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The Back flashover generated from a lightning stroke hit on an overhead ground wire (OHGW) or a pole top is one of the major causes of sustained interruption in Metropolitan Electricity Authority (MEA)'s distribution system. One effective way to reduce the effects of lightning overvoltage from back flashover is an attachment of external ground wire connected between the overhead ground wires and a...
The study provides comparison of grounding performance between square and rectangle ground grid, when given the same size of area of coverage. The result shows that the rectangle ground grid possesses better grounding performance than the square one. The study also finds the optimum compression ratio (OCR) of both grounding configuration. The OCR of square and rectangle ground grids are found to be...
This paper presents construction planning procedures for a new permanent substation to replace an small (temporary) substation that is served to supply the load of the old existing substation while it has not been removed. In the meantime when the ground grids of the two substations are electrically disconnected, the auxiliary grounding system of substation can create steep ground potential rise between...
This paper proposes characteristic of uniform (homogeneous) soil and grounding performance assessment which consist of ground potential rise (GPR), touch voltage and step voltage of ground grid buried in 0.5 m depth of uniform and two-layer soil. The study is separated in 2 parts. Part 1 involves characteristic of uniform soil. If the upper layer of two-layer soil is greater than 16 m, the characteristic...
As the impacts of distributed generators (DGs) on distribution systems are significant, this paper proposes a particle swarm-based optimization technique to define an optimal coordination of DGs, an under load tap changer (ULTC) including substation and feeder capacitors for volt/VAr control. The objective for the coordination is considered in the view point of the distribution system operators as...
This paper presents an approach for finding the optimal implementation of feeder reconfiguration in unbalanced loading distribution systems with the objective of power loss reduction. The optimization problem is subjected to system constraints consisting of load-point voltage limits, radial configuration format, no load-point interruption and feeder capability limits. The system power losses and bus...
This paper analyzes the performance of grounding system that is made of copper conductors and significantly influenced by soil resistivity. The grounding performance is evaluated in terms of ground potential rise, touch voltage and step voltage caused by a short circuit that generates a flow of large currents in the aboveground structures and grounding system and dissipates in the soil. These currents...
This paper presents the optimal dispatch for the under load tap changer (ULTC) of a substation transformer, substation capacitors, and feeder capacitors for volt/VAr control in a distribution system. Three objectives of interest in the problem consist of energy loss, total capacitor kVAr to be switched on, and total number of daily switching operations of the ULTC and all capacitors. The optimization...
This paper proposes a methodology based on fuzzy multiobjective and tabu search to determine the optimal on/off patterns of tie and sectionalizing switches for feeder reconfiguration in a distribution system with distributed generators. Three main objectives considered in the feeder reconfiguration problem consist of power loss, feeder load balancing, and number of switching operations of the switches...
Back flashover generated from a lightning stroke hit on an overhead ground wire or a pole is one of the major causes of sustained interruption in Metropolitan Electricity Authority (MEA)'s distribution system. One effective way to reduce the effects of lightning overvoltage from back flashover is an attachment of external ground wire connected between the overhead ground wires and a ground rod. This...
This paper describes an optimal dispatch for the under load tap changer (ULTC) of a substation transformer, substation capacitors, and feeder capacitors for volt/VAr control. The objective function of the problem is to minimize the system energy loss for a given daily load pattern. The problem is subjected to power flow equations, bus voltage limits, voltage distortion constraint and the maximum number...
Reactive power planning by optimal allocation of static VAr compensator (SVC) and thyristor controlled series capacitor (TCSC) is presented in this paper. Three objective functions (minimization of the installation cost of SVC or TCSC, minimization of the energy loss cost, and minimization of the total cost defined as the sum of the installation cost and energy loss cost) are considered for comparison...
This paper presents a feeder reconfiguration problem to the distribution system with dispatchable distributed generators. The feeder configuration of the system and the dispatch of the distributed generators are two problems that need to be considered. A tabu search algorithm is applied to search for the on/off patterns of the sectionalizing switches and tie switches to obtain the minimum total power...
This paper presents a unified Newton-Raphson method to solve an AC power flow problem with the presence of a DC link and a tyristor controlled series capacitors (TCSC). A DC link provides an economical way to interconnect areas with long-distance separation or those with different frequencies or incompatible frequency control. A TCSC, a series capacitor bank shunted by a thyristor-controlled reactor,...
Distribution network reconfiguration provides an effective way to control the tie and sectionalizing switches in the system to give an appropriate connection for certain reasons. In this paper, the emphasis of distribution network reconfiguration is on enhancing the reliability of electric power supply so that customer interruption cost is minimized subject to system operational constraints. A simulated...
This paper presents a control technique to reduce the effect of unbalanced voltages on the line side converter of the wind energy conversion system with a doubly fed induction generator (DFIG). The unbalanced voltages produce oscillations of instantaneous active power and dc bus voltage. When the model of the unbalanced system is transformed onto the synchronously rotating reference frame, the d-q...
This paper presents a control technique to reduce the effect of unbalanced voltages in the doubly fed induction generator (DFIG) in wind energy conversion systems. The unbalanced voltages cause negative effects to the DFIG such as torque pulsation and increased stator current. Based on the symmetrical component theory, the negative sequence of the stator voltage can be extracted from the three-phase...
This paper presents three alternative maxium peak power tracking-based control algorithms with stall regulation for optimal wind energy capture: torque reference-based MPPT algorithm, searching-based MPPT algorithm and fuzzy-based MPPT algorithm. The first algorithm uses a torque reference as a guideline for tracking. The second method searches an optimal operating point from the slope of the power-rotational...
This paper analyses the transient stability limit of stator reactive power compensation of doubly fed induction machines under the operation of decoupled control of active power and reactive power. Based on the stator-fleld-oriented reference frame, voltage equations are linearized and the corresponding eigenvalues are determined to identify a stable operating region. With the eigenvalues, the maximum...
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