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  • 1.
    Almas, Muhammad Shoaib
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Vanfretti, Luigi
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems. Statnett.
    Singh, Ravi Shankar
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems. KTH Royal Institute of Technology.
    Jonsdottir, Gudrun Margret
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems. KTH Royal Institute of Technology.
    Vulnerability of Synchrophasor-based WAMPAC Applications’ to Time Synchronization Spoofing2017In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. PP, no PP, p. 1-1Article in journal (Refereed)
    Abstract [en]

    This paper experimentally assesses the impact of time synchronization spoofing attacks (TSSA) on synchrophasor-based Wide-Area Monitoring, Protection and Control applications. Phase Angle Monitoring (PAM), anti-islanding protection and power oscillation damping applications are investigated. TSSA are created using a real-time IRIG-B signal generator and power system models are executed using a real-time simulator with commercial phasor measurement units (PMUs) coupled to them as hardware-in-the-loop. Because PMUs utilize time synchronization signals to compute synchrophasors, an error in the PMUs’ time input introduces a proportional phase error in the voltage or current phase measurements provided by the PMU. The experiments conclude that a phase angle monitoring application will show erroneous power transfers, whereas the anti-islanding protection mal-operates and the damping controller introduces negative damping in the system as a result of the time synchronization error incurred in the PMUs due to TSSA.The proposed test-bench and TSSA approach can be used to investigate the impact of TSSA on any WAMPAC application and to determine the time synchronization error threshold that can be tolerated by these WAMPAC applications.

  • 2.
    Babu, Sajeesh
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Hilber, Patrik
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Shayesteh, Ebrahim
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Enarsson, Lars Einar
    Reliability Evaluation of Distribution Structures Considering the Presence of False Trips2016In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061Article in journal (Other academic)
    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.

  • 3. Bahramirad, Shay
    et al.
    Khodaei, Amin
    Matevson, Julia
    Li, Zuyi
    Bertling, Lina
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Passo, Essa Aleksi
    Fotuhi-Firuzabad, Mahmud
    Special Section on Asset Management in Smart Grid2015In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 6, no 2, p. 953-954Article in journal (Other academic)
  • 4. Bangalore, Pramod
    et al.
    Tjernberg, Lina Bertling
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    An Artificial Neural Network Approach for Early Fault Detection of Gearbox Bearings2015In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 6, no 2, p. 980-987Article in journal (Refereed)
    Abstract [en]

    Gearbox has proven to be a major contributor toward downtime in wind turbines. The majority of failures in the gearbox originate from the gearbox bearings. An early indication of possible wear and tear in the gearbox bearings may be used for effective predictive maintenance, thereby reducing the overall cost of maintenance. This paper introduces a self-evolving maintenance scheduler framework for maintenance management of wind turbines. Furthermore, an artificial neural network (ANN)-based condition monitoring approach using data from supervisory control and data acquisition system is proposed. The ANN-based condition monitoring approach is applied to gearbox bearings with real data from onshore wind turbines, rated 2 MW, and located in the south of Sweden. The results demonstrate that the proposed ANN-based condition monitoring approach is capable of indicating severe damage in the components being monitored in advance.

  • 5.
    Barreto, Sergio
    et al.
    EPFL.
    Pignati, Marco
    EPFL.
    Dán, György
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Paolone, Mario
    EPFL.
    Le Boudec, Jean-Yves
    EPFL.
    Undetectable PMU Timing-Attack on Linear State-Estimation by UsingRank-1 Approximation2016In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061Article in journal (Refereed)
    Abstract [en]

    Smart-grid applications based on synchrophasor measurements have recently been shown to be vulnerable to timing attacks. A fundamental question is whether timing attacks could remain undetected by bad-data detection algorithms used in conjunction with state-of-the-art situational-awareness state estimators. In this paper, we analyze the detectability of timing attacks on linear state-estimation. We show that it is possible to forge delay attacks that are undetectable. We give a closed form for an undetectable attack; it imposes two phase offsets to two or more synchrophasor-based measurement units that can be translated to synchrophasors’ time delays. We also propose different methods for combining two-delays attacks to produce a larger impact. We simulate the attacks on a benchmark powertransmission grid, we show that they are successful and can lead to physical grid damage. To prove undetectability, we use classic bad-data detection techniques such as the largest normalized residual and the 2-test.

  • 6.
    Feng, Wang
    et al.
    Chalmers, Div Elect Power Engn, S-41296 Gothenburg, Sweden.
    Tuan, Le
    Chalmers, Div Elect Power Engn, S-41296 Gothenburg, Sweden.
    Bertling Tjernberg, Lina
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Chalmers, Div Elect Power Engn, S-41296 Gothenburg, Sweden.
    Mannikoff, Anders
    SP Technical Research Institute of Sweden, Borås 501 15, Sweden.
    Bergman, Anders
    SP Tech Res Inst Sweden, S-50115 Boras, Sweden.
    A New Approach for Benefit Evaluation of Multiterminal VSC–HVDC Using A Proposed Mixed AC/DC Optimal Power Flow2014In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, ISSN 1949-3053, Vol. 29, no 1, p. 432-443Article in journal (Refereed)
    Abstract [en]

    In this paper, an extended optimal power-flow (OPF) model incorporating a detailed model of a voltage-source con- verter-based–multiterminal high-voltage direct current system (VSC–MTDC) is proposed, hereafter referred to as the mixed ac/dc OPF (M-OPF) model. A cost-benefit analysis approach using the M-OPF model as the calculation engine is proposed to determine the preferred VSC-MTDC alternative to be installed in an existing ac transmission system. In this approach, the op- erational benefits of VSC–MTDC systems are evaluated against their investment costs to derive the benefit-to-cost ratios (BCR) which reflect the cost-effectiveness of the alternatives. A case study has been carried out using a modified Nordic 32-bus system. The results of the study show that VSC–MTDC systems might lead to a reduction in total operation cost, and the reduction of the total system transmission loss depends to a large extent on the VSC–MTDC configuration. The results from sensitivity analyses show that if the VSC loss could be reduced to a third of the original level, the total benefit from the system would be increased by about 70%. A suggestion for the placement and configuration of a VSC–MTDC system is made based on calculated BCRs. 

  • 7.
    Grahn, Pia
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Alvehag, Karin
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    PHEV Utilization Model Considering Type-of-Trip and Recharging Flexibility2014In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 5, no 1, p. 139-148Article in journal (Refereed)
    Abstract [en]

    Electric vehicles (EVs) may soon enter the vehicle market in large numbers and change the overall fuel usage within the passenger transport sector. With increased variable consumption from EVs together with anticipated increased production from variable sources, due to renewable wind and solar power, also the balancing of the electric power system incur increased attention. This emphasizes the importance of developing models to estimate and investigate the stochasticity of personal car travel behavior and induced EV charging load. Several studies have been made in order to model the stochasticity of passenger car travel behavior but none have captured the charging behavior dependence of the type-of-trip conducted. This paper proposes a new model for plug-in-hybrid electric vehicle (PHEV) utilization and recharging price sensitivity, to determine charging load profiles based on driving patterns due to the type-of-trip and corresponding charging need. This approach makes it possible to relate the type-of-trip with the consumption level, the parking location, and the charging opportunity. The proposed model is applied in a case study using Swedish car travel data. The results show the charging load impact and variation due to the stochastic PHEV type-of-trip mobility, allowing quantification of the PHEV charging impact on the system.

  • 8.
    Hasananpor Divshali, Poria
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Improving Hosting Capacity of Rooftop PVs by Quadratic Control of an LV-Central BSS2017In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. PP, no 99, p. 1-1Article in journal (Refereed)
    Abstract [en]

    High integration of rooftop photovoltaic (PV) plants in distribution systems leads to new technical challenges: reverse-active power and voltage rise in low-voltage (LV) and medium-voltage (MV) grids. These challenges limit the maximum amount of power can be produced by PVs in LV and MV grids, called the hosting capacity (HC). Battery storage systems (BSSs) have been used in many studies to decrease the reverse power and improve the HC by controlling the active power. However, the influence of a central BSS on the HC can be greatly improved by using a quadratic power control, simultaneous active and reactive power control, and by selecting of the optimal battery size, the converter size, and the place of the central BSS. The effectiveness of the quadratic power control was not seen in previous works due to the fact that grids with one level of voltage without modeling of MV/LV transformers were simulated. This paper develops a method to select the optimal size of the battery and converter unit as well as the optimal place of an LV-central BSS having an optimal quadratic power control. The simulation results show considerable effects of the optimal selection of an LV-central BSS on the HC improvement.

  • 9.
    König, Johan
    et al.
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Nordström, Lars
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Österlind, Magnus
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Reliability Analysis of Substation Automation Functions using PRMs2013In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 4, no 1, p. 206-213Article in journal (Refereed)
    Abstract [en]

    This paper presents the application of a framework for reliability analysis of substation automation (SA) system functions. The framework is based on probabilistic relational models which combines probabilistic reasoning offered by Bayesian networks together with architecture models in form of entity relationship diagrams. In the analysis, both the physical infrastructure, and the logical structure of the system, is regarded in terms of qualitative modeling and quantitative analysis. Moreover, the framework treats the aspect of failures caused by software. An example is detailed with the framework applied to an IEC 61850-based SA system. The logical structure, including functions and their relations, is modeled in accordance with Pieces of Information for COMmunication (PICOM) defined in the IEC 61850 standard. By applying PICOMs as frame of reference when modeling functions the model instantiation becomes more standardized compared to subjectively defining functions. A quantitative reliability analysis is performed on a function for tipping a circuit breaker in case of mismatch between currents. The result is presented both in terms of a qualitative architecture model and a quantitative result showing the probability of successful operation during a period of one year.

  • 10. Lavaei, J.
    et al.
    Low, S.
    Baldick, R.
    Zhang, B.
    Molzahn, D.
    Dorfler, F.
    Sandberg, Henrik
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Guest Editorial Distributed Control and Efficient Optimization Methods for Smart Grid2017In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 8, no 6, p. 2939-2940, article id 8075192Article in journal (Refereed)
  • 11. Li, Hongyang
    et al.
    Dán, György
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Nahrstedt, Klara
    Portunes plus: Privacy-Preserving Fast Authentication for Dynamic Electric Vehicle Charging2017In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 8, no 5, p. 2305-2313Article in journal (Refereed)
    Abstract [en]

    Dynamic contactless charging is an emerging technology for charging electric vehicles (EVs) on the move. For efficient charging and for proper billing, dynamic charging requires secure communication between the charging infrastructure and the EVs that supports very frequent real-time message exchange for EV authentication. In this paper, we propose Portunes+, an authentication protocol for charging pads to authenticate an EVs identity. Portunes+ uses pseudonyms to provide location privacy, allows EVs to roam between different charging sections and receive a single bill, and achieves fast authentication by relying on symmetric keys and on the spatiotemporal location of the EV. We have implemented Portunes+ on RaspberryPi 2 Model B with 900 MHz CPU and 1 GB RAM. Portunes+ allows the EV to generate authentication information within 0.15 ms and allows charging pads to verify the information within 0.11 ms. In comparison, Elliptic Curve Digital Signature Algorithm signature generation and verification take over 9 ms and over 14 ms, respectively.

  • 12.
    Momber, Ilan
    et al.
    KTH, School of Electrical Engineering (EES).
    Morales-España, Germán
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Ramos, Andres
    Gomez, Tomas
    PEV Storage in Multi-Bus Scheduling Problems2014In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 5, no 2, p. 1079-1087Article in journal (Refereed)
    Abstract [en]

    Modeling electricity storage to address challenges and opportunities of its applications for smart grids requires inter-temporal equalities to keep track of energy content over time. Prevalently, these constraints present crucial modeling elements as to what extent energy storage applications can enhance future electric power systems' sustainability, reliability, and efficiency. This paper presents a novel and improved mixed-integer linear problem (MILP) formulation for energy storage of plug-in (hybrid) electric vehicles (PEVs) for reserves in power system models. It is based on insights from the field of System Dynamics, in which complex interactions between different elements are studied by means of feedback loops as well as stocks, flows and co-flows. Generalized to a multi-bus system, this formulation includes improvements in the energy balance and surpasses shortcomings in the way existing literature deals with reserve constraints. Tested on the IEEE 14-bus system with realistic PEV mobility patterns, the deterministic results show changes in the scheduling of the units, often referred to as unit commitment (UC).

  • 13. Mueller, Sven Christian
    et al.
    Georg, Hanno
    Nutaro, James J.
    Widl, Edmund
    Deng, Yi
    Palensky, Peter
    Awais, Muhammad U.
    Chenine, Moustafa
    KTH.
    Kuech, Markus
    Stifter, Matthias
    Lin, Hua
    Shukla, Sandeep K.
    Wietfeld, Christian
    Rehtanz, Christian
    Dufour, Christian
    Wang, Xiaoyu
    Dinavahi, Venkata
    Faruque, Md Omar
    Meng, Wenchao
    Liu, Shichao
    Monti, Antonello
    Ni, Ming
    Davoudi, Ali
    Mehrizi-Sani, Ali
    Interfacing Power System and ICT Simulators: Challenges, State-of-the-Art, and Case Studies2018In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 9, no 1, p. 14-24Article in journal (Refereed)
    Abstract [en]

    With the transition toward a smart grid, the power system has become strongly intertwined with the information and communication technology (ICT) infrastructure. The interdependency of both domains requires a combined analysis of physical and ICT processes, but simulating these together is a major challenge due to the fundamentally different modeling and simulation concepts. After outlining these challenges, such as time synchronization and event handling, this paper presents an overview of state-of-the-art solutions to interface power system and ICT simulators. Due to their prominence in recent research, a special focus is set on co-simulation approaches and their challenges and potentials. Further, two case studies analyzing the impact of ICT on applications in power system operation illustrate the necessity of a holistic approach and show the capabilities of state-of-the-art co-simulation platforms.

  • 14.
    Picciariello, Angela
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Alvehag, Karin
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Impact of Network Regulation on the Incentive for DG Integration for the DSO: Opportunities for a Transition Toward a Smart Grid2015In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 6, no 4, p. 1730-1739Article in journal (Refereed)
    Abstract [en]

    The integration of distributed generation (DG) in distribution grids is one of the pillars of smart grid deployment. However, an increasing amount of DG connected to distribution grids is likely to affect the operation of the grids themselves, e.g., changing the magnitude, and in some cases the direction, of power flows. In order to perform the transition to a smart grid, it is therefore essential to have the distribution system operators (DSOs) involved in the process. However, being that the DSOs' business is controlled by regulators, regulation has a fundamental impact on the speed and the actual performance of DSOs' involvement in the transition toward a smart grid. Therefore, a method is needed to assess network regulation impact on DSOs' incentive to integrate DG into their grids. This paper proposes a new method for the calculation of such incentive, and the method has been applied on a case study to the Portuguese, Danish, and Swedish regulations for different scenarios of DG penetration. The focus is on DSOs' operational costs and revenues. The analyses indicate that DG has a different impact on DSOs business, depending on the different regulations, the most relevant aspects being the structure of customer tariffs and the regulatory treatment of network losses.

  • 15.
    Samadi, Afshin
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Shayesteh, Ebrahim
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Eriksson, Robert
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Static Equivalent of Distribution Grids With High Penetration of PV Systems2015In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 6, no 4, p. 1763-1774Article in journal (Refereed)
    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.

  • 16.
    Sou, Kin Cheong
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. Chalmers University of Technology.
    Sandberg, Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Data Attack Isolation in Power Networks Using Secure Voltage Magnitude Measurements2014In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 5, no 1, p. 14-28Article in journal (Refereed)
    Abstract [en]

    In this paper a procedure to detect and isolate data attacks on power network power flow measurements is proposed. This method can be used in conjunction with available bad data detection (BDD) methods to isolate multiple bad data which are otherwise difficult to handle. The proposed procedure relies on secure measurements of bus voltage magnitudes to define a measurement residual using potentially compromised active and reactive power flow measurements on transmission lines. The proposed residual can be calculated in real-time. In addition, the component of the proposed residual on any particular line depends only locally on the component of the data attack on the same line. This makes the proposed residual well-suited for distributed data attack isolation in large-scale power networks. Furthermore, it can be shown that the proposed procedure becomes more effective when measurements from multiple time instances can be utilized. A detailed numerical case study on the IEEE 14-bus benchmark system demonstrates the effectiveness of the proposed procedure.

  • 17.
    Sou, Kin Cheong
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Sandberg, Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    On the Exact Solution to a Smart Grid Cyber-Security Analysis Problem2013In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 4, no 2, p. 856-865Article in journal (Refereed)
    Abstract [en]

    This paper considers a smart grid cyber-security problem analyzing the vulnerabilities of electric power networks to false data attacks. The analysis problem is related to a constrained cardinality minimization problem. The main result shows that an l1 relaxation technique provides an exact optimal solution to this cardinality minimization problem. The proposed result is based on a polyhedral combinatorics argument. It is different from well-known results based on mutual coherence and restricted isometry property. The results are illustrated on benchmarks including the IEEE 118-bus, IEEE 300-bus and the Polish 2383-bus and 2736-bus systems.

  • 18.
    Wallnerström, Carl Johan
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Huang, Yalin
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Impact from Dynamic Line Rating on Wind Power Integration2015In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 6, no 1, p. 343-350Article in journal (Refereed)
    Abstract [en]

    The concept of dynamic rating (DR) implies that the capacity of a component varies dynamically as a function of external parameters, while the rating traditionally is based on the worst-case. The value of DR thus lies in utilizing existing equipment to a greater extent. By implementing DR and correlating the new ratings with wind power generation, more generation can be implemented. The aim is hence to facilitate connection of renewable electricity production. This paper provides two main contributions: 1) a general dynamic line rating (DLR) calculation model on overhead lines; and 2) an economic optimization simulation model regarding wind power integration comparing DLR with more traditional approaches. These models can both be implemented together, but also separately. The DLR calculation model is easy to use by companies in daily operation where the dynamic line capacity is calculated as a function of static line capacity, wind speed, and ambient temperature. The DLR calculation model is furthermore compared with more comprehensive calculations that validate that the model is accurate enough. This paper also provides an application study where both proposed models are exemplified together and evaluated. Results from this study conclude that it is a significant economic potential of implementing DR within wind power integration.

  • 19.
    Yuan, Zhao
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Reza Hesamzadeh, Mohammad
    A Modified Benders Decomposition Algorithm to Solve Second-Order Cone AC Optimal Power FlowIn: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061Article in journal (Refereed)
    Abstract [en]

    This paper proposes to speed up solving large-scale second-order cone AC optimal power flow (SOC-ACOPF) problem by decomposition and parallelization. Firstly, we use spectral factorization to partition large power network to multiple subnetworks connected by tie-lines. Then a modified Benders decomposition algorithm (M-BDA) is proposed to solve the SOC-ACOPF problem iteratively. Taking the total power output of each subnetwork as the complicating variable, we formulate the SOC-ACOPF problem of tie-lines as the master problem and the SOC-ACOPF problems of the subnetworks as the subproblems in the proposed M-BDA. The feasibility and optimality (preserving the original optimal solution of the SOC-ACOPF model) of the proposed M-BDA are analytically and numerically proved. A GAMS grid computing framework is designed to compute the formulated subproblems of M-BDA in parallel. The numerical results show that the proposed M-BDA can solve large-scale SOC-ACOPF problem efficiently. Accelerated M-BDA by parallel computing converges within few iterations. The computational efficiency (reducing computation CPU time and computer RAM requirement) can be improved by increasing the number of partitioned subnetworks.

  • 20.
    Yuan, Zhao
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Reza Hesamzadeh, Mohammad
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    R.~Biggar, Darryl
    Australian Competition and Consumer Commission.
    Distribution Locational Marginal Pricing by Convexified ACOPF and Hierarchical Dispatch2016In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061Article in journal (Refereed)
    Abstract [en]

    This paper proposes a hierarchical economic dispatch (HED) mechanism for computing distribution locational marginal prices (DLMPs). The HED mechanism involves three levels: The top level is the national (regional) transmission network, the middle level is the distribution network, while the lowest level reflects local embedded networks or microgrids. Each network operator communicates its generalized bid functions (GBFs) to the next higher level of the hierarchy. The GBFs approximate the true cost function of a network by a series of affine functions. The concept of Benders cuts are employed in simulating the GBFs. The AC optimal power flow (ACOPF) is convexified and then used for dispatching generators and calculating GBFs and DLMPs. The proposed convexification is based on the second order cone reformulation. A sequential optimization algorithm is developed to tighten the proposed second order cone relaxation of ACOPF. The properties of the sequential tightness algorithm are discussed and proved. The HED is implemented in the GAMS grid computing platform. The GBFs and DLMPs are calculated for the modified IEEE 342 node low voltage test system. The numerical results show the utility of the proposed HED and GBF in implementing DLMP.

  • 21.
    Zhu, Kun
    et al.
    Ventyx ABB Co, S-10044 Vasteras, Sweden.
    Chenine, Moustafa
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Nordström, Lars
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Holmström, Sture
    Ericsson, Göran
    Design Requirements of Wide-Area Damping Systems-Using Empirical Data From a Utility IP Network2014In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 5, no 2, p. 829-838Article in journal (Refereed)
    Abstract [en]

    Phasor Measurement Unit (PMU) communication delays and data frame losses play a critical role in designing of wide-area damping systems driven by synchrophasor technology. While there are a plethora of simulation-based studies addressing this issue, empirical results from actual PMUs deployed in the field are rare. This paper provides important insights into the characterization of PMU communication delays and data frame losses based on empirical results collected from a utility IP network. Additionally, efforts are also made to elicit design requirements considering the above PMU data quality problems. Furthermore, three distinct delay-robust wide-area damping control schemes parameterized according to the proposed requirements are validated against the empirical delays and data frame losses. Time-domain simulation results suggest that the control schemes in question can effectively stabilize the power system in all of the tested scenarios.

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