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  • 1.
    Babu, Sajeesh
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Hilber, Patrik
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Shayesteh, Ebrahim
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Enarsson, Lars Einar
    Reliability Evaluation of Distribution Structures Considering the Presence of False Trips2018Inngår i: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a method for modelling the different modes of failures in a substation and feeder architecture along with updating the possible false tripping scenarios in it. A traditional approach to collectively assess the failure modes using reliability block diagram is reviewed, and the method is updated to count in the unaccounted false tripping scenarios. A generalizable radial feeder branching structure is adopted and the effect of total feeder length and number of feeders from each busbar is examined and modelled with the help of the updated reliability block diagram. The modelled trends are also studied from real-world substation architectures. Thus, the analysis attains an improved estimation of the complex hidden failure probabilities combining theoretical and practical models.

  • 2.
    Babu, Sajeesh
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Shayesteh, Ebrahim
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Hilber, Patrik
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Analysing Correlated Events in Power System Using Fault Statistics2016Inngår i: Probabilistic Methods Applied to Power Systems (PMAPS), 2016 International Conference on, IEEE, 2016Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Power system automation requires logical presumptions made on practical grids to correctly comprehend and manage complex and correlated faults occurring in real world systems. Traditional grid fault analysis methods lack in-depth understanding of these complex events and demand development of approaches that make use of available data to address this problem. Here, the traditional classification approach and challenges relating control equipment in power system are reviewed and a method observing the affected customers during faults along with grid design is discussed based on Swedish case study data. Various contrasting observations are made on the data recorded over two time periods to understand the trend developing over years. Moreover, it will be shown that the classification method also has potential in identifying weak spots in the grid when it comes to the reliability of control equipment.

  • 3.
    Duvnjak Zarkovic, Sanja
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Hilber, Patrik
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Shayesteh, Ebrahim
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    On the Security of Electricity Supply in Power Distribution Systems2018Inngår i: 2018 IEEE International Conference on Probabilistic Methods Applied to Power Systems (PMAPS), IEEE conference proceedings, 2018, artikkel-id 8440489Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Security of electricity supply has become a fundamental requirement for modern societies. However, attempts to define and evaluate security of supply have differed from one another. This paper reviews relevant studies in order to give a comprehensive explanation of the security of supply concept. The paper includes theory, assessment, methodology, regulations, data and practical issues associated with the security of supply and power system reliability. Special focus is given to the methodologies used for improving the reliability and security of supply in power distribution systems.

  • 4.
    Duvnjak Zarkovic, Sanja
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Stankovic, Stefan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Shayesteh, Ebrahim
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Hilber, Patrik
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Reliability improvement of distribution system through distribution system planning: MILP vs. GA2019Inngår i: 2019 IEEE Milan PowerTech, 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Distribution system planning (DSP) is very important because it can result in reliability enhancement and large cost savings for both utilities and consumers. DSP is a complex nonlinear problem, which can be solved with different optimization methods. This paper compares two such optimization methods, conventional (mixed-integer linear programming - MILP) and meta-heuristic (genetic algorithm - GA), applied to the DSP problem: construction of feeders in distribution power system from scratch. The main objective of DSP is to minimize the total cost, where both the investment and operational outage costs are considered, while the reliability of the whole system is maximized. DSP problem is applied to an actual distribution system. Solution methods are outlined, and computational results show that even though GA gives reasonably good results in faster computation time, MILP provides a better optimal solution with simpler implementation.

  • 5.
    Fazlagic, Berina
    et al.
    KTH.
    Wallnerström, C. J.
    Shayesteh, Ebrahim
    KTH.
    Hilber, Patrik
    KTH.
    Development of the utilisation and smart grid incentive scheme within the Swedish revenue cap regulation2017Inngår i: CIRED - Open Access Proceedings Journal, Institution of Engineering and Technology, 2017, Vol. 2017, nr 1, s. 2696-2699, artikkel-id 1Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This study provides a summary on how Swedish distribution system operators (DSO) are regulated after a revenue cap model, and describes a potential development on the current utilization incentive scheme within this regulation. The analyses are based on data from a Swedish DSO, which have been elaborated with the use of demand response program. The outcome of the demand response simulation has in a later step been applied to calculate the incentive in the revenue cap regulation. Two different calculation approaches are used and compared in order to calculate the load factor in the revenue cap regulation. The results of the case study show that by applying a weighted daily load factor, the DSO in the case study can receive ~3% additional economic income compared to applying an average daily load factor in the incentive calculation. The motivation behind applying weighted load factor is to prioritize days with high energy consumption since those days have more impact on the costs. Most important, the analysis display that replacing the average load factor with a weighted load factor have a non-negligible impact on the incentive calculation and hence if the change fulfill its purpose enough.

  • 6.
    Hamon, Camille
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Shayesteh, Ebrahim
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Amelin, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Two partitioning methods for multi-area studies in large power systems2015Inngår i: International Transactions on Electrical Energy Systems, E-ISSN 2050-7038, Vol. 25, nr 4, s. 648-660Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multi-area studies are an important tool for today's and future power systems. In this paper, a two-step algorithm for creating multi-area models is presented that, first, identifies areas, and, second, computes reduced models of these areas. For the first step, two new methods to identify areas in power systems have been developed. The first method is based upon spectral partitioning, whereas the second one is formulated as a linear optimization problem. The methods are compared in terms of computation time on the IEEE 118 bus system, and the first method clearly stands out in this comparison. The first method is then applied to the IEEE 300 bus system and to a model of the Polish power system with 2746 buses to study how it scales in large power systems. Even in the latter case, it runs in less than 30s. For the second step, existing equivalencing methods can be used. As an example, radial, equivalent, and independent equivalents are used to model the areas identified by the partitioning methods. The partitioning and equivalencing methods have been tested on the IEEE 118 bus system by running 1000 regular and optimal power flows. Comparisons with the original IEEE 118 bus system in terms of flows, costs and losses are carried out.

  • 7.
    Mazidi, Peyman
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik. Comillas Pontifical University, Spain.
    Bobi, Miguel A. Sanz
    Shayesteh, Ebrahim
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Hilber, Patrik
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Impact of health indicators on maintenance management and operation of power systems2017Inngår i: Journal of Risk and Reliability, ISSN 1748-006X, E-ISSN 1748-0078, Vol. 231, nr 6, s. 716-731Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article proposes a maintenance management and risk reduction approach. The approach introduces two reliability-based indexes called condition indicator and risk indicator. Condition indicator is a unit-less parameter that comes directly from monitored condition of a component and converts the categorical condition into a numerical value. Risk indicator in megawatt represents the risk imposed by the health of a component onto the system. To demonstrate application of the indicators, they are implemented through an hourly network constraint unit commitment problem and applied in a test system where the analysis of impact of condition of the generators to the operation is the new contribution. The results demonstrate how addition of such indicators will impact the operation of the grid and maintenance scheduling. The results show the benefit for the system operator as the overall failure risk in the system is taken into account, and the benefit for the asset owner as the direct impact of the maintenance to be carried out can be investigated. Two of the main outcomes of the maintenance management and risk reduction approach are as follows: asset owners can analyze their maintenance strategies and evaluate their impacts in the maintenance scheduling, and system operators can operate the grid with higher security and lower risk of failure.

  • 8.
    Pham, Cong-Toan
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Månsson, Daniel
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Hilber, Patrik
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Shayesteh, Ebrahim
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Reliability consideration in the energy storagesystem design process2018Inngår i: 2018 IEEE International Conference on Probabilistic Methods Applied to Power Systems (PMAPS), IEEE, 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Energy storage systems are an important asset inthe future power grid, ensuring the safety and reliability inface of growing power consumption and intermittent supply.Occupying a vital role, the reliability of the storage system itselfhas to be guaranteed and taken into account for, especially inthe design procedure. This study utilizes reliability methods toanalyze the storage’s system reliability and optimize the systemsize to an appropriate level. A residential building with a 3.3kWphotovoltaic system serves as a case study to analyze differentenergy storage types and their resulting optimum systemstructure. The paper also includes an economic evaluation tomeasure the storage’s suitability for the particular case with thephotovoltaic system.

  • 9.
    Samadi, Afshin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Shayesteh, Ebrahim
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Eriksson, Robert
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Rawn, Barry
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Multi-objective coordinated droop-based voltage regulation in distribution grids with PV systems2014Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 71, s. 315-323Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High penetrations of photovoltaic (PV) systems in distribution grids have caused new challenges such as reverse power flow and voltage rise. Reactive power contribution by PV systems has been proposed by grid codes and literature as one of the remedies for voltage profile violation. Recent German Grid Codes (GGC), for instance, introduce a standard active power dependent reactive power characteristic, Q(P), for inverter-coupled distributed generators. Nevertheless, the GGC recommends a voltage dependent reactive power characteristic Q(V) for the near future, recognizing that the Q(P) characteristic cannot explicitly address voltage limits. This study utilizes the voltage sensitivity matrix and quasi-static analysis in order to develop a coordinated Q(V) characteristic for each PV system along a radial feeder using only the local measurement and drooping technique concepts. The aim of this paper is using a multi-objective design to adjust the parameters of the Q(V) characteristic in the proposed droop-based voltage regulation in order to minimize the reactive power consumption and line losses. On the other hand, it is also possible to adjust the parameters in order to reach equal reactive power sharing among all PV systems. A radial test distribution grid, which consist of five PV systems, is used to calculate power flow and, in turn, the voltage sensitivity matrix. The comparison of results demonstrates that both approaches in the proposed droop-based voltage regulation can successfully regulate the voltage to the steady-state limit. Moreover, it is shown that the profile of reactive power consumption and line losses are considerably reduced by the multi-objective design.

  • 10.
    Samadi, Afshin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Shayesteh, Ebrahim
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Optimal Coordination of Q(P) Characteristics for PV Systems in Distribution Grids for Minimizing Reactive Power Consumption2014Inngår i: AORC Technical Meeting 2014, 2014Konferansepaper (Fagfellevurdert)
  • 11.
    Samadi, Afshin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Shayesteh, Ebrahim
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Eriksson, Robert
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Static Equivalent of Distribution Grids with High Penetration of PV SystemsManuskript (preprint) (Annet vitenskapelig)
  • 12.
    Samadi, Afshin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Shayesteh, Ebrahim
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Eriksson, Robert
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Static Equivalent of Distribution Grids With High Penetration of PV Systems2015Inngår i: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 6, nr 4, s. 1763-1774Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High penetrations of photovoltaic (PV) systems within load pockets in distribution grids have changed pure consumers to prosumers. This can cause technical challenges in distribution and transmission grids, such as overvoltage and reverse power flow. Embedding voltage support schemes into PVs, such as standard cos phi(P) characteristic proposed by the German grid codes, may cause more changes in the steady-state behavior of distribution grids and, in turn, the transmission side. Accordingly, it is important to properly model active distribution grids to analyze the system impacts of these changes to plan and operate future smart power grids. However, due to the high dimension of distribution grids, considering a detailed distribution grid to study the transmission side or a fraction of the distribution grid is either cumbersome or impractical. Therefore, it is required to develop a reasonable equivalent that can fairly capture the dominant behavior of the distribution grids. The aim of this paper is to use gray-box modeling concepts to develop a static equivalent of distribution grids comprising a large number of PV systems embedded with voltage support schemes. In the proposed model, the PV systems are aggregated as a separate entity, and not as a negative load, which is traditionally done. The results demonstrate the superior quality of the proposed model compared with the model with PV systems as the negative load.

  • 13.
    Shayesteh, E.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Gayme, D. F.
    Amelin, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    System reduction techniques for storage allocation in large power systems2018Inngår i: International Journal of Electrical Power & Energy Systems, ISSN 0142-0615, E-ISSN 1879-3517, Vol. 95, s. 108-117Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Semi-Definite Relaxation (SDR) techniques for AC optimal power flow (OPF) have recently been proposed as a means of obtaining a provably global optimal solution for many IEEE benchmark power systems. Solving the resulting semi-definite programs (SDP) can, however, be computationally intensive. Therefore new algorithms and techniques that enable more efficient computations are needed to extend the applicability of SDP based AC OPF algorithms to very large power networks. This paper proposes a three-stage algorithm for AC OPF based storage placement in large power systems. The first step involves network reduction whereby a small equivalent system that approximates the original power network is obtained. The AC OPF problem for this equivalent system is then solved by applying an SDR to the non-convex problem. Finally, the results from the reduced system are transferred to the original system using a set of repeating optimizations. The efficacy of the algorithm is tested through case studies using two IEEE benchmark systems and comparing the solutions obtained to those of DC OPF based storage allocation. The simulation results demonstrate that the proposed algorithm produces more accurate results than the DC OPF based algorithm.

  • 14.
    Shayesteh, Ebrahim
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Efficient Simulation Methods of Large Power Systems with High Penetration of Renewable Energy Resources: Theory and Applications2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Electrical energy is one of the most common forms of energy these days. Consequently, electric power system is an indispensable part of any society. However, due to the deregulation of electricity markets and the growth in the share of power generation by uncontrollable renewable energies such as wind and solar, power system simulations are more challenging than earlier. Thus, new techniques for simplifying these simulations are needed. One important example of such simplification techniques is the power system reduction.

    Power system reduction can be used at least for four different purposes: a) Simplifying the power system simulations, b) Reducing the computational complexity, c) Compensating the data unavailability, and d) Reducing the existing uncertainty. Due to such reasons, power system reduction is an important and necessary subject, but a challenging task to do. Power system reduction is even more essential when system operators are facing very large-scale power systems and when the renewable energy resources like hydro, wind, and solar have a high share in power generation.

    This thesis focuses on the topic of large-scale power system reduction with high penetration of renewable energy resources and tries to pursue the following goals:

    • The thesis first reviews the different methods which can be used for simplifying the power system studies, including the power system reduction. A comparison among three important simplification techniques is also performed to reveal which simplification results in less error and more simulation time decrement.

    • Secondly, different steps and methods for power system reduction, including network aggregation and generation aggregation, are introduced, described and discussed.

    • Some improvements regarding the subject of power system reduction, i.e. on both network aggregation and generation aggregation, are developed.

    • Finally, power system reduction is applied to some power system problems and the results of these applications are evaluated.

    A general conclusion is that using power system simplification techniques and specially the system reduction can provides many important advantages in studying large-scale power systems with high share of renewable energy generations. In most of applications, not only the power system reduction highly reduces the complexity of the power system study under consideration, but it also results in small errors. Therefore, it can be used as an efficient method for dealing with current bulk power systems with huge amounts of renewable and distributed generations.

  • 15.
    Shayesteh, Ebrahim
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Amelin, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Area equivalents for spinning reserve determination in interconnected power systems2015Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 88, s. 907-916Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The current study applies the cost-benefit analysis method to determine the optimal amount of spinning reserve. However, it is difficult for the method to handle large size problem, like large interconnected power systems with several control areas, directly. Therefore, this paper proposes a power system equivalent for the original system to reduce the complexity of the original problem. According to the proposed algorithm, each area of the system is first modeled by an equivalent system, obtained by the RE! (radial - equivalent - independent) method, and an interconnected REI equivalent is obtained for the original interconnected system. A cost-benefit analysis is then performed to determine the spinning reserve requirements of both the original and equivalent systems. The cost-benefit algorithm considers either the SCUC (security constrained unit commitment) or the SCED (security constrained economic dispatch). Finally, the proposed interconnected REI equivalent is evaluated by comparing the spinning reserve of each control area in the original system with that in the equivalent system. Numerical studies are performed on two IEEE test systems. (C) 2015 Elsevier Ltd. All rights reserved.

  • 16.
    Shayesteh, Ebrahim
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Amelin, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Multi-Station Equivalents for Short-Term Hydropower Scheduling2016Inngår i: IEEE Transactions on Power Systems, ISSN 0885-8950, E-ISSN 1558-0679, Vol. 31, nr 6, s. 4616-4625Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hydropower scheduling in day-ahead electricity markets is complex due to uncertainty in the electricity price. Internal cascade dependency of hydro power plants can also increase this complexity. One way to overcome this complexity is to replace the original hydropower system by an equivalent system, which provides simulation results sufficiently close to the ones of the original system. This paper presents a method to obtain multi-station equivalent models using a bilevel optimization problem, where the objective is to minimize the difference in outcomes between the original and the equivalent models. This bilevel problem is then transformed into a single-level optimization problem that can be solved using standard optimization techniques. Finally, the errors between the simulation results of the original and equivalent hydropower models are computed and analyzed for a Swedish system to show the accuracy of different multi-station equivalents.

  • 17.
    Shayesteh, Ebrahim
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Amelin, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Power system equivalents for spinning reserve determination in multi-area power systemsManuskript (preprint) (Annet vitenskapelig)
  • 18.
    Shayesteh, Ebrahim
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Gayme, D.
    Amelin, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    System Reduction Techniques for Storage Allocation in Large Power SystemsManuskript (preprint) (Annet vitenskapelig)
  • 19.
    Shayesteh, Ebrahim
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Hamon, Camille
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Amelin, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    REI method for multi-area modeling of power systems2014Inngår i: International Journal of Electrical Power & Energy Systems, ISSN 0142-0615, E-ISSN 1879-3517, Vol. 60, s. 283-292Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Interconnections between different electricity markets and high penetration levels of wind power have resulted in an increase in the size of power systems with higher levels of uncertainties. This paper presents an algorithm for bulk power system simulations with large wind power penetrations, based on multi-area modeling with transmission constraints. The present study differs from previous multi-area studies by taking into account the capacity of intra-area lines during the simulations, which leads to more accurate results. The method that we introduce consists of three steps. First, a power system with high wind power penetration is divided into several areas using a practical measure, admittance matrix. Second, the internal system of each area is replaced with a smaller system, to which an improved version of the REI (Radial, Equivalent, and Independent) method is developed and applied. Finally, the technical properties of the reduced power system (such as voltage limits and transmission capacities) are tuned by adjusting optimization, in a way that the simulation results of the reduced power system are comparable with those of the original system. The IEEE 30-bus and IEEE 118-bus test systems are used to show the efficiency of the proposed algorithm.

  • 20.
    Shayesteh, Ebrahim
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Hilber, Patrik
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Reliability-Centered Asset Management Using Component Reliability Importance2016Inngår i: 2016 INTERNATIONAL CONFERENCE ON PROBABILISTIC METHODS APPLIED TO POWER SYSTEMS (PMAPS), IEEE, 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Asset management is an important topic in all fields especially in power system which has very high investment costs and very expensive elements. Reliability Centered Asset Management (RCAM) is an effective technique to perform the power system asset management with quantitative methods such that, on the one hand, the total cost is minimized and, on the other hand, the reliability of the system is maximized Nevertheless, the need for an appropriate optimization-based algorithm for RCAM implementation in power system is still sensed. This paper proposes an algorithm to fulfil such needs including the following steps. First, the component reliability importance index is calculated for all components of the system. Then, a set of all potential maintenance strategies of each component are defined and together with the component reliability importance indices are used as inputs in the third step. In the third step, an optimization problem is proposed to select the optimum maintenance strategy for each component in the system. The proposed three-step algorithm is tested on a Swedish distribution system. The results highlight the advantages of the proposed method for well-organizing the maintenance strategies for all components of the system.

  • 21.
    Shayesteh, Ebrahim
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Hobbs, B. F.
    Amelin, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Scenario reduction, network aggregation, and DC linearization: which simplifications matter most in market simulations?Manuskript (preprint) (Annet vitenskapelig)
  • 22.
    Shayesteh, Ebrahim
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Hobbs, B. F.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Amelin, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    ATC-Based System Reduction for Planning Power Systems With Correlated Wind and Loads2015Inngår i: IEEE Transactions on Power Systems, ISSN 0885-8950, E-ISSN 1558-0679, Vol. 30, nr 1, s. 429-438Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Simulations of production costs, flows, and prices are crucial inputs to generation and transmission planning studies. To calculate average system performance for many alternatives over long time periods, it is necessary to simulate large numbers of hourly combinations of renewable production and loads across large regions. As this is usually impractical for full network representations of such systems, aggregation of buses and lines is desirable. We propose an improved aggregation method for creating multi-area representations of power systems that yields more accurate estimates of the quantities required by planners. The method is based on partitioning the original large system into smaller areas and making a reduced equivalent for each area. The partitioning is based on available transfer capability (ATC) between each pair of network buses. Because ATC depends on net load conditions, separate partitions are defined for subsets of similar load and wind conditions, significantly enhancing the accuracy of optimal power flow solutions. We test the method on the IEEE 118-bus test system and the Polish 3120-bus system considering 150 load/wind scenarios, comparing the results to those of admittance-based partitioning methods. Accuracy is improved with only a negligible increase in simulation time.

  • 23.
    Shayesteh, Ebrahim
    et al.
    KTH, Skolan för elektro- och systemteknik (EES).
    Yu, J.
    KTH, Skolan för elektro- och systemteknik (EES).
    Hilber, Patrik
    KTH, Skolan för elektro- och systemteknik (EES).
    Maintenance optimization of power systems with renewable energy sources integrated2018Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 149, s. 577-586Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper proposes a quantitative maintenance optimization problem for developing reliability centred maintenance for a power system with renewable energy sources. Reliability and cost are two important interlinked aspects considered by system operators in many deregulated power systems. Reliability centred maintenance is an effective method to consider both of these aspects when performing the maintenance optimization. Nevertheless, this method has not adequately studied for a power system with renewable energy sources included. According to the maintenance optimization problem proposed in this paper, first, the most critical components of the system are selected. Then, a set of maintenance strategies are proposed for all critical components. After that, the total cost of each maintenance strategy for all critical components are calculated as the summation of operation, maintenance, environmental, and interruption costs. Finally, the best maintenance strategy for each critical component is selected by identifying the lowest total cost of different maintenance strategies. The proposed method is tested on IEEE 14-bus system. The results show that the proposed maintenance optimization method provides a useful way for deciding the most proper maintenance strategies for the studied system.

  • 24.
    Song, Meng
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Amelin, Mikael
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Shayesteh, Ebrahim
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Hilber, Patrik
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Impacts of flexible demand on the reliability of power systems2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Demand response provides flexibility to power systems through adjusting the power consumption. This study investigates the impact of flexible demands on the system reliability with real-time price-based demand response. It assumes that the power demand is sensitive to nodal price and the price is communicated to consumers as soon as it is cleared on market. The uncertainties of nodal price and potential flexibility are considered. Models are proposed for the optimal operation of a power system with and without demand response, respectively. The proposed models are evaluated through application to a 6-bus system using Monte Carlo simulation. The result shows that the reliability indices LOLP and EENS are improved for the system and for each bus when the demand is sensitive to nodal price. Moreover, the nodal prices decrease, reflecting a more efficient operation and a lower electricity price charged on consumers.

1 - 24 of 24
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