Mohsen Mohammadi Alamuti

Intermittent Fault Location in Distribution Feeders

Due to the utilization of fundamental frequency, current impedance-based fault-location methods are able to locate only permanent and linear faults. The duration of the arc in low- and medium-voltage systems can be as short as a quarter of a cycle. This period, which is normal for intermittent faults, is insufficient for fundamental frequency-based fault-location algorithms. Therefore, available methods are not applicable for an intermittent arcing fault location. In this paper, a novel method is proposed for arcing fault location in radial feeders, utilizing time-based formulation considering the short duration of the faults. The advantage of the proposed method over available methods is its capability for locating faults using fewer samples, which is suitable for arcing faults as well as normal faults in the network. Also, different types of faults are taken into account in the proposed algorithm. The validity of the devised algorithm is studied within the PSCAD-EMTDC environment and the results obtained show good accuracy for arcing faults. The application of the proposed algorithm in real systems is based on the availability of measured voltage and current waveforms at one end of the network and knowledge of cable/line parameters (self and mutual impedances).

Comprehensive Distribution Network Fault Location Using the Distributed Parameter Model

A typical low- or medium-voltage distribution feeder consists of numerous branches as well as laterals and heterogenic conductor lines. The lack of measurement points and the presence of unbalanced loads make it more complicated for the construction of fault-location algorithms. In this paper, a brief and comprehensive review is presented which introduces and compares published papers in this area to date. In addition, the authors have devised a single-end fault-location algorithm using the distributed parameter model to overcome all of the aforementioned limitations in distribution feeders. The validity of the devised algorithm is studied within the PSCAD-EMTDC environment. This model provides more accurate results as the distributed nature of losses and capacitive effects are considered whereas in the available algorithms, these are ignored. A comparison which is made between the proposed method and two of the most complete available algorithms shows the superiority of our algorithm. Also, the proposed algorithm is able to locate various fault types in the network that has different phase laterals unbalanced loads and heterogeneity of the feeder line.

System stability improvement through HVDC supplementary Model Predictive Control

Bulk power transfer requirements over long distances within a country or between neighboring countries as well as rapid increase in the number of offshore wind farms, have increased the application of high voltage DC links. Apart from the controllable power flow function of HVDC systems, advanced controllers can be employed to extend their functionality for dynamic and transient stability improvement of AC systems. As an attempt to improve the influence of HVDC technology on AC system stability, this paper proposes a supplementary active power controller for the HVDC system. The Model Predictive Control (MPC) approach is considered for the control design. The design process of weight tuning and parameterization of the MPC controller has been investigated. Additionally the effect of controller model reduction is demonstrated in the presented results.

An efficient coupled GA and load flow algorithm for optimal placement and sizing of distributed generators

A genetic algorithm is used in conjunction with an efficient load flow programme to determine the optimal locations and sizing of the predefined DGs within MATLAB software. The best location for the DGs and the sizing of the DGs are determined using the genetic algorithm. The branch electrical loss is considered as the objective function and the system total loss represent the fitness evaluation function for driving the GA. The load flow equations are considered as equality constraints and the equations of nodal voltage and branch capacity are considered as inequality constraints. The approach is tested on a 15 bus IEEE distribution feeder.

A novel VSC HVDC active power control strategy to improve AC system stability

Bulk power transfer requirements over long distances within a country or between neighboring countries as, well as a large growth in offshore wind farms, have increased the number of high voltage DC links. Apart from the controllable power flow function of HVDC systems, advanced controllers can be employed to extend their functionality for dynamic and transient stability improvement of AC systems. As an attempt to improve the influence of HVDC technology on AC system transient stability, this paper proposes a supplementary active power controller for the VSC HVDC grid side converter. The presented simulation results prove the effectiveness of the proposed method. Relatively large-sized dump loads have been installed within the power system for protective measures against a surplus of generated power. They are distributed over the network and they normally connect to the circuit when a trip signal is issued. DC choppers in HVDC systems as well as wind turbine converters, dump loads in synchronous generators and in wind turbines comprise these distributed dump resistive loads in the network. The effect of the DC chopper to improve active power controllability for improved transient stability has also been tested and verified through the simulations.