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This work presents a way to handle the DC component of input signals for PLL and notch filter applications, which are utilized for filtering and synchronization. The input signal of a DC component may be due to some sort of malfunction, or it may be the result of the structure and restrictions of the measurement/conversion procedures. This part makes the system's loop oscillate at low frequencies and no filter can fully filter them out because that would significantly harm the system's dynamic response. The proposal involves augmenting the PLL structure with a new loop. It is basic architecturally and in contrast to a currently presented method and it does not detract from the algorithm's high-frequency filtering level. This Orthogonal Signal Generators (OSG) control algorithm is used for active power filter to maintain unity power factor, neutral current compensation using star/three single transformer & current harmonics mitigation. The MATLAB/Simulink results are demonstrated for the above stated Power Quality (PQ) problems.

In this paper, an Internet of Things (IoT) platform is proposed for Multi-Microgrid (MMG) system to improve unbalance compensation functionality employing three-phase four-leg (3P-4L) voltage source inverters (VSIs). The two level communication system connects the MMG system, implemented in Power System Computer Aided Design (PSCAD), to the cloud server. The local communication level utilizes Modbus Transmission Control Protocol/Internet Protocol (TCP/IP) and Message Queuing Telemetry Transport (MQTT) is used as the protocol for global communication level. A communication operation algorithm is developed to manage the communication operation under various communication failure scenarios. To test the communication system, it is implemented on an experimental testbed to investigate its functionality for MMG neutral current compensation (NCC). To compensate the neutral current in MMG, a dynamic NCC algorithm is proposed, which enables the MGs to further improve the NCC by sharing their data using the IoT platform. The performance of the control and communication system using dynamic NCC is compared with the fixed capacity NCC for unbalance compensation under different communication failure conditions. The impact of the communication system performance on the NCC sharing is the focus of this research. The results show that the proposed system provides better neutral current compensation and phase balancing in case of MMG operation by sharing the data effectively even if the communication system is failing partially.

This paper proposes a Photovoltaic (PV)-based three-phase four-wire Series Hybrid Active Power Filter (SHAPF), it comprises of a Series Active Power Filter (SAPF) and an LC shunt passive filter. The proposed system eliminates both the current and voltage harmonics and compensates reactive power, neutral current and voltage interruption. A SAPF demands a source of energy for compensating the voltage sag/swell. This system found a new topology for SHAPF which utilizes the PV with DC–DC boost converter as a source of DC power for the series active filter. The compensation current reference evaluation is based on the twin formulation of the vectorial theory of electrical power theorem with Fuzzy Logic Controller (FLC). The PV array/battery managed DC–DC boost converter is employed to step up the voltage to meet the DC bus voltage requirement of the three-leg Voltage Source Inverter (VSI). The foremost benefit of the proposed system is that, it will provide uninterrupted compensation for the whole day. This system utilizes the renewable energy; accordingly saves the energy and provides the uninterruptable power supply to critical/sensitive load, through the PV array/battery bank during both day time and night time. An experimental model was established and results were obtained, which indicated the capability of the proposed control scheme.

In this paper, a new topology is developed for a three-phase four-wire (3P4W) distribution system utilizing a scott-transformer supported three-legs VSIs based three-phase three-wire (3P3W) Unified Power Quality Conditioner (UPQC).In this proposed topology the neutral point of the star connected transformer, used for the connection of series active power filter (APF) of 3P3W UPQC, is utilized as a fourth wire for 3P4W distribution system. The scott-connected transformer is connected near the load to compensate the neutral current that may flow toward the neutral point of the series transformer of series APF. For the mitigation of different power quality(PQ) problems a control technique based on the combination of unit template technique(UTT) and power balance theory(PBT)is used for the control of UPQC. In this control scheme of UPQC, the current/voltage control is applied over the fundamental supply currents/voltages instead of fast changing APFs currents/voltages, there by reducing the computational delay and the required sensors. The performance of the proposed topology of UPQC is analyzed through simulations results using MATLAB software with its Simulink and Power System Block set toolboxes. [PUBLICATION ABSTRACT]

A study of passive shunt and series compensation is made to provide an exposure on various issues of power quality, which can easily be mitigated using lossless passive components such as capacitors and inductors for enhancing the efficiency and utilization of equipment in distribution systems. The use of these passive shunt and series compensators has been demonstrated through several numerical examples in distribution systems for improving the voltage profile at the point of common coupling (PCC), loss reduction, power factor correction, load balancing, neutral current compensation, and better utilization of distribution equipment. The passive shunt and series compensators are considered as good alternatives for power quality improvement due to voltage‐ and current‐based power quality mitigation, simple design, and high reliability compared with other options of power quality improvement especially in the absence of harmonic voltages and currents. It is considered to be beneficial to the designers, users, manufacturers, and research engineers dealing with power quality improvement in the distribution systems such as furnaces, traction systems, and rural supply systems to balance consumer loads and to reduce negative‐sequence voltages at the point of common coupling, to improve power factor, and to improve voltage regulation. This chapter illustrates these concepts of load compensation with suitable formulations and numerical examples that are expected to meet the requirements of the design and practice engineers.

Neutral beam injection is one of the most important methods of plasma heating in thermonuclear fusion experiments, allowing the attainment of fusion conditions as well as driving the plasma current. Neutral beams are generally produced by electrostatically accelerating ions, which are neutralised before injection into the magnetised plasma. At the particle energy required for the most advanced thermonuclear devices and particularly for ITER, neutralisation of positive ions is very inefficient so that negative ions are used. The present paper is devoted to the description of the phenomena occurring when a high-power multi-ampere negative ion beam travels from the beam source towards the plasma. Simulation of the trajectory of the beam and of its features requires various numerical codes, which must take into account all relevant phenomena. The leitmotiv is represented by the interaction of the beam with the background gas. The main outcome is the partial neutralisation of the beam particles, but ionisation of the background gas also occurs, with several physical and technological consequences. Diagnostic methods capable of investigating the beam properties and of assessing the relevance of the various phenomena will be discussed. Examples will be given regarding the measurements collected in the small flexible NIO1 source and regarding the expected results of the prototype of the neutral beam injectors for ITER. The tight connection between measurements and simulations in view of the operation of the beam is highlighted.

Three-level neutral-point clamped (NPC) inverters are widely used in the new energy power generation, motor drive, and many other occasions. However, the neutral-point voltage imbalance of an NPC inverter will affect the output of the inverter system, and the control of the neutral point voltage has become a popular research topic. In this paper, a compensation-voltage-injection-based neutral-point voltage balancing method is proposed. During the switching cycle, the average value model of the neutral-point current under different voltage vectors is applied to calculate the value of the compensation voltage that needs to be injected. The self-balance of the neutral-point voltage based on a switching cycle is realized, and the influence of modulation ratio and power factor on equalization ability is discussed. A MATLAB/Simulink simulation model and a small power prototype are established to verify the effectiveness of the method, and the simulation and experimental results show that the proposed method can effectively suppress the neutral-point voltage fluctuation in a wide range of modulation ratios and power factors.

The major problem in grid connected transmission and distribution networks are the power quality issues due to the unbalance loads. The power quality issues relate to the current and voltage based issues generated at the point of common coupling. Some of the current based power quality issues relate to reactive power extraction, poor zero voltage regulation, harmonics in the load currents undesired neutral current and power factor and. Several DSTATCOM compensation techniques has been introduced for compensation of reactive power and power quality issues in the three phase, four wire system. The proposed system focus on DSTATCOM soft computing techniques such as: Widrow–Hoff least mean square, vectorial filter, discrete adaptive filter and quasi Newton control algorithms. The proposed algorithms controlled the switches pulses to drive the voltage source converter section in the DSTATCOM network thereby mitigating power quality issues and reactive power generation in the grid connected photovoltaic system. The soft computing techniques has maintained constant DC bus capacitor voltage and common coupling voltage along with unity power factor, zero voltage regulation under linear and non-linear load conditions, eliminating the harmonics in the load currents. The proportional integral controller is used for error correction between the reference and capacitor voltage. The novel drift-free maximum power point technique has shown better results under varying temperature and irradiances conditions. The DSTATCOM soft computing techniques has been implemented and simulated in MATLAB/SIMULINK.

This paper proposes a normalized compensation method for voltage nonlinearity of the three-level active neutral point clamped (3L ANPC) inverter. The operation of the 3L ANPC inverter includes the voltage nonlinearity caused by voltage errors, which are induced by the nonlinear components of switching devices and their operations. Since this voltage nonlinearity seriously distorts the phase current, it must be compensated to improve the quality of power conversion. For the 3L ANPC inverter, however, the voltage nonlinearity varies depending on the topology and modulation scheme, as well as the power factor of the system. Although many conventional methods have been proposed, these methods do not fully deal with the factors affecting the voltage nonlinearity. In this paper, a normalized compensation method for the voltage nonlinearity considering the characteristics of the 3L ANPC inverter and the power factor of the system is proposed. Two general topologies and modulation schemes of the 3L ANPC inverter are discussed in this paper, and the voltage nonlinearity is analyzed to derive the compensation components. By executing the compensation based on these analyses, the proposed method ensures its performance remains consistent across operating conditions, and is simply implemented. The effectiveness of the proposed method is verified by experimental results.