Multilevel inverter (MLI) topologies play a crucial role in the dc-ac power conversion due to their high-quality performance and efficiency. This article aims to propose a new switched-capacitor-based boost multilevel inverter topology (SCMLI). The proposed topology consists of nine power semiconductor switches with one dc voltage source and two capacitors, capable of generating a nine-level output voltage waveform with twice voltage gain. With the addition of two switches, the proposed topology can be used for higher voltage-gain applications. Other features of the proposed topology include the self-voltage balancing of the capacitors, parallel operation of the capacitors, lower voltage stress across the switches, along with the inherent polarity changing capability. To obtain the high-quality output waveform, a selective harmonic elimination pulsewidth modulation technique is applied. In this technique, the detrimental low-order harmonics can easily be regulated and eliminated from the output voltage of MLI. The proposed topology is compared with the recently introduced SCMLI topologies considering various parameters to set the benchmark of the proposed topology. The performance of the proposed MLI is investigated through various experimental results using a laboratory prototype setup.

This paper proposes a new algorithm to generate reference voltage for a distribution static compensator (DSTATCOM) operating in voltage-control mode. The proposed scheme exhibits several advantages compared to traditional voltage-controlled DSTATCOM where the reference voltage is arbitrarily taken as 1.0 p.u. The proposed scheme ensures that unity power factor (UPF) is achieved at the load terminal during nominal operation, which is not possible in the traditional method. Also, the compensator injects lower currents and, therefore, reduces losses in the feeder and voltage-source inverter. Further, a saving in the rating of DSTATCOM is achieved which increases its capacity to mitigate voltage sag. Nearly UPF is maintained, while regulating voltage at the load terminal, during load change. The state-space model of DSTATCOM is incorporated with the deadbeat predictive controller for fast load voltage regulation during voltage disturbances. With these features, this scheme allows DSTATCOM to tackle power-quality issues by providing power factor correction, harmonic elimination, load balancing, and voltage regulation based on the load requirement. Simulation and experimental results are presented to demonstrate the efficacy of the proposed algorithm.

This paper proposes an improved hybrid distribution static compensator (DSTATCOM) topology to address some practical issues such as power rating, filter size, compensation performance, and power loss. An LCL filter has been used at the front end of a voltage source inverter (VSI), which provides better switching harmonics elimination while using much smaller value of an inductor as compared with the traditional L filter. A capacitor is used in series with an LCL filter to reduce the dc-link voltage of the DSTATCOM. This consequently reduces the power rating of the VSI. With reduced dc-link voltage, the voltage across the shunt capacitor of the LCL filter will be also less. It will reduce the power losses in the damping resistor as compared with the traditional LCL filter with passive damping. Therefore, the proposed DSTATCOM topology will have reduced weight, cost, rating, and size with improved efficiency and current compensation capability compared with the traditional topology. A systematic procedure to design the components of the passive filter has been presented. The effectiveness of the proposed DSTATCOM topology over traditional topologies is validated through both simulation and experimental studies.

Peak shaving of utility grid power is an important application, which benefits both grid operators and end users. In this article, an optimal rule-based peak shaving control strategy with dynamic demand and feed-in limits is proposed for grid-connected photovoltaic (PV) systems with battery energy storage systems. A method to determine demand and feed-in limits depending on the day-ahead predictions of load demand and PV power profiles is developed. Furthermore, an optimal rule-based control strategy that determines day-ahead charge/discharge schedules of battery for peak shaving of utility grid power is proposed. The rules are formulated such that the peak utility grid demand and feed-in powers are limited to the corresponding demand and feed-in limits of the day, respectively, while ensuring that the state-of-charge (SoC) of the battery at the end of the day is the same as the SoC of the start of the day. The optimal inputs required for applying the proposed rule-based control strategy are determined using a genetic algorithm for minimizing peak energy drawn from the utility grid. The proposed control algorithm is tested for various PV power and load demand profiles using MATLAB.

This paper presents a dual voltage source inverter (DVSI) scheme to enhance the power quality and reliability of the microgrid system. The proposed scheme is comprised of two inverters, which enables the microgrid to exchange power generated by the distributed energy resources (DERs) and also to compensate the local unbalanced and nonlinear load. The control algorithms are developed based on instantaneous symmetrical component theory (ISCT) to operate DVSI in grid sharing and grid injecting modes. The proposed scheme has increased reliability, lower bandwidth requirement of the main inverter, lower cost due to reduction in filter size, and better utilization of microgrid power while using reduced dc-link voltage rating for the main inverter. These features make the DVSI scheme a promising option for microgrid supplying sensitive loads. The topology and control algorithm are validated through extensive simulation and experimental results.