Volume 22, Issue 2

Due to the existence of different branches in the electricity distribution network and only available voltage and current information at the beginning of the line and lack of access to the information at the end of the network line, the detection of the faulted section in the distribution network has become more important. Today, smart meters are used to measure the voltage and current of network lines, but due to the limitations of the installation sites, these devices are not possible in all network lines. In this paper, two techniques have been used to identify the faulted section and fault location in the network so that the fault distance at the beginning of the line can be estimated by estimating the current at the end of each network line. Therefore, in this project, by installing smart meters in the main branch of the network and also the information obtained from power flow in the network normal mode, it has been tried to practically estimate the voltage and current at the beginning and end of each distribution network line. In this method, more power flow is used to calculate the voltage drop of the lines and estimate the voltage and current at the end of the network lines so that the faulted part can be identified. Finally, the proposed method is implemented on the IEEE_15, 37 bus networks, the results of which show the proper performance of the proposed method in estimating location and Fault resistance for different types of faults in the distribution network.

In the transmission line, the series compensation device is often used to improve the transmission capacity. However, when the fixed series capacitor (FSC) is used in high compensation series compensation device, the stability margin cannot meet the requirements. Therefore, thyristor controlled series compensator (TCSC) is often installed in transmission lines to improve the transmission capacity of the line and the stability of the system. For cost considerations, the hybrid compensation mode of FSC and TCSC is often adopted. However, when a single-phase grounding fault occurs in a transmission line with increased series compensation degree, the unreasonable distribution of FSC and TCSC will lead to the excessive amplitude of secondary arc current, which is not conducive to rapid arc extinguishing. To solve this problem, this paper is based on 1000 kV Changzhi-Nanyang-Jingmen UHV series compensation transmission system, using PSCAD simulation program to established UHV series compensation simulation model, The variation law of secondary arc current and recovery voltage during operation in fine tuning mode after adding TCSC to UHV transmission line is analyzed, and the effect of increasing series compensation degree on secondary arc current and recovery voltage characteristics is studied. And analyze the secondary arc current and recovery voltage when using different FSC and TCSC series compensation degree schemes, and get the most reasonable series compensation configuration scheme. The results show that TCSC compensation is more beneficial to arc extinguishing under the same series compensation. Compared with several series compensation schemes, it is found that with the increase of the proportion of TCSC, the amplitude of secondary arc current and recovery voltage vary greatly. Considering various factors, the scheme that is more conducive to accelerating arc extinguishing is chosen.

This work investigates the performance of a single-phase grid-connected photovoltaic (PV) system under non-ideal source voltage conditions using a fuzzy logic controller. The single-phase instantaneous reactive power theory has been modified to explore the harmonic and reactive power compensation with distorted grid voltage excitation while transferring active and reactive power to the grid and the non-linear load. Instead of a traditional Proportional-Integral (PI) controller, the proposed method implements a fuzzy logic controller for the extraction of the reference compensating current. This method is compared with the traditional single-phase instantaneous reactive power theory. The advantage associated with a fuzzy logic controller is that it does not need accurate mathematical modeling of the system, instead, it is based upon the linguistic characterization of the input and output variables. Besides, care has been taken to provide uninterrupted compensation throughout the variation of the solar irradiation level. The proposed method has also been verified through a laboratory-developed prototype using a DS1103 processor.

Value based services are the new emerging area in Indian Electricity Market. Technically, such value added services in the electricity market are known as Ancillary Services. Voltage Control Ancillary Service (VCAS) deals with local level voltage control problem of power sector. According to IEEE standards 1159:1995, 1250:2011, only ±5% voltage variation is allowed with almost 0 deviations in frequency (±0.03% maximum variation limit) to interconnect any new generating plant with a grid. The utilization of squirrel cage induction generators (SCIG) as wind operated micro grid may be in a fix without adequate availability of reactive power. Besides SCIG, load changes also cause voltage varying problems and so, this paper investigates how load change can be coped up with fast acting reactive power compensator for such arrangements. To demonstrate this real time Simulink models for fixed capacitor and STATCOM are developed using MATLAB software. The SCIG starting and load change conditions are tested with fixed capacitor, six and 12 pulse STATCOM as reactive power compensators. The SCIG performances in terms of rotor speed, voltage, and frequency control characteristics during starting of the machine as well as at the time of load perturbation are compared.

This paper proposes a novel non-isolated multi-input dc-dc boost converter for electrical vehicle application. A hybrid system balances the power of the system by using two or more sources. The power between the input sources can be flexibly distributed without any distortion. The charging or discharging of the energy storage systems by other input energy sources can also be monitored in a proper manner and is a feasible task. The design consists of only one inductor and the charging and discharging of the energy storage system decides the operation modes of the converter. In this paper, every operating mode has a small signal model that leads to the control system design for the converter. Simulation and experimental results are provided to prove the validity of the converter and the performance of its control system.

Very Fast Transient Over voltages (VFTOs) generate during operation of the disconnector switches or circuit breakers in a gas insulated substation (GIS). These transient voltages stress the insulation system in GIS and further result in mal-operation of the control circuitry as well as the secondary equipment connected to it. Since the VFTOs affect the reliability of GIS, it is necessary to mitigate them. This paper presents the mitigation of the very fast transient over voltages and the associated very fast transient currents (VFTCs) using the nano-crystalline rings in a 245 kV GIS. The mitigation in the peak amplitude of VFTOs and VFTCs at various locations in the GIS for various switching configurations are analyzed in this paper. The nano-crystalline rings of different geometries and permeabilities are considered to understand the damping effect being offered. The nano-crystalline rings are considered at all the possible switches of 245 kV GIS bays. An equivalent circuit model of the nano-crystalline ring is obtained through an iterative algorithm. The very fast transients have been calculated using Electromagnetic Transients Program software. Further, attenuation in the dominant frequency components of VFTOs and VFTCs at different GIS components is also studied for various switching configurations with nano-crystalline rings.

This study presents a computational approach to compute locational marginal price (LMP) at distributed generation (DG) buses in an electric power distribution system using self-adaptive levy flight based JAYA algorithm and proportional nucleolus theory (PNT). This method provides financial incentive to DG owners based on their contribution in reliability improvement, loss and emission reduction. In this study expected energy not supplied (EENS) is used for measuring the reliability of a given radial distribution network. This method is implemented on 38 bus distribution system under MATLAB environment to compute LMP values at each DG as per its contribution towards reliability improvement, loss reduction and emission reduction. It is found from the study that reliability has been improved, losses and emissions of system were reduced by providing proper financial incentives to DG owners. The proposed method can be utilized by a distribution company (DISCO) to operate network optimally and to estimate state of network.

Demand response programs are useful options in reducing electricity price, congestion relief, load shifting, peak clipping, valley filling and resource adequacy from the system operator’s viewpoint. For this purpose, many models of these programs have been developed. However, the availability of these resources has not been properly modeled in demand response models making them not practical for long-term studies such as in the resource adequacy problem where considering the providers’ responding uncertainties is necessary for long-term studies. In this paper, a model considering providers’ unavailability for unforced demand response programs has been developed. Temperature changes, equipment failures, simultaneous implementation of demand side management resources, popular TV programs and family visits are the main reasons that may affect the availability of the demand response providers to fulfill their commitments. The effectiveness of the proposed model has been demonstrated by numerical simulation.

The uncertainty of wind speed may lead to the deviation and change of wind power output, which influences the stability of wind farm. Therefore, in this paper, a probability box (p-box) based uncertain power flow model for wind power is proposed, which initially introduces p-box to power flow calculation. A probabilistic interval power flow model with both probability and interval is established. Firstly, the drift interval of wind speed is obtained and its p-box model is established by analyzing the distribution of wind speed. Secondly, the wind power output p-box is derived from the wind speed p-box based on the relationship between wind power output and wind speed, then the p-box of wind power output is discretized and introduced into the power flow equation to obtain the power flow p-box model. Finally, Newton–Raphson method is used to solve the power flow p-box model. Experiments on data collected from a wind farm (running standard IEEE30-bus test system) in Inner Mongolia demonstrate that our method is more effective and accurate than the traditional Monte Carlo simulation (MCS) and classical interval power flow (IPF) method.