پروفسور گئورگ قره پتیان

Transmission lines and transformers are the most important equipment of a power network, the outage of which can lead to cascading failure. This paper tries to identify those lines or transformers that cannot be prevented from being overloaded by operations such as load shedding or production decrease through considering a model of cascade outage simulation. Also, one of the risk assessment methods, called Failure Modes and Effects Analysis (FMEA) method, is used to identify the critical network lines and transformers known as initial events of cascading failures. This method through the evaluation of three criteria ofseverity, occurrence, and detection assesses and categorizes the risk priority number (RPN) of the combination of possible N-K (1). The proposed method was implemented in the IEEE 39-bus test system, and its results showed its accuracy compared to the other methods.

An increase in global temperature, the vital need to reduce environmental emissions resulted from greenhouse gases, and the nonrenewablity of those energy resources have led to a change in attitudes and a turn to deploy advanced technologies and renewable energy resources as an alternative in electric power generation equipment. However, renewable energy resources are not reliable. In fact, the non-reliable nature of these resources has caused the deployment of diesel generators as a backup resource to cover loads in emergency situations. Among these non-reliable resources, biofuels as a substitute for fossil fuels in diesel generators not only stop the emissions of pure CO2 and other toxic pollutants in the air but also save money in the future. In this study, it has been tried to preserve technical specifications and the reliability of system by adding a hydroelectric power plant in addition to wind and solar systems. Furthermore, the use of biodiesel (biofuel) as an alternative in diesel generators can help identify an optimized autonomous hybrid system in terms of minimum costs while considering social costs and emission limits by Homer software of. Vanaei village in Lorestan province, Iran, is presented as acase study.

The combined heat and power (CHP) generation is an energy-saving method in which power and heat are simultaneously generated. The important features of heat and power units are the interdependence between the amount of power and heat generated, which increases the complexity of the problem and can be solved by powerful optimization methods. In this paper, planning and optimizing the combined heat and power generation, including the supply of electrical and thermal power required by the network, are performed. This goal is achieved with two main approaches, including the valve point effect and examining this effect while modeling load peak in the presence of energy storage systems of the battery type, which is the novelty of this paper. This paper offers the hyper-spherical search (HSS) algorithm and particle swarm optimization method to optimize and solve the problem of CHPED in large units and, then, compares and validates the results. The simulation results show that the proposed methods can be used as a reliable method to solve the problem of CHPED by considering different constraints.

This paperproposes a method for accurate sharing of harmonic and unbalanced loads in islanded microgrids. The proposed method can adaptively improve the load sharing among Distributed Generation (DG) units based on the circulating current rules and the harmonic and unbalanced power provided by each DG. Compared with previous methods, the proposed method does not require a dedicated central controller, and a relation should only be established among the adjacent DGs. Moreover, in this method, there is no need to know the values of the impedance of the DGs feeder and the loading conditions, and the effect of the proposed method on the quality of the output voltage of the DGs is less. The design process of the proposed method has fully been described; furthermore, to demonstrate the efficiency of the method, studies on the simulation have been performed on a sample islanded microgrids in MATLAB/Simulink environment.

With appearance and development of Microgrids (MGs), the number of MGs is continuously increased in smart distribution networks. Hence the future distribution network operation and planning is encountered with new challenges. In this paper, the problem of networked-microgrids based distribution network planning is considered. The parking lot for electric vehicles as storage resources to reduce the impacts of uncertainties on networked-MGs design is investigated. The boundary of MGs is determined and segmented considering techno-economical constraints such as total network planning and operation costs, reliability improvement of MGs, optimal sizing and locating of energy resources within each MGs and the voltage profile improvement in the presence of EV’s parking lot as storages. For each objective function, optimal border of each MG, its relevant energy resources and EV parking lot capacity and location as well as optimal layout of smart distribution network is obtained. The results are represented both tabular form and graphically.

Parallel, standby and series configurations are different types of power switch configuration that can be considered in semiconductor switches to improve the reliability of power electronic converters and theirs lifetime, especially in specific application such as high power industrial applications, satellites, power electronic interface for renewable energies and etc. In this paper, the reliability models of series traditional configuration and the new type are developed based on the Markov process. The mean time to failure (MTTF) of series and new configuration are derived. The reliability and MTTF of triple and new configuration are compared together. In some cases, some redundancy configurations have the same MTTF in a boundary condition. The analytical result illustrated that the new configuration is a suitable alternative instead of the standby configuration. The result showed the series and parallel configuration are suitable for high voltage and high current applications .

In this paper, frequency response analysis (FRA) of transformer based on the detailed model of the transformer windings, is investigated. The determination of the detailed model parameters, which can be considered as a large scale model, is a complex task. To overcome this problem, a heuristic method is presented in this paper. This method is applied to a large scale detailed model with nineteen sections.The state equation model is used, to extract the transfer function of the large scale detail model of the transformer. In this paper, all parameters of the model are assumed to be frequency dependent. Also, a new improved detailed model is presented. It is shown that this model can represent the transient behavior of the transformer winding better than the well-known detailed model. In the laboratory, all new ideas presented in this paper, are applied to a 20/0.4-kV and 1600-kVA transformer. The comparison of simulation and measurement results show the privilege of the improved detailed model in comparison with the conventional ones.

Recently connection of some Distributed generation and load has created Microgrids (MGs). This MG can operate in grid connected mode or disconnects from main grid. Maintaining stability of MG When it is disconnected from main grid, is an important problem. Frequency stability is one of aspects of stability. Using of energy storage with appropriate control strategy can be effective in this subject. In this paper A flywheel energy storage system (FESS) in detailed is described and is used for frequency control in islanding mode. Two control strategies for DGs inverters are stated and suitable method for each DG and FESS is selected. Simulation is carried by MATLAB/Simulink. Two case studies are examined. In two cases, FESS effect on frequency in islanding process is discussed. Results of simulation verify appropriate operation of FESS and confirm effectiveness of this application.

In order to prevent energy waste by throttle valve in gas pressure reducing station of Neka thermal power plant, a turbo-expander with a capacity of 9.8 MW for the power plant was prepared and installed. Presence of turbo-expander in Neka power plant due to the absorption of 63 MVAr reactive power at the moment of starting, resulted in severe voltage drops in the auxiliary service system and outage of sensitive equipment to voltage level, which makes impossible the operation of the turbo-expander. In this paper, while pathology of turbo-expander and their performance Improvement using compensator, to review all topologies of dynamic voltage restorer compensator and improved topology will be presented. Then, for optimal performance of compensators the possible points presence of them on the auxiliary service system of Neka power plant in various scenarios under synchronization of fault occurring conditions and starting will be tested. The results of PSCAD / EMTDC software simulation show by using improved topology of dynamic voltage restorer, voltage sag of turbo-expander starting compensated in various scenarios and can be provide the total auxiliary service system power consumption of this power plant by turbo-expander instead of using the generation of power plant.

Generation Expansion Planning (GEP) is a large-scale nonlinear optimization problem with stochastic behavior. Generation system planers tend to use many different methods to address the expansion problem and to determine optimum plans by minimizing the mathematical objective function subject to different constraints. This paper presents an Improved Genetic Algorithm (IGA) to solve (GEP) problem. This algorithm uses Capacity Outage Table (COT) method، Analytical Hierarchy Process (AHP)، Successive Forward and Backward method and a new approach to improve the GA. The expert engineers suggestions have important role in this algorithm.

Due to the high penetration of wind farms in the networks, they can have a significant role in the control of power systems. In this paper, wind farms (WFs) are used to improve the static security margins of the power system. Generation rescheduling is one of the remedies to improve the static security margins of the power system. In this paper, the generation rescheduling is presented based on wind farms. To assess the security of the power system, the net active and reactive (generation minus demand) powers of all buses are selected as features. The numbers of the features are reduced based on one of the famous methods of the feature extraction methods named Principle Component Analysis (PCA). The feature extraction method is used to save all features effects on the security of the power system. In this paper, to find the most optimum way to improve the static security margins, two optimization problems are introduced for the two strategies presented. The proposed method is implemented on the IEEE 39-bus network and the results show its effectiveness on the static security margin. It should be mentioned that the proposed method can deal with correlated random variables. Nataf transformation is used to build more accurate and more realistic database to train the classifier to assess the static security margins of the power system. The real data of Iran's grid are used to validate the Nataf transformation

This article is introducing a new controlling scheme for islanding operating of inverter-based distributed generations. That in this method load protection at the time of connection to the network and islanding operation is completely intended. Moreover, the islanding detection algorithm which is based on ROCOF relaying, for detecting islanding phenomenon is provided. The algorithm is also equipped with synchronization block that at the time of network retrieval would be able to reconnect the upper network to the distributed generation. It is necessary to mention that all the simulations and tests are carried out in the MATLAB / Simulink environment.Provided method has security and flexibility and will have no interference with operation of voltage regulation instruments in the distribution network.

T‌h‌e h‌a‌r‌m‌o‌n‌i‌c c‌o‌n‌t‌e‌n‌t o‌f s‌u‌p‌p‌l‌y v‌o‌l‌t‌a‌g‌e‌s i‌n‌c‌r‌e‌a‌s‌e‌s t‌h‌e p‌o‌w‌e‌r c‌o‌n‌s‌u‌m‌p‌t‌i‌o‌n o‌f t‌h‌e l‌o‌a‌d‌s a‌n‌d i‌m‌p‌o‌s‌e‌s e‌c‌o‌n‌o‌m‌i‌c‌a‌l l‌o‌s‌s‌e‌s o‌n c‌u‌s‌t‌o‌m‌e‌r‌s. H‌o‌w‌e‌v‌e‌r, t‌h‌e l‌e‌v‌e‌l o‌f e‌c‌o‌n‌o‌m‌i‌c e‌f‌f‌e‌c‌t‌s a‌n‌d a‌l‌s‌o t‌h‌e r‌o‌l‌e o‌f p‌o‌w‌e‌r q‌u‌a‌l‌i‌t‌y i‌n‌s‌t‌r‌u‌m‌e‌n‌t‌s f‌o‌r d‌e‌c‌r‌e‌a‌s‌i‌n‌g p‌o‌w‌e‌r l‌o‌s‌s‌e‌s a‌r‌e u‌n‌k‌n‌o‌w‌n. I‌n t‌h‌i‌s p‌a‌p‌e‌r, a‌n i‌m‌p‌r‌o‌v‌e‌d m‌o‌d‌e‌l f‌o‌r a‌g‌g‌r‌e‌g‌a‌t‌e‌d l‌o‌a‌d‌s i‌s p‌r‌o‌p‌o‌s‌e‌d. B‌a‌s‌e‌d o‌n t‌h‌i‌s m‌o‌d‌e‌l, t‌h‌e e‌f‌f‌e‌c‌t‌s o‌f v‌o‌l‌t‌a‌g‌e h‌a‌r‌m‌o‌n‌i‌c‌s o‌n l‌o‌a‌d p‌o‌w‌e‌r c‌o‌n‌s‌u‌m‌p‌t‌i‌o‌n a‌n‌d i‌t‌s e‌c‌o‌n‌o‌m‌i‌c‌a‌l a‌s‌p‌e‌c‌t‌s a‌r‌e i‌n‌v‌e‌s‌t‌i‌g‌a‌t‌e‌d. T‌h‌e m‌o‌d‌e‌l p‌a‌r‌a‌m‌e‌t‌e‌r‌s a‌r‌e i‌d‌e‌n‌t‌i‌f‌i‌e‌d b‌y p‌r‌a‌c‌t‌i‌c‌a‌l m‌e‌a‌n‌s, s‌u‌c‌h a‌s c‌a‌p‌a‌c‌i‌t‌o‌r b‌a‌n‌k s‌w‌i‌t‌c‌h‌i‌n‌g o‌r l‌o‌a‌d s‌w‌i‌t‌c‌h‌i‌n‌g m‌e‌t‌h‌o‌d‌s. T‌h‌e p‌r‌o‌p‌o‌s‌e‌d m‌o‌d‌e‌l i‌s v‌e‌r‌i‌f‌i‌e‌d b‌y c‌o‌m‌p‌a‌r‌i‌s‌o‌n o‌f t‌h‌e s‌i‌m‌u‌l‌a‌t‌e‌d a‌n‌d m‌e‌a‌s‌u‌r‌e‌d r‌e‌s‌u‌l‌t‌s.