Sejid Tešnjak

Bio: Sejid Tešnjak is an academic researcher from University of Zagreb. The author has contributed to research in topics: Electric power system & Control theory. The author has an hindex of 9, co-authored 48 publications receiving 274 citations.

A component-based power system model-driven architecture

Abstract: This letter describes an approach of applying the model-driven development in power systems. A component-based model-driven architecture, that gives full flexibility of the automation in source code generation, is introduced. A design pattern to code generation is described.

Undervoltage load shedding using global voltage collapse index

Abstract: Increasingly higher demand in power created problems in power system operation since the growth of the transmission system is restricted. System often function close to their stability limits and sometimes loads need to be shed in order to prevent system from collapsing. In this paper one undervoltage load shedding (UVLS) method to prevent voltage collapse is presented. This method is based on a global index, which indicates voltage collapse proximity and voltage magnitudes on critical buses. Global index for voltage collapse proximity determination is calculated based on power flow Jacobian matrix operations. Considering that on the voltage stability limit Jacobian matrix becomes singular, it cannot be inverted. Therefore method involving eigenvalue calculation is used here. IEEE 14 bus system was used as a numerical example, which showed how loads and system in general can be saved from voltage collapse using UVLS.

An overview of ancillary services in an open market environment

Abstract: The worldwide restructuring of the electrical energy industry is followed by processes like deregulation, liberalization and commercialization. These changes introduce new paradigms such as competition in generation and the concept of electricity supply as a commodity market and creates a new set of transactions among utilities and new agents and end users. An important aspect is the role of competitive markets stressed by the new regulation in procurement and remuneration of ancillary services. These services are required to provide stability and security of supply. Ancillary services have a variety of terms used through the world to name them (e.g. system services, support services) and it is not easy to define or classify them. The objective of this paper is to give a possible classification scheme for ancillary services to allow an easier identification of the roles of suppliers and buyers. Also, means by which the costs of various services can be measured, quantified and allocated are discussed and one method for cost allocation is proposed.

An adaptive approach to setting underfrequency load shedding relays for an isolated power system with private generation

Abstract: The problem of frequency load shedding in an isolated power system is considered. A proper design of the load shedding scheme should minimize consumer disruption in the case of the load excess and help balance the load to the remaining generation in a system. An adaptive strategy, which can reduce total amount of shed close to the theoretical minimum, is proposed and compared to conventional load shedding scheme.

Information fusion for wireless sensor networks: Methods, models, and classifications

Abstract: Wireless sensor networks produce a large amount of data that needs to be processed, delivered, and assessed according to the application objectives. The way these data are manipulated by the sensor nodes is a fundamental issue. Information fusion arises as a response to process data gathered by sensor nodes and benefits from their processing capability. By exploiting the synergy among the available data, information fusion techniques can reduce the amount of data traffic, filter noisy measurements, and make predictions and inferences about a monitored entity. In this work, we survey the current state-of-the-art of information fusion by presenting the known methods, algorithms, architectures, and models of information fusion, and discuss their applicability in the context of wireless sensor networks.

Load Modeling—A Review

Abstract: Load modeling has significant impact on power system studies. This paper presents a review on load modeling and identification techniques. Load models can be classified into two broad categories: 1) static and 2) dynamic models, while there are two types of approaches to identify model parameters: 1) measurement-based and 2) component-based. Load modeling has received more attention in recent years because of the renewable integration, demand-side management, and smart metering devices. However, the commonly used load models are outdated, and cannot represent emerging loads. There is a need to systematically review existing load modeling techniques and suggest future research directions to meet the increasing interests from industry and academia. In this paper, we provide a thorough survey on the academic research progress and industry practices, and highlight existing issues and new trends in load modeling.

Control barrier function based quadratic programs with application to bipedal robotic walking

Abstract: This paper presents a methodology for the development of control barrier functions (CBFs) through a backstepping inspired approach. Given a set defined as the superlevel set of a function, h, the main result is a constructive means for generating control barrier functions that guarantee forward invariance of this set. In particular, if the function defining the set has relative degree n, an iterative methodology utilizing higher order derivatives of h provably results in a control barrier function that can be explicitly derived. To demonstrate these formal results, they are applied in the context of bipedal robotic walking. Physical constraints, e.g., joint limits, are represented by control barrier functions and unified with control objectives expressed through control Lyapunov functions (CLFs) via quadratic program (QP) based controllers. The end result is the generation of stable walking satisfying physical realizability constraints for a model of the bipedal robot AMBER2.