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This paper describes sensitivity analysis to q-axis inductance variation of the position estimation using Extended Electromitive Force (EEMF) excited by High Frequency (HF) signal injection based on the mathematical formula evaluation, and it shows that the influence on the q-axis inductance variation is very small. Finally, experimental results indicate that position estimation can be performed well...
A circulating current is a major problem introduced by directly connecting voltage source inverter (VSI) in parallel. This circulating current occurs as a zero-sequence current between the inverters by specic switch states. Its alternatives were presented by hardware and software methods in many papers. When coupled inductor (CI) are employed for the high frequency circulating current, a circulating...
This paper describes a method of deriving frequency characteristics of PMSM current control system based on Model Predictive Control (MPC). MPC controller predicts the current behavior using the mathematical model of PMSM and directly selects the optimal switch state based on evaluation of these predicted results. So, we have focused the possibility of MPC, which makes it possible to drive machines...
Power system restoration takes place where power systems experience a blackout and might be splitted into several islands with limited number of black start units. The main challenge of the restoration process is to keep both frequency and voltage within allowable limits while restoring the network through energizing lines and transformers as well as load pickup. The load pickup scheme is determined...
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...
In this paper, the disturbance rejection performance of the cascaded control strategy for UPS system is investigated. The comparison of closed loop system performance between conventional cascaded control (CCC) strategy and state-decoupling cascaded control (SDCC) strategy are further explored. In order to further increase the load current disturbance rejection capability of the state-decoupling in...
This paper is introducing a new method of operation for a series resonant converter, with intended application in megawatt high voltage DC wind turbines. Compared to a frequency-controlled series resonant converter operated in sub-resonant mode, the new method (entitled pulse removal technique) allows the transformer design to be determined by peak load and maximum switching frequency, while still...
In this paper, a self-adaptive resonance frequency tracking method is presented. The resonance frequency tracking is used in a LCL-filter-based active power filter to adapt the frequency of the notch filter applied for active resonance damping. By determining the resonance frequency of the LCL-filter and adapting the notch filter frequency, the bandwidth of the notch filter can be decreased, whereby...
One of the main revenue streams of the power system industries is provide a stable frequency all the time. Energy storage systems are well suited for the purpose because of their bidirectional capabilities. Recently converter based energy storage system has been gaining interests for providing frequency response replacing traditional generator based solutions due to the speed of the power electronic...
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...
This paper proposes improved multi-loop control strategies for three-phase four-leg virtual synchronous generator with unbalanced loads. Through the decoupling control of active and reactive power, inverter can simulate the characteristics of synchronous generator, including primary frequency modulation, primary voltage modulation, inertia and excitation characteristics. To improve the dynamic performance...
Frequency regulation of electric power systems efficiency depends on response time and on power reserves for frequency regulation. As integration of non-dispatchable renewable generation in the power system results with increased need for power reserves from fast responding power units, the idea of using aggregated DC microgrids in frequency regulation is presented. Model proposed in this work is...
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