utility interfaces distributed generation. However, these tend be developed comparatively evaluated a particular application, with other presented as independent new developments. This paper presents generalized analysis different multiloop approaches using alternative feedback variables several...

Most of the many reported control algorithms for uninterruptible power supplies (UPSs) use either filter inductor or capacitor currents as feedback variables to regulate output voltage. This paper explores fundamental performance issues associated with these quantities variables, a view determining their contribution transient system response and harmonic compensation in any particular situation. A proportional plus resonant (P+resonant) compensator is then added into outer voltage...

This paper investigates the inherent damping characteristic of LCL- filters for three-phase grid-connected voltage source inverters. Specifically, it is found that when converter-side current used implementing feedback control, there will be an term embedded in control loop, which can neutralize resonance introduced by filters. Theoretical analysis then presented to suggest a general design guideline choosing values grid- and inductors, so optimum naturally achieved solely using converter...

The coexistence of ac and dc subgrids in a hybrid microgrid is likely given that modern distributed sources can either be or dc. Linking these power converter, whose topology should preferably not too unconventional. This to avoid unnecessary compromises reliability, simplicity, industry relevance the converter. desired operating features then added through this interlinking To demonstrate, an appropriate control scheme now developed for controlling objective keep autonomous operation with...

This paper presents a three-phase four-wire grid-interfacing power quality compensator for microgrid applications. The is proposed use with each individual distributed generation (DG) system in the and consists of two four-phase-leg inverters (a shunt series), optimally controlled to achieve an enhancement both within currents flowing between utility system. During grid voltage unbalance, can compensate all unwanted positive-, negative-, zero-sequence voltage-current components found...

This paper investigates active damping of LCL-filter resonance in a grid-connected voltage-source converter with only grid-current feedback control. Basic analysis the s-domain shows that proposed technique negative high-pass filter along its path is equivalent to adding virtual impedance across grid-side inductance. added more precisely represented by series RL branch parallel The inductance helps mitigate phase lag caused time delays found digitally controlled system. mitigation phase-lag,...

Impedance-source networks cover the entire spectrum of electric power conversion applications (dc-dc, dc-ac, ac-dc, ac-ac) controlled and modulated by different modulation strategies to generate desired dc or ac voltage current at output. A comprehensive review various impedance-source-network-based converters has been covered in a previous paper main topologies were discussed from an application point view. Now Part II provides most popular control for impedance-source network-based...

Resonant poles of LCL filters may challenge the entire system stability especially in digital-controlled pulse width modulation (PWM) inverters. In order to tackle resonance issues, many active damping solutions have been reported. For instance, a notch filter can be employed damp resonance, where frequency should aligned exactly resonant filter. However, parameter variations as well time delay appearing digital control systems will induce drifting, and thus break this alignment, possibly...

Single-phase ac/dc or dc/ac systems are inherently subject to the harmonic disturbance that is caused by well-known double-line frequency ripple power. This issue can be eased through installation of bulky electrolytic capacitors in dc link. Unfortunately, such passive filtering approach may inevitably lead low power density and limited system lifetime. An alternative use active decoupling so diverted into other energy storage devices gain an improved performance. Nevertheless, all existing...

Voltage-type Γ-Z-source inverters are proposed in this letter. They use a unique Γ-shaped impedance network for boosting their output voltage addition to usual voltage-buck behavior. Comparing them with other topologies, the lesser components and coupled transformer producing high-gain modulation ratio simultaneously. The obtained gain can be tuned by varying turns γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ΓZ</sub> of within narrow range...

Active damping and harmonic compensation are two common challenges faced by LCL-filtered voltage source converters. To manage them holistically, this paper begins proposing a virtual RC damper in parallel with the passive filter capacitor. The is actively inserted feeding back capacitor current through high-pass filter, which indirectly, furnishes superior features. They mitigation of phase lag experienced conventional avoidance instability caused negative resistance unintentionally....

This paper presents a distributed control scheme for reliable autonomous operation of hybrid three-port ac/dc/distributed storage (ds) microgrid by means power sharing in individual network, exchange between ac and dc networks, management among three networks. The proposed includes: 1) fully decentralized control, which is achieved local (LPS) or global (GPS) throughout ac/dc (SPS) storages. Upon each module can operate independently without communication links. would benefit riding through...

The second-order generalized integrator based quadrature signal generator (SOGI-QSG) is able to produce in-quadrature signals for many applications, such as frequency estimation, grid synchronization, and harmonic extraction. However, the SOGI-QSG sensitive input dc components with unknown frequencies (e.g., interharmonics). To overcome drawback, this letter begins by analyzing dynamic response of from first-order system (FOS) perspective. A (SO-SOGI-QSG) a fourth-order transfer function...

This paper presents a transformerless inverter topology, which is capable of simultaneously solving leakage current and pulsating power issues in grid-connected photovoltaic (PV) systems. Without adding any additional components to the system, caused by PV-to-ground parasitic capacitance can be bypassed introducing common-mode (CM) conducting path inverter. The resulting ground therefore well controlled below regulation limit. Furthermore, proposed also eliminate well-known...

This paper addresses the harmonic stability resulting from current-control interactions of multiparalleled, LCL-filtered voltage-source converters. First, an alternative impedance model is proposed for single-loop current control. The control output admittance converter decomposed into a passive filter in series with active admittance, which dependent on controller and time delay. frequency-domain passivity theory then applied to system analysis. It reveals that region grid not only delay,...