O. Shariati

Optimal Sizing and Siting of Distributed Generators by a Weighted Exhaustive Search

Abstract Dispersed generation generally refers to power generation on the customer side of the power network. This article demonstrates the improvement in network parameters that could be achieved by the usage of single and multiple distributed generation (DG) units in three selected standard networks. A reliable multi-variable method is suggested for finding the optimal installation point and size of distributed generation units. Their sites and sizes are recognized by the implementation of the proposed method with an exhaustive search. Optimization is applied on network total active and reactive losses together with voltage variation. IEEE 6-, 14-, and 30-bus standard networks are selected as study cases. The total active and reactive power losses are minimized, while the voltage profile is improved by installing distributed generation units on the recognized optimal points with the achieved optimal size.

Application of neural network observer for on-line estimation of salient-pole synchronous generators' dynamic parameters using the operating data

Parameter identification is critical for modern control strategies in electrical power systems which is considered both dynamic performance and energy efficiency. This paper presents a novel application of ANN observers in estimating and tracking Salient-Pole Synchronous Generator Dynamic Parameters using time-domain, on-line disturbance measurements. The data for training ANN Observers are obtained through off-line simulations of a salient-pole synchronous generator operating in a one-machine-infinite-bus environment. The Levenberg-Marquardt algorithm has been adopted and assimilated into the back-propagation learning algorithm for training feed-forward neural networks. The inputs of ANNs are organized in conformity with the results of the observability analysis of synchronous generator dynamic parameters in its dynamic behavior. A collection of ANNs with same inputs but different outputs are developed to determine a set of the dynamic parameters. The ANNs are employed to estimate the dynamic parameters by the measurements which are carried out within each kind of fault separately. The trained ANNs are tested with on-line measurements to identify the dynamic parameters. Simulation studies indicate the ANN observer has a great ability to identify the dynamic parameters of salient-pole synchronous generator. The results also show that the tests which have given better results in estimation of each dynamic parameter can be obtained.

Feasibility study of wave energy potential in southern coasts of Caspian Sea in Iran

Wave energy as a predictable renewable energy, can be directly captured from surface wave, which has a significant power. Although the application of wave energy in recent years is rapidly increased all over the world especially in Europe, but there is a lack of research in this field in some developing countries. Hence, in this study a new research about potential of wave in Southern border of Caspian Sea in Iran is performed. Moreover, the climate effect that has contributed to the increasing wave power is also investigated. The results show that Mazandaran seashore in north of Iran has a proper potential for extracting electricity from sea wave. Furthermore, based on a comparison of established wave energy converters, Wave Dragoon is a suitable converter for the study case.

An Integrated Method for under Frequency Load Shedding Based on Hybrid Intelligent System-Part I: Dynamic Simulation

Security is one of the most vital requirements in the operation of power systems. Frequency is a reliable indicator to determine instability condition in power system, i.e. the stability of power system is closely dependent on the value of system frequency. Under Frequency Load Shedding (UFLS) is one of the most important protection systems as in many cases it is the last action taken to prevent a system blackout after a serious disturbance occurs in power system. The first part of this two part paper presents various factors in modern power systems which have significant contribution on Under Frequency Load Shedding (UFLS). A high-order multi-machine frequency response model is utilized as it the best strategy of power system dynamic simulation. Classification of modern power system components and using an equal unit for each class is proposed in this work. The results show that ANN models can also be implemented as well as a fast dynamic simulator of electric power system. This assessment includes a review of significant researches on power system dynamic simulation and frequency response model leading to an integrated UFLS system design.

Optimal Sizing and Siting of Distributed Generators by Exhaustive Search

ABSTRACTDispersed generation generally refers to power generation on the customer side of a power network. This article demonstrates the improvement in network parameters which could be achieved by using single and multiple Distributed Generation units in three selected standard networks. A reliable multi variable method is used for finding optimal installation point and size of distributed generation units. Their sites and sizes are recognized by implementation of a proposed method with exhaustive search. Optimization has been applied on network total active and reactive losses together with voltage variation. IEEE 6, 14 and 30 buses standard networks have been selected as study cases. The total active and reactive power losses are minimized while voltage profile is improved by installing Distributed Generation units on recognized optimal points with achieved optimal size.

Feasibility and impact of using six-phase line in a specific distribution and sub-transmission system

Power loss issue is one of the most significant issues encountered in electrical industry and it is essential to note. System design is essentially to ensure that the increased electricity demand could be meeting by power system development, so that it becomes technically a suitable and economical system. Distribution system has a particular importance in electrification due to: 1) near perfectly to the consumers 2) high investment cost. On the other hand, about 67% of power grid loss is related to the distribution system. Beside, conversion of 3-Phase Double-Circuit (3PDC) to 6-Phase Single-Circuit (6PSC) line is known as a well method to increase the power transfer capability of existing ROWs. Thus, in this paper, an investigation of conversion of existing 3-Phase Single-Circuit (3PSC) lines to the 3PDC to 6PSC lines is studied and compared. It is found that with the same transmitted power in the 3PDC and 6PSC states, using the 6PSC line in suitable places of sub-transmission and distribution systems will dramatically result in decreased loss and improved voltage regulation. In all the cases, test power system is assumed as a balanced system.

On-line overcurrent relays setting approach in distribution networks by implementing new adaptive protection algorithm

In order to meet the ever increasing demand for power, the government has revised its targets in increasing power generation. For this purpose, installation of new equipment or utilization of Distributed Generation (DG) has been employed. In addition to changes in topology of power grid, the amplitude of the short circuit currents also can be affected due to these developments. In this condition, fixed setting for the protective relays cannot respond correctly. In order to prevent any miscoordination or mal-operation, relays have to be adaptively coordinated for a new system configuration to achieve correct fault clearance operation. In this paper, a reliable protection scheme is achieved by implementing the proposed adaptive protection algorithm. As results show, proposed new settings for the relays avoid the risk of unnecessary blackout for distribution network consumers. In addition, sensitive and reliable protection scheme is achieved by implementing the proposed adaptive algorithm.

An Integrated Method for under Frequency Load Shedding Based on Hybrid Intelligent System-Part II: UFLS Design

The first part of this two part paper has proposed a novel strategy for frequency response modelling of modern power system, as it recommended a new application of artificial neural network in assessment of power system dynamic performance. The intelligent methods have shown a high ability in estimation and optimisation problems, as the recent advances in computer systems and intelligent methods have created new opportunities. The current paper proposes an integrated under frequency load shedding system based on genetic algorithm which is able to consider all effective factors at the same time. It also presents a new hybrid artificial neural network-genetic algorithm basis system for under frequency load shedding which is a quick, simple and applied method of UFLS. This assessment includes a review of significant researches on under frequency load shedding design and application.

Disturbance analysis in conversion of double three-phase to six-phase transmission network

Fault occurrence in power systems could result in losing their stability and cause severe damages in faulted devices or adjacent healthy devices. Also, stability proposition is charged as an important component in energy management and planning of power systems. Moreover, during the motor starting period, it draws a large current from the system, results in voltage drop of system and poses disturbances to the normal operation of other loads. Hence, fault and induction motor starting analysis are important studies in design and development of power systems. Beside, conversion of 3-phase double-circuit (3PDC) to 6-phase single-circuit (6PSC) line is a well known method to increase the power transfer capability of the network. So in this paper, an investigation of fault occurrence and motor starting for 3PDC converted to 6PSC transmission line is studied. According to the achieved results, if network is converted to 6PSC network, then system performance from view of transient stability and motor starting could improve, but magnitude of fault current may be increased than the 3PDC network. In this study, power system is assumed as a balanced system. Other economical and practical factors can be studied for planning, development and design of future transmission networks.

Network losses reduction by replacing conventional generation with dispersed generators on MV side

Dispersed generation generally refers to power generation on costumer side of power network. This paper demonstrates the improvement in power losses which achieved by usage of DGs in a selected network. A reliable method for finding optimal installation point of distributed generation units by exhaustive search is presented. Optimal point selection has been applied on network total power loss. An IEEE 14 buses standard network has been selected as the case study. The total active and reactive power losses are minimized while voltage profile is improved by installing DG units on recognized optimal points.