Large amounts of active power injection by inverter-interfaced distributed energy resources (DER) is a common cause of overvoltage in low-voltage networks. Hence, local active and reactive power control (i.e., Volt/Watt and Volt/VAR, respectively) are adopted to limit voltage rise, leading to active power curtailment. This paper proposes an automatic control strategy to steer non-dispatchable (nd-DER) and dispatchable (d-DER) inverters in low-voltage networks, mitigating overvoltage through integrated local and coordinated Volt/Watt and Volt/VAR functionalities. Moreover, active power curtailment is avoided whenever possible. The method does not require i ) the implementation of optimization algorithms or ii ) knowledge about line impedance parameters or the location of DERs. The control approach exploits the power flow dispatchability of low-voltage networks comprising one point-of-common coupling with the distribution grid, allowing DERs close to the distribution transformer to also contribute to voltage regulation by only using a low-bandwidth communication link. Simulation results show the flexibilities of the proposed approach and demonstrate that active power injection can be increased by up to 25% for the considered scenario in comparison to conventional local Volt/Watt or Volt/VAR schemes. Experimental results based on a laboratory prototype with three inverter-interfaced DERs certify the applicability of the approach to real-life implementations.

A complete description of an FPGA-based smart energy meter is presented in this paper. By implementing the power quantities definitions of the IEEE 1459-2010 Standard, a novel power quality analyzer capable of performing remote monitoring of electric power systems operating under sinusoidal, non-sinusoidal, balanced and/or unbalanced conditions, was developed. In order to ensure portability, the digital signal processing algorithms implemented on the FPGA device were entirely coded in hardware description languages, and all equations of them are fully described to be applied to any digital signal processing environment. These algorithms are completely defined as functions of the grid fundamental frequency and by adjusting the sampling frequency the adaptability of all modules developed is ensured. Experimental results were obtained using the developed platform in a three-phase 4-wire system operating under several conditions, which were defined by the presence of harmonic components imposed by non-linear loads and supply voltages, as well as, by setting bi-directional power-flow in distributed generation scenarios by employing a Photovoltaic system. Real-time and parallel processes are validated as well.

This work proposes a flexible and comprehensive Internet of Things (IoT) architecture designed for application on smart campuses to build their smart infrastructure and facilitate their transition to becoming smart. The concept of a smart campus is derived from the concept of a smart city, which was developed to demonstrate how urban areas were addressing their new and dynamic challenges by integrating technology and data-driven decision-making. Although the concept of the smart campus was initially conceived to study the smart city in a less complex setting, over time, both concepts have evolved into distinct areas of inquiry, exhibiting unique characteristics and impacts. In general, a smart campus is a university campus where information and communication technologies and IoT are applied to some or all the campus processes, thereby making these processes more efficient, cost-effective and environmentally sustainable for the institution, its members and the surrounding community. Additionally to presenting the proposal for a flexible and comprehensive architecture for a smart campus, this paper also demonstrates its interpretation for implementation on a Brazilian campus transitioning to become smart, the Institute of Science and Technology, Sorocaba (ICTS) – campus of the São Paulo State University (Unesp) in Sorocaba, Brazil. To the best of the authors’ knowledge, there is a scarcity of existing works which address this level of detail when proposing an IoT architecture for a smart campus. The implementation of this architecture has demonstrated that it can be successfully deployed using only open-source technologies. Furthermore, it has been shown that anyone with access to the campus website can access most of the data collected and stored on the system.

This paper introduces a novel control strategy for multifunctional grid-tied inverters in industrial/commercial power systems, aiming to address the compensation of instantaneous power oscillations. The proposed strategy is derived from the Conservative Power Theory, which offers the ability to extract and analyze oscillating power terms directly in the abc frame. To demonstrate the efficacy of the proposed strategy, simulation results are presented, considering a scenario with a three-phase multi-functional grid-tied inverter with an LCL filter operating in a laboratory scale prototype. The power system includes various types of loads, such as linear, non-linear, unbalanced loads and a three-phase induction motor with capacitive compensation. Simulation results show the effectiveness of the proposed strategy in coping with the active power dispatch provided by the inverter, concomitantly ensuring that the induction motor operates with constant torque, as well as that the industrial/commercial electric system operates with improved power quality. Furthermore, the proposed strategy is also validated by means of experimental results obtained from a 3.6 kVA inverter prototype. The experimental findings affirm that the compensation of the targeted oscillating power terms is successfully achieved. Such a validation underscores the practical viability of applying the proposed strategy to real-world scenarios.

Low-voltage grid-connected microgrids rely on the exploitation of inverter-interfaced distributed energy resources (DERs) in order to feed loads and to achieve bidirectional power flow controllability at their point of common coupling (PCC) with the upstream grid. However, adverse operational conditions, such as the existence of DERs of different operation natures, DERs of non-equal power ratings, as well as the occurrence of non-steady and non-sinusoidal grid voltage scenarios, bring complications to microgrid energy management. Consequently, control strategies employed to coordinate DERs in dispatchable microgrids need to be resilient to such non-ideal conditions. Hence, this paper demonstrates that a multi-purpose strategy, so-called the Generalized Current-Based Control (GCBC) approach, is capable of steering DERs under such adverse operational scenarios, ensuring proportional current sharing among them while also regulating the microgrid power dispatchability at the PCC. The discussions are supported by an extensive experimental validation on a laboratory-scale single-phase microgrid prototype, demonstrating that the GCBC approach allows DERs of different operational natures to be coordinated, respecting their power ratings, and allowing the single-controllable microgrid to endure operation under distorted voltages and support voltage ride-through conditions.

This article proposes an approach to active LCL-resonance damping in grid-connected inverters, leveraging capacitor voltage feedback and the Parks-McClellan (PM) algorithm. The advantage of damping the resonance of an LCL filter through the capacitor voltage feedback offers a reduction in the number of sensors required for the signal conditioning system. However, this approach requires the use of a derivative function, which, if not designed correctly, may amplify noise components and induce instability. In this regard, a digital differentiator that exhibits minimal amplification of noise and guarantees a reduced phase delay is essential to address this issue. Therefore, a digital differentiator based on an optimized wideband finite impulse response (FIR) filter is proposed and designed using the PM algorithm. This includes an outline of the frequency response, a description of the coefficient computation procedure, and an examination of the effects of different orders. In addition, a comprehensive system description and an in-depth analysis of the current controller design are presented. Experimental results demonstrate the effectiveness of the proposed method in damping the LCL resonance of a single-phase grid-connected inverter under varying grid impedance, filter orders, and reference step conditions.