Dfig in neplan
Fault identification is established based on the changes in the long axis, short axis, eccentricity, and tilt angle of the track. A cross-connected grounding simulation model of a high-voltage cable is developed, and several faults at different locations are simulated.
The fault criteria and database are established to detect the fault by analyzing the changes of the locus characteristic parameters. By simultaneously measuring two circulating currents in a coaxial cable, a two-dimensional locus diagram is drawn. To address these problems, an online monitoring method based on the locus-analysis for HV cable faults is developed. Power cable fault monitoring is not accurate, and the degree of data fusion analysis of current methods is insufficient.
Online diagnosis methods for high-voltage (HV) cable faults have been extensively studied. Simulation and experimental results are provided to verify the effectiveness of the proposed converter topology and its control strategy. The operating principle and control strategy of the proposed converter are presented. Due to the symmetrical structure of the circuit, there is no defined high voltage or low voltage side as in traditional isolated bidirectional DC-DC converter. Apart from that, shoot-through states are incorporated in its operating cycle to boost the input voltage resulting in high reliability of the proposed converter. It has a wider input/output voltage operating range, soft-switching capabilities without additional devices, and higher boost capability than a traditional dual active bridge circuit. The converter utilizes a dual active bridge circuit with a quasi-Z-source network on both sides, so the converter works as buck/boost converter from either side. This paper presents a quasi-Z-source based isolated bidirectional DC-DC converter (qZIBDC) for renewable energy applications. Finally, the validity and feasibility of the control strategy are verified by simulation and experimental results. Simultaneously, the proportional-limiter method is adopted to minimize the harmonics from the SVG by optimizing the waveform of the modulation wave and limiting its amplitude. Each component is compensated separately by the SVG. According to the symmetric component method and dual dq synchronous transformation theory, the load currents are transformed into four components under dual dq coordinates. In this study, a new type of current compensation control strategy of a three-phase three-wire SVG under an asymmetric load is proposed. Therefore, increasing numbers of static var generators (SVGs) are used to stabilize the power grid. In the case of asymmetric loads of power grid, load currents are composed of four components: positive sequence active and reactive components and negative sequence active and reactive components that can pollute the power grid with harmonics and reactive power and interrupt the normal operation of power grid. The efficiency of the MPSO is achieved with the least number of steady-state oscillations under partial shading conditions compared with the neural network method. The experimental results show that the proposed method can decrease the interference of the local maximum power-point to cause the PV system to operate at a global maximum power-point. The proposed method is examined under several scenarios for partial shading condition and non-uniform irradiation levels using Matlab, and to investigate its effectiveness adequately, the results of the proposed method are compared with those of the neural network technique. Hence, the proposed algorithm, which is based on the modified particle-swarm optimization (MPSO) technique, increases the output power of PV systems under such abnormal conditions and has a better performance compared to other methods. The existence of partially shaded conditions leads to the presence of several peaks on PV curves, which decrease the efficiency of conventional techniques. A novel maximum power-point tracking approach is proposed based on studies investigating the output characteristics of photovoltaic (PV) systems under partial shading conditions.