Designing propulsion systems for agricultural drones involves a repetitive process that is both expensive and time-intensive. At the same time, conducting comprehensive experimental tests demands specialized equipment and strict safety protocols. In this work, the design and assessment of the propulsion system (propeller, motor, and battery) for large-sized drones in agricultural applications are conducted using numerical methods. To properly predict and validate the performance of a brushless direct current motor, a three half-bridge inverter circuit, featuring a trapezoidal commutation, is implemented and constructed. First, the propeller is studied using the finite volume method, obtaining a maximum variation of 6.32% for thrust and 10.1% for torque. Additionally, an electromagnetic analysis on a commercial brushless direct current motor (BLDC) using JMAG software from JSOL corporation (JMAG designer 23.2, Cd.Obregón, México) resulted in 4.43% deviation from experimental electrical measurements. The selected propulsion system is implemented in a 30 kg drone, where motor performance is evaluated for two instants of time in a typical agriculture trajectory. The findings demonstrate that numerical methods provide valuable insights in large-sized unmanned aerial vehicle (UAV) design, decreasing the experimental tests conducted and accelerating implementation time.

This paper proposes a method to balance the power of transformers in low voltage distribution by using the Back-to-Back (BTB) converter. Through the exchange of active power and the compensation of reactive power between feeders, the overloading of transformers is avoided. In the proposed method, the load is considered as a variable that is constantly changing. The control structure is designed in the dq frame of reference and classical theory is employed. A test system composed by two 50kVA transformers supplying several loads is used to validate the efficacy of the method. For simulations a 30kVA BTB converter is used, and for experimental results a 10:1 BTB converter is implemented.

This paper presents how a three-phase BTB converter is actively controlled to operate as a power compensator and a harmonic current filter, simultaneously. The main goal of the proposed control scheme is to analyze the current injected by the BTB converter at the PCC using three components. These components are used to compensate: the active power, the reactive power and the current harmonics. The current components of nonlinear loads are obtained and incorporated to the current controllers in order to achieve the filtering function. For the analysis, the active power compensation is a priority and it is accomplished. A 30 kVA BTB converter is used for simulations. Experimental tests were carried out with a 3 kVA prototype.

This paper presents a study on the utilization of a single phase three-level bridge inverter to inject active power from a photovoltaic power source. Simultaneously, it compensates reactive power and harmonic current components, allowing power factor correction (PFC). An analysis on the design of passive elements, considering active and reactive power maximum values, is made. Additionally, the process of power injection is described in a straightforward way, whenever photovoltaic active power is available. Simulation results are presented to validate the design criteria, photovoltaic injection description, and PFC. A 5 kW-10 kvar system is proposed a case of study. Simulations show that the three functions can be made without intervening with each other.

The Microgrid (MG) operating modes are Grid-Tied Mode (GTM) and Islanded Mode (ISM). However, the transitions from GTM to ISM (GTM-ISM) and from ISM to GTM (ISM-GTM) are currently studied as operation modes. To correctly perform GTM-ISM and ISM-GTM, in this paper an Islanding Detection Algorithm (IDA) and Grid-Synchronization Algorithm (GSA) are developed. The development of IDA and GSA is based on the DQ transformation and the IEEE 1547 Standard. Both IDA and GSA operate together as a secondary control level to provide synchronizing signals to the primary control level. The results show a correct IDA and GSA performance, which allowed the Grid-Forming Type Converter (GFTC) to be capable of carrying out both GTM-ISM and ISM-GTM, correctly. This is possible because of the cascade control schemes outstandingly perform tasks such as: to extract mains power, to charge the battery, to regulate the DC bus voltage, and to synchronize and to regulate the GFTC output voltage.

This paper presents a generalized DC voltage regulation strategy, for both symmetric (eta = 1) and asymmetric (eta = 2, 3) multilevel converters used in a static VAR compensator. The objective is to keep regulated the DC links and the reactive power compensation. The strategy is applied to a single phase converter with a combination of staircase and PWM technique. Simulation results on PSIM are presented showing a good performance of proposed control strategy.