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The paper examines the work of the microgenerator inverter during two-phase short circuits. It has been shown that the cause of the oscillation is incorrect synchronization of the inverter. It has been demonstrated that the reduction of the oscillations can be achieved by adapting the synchronization signal to the representation of unbalanced system voltages.
This paper presents the possibility of using a point-to-point voltage source converter — high voltage direct current (VSC-HVDC) transmission system connecting offshore wind power plant (WPP) to the onshore grid as black start unit to initiate the restoration process for an interconnected electrical system after a large area system blackout. The onshore converter station (CS) provides voltage in order...
This paper introduces a control method for Reverse-Conducting (RC-)IGBTs which reduces the control dead time of RC-IGBT inverters. Switching measurements with 6.5 kV RC-IGBTs concerning the applicability of the introduced control method and the effect of a load current direction change during the desaturation pulse are presented.
In electrical systems parasitic capacitances are forming resonant circuits in combination with the inductances of the system. Each inverter switching operation is stimulating common-mode oscillations in these resonant circuit which can lead to critical overvoltages at the motor terminals. These voltages could damage the insulation system of the electrical machine and reduce the service life of the...
Most control papers related to variable speed drives are focused on the current and torque control of the electric machine. However, the slower outer loop is also very important. This considers the control of a variable parameter resonant rotating load using a novel control algorithm called Local Vector Control (LVC). Resonant loads naturally occur in, for example, building elevator applications....
This paper extensively analyzes the operation limits, system stability and disturbance rejection capability of the voltage control loops used in master-slave AC and DC Microgrids (MGs). Two different control schemes are studied analytically, simulated and experimentally tested, focusing on Constant Power Loads (CPL). Additionally, the use of the virtual capacitance (VC) as a tool for response enhancement...
This paper describes fuzzy cooperative coevolution adaptive control which uses a common genetic algorithm to obtain the coefficients of the adaptive fuzzy regulator. The plant under consideration is multi-mass drive system with elastic couplings. A comparison between systems with fuzzy control and conventional PID-control is considered. It is shown that fuzzy method allows to suppress torsional vibrations...
Microgrid systems provide benefits to strong, weak and remote power grids. Using multiple sources with differing characteristics and native constraints makes it a challenge to control the microgrid. Compared to the traditional central controller approach, a decentralized microgrid controller architecture has benefits including resiliency to asset and communication failures, which are experimentally...
The use of LC and LCL filters and grid impedance variations are creating new challenges on the controller design for current control loops of photovoltaic and wind turbine inverters. In the design process, stability criteria such as Bode and revised Bode are commonly used. This paper analyses the limitations of Bode and revised Bode criteria to reliably determine stability and proposes a sufficient...
In the past few years, the interest in model predictive control (MPC) for power electronics has increased significantly. It proves to be a good alternative to space-vector modulation at low switching frequencies. It has been shown that an increase in the prediction horizon improves the system performance. Unfortunately, increasing the horizon leads to an exponential increase in the complexity of the...
The paper objective is to propose an innovative power converter topology combining the advantages of capacitor discharge and switch-mode converters to generate half sinusoidal fast current pulses with high precision. The capacitor discharge operation mode of the converter allows the generation of current pulses with fast transient response and the switch-mode operation enables the control of the pulse...
This paper addresses the proposal and simulation of a direct voltage and frequency control (DVFC) of an offshore wind farm (OWF) with LCC-HVDC connection. The proposed control system allows the connection of the OWF to the LCC rectifier by generating a controlled voltage and frequency in a capacitor bank. The decoupled control of the d-q component of the voltage at the capacitor bank, connected to...
With the rapid development of voltage source converter (VSC) based high voltage direct current (HVDC) transmission technology, the HVDC grid will be an effective solution for large-scale renewable energy generations integration. The modular multilevel converter (MMC) is one the most promising topology for HVDC and DC grid presently. The precharge of the MMCs and start-up of DC grid are essential problems...
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