Electric Power Systems

This paper presents an effective algorithm to locate Single Line to Ground (SLG) fault at a transmission line. Post fault voltages and currents from both substation terminals were
used as the input parameters to the algorithm. Discrete Fourier Transform (DFT) was used to extract the magnitudes and phase angles of three phase voltages and currents. The modeling of the transmission line along with the algorithm was performed using Matlab/Simulink package. The results of fault location for SLG faults along the transmission line demonstrated the validity of the algorithm used even for high resistance earth fault.

This paper discusses the impact of wind penetration on frequency control of a thermal dominated system considering Generation Rate Constraints (GRC) and dead band non-linearities. The hidden inertia emulation and coordinated operation of conventional power generation systems with wind energy can effectively alleviate the frequency excursions during sudden load disturbances. Conventional energy storage device like Flywheel Energy Storage (FES) system can be used in conjunction with wind integrated power system to overcome the intermittent nature of power generation. Thyristor Controlled Series Compensator (TCSC) is found to be effective in damping low frequency oscillations in weak tie-lines and supplement the frequency regulation. A stochastic population based evolutionary computation technique-Particle Swarm Optimization (PSO) is used to tune the controller gains. A strategy comprising inertia control, coordinated operation of conventional generation units with wind energy and TCSC-FES has been proposed to enhance the frequency regulation which is effective in controlling low frequency oscillations as established by the simulation results.

В монографії викладені теоретичні основи високовольтних техноло-гій у морській електроінженерії, вимоги класифікаційних товариств до морсь-кого високовольтного електроустаткування, основи безпечної експлуатації високовольтного електроустаткування, конструктивні особливості побудови електроенергетичних систем, систем захисту, а також процедури обслугову-вання і тестування електрообладнання напругою вище за 1000 вольт.
Матеріал монографії повністю охоплює вимоги мінімального стан-дарту компетентності Кодексу ПДНВ А-ІІІ/6 щодо підготовки суднових еле-ктромеханіків з компетенції «Експлуатація та технічне обслуговування сило-вих систем з напругою більше ніж 1000 вольт» та А-III/5 щодо підготовки суднових механіків з компетенції «Електрообладнання, електронна апарату-ра і системи управління на допоміжному рівні».
Монографія призначена для науково-педагогічних працівників, які займаються викладанням навчальних курсів з високовольтних технологій, інженерно-технічних працівників, для здобувачів вищої освіти зі спеціальнос-ті 271 «Річковий та морський транспорт» спеціалізацій: 271.03 «Експлуатація суднового електрообладнання і засобів автоматики» та 271.02 «Управління судновими технічними системами і комплексами», а також для суднового інженерно-технічного персоналу, що проходить, за вимогами безпечної екс-плуатації суднового високовольтного електричного устаткування, спеціаль-ний курс High Voltage Safety and Operational Procedures.
Схвалено рішенням Вченої ради НУ «ОМА» від 25.06.2020, Прото-кол № 9.

The increasing wind power generation requires the updating of the computational tools that support decision making in the operation and planning of electric power systems. This work describes a methodology to model the spatial correlations among wind speeds probability distributions in probabilistic power flow. The proposed methodology is based on Nataf transformation and Monte Carlo Simulation. The proposed methodology is illustrated in case studies with the IEEE 24 bus test system, highlighting the importance of adequately considering such correlations.

This paper investigates the concept of network reconfiguration by considering the seasonal load changeon feeders. The author tried to establish that the reconfiguration of networks can be carried out for load balancing during the seasonal change in loads depicted by the chronological load curves of the feeders. In electrical power distribution systems, some feeders supply consumers with the same type of loads in particular areas. Like thefeeders dedicated to supply residential areas, the dominated loads are domestic and commercial. While somefeeders may be dominated with industrial loads, some with agriculture etc. By examining the chronological loadcurves the possibilities of feeder reconfiguration are identified. Seasonal reconfiguration will increase thereliability of supply, reduce line losses and improve voltage profile.

The Niagara Falls speak to us with great clarity about the evolution of the relationship between man and nature in Western culture. Here a shift can be recognized both in aesthetic and physical terms – from feelings of repulsion and anxiety to ones of enchantment and delight, from the fear of the overwhelming power of the falling waters to the illusion of man’s total control of them. Paradoxically, the Niagara region, a key node of the Great Lakes ecological and economic system, is a region that did not lack planning: the construction of the western end of the Erie Canal, the system of parks designed by Olmsted and Vaux in both Niagara Falls and Buffalo, and the large infrastructures Robert Moses and his Power Authority built in Niagara County, not to mention all of the utopian urban projects that were developed for Grand Island and Niagara Falls. Yet today Niagara is one of the poorest and most socially devastated counties in the state of New York. Its once booming industry has nearly completely evaporated, hiding a territory riddled with toxic landfills and decrepit neighbourhoods behind the touristy curtain of the falls. So what went wrong? How did the grandeur of the past get lost?

Alternative energy sources are becoming more cost effective, and many utilities are now providing incentives for alternative power. Placing these alternative energy sources, as well as other smaller traditional energy sources, on the distribution power system, allows the development of a new paradigm related to distributed generation (DG). The size and site of the DG will have an effect on the voltages and operations of the distribution power system in the future. This paper discusses a procedure for evaluating the impact of site and size on both the original distribution power system as well as a reconfigured power system after a fault. Validation of this work is done using the IEEE 37 node distribution feeder and the results and trends are presented.

A modified adaptive neuro-fuzzy inference system sliding mode control (ANFIS-SMC) by using two-level space vector pulse width modulation (SVPWM) for doubly fed induction generator (DFIG) is proposed in this article. ANFIS-SMC with SVPWM strategy improves the basic SMC performances, which features low stator active and reactive power and also minimize the total distortion harmonic (THD) of stator current. The computer simulation results, in Matlab, demonstrate the effectiveness of the proposed control strategy which improves the performance of the DFIG. Keywords: ANFIS-SMC DFIG SMC SVM THD This is an open access article under the CC BY-SA license. NOMENCLATURE WTS Wind turbine system DFIG Doubly fed induction generator WECS Wind energy conversion systems ANFIS Adaptive neuro-fuzzy inference system SMC Sliding mode control THD Total distortion harmonic SVPWM Space vector pulse width modulation DTC Direct vector control DPC Direct power control SOSMC Second order sliding mode controller ANN Artificial neural network FL Fuzzy logic Lr, Ls Stator and rotor self-inductances Lm Mutual inductance Rr, Rs Stator and rotor resistances ѱr, ѱs Rotor and Stator flux vectors Is, Ir Rotor and stator current vectors Vs, Vr Rotor and stator voltage vectors Ps, Qs Active and reactive powers. r, s Rotor, stator d, q Synchronous d-q axis Int J Appl Power Eng ISSN: 2252-8792  ANFIS-sliding mode control of a DFIG supplied by a two-level SVPWM technique… (Habib Benbouhenni) 37 1. INTRODUCTION Traditionally, DFIG based wind turbine systems (WTSs) are mainly installed in remote and rural areas [1]. Operation and control of DFIG has been the subject of intense research during last few years. The rotor of the DFIG is connected to AC-DC-AC converter and the stator is connected to the power grid [2]. The principal advantage of the DFIG is that the rotor side converter (RSC) is only sized for 30% of rated power compared to other generators used in variable speed WTSs. Various control strategies have been proposed for studying the behavior of DFIG-based wind energy conversion systems (WECSs) during normal operation. Indirect vector control [3] and a direct vector control [4] have been proposed for DFIG. In these techniques, the decoupling between q-axis and d-axis current is achieved with feedforward compensation, and thus the DFIG model becomes less difficult and PI controllers can be used [5]. In [6], direct vector control (DTC) was proposed to control DFIG. Similar to the DTC method, a direct power control (DPC) of DFIG based wind energy conversion system has proposed recently [7-9]. In [10], DPC control based on neural network (NNs) has been proposed. In [11], a modified DTC technique was proposed based on second order sliding mode controller (SOSMC) to regulate the electromagnetic torque and rotor flux. In [12], an reactive and active stator power proportional-integral controllers and space vector pulse width modulation (SVPWM) strategy were combined to replace the traditional hysteresis comparators. In [13], a modified DPC strategy was proposed based on SOSMC technique to regulate the reactive and active stator power of the DFIG-based WECS. SOSMC and fuzzy logic (FL) are combined to control the DFIG [14]. In [15], fuzzy sliding mode controller (FSMC) was designed to regulate the active and reactive power of the DFIG-based WTSs. Neuro-sliding mode controller (NSMC) is proposed to control electromagnetic torque, reactive and active stator power of the DFIG [16]. Artificial neural networks (ANNs) and SOSMC are combined to control the stator reactive and active power of the DFIG [17]. Backstopping control was proposed to control DFIG [18]. In [19], LQR method was designed to control flux and electromagnetic torque of DFIG. In [20], neural space vector pulse width modulation (NSVPWM) and NSMC technique were combined to control DFIG. Fuzzy SVPWM strategy is proposed to reduce the total harmonic distortion (THD) of current and powers ripples of DFIG [21]. In literature [22], vector control (VC) is the most popular technique used in the DFIG based WECS. This control scheme is simple and easy to implement. On the other hand, this strategy gives more THD value of rotor current and powers ripples of DFIG. To obtain high performance VC, a simple and robust ANFIS-SMC controller is designed to control the RSC and regulate the stator reactive and active stator power. The ANFIS-SMC controller is designed to avoid the reaching phase stability problem. The proposed scheme preserves the advantages of the conventional SMC such as simplicity, less parameters dependence and fast response. In addition, axes transformation of the stator voltage or current is not required. The stability of the ANFIS-SMC controller is proven using lyapunov stability theorem. Finally, the proposed and conventional SMC techniques performance is verified by the simulation study on 1.5 MW DFIG systems under variation parameters, harmonic distortion of stator current and reference tracking.

Power quality is a very important issue. Non-linear loads and semi-conductor devices connected to AC electric mains generate unwanted signals  (harmonics) in the dynamics of current which are responsible for additional power losses in heat loss and the risk of equipment damage or malfunctioning.
In the simulink model of shunt active filter fuzzy logic
controller and hysteresis current controller for reducing the
harmonic distortion. Powergui tool of mat lab provides the
function of FFT analysis which is very important to calculate
total harmonic distortion in source current. By taking various
firing angles the total harmonic distortion is calculated by FFT
analysis.

A generalized macroscopic representation of electrical steels used in transformer manufacturing industry is developed. The proposed representation is specifically formulated for integration in the finite element method. Usage of the specific technique enables the accurate evaluation of electromagnetic field distribution of transformer cores under heavily saturated conditions. Advantages over conventional techniques include numerical stability, numerical accuracy, and reduction of iterations of the Newton–Raphson method.

This paper summarizes the fundamental analysis of natural gas supply and demand in US power markets released in 2007 at the Global Energy Decisions Natural Gas Reference Case.  This gas reference case and its companion power market reference cases were used widely as an independent starting point for integrated resource planning b y investor owned utilities, state regulatory commissions, and investment banks.  This service was available for 8 years from 2000-2008.

Increase in use of power electronics in power system addressed power quality problems. Converters are widely used in industrial area for different application. They are non-linear devices and degrade power quality of system. In this paper, 12 – pulse ac – dc power supply is taken as non-linear load example. Power supply, here discuss is use in low voltage, high dc current application. High dc current is generated by connecting four M3 converters in parallel. Phase-shifting transformer is also introduce for require phase displacement. Converter can affect power quality in terms of inject harmonics and decrease power factor. It can be used as dynamic load; therefore, it is necessary to evaluate active and reactive power for different loading condition. This paper represents assessment of power quality for such system.

This work presents a case study on technology assessment for power quality improvement devices. A system compatibility test protocol for power quality mitigation devices was developed in order to evaluate the functionality of three-phase voltage restoration devices. In order to validate this test protocol, the micro-DVR, a reduced power development platform for DVR (dynamic voltage restorer) devices, was tested and the results are discussed based on voltage disturbances standards.► We present a case study on technology assessment for power quality improvement devices. ► We developed a system compatibility test protocol for power quality mitigation devices. ► The proposed test protocol evaluates the functionality of three-phase voltage restoration devices. ► In order to validate this test protocol, the micro-DVR, a reduced power development platform for DVR (dynamic voltage restorer) devices, was tested. ► The results are discussed based on voltage disturbances standards.

The energy sector in Kenya is one of the foundations on which the economic pillar of vision 2030 is based.  Sustainability of the vision’s pillar is based on the idea that development projects proposed under it will increase the demand of energy supply in Kenya. The goal of the vision is that Kenya will by that time have put in place mechanisms and facilities in a bid to generate more energy at a lower cost given that at the moment the cost of energy production in Kenya is significantly higher as compared to neighbouring nations.  Similarly, Kenyans are expected to be connected with affordable electricity by turn of the year 2030.
The vision 2030 blueprint requires that government put in place a more robust legal, institutional and policy framework aimed at not only encouraging more private involvement in power generation and reduction on overreliance on Kenya Generating Company Ltd (KenGen) and Kenya Power and Lightening Company (KPLC) but also exploitation of renewable energy sources particularly solar and wind for purposes of enabling energy-surplus.

In this paper, residential demand response is studied through the scheduling of typical home appliances in order to minimize electricity cost and earn the relevant incentive. A mixed integer nonlinear optimization model is built under a time-of-use electricity tariff. A case study shows that a household is able to shift consumption in response to the varying prices and incentives, through which the consumer may realize an electricity cost saving of more than 25%. It has also been shown that at different values of the weighting factor α gives varying costs, from which the consumer is able to choose according to their preferences. Therefore a final decision about participation in the program could be made.

Regulating transformers with on-load tap changers are extensively used in distribution networks or with loads which are sensitive to voltage fluctuations. Voltage sags of below 85% can cause supply disruption and increased down time which may prove very costly for a production industry. In power system, regulating transformer aided by the tap changers quickly restore the system voltage to avoid outages as a result of under-voltage operation. There are two new approaches to accomplish on-load tap changers: Thyristor assisted and fully static solid state tap changers. This paper will review the two approaches discussing the related merits and demerits of each of these approaches.

This paper represents modelling & simulation of direct vector control (DVC) for doubly fed induction generator
(DFIG) using two-level neural space vector modulation (NSVM) and five-level NSVM technique. This paper provides the
solution through direct vector control & NSVM strategy for multilevel inverter. A comparison and performance of two-level
and five-level inverters are used in DFIG to control reactive power, active power, rotor current and electromagnetic torque.
Matlab simulation environment is taken to simulate DVC control for DFIG-based wind turbine systems (WTSs) using twolevel
and five-level inverter, so reactive and active power ripple minimization, lower order harmonics are reduced,
electromagnetic torque, active and reactive powers are determined through simulation results. The applications under operating
conditions are performed better total harmonic distortion (THD), better reliability in DFIG-based WTSs.

This paper proposes an industrial solution (equipment) for lightning and surge protection of distribution transformers. The proposed protection equipment has been installed at 100 distribution transformers (sample) of the Public Power Corporation (PPC) of Greece. The article estimates the future transformer failures, considering two different cases: (a) transformer without the proposed protection system; and (b) transformer equipped with the proposed protection system. Three different methods are used to estimate the future transformer failures without the proposed protection system: Monte Carlo simulation , Poisson statistical distribution, and binomial statistical distribution. These three methods together with the c control chart method are also used in this paper, for the case of transformers equipped with the proposed protection system, to estimate the maximum allowable number of yearly transformer failures in order the proposed protection system to be considered as an effective protection means. Moreover, the article computes the satisfactory sample size of transformers in which the protection system has to be installed in order to be able to obtain statistically reliable results regarding the effectiveness of the proposed protection system. The results show that the proposed method is an excellent means for lightning and surge protection of distribution transformers, since zero transformer failures have been observed so far during the whole period of its operation (29 months), in contrast with 8.36 average lightning and surge related failures per year in the same sample of 100 transformers before the installation of the proposed protection equipment.

In this paper a robust three-dimensional (3D) finite element (FE) anisotropy model is introduced based on a particular scalar potential formulation. The specific 3D FE model is suitable for the accurate evaluation of the peak flux density distribution and no load loss of one-phase and three-phase wound core distribution transformers. The accuracy of the proposed 3D FE anisotropy model is validated by local flux density and no load loss measurements.

Description of editions of Proceeding  “Controlled Transmission  Lines” is described. During 1972-1988, the Proceeding were published in separate issues, and since 1989 they have been published as a series “Controlled Transmission  Lines”  with sequential numbers. Lists of articles for each issue of the series №1-10 are given in the annexes  to this article.

Objectives: Load forecasting is an operation of predicting the future of load demands in electrical systems using previous or historical data. This paper reports the study on a medium-term load forecast carried out with load demand data set obtained from Covenant University campus in Nigeria and carry out comparative study of the two methods used in this paper. Methods/Statistical analysis: The regression analysis and Artificial Neural Network (ANN) models were used to show the feasibility of generating an accurate medium-term load forecast for the case study despite the peculiarity of its load data. The statistical evaluation methods used are Mean Absolute Percentage Error (MAPE) and root mean square error. Findings: The results from the comparative study show that the ANN model is a superior method for load forecast
due to its ability to handle the load data and it has lower MAPE and RMSE of 0.0285 and 1.124 respectively which is far better result than the regression model. Application/Improvements: This result provides a benchmark for power system planning and future studies in this research domain.