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Microgrids (MGs) have emerged throughout the world as the major means of integrating a variety of distributed energy resource (DER) technologies into the distribution system. These DER technologies are mostly coupled through electronic power converters (EPCs). This fact has created new operation challenges as these converter-interfaced DERs could compromise the MG stability, reliability, and resilience margins. On the other hand, induction motor-type loads (IMs) are dynamic loads with the greatest incidence in distribution grids. Air conditioning (A/C) type loads have IMs among their components. IMs demand considerable amounts of reactive power for their correct operation. In particular, when there are disturbances in MGs with high penetration of these types of loads, the phenomenon of fault-induced delay voltage recovery (FIDVR) occurs. This phenomenon causes problems with the dynamic voltage stability (DVS) due to the deficit and inability to supply reactive power of the DERs generator park composing the MG, which could lead to a voltage collapse. To face these new issues, this work proposes an approach to incorporate flexible ac transmission system (FACTS) controllers, such as an SVC and a DSTATCOM, into the grid as reactive power supply resources for improving the microgrid dynamic voltage stability. The proposal includes the design, optimal location, and dynamic modeling of FACTS devices aiming at enhancing MG operation resilience. For validation of the developed methodology, an MG test system reported in the literature and a real microgrid system of the Galapagos Islands in Ecuador have been used. The results demonstrated the superiority of DSTATCOM over SVC in enhancing DVS, FIDVR mitigation, and consequently operational resilience.

The three-phase DSTATCOM is prone to higher dynamics due to grid disturbances. The proportionate affine projection algorithm (PAPA) is an adaptive filter that can be used for DSTATCOM control. In order to overcome the sluggish convergence speed of adaptive filters, PAPA is proposed in this paper. The convergence rate versus the steady-state error is a trade-off in conventional adaptive filters. However, the utilization of two adaptive filters in CSS-PAPA increases the convergence and decreases the steady-state error. The suggested filter has the advantage of having a lower computational cost than a standard adaptive filter. The proposed filter helps the inverter to work as a shunt compensator. The goal of the suggested controller is to adjust for reactive power and unity power factor during faulty conditions. The proposed DSTATCOM controller has undergone experimental validation in the laboratory.

A droop controlled microgrid with distribution static compensator (DSTATCOM) is developed to improve the power quality in this study. Due to the reactive power/voltage Q-V droop characteristic and the existence of the unbalanced, linear inductive and nonlinear loads, the power quality problems, including the voltage drop, unbalanced currents, lagging power factor (PF) and current harmonics, are very serious in the islanded microgrid. Moreover, owing to the instantaneous power following into or out of the DC-link capacitor of the DSTATCOM under load variation, the performance of the DSTATCOM for power quality improvement is seriously degenerated. Hence, to effectively improve the power quality of the droop controlled microgrid and the transient response of the DC-link voltage of the DSTATCOM under load variation, an online trained polynomial petri fuzzy neural network (PPFNN) controller is firstly proposed as the DC-link voltage controller to supersede the conventional proportional-integral (PI) controller in the DSTATCOM. The network structure and the online learning strategy of the proposed PPFNN are detailedly derived. Finally, the effectiveness of the DSTATCOM using the proposed PPFNN controller to improve the unbalanced currents, the total harmonic distortion (THD) reduction of the current and to compensate the reactive power for the voltage support and PF correction in the droop controlled microgrid is certified.

The phase and frequency correction with a three-phase grid-connected solar photovoltaic-distributed static compensator (SPV-DSTATCOM) is challenging. For grid-connected SPV-DSTATCOM, this paper proposes a cascaded enhanced second-order general integrator frequency locked loop with prefilter (CESOGI-FLL-WPF) controller. The suggested work uses the available SPV power to meet the active power requirement of local loads. Furthermore, after addressing the local load demands, the extra SPV power is pumped into the grid. The voltage source converter (VSC) operates as a DC/AC inverter when sunlight is available and as a DSTATCOM when sunlight is not available. As a result, the VSC contributes to reactive power compensation, improved power quality, improved power factor, zero voltage regulation, efficient load balancing, and increased device utilization. The CESOGI-FLL-WPF controller is able to extract the fundamental components from nonlinear load currents, resulting in superior harmonics compensation and a highly rapid and stable dynamic response of the overall system under varied conditions. The suggested system is modelled and simulated using the MATLAB/Simulink software. The proposed SPV-DSTATCOM prototype is tested in the laboratory to ensure that it performs as expected.

In the current scenario, integration of renewables, growth of non-linear industrial and commercial loads results in various power quality issues. Among commercial utilities connected to the grid, hospital-operated loads include sensitive, linear, non-linear, and unbalanced loads. These loads are diverse as well as prioritized, which also causes major power quality issues in the local distribution system. Due to its widespread divergence, it leads to harmonic injection and reactive power imbalance. Distribution Static Compensator (DSTATCOM) is proposed as a solution for harmonic mitigation, load balancing, reactive power imbalances, and neutral current compensation. The present work utilizes Interval Type-2 Fuzzy Logic Controller (IT2FLC) with Recursive Least Square (RLS) filter for generating switching pulses for IGBT switches in the DSTATCOM to improve power quality in the Local Distribution Grid. The proposed approach also shows superior performance over Type 1 fuzzy logic controller and Conventional PI controller in mitigating harmonics. For effective realization, the proposed system is simulated using MATLAB software.

Optimal planning of integration the Photovoltage Distributed Generation (PV-DG) and DSTATCOM is a crucial task due to the stochastic variations of PV output power and the load demand which are related to solar irradiance variations and the activities of the customers, respectively. In this article, the optimal planning problem of the PV-DG and DSTATCOM system is solved. The proposed model considers the uncertainties of the solar irradiance and the load demand for a multi-objective function, including the cost reduction, the voltage profile, and stability index improvement. Modified Ant Lion Optimizer (MALO) is proposed to enhance the basic ALO searching ability using two strategies. The first strategy is based on Levy Flight Distribution (LFD) to strengthen the exploration of the algorithm and avoid the premature of the basic ALO. In contrast, the second strategy is based on updating the solutions in a spiral orientation to improve the exploitation of the algorithm. The IEEE 69-bus and 118-bus radial distribution systems are used to demonstrate the effectiveness of the proposed method, and the yielded simulations are compared with the basic ALO and other well-known optimization techniques for power loss minimization under deterministic conditions. The simulation results demonstrate that the techno-economic benefits can be increased considerably by optimal inclusion of two PV-DGs and DSTATCOMs compared with a single system.

This work deals with a single-stage three-phase grid-connected solar photovoltaic distribution static compensator (SPV-DSTATCOM) under partial shading condition (PSC). During PSC, the SPV-DSTATCOM is connected to the distribution network to solve issues like active current sharing, reactive power control, and harmonic elimination. The conventional Proportional Resonant (PR) controller for SPV-DSTATCOM behaves as a notch filter at resonance frequency with high gain of magnitude and has less DC offset rejection capability. Here, an improved PR based on second-order generalized integrator (IPR-SOGI) control architecture with unity gain at the fundamental frequency and more DC offset rejection capability is presented to address the drawback of the conventional PR controller. The performance of the proposed controller is examined under different loading conditions in steady-state and dynamic conditions. Finally, a comparison between the proposed controller with the conventional PR controller and adaptive PR controller are provided with the experimental validation.

This paper proposes a mathematical fractional order modelling of Voltage Source Converters (VSC). Fractional behaviour helps to model and describe a real object more accurately than the integer order model. State-space equations of VSC is obtained using fractional calculus in d-q domain. The Caputo derivative method is employed to eliminate complex definitions of fractional calculus and to get approximate solution with optimal design of parameters. A detailed analysis is performed on developed mathematical fractional order model of VSC including small-signal analysis and DC analysis. The stability and time-domain transient analysis is carried out to validate the fractional order VSC for its application as Distribution STATtic COMpensator (DSTATCOM) in power distribution system, using real-time simulator. Fractional-order capacitor and inductor are designed and modelled for verification of fractional order VSC through simulations. The real-time simulation results verify the effectiveness of proposed model. It shows that fractional order model can describe the operating characteristics of VSC more accurately. The comparative performance analysis demonstrates superior transient response in case of fractional order devices as compared to integer order.