This work contributes to both Romania’s and the European Union’s energy policies by highlighting the research results obtained within the Dunarea de Jos University of Galati, but also through the technological transfer of this knowledge to the industry. In order to improve the power quality of the nonlinear loads connected to the electrical grid, a three-phase shunt active power filter prototype based on the Harmonic Component Separation Method with a Low-Pass Filter was used. The active power filter is connected at the Point of Common Coupling to compensate for individual loads or even all of them simultaneously. Therefore, active power filters can be used to compensate for the power factor and reduce the harmonic distortion of power supplies, or for processes subsequently connected to additional nonlinear loads, thus improving the energy efficiency. The shunt active power filter prototype is composed of the power side (three-phase insulated gate bipolar transistor bridge, DC link capacitor precharge system, inductive filter) and the control side (gate drive circuits, control subsystems, signal acquisition system). The filter control strategy is based on the principle of separating harmonic components with a low-pass filter, implemented by the authors on the industrial prototype. In this paper, the main technical features of the industrial shunt active power filter prototype are specified. The authors of this paper involved three cascaded control loops: the DC link voltage control loop, the shunt active power filter current control loop and the phase-locked loop. Both simulation and experimental results for the shunt-type active power filter prototype were obtained. By analyzing the obtained waveforms of the power supply source in two cases (with and without an active power filter), a decrease in the total harmonic distortion was demonstrated, both the voltage harmonic distortion factor THDu and the current harmonic distortion factor THDi in the case of the active power filter connection. By using the Field-Programmed Gate Array processing platform, the powerful computational speed features were exploited to implement the active shunt power filter control on an experimental test bench. Conducting source current harmonics mitigation increased the efficiency of the power system by decreasing the respective harmonic Joule losses. The energy-saving feature led to the increased added value of the parallel active power filter. Through the performed laboratory tests, the authors demonstrated the feasibility of the proposed control solution for the industrial prototype. In accordance with the European Union’s Research and Technological Development Policy, the development of an innovation ecosystem was taken into consideration. The unified and efficient integration of all the specific actors (enterprises, research institutes, universities and entrepreneurs) in innovation was achieved.

The dynamic development of photovoltaic systems in the world and in Poland is mainly related to the drop in prices of installation components. Currently, electricity from photovoltaics is one of the cheapest renewable energy sources. The basis for effective energy generation is, first of all, failure-free operation of the photovoltaic system over a long period of operation, up to 30 years. The paper presents the results of a study of a low-cost distributed system for monitoring and diagnosis of photovoltaic installations (SmartPV), capable of assessing the operating parameters of individual photovoltaic panels. The devices were tested by connecting them to an existing photovoltaic installation, allowing the measurement of operational parameters of individual photovoltaic panels as well as operating conditions such as illuminance and panel surface temperature. The data were recorded on a server using wireless Wi-Fi transmission. Interesting data were collected during the tests, confirming the usefulness of the suggested device for monitoring the photovoltaic installations. Differences in performance of the photovoltaic panel depending on solar radiation and surface temperature were recorded. The temperature coefficient of power was determined, allowing for increased accuracy in the prediction of generated power. The correct recording in different situation, i.e., shading, sensor damage or weather anomalies, was verified. Based on the collected data, rules will be defined for an expert application which, in combination with SmartPV devices, will ensure a quick response to any malfunctions of the photovoltaic system, both related to failures and those resulting from natural degradation during operation.

This paper shows the topology of grid-connected green power system and the performances of the front-end threephase power inverter by applying an advanced state feedback control. The proposed topology benefits a common DCAC inverter which injects the generated power into the grid. The control structure of the power inverter is of vector control type, in synchronous reference frame, and it uses the power balance concept. The solution presented in this paper adds supplementary benefits to the power system beside to the conventional state feedback control: the designed input filter assures zero steady state error and an adequate component is added for dynamic rejection of the load disturbance. The obtained experimental results are shown

The objectives of the steel manufacturers are to improve their productivity and to optimize their process parameters to maximum efficiency and quality. In steel industry, the one or the more client motors are often arranged to follow the velocity of the master motor. The speed difference between these motors will affect the tension of the product. Hence, the synchronized control and the tension control are the important research topics in the strip manufacturing process. This paper proposes a novel multi-input-multi-output optimal control system for the synchronism control of dual motor system. The control strategy has in view the synchronization of the dual motor system in optimal manner combined with designing of an appropriate reference filter in order to obtain a zero steady state error between the references and the corresponding feedback signal values; the Permanent Magnet Synchronous Motors (PMSMs) operating with constant (rated) flux. The dual motor system was linearized in Matlab/ Simulink. This method employs a simplified model of the plant to be controlled. The simulated results indicate that the method is highly effective and the precision is better than that of the traditional state feedback methods [1]-[3]. Simulation results will show the feasibility and the practicability of the proposed optimal controller. A study of conventional control applied to permanent magnet synchronous motors has also been performed.