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Special Issue: Fault Tolerant Control of Power Grids
Peter Odgaard, Christophe Aubrun, Yrjo Majanne
To cite this version:
Peter Odgaard, Christophe Aubrun, Yrjo Majanne. Special Issue: Fault Tolerant Control of
Power Grids. International Journal of Robust and Nonlinear Control, Wiley-Blackwell, 2014,
24 (8-9), pp.1281-1282. <10.1002/rnc.3148>. <hal-00992200>
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INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL
Int. J. Robust. Nonlinear Control 2014; 00:
12
Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/rnc
Fault Tolerant Power Grids
P. F. Odgaard
1
and C. Aubrunp,
2
and Y. Majanne,
3
1
Aalborg University, 9220 Aalborg East, Denmark
2
CRAN, University of Lorraine, 54506 Vandoeuvre-Les-Nancy, France
3
Tampare Universty of Technology, 33720 Tampere, Finland
SUMMARY
This special issue contains article on fault detection and isolation and fault tolerant control methods applied
to different aspects of modern power grids, both for accommodating faults in the power grid, and for
accommodation of faults in power generating units. Copyright
c
2014 John Wiley & Sons, Ltd.
Received ...
KEY WORDS: Power Grids, Wind Turbines, Fault Tolerant Control, Fault Detection and Isolation
In the recent years a high focus has been drawn to making power grids smarter for a number
of reasons. The main reason is to ensure grid stability and power quality in power grid, which has
changed its nature from being dominated by a few large generating units to a grid dominated by
many smaller generating units, with an increasing number of renewable generating sources like
wind turbines and photo electric units. This has lead to a high research level in (Smart) Power Grids
in general and as well in control of these grids. In the process of ensuring grid stability and quality
it is important to detect, isolate and accommodate faults occurring in the physical grid or in the
generating units.
The focus of this special issue on fault tolerant control in power grids is to draw research interest
into different aspects of fault detection and isolation as well as fault tolerant control of power grids
and power generating units. These methods plays an important role in the general handling of faults
which could in the worst case result in stability problems in the grid.
This special issue contains a broad spectrum of contributions dealing with faults in wind turbine
to a number of different aspects of fault detection and isolation and fault tolerant control in the
actual power grid. These works apply a number of different methods. One trend can, however, be
seen. Most solutions proposed for fault detection, isolation and accommodation in power grids are
distributed solutions, which are beneficial as the grids are dominated in a higher and higher degree
of smaller geographically distributed units.
Simani and Castaldi, [
1], present a fault tolerant control solution for a wind turbine connected
to a power grid. They focus on accommodation of faults in hydraulic pitch actuator, by using
adaptive filters designed using a nonlinear geometric approach. The proposed approach is evaluated
on known wind turbine fault tolerant control benchmark model.
Segundo Sevilla, et. al., [
2], present both passive and active fault tolerant control approaches for
inter areadamping in a power grid. A combination of local and remote sensors are used in the design.
The schemes are tested on both a linear and nonlinear models of the Nordic equivalent power grid.
Juelsgaard, et. al., [
3], present a fault tolerant for portfolio balancing control approach. It consists
of a distributed power optimization scheme for grid balancing, which provides tolerance to the grid
in the way that it accommodates changes in the portfolio either due to faults or reasons. It also
Correspondence to: Aalborg University, 9220 Aalborg East, Denmark (e-mail: pfo@es.aau.dk)
Copyright
c
2014 John Wiley & Sons, Ltd.
Prepared using rncauth.cls [Version: 2010/03/27 v2.00]
2 P.F. ODGAARD AND C. AUBRUN AND Y. MAJANNE
includes controllable users in the distributed optimization. The work is evaluated with a numerical
example.
Huang and Wu, [
4], deal with the problem of inclusion of additional Phase Measuring Units
(PMU) into the power grid control structure, and as well communication with these PMUs. The
design is made tolerant towards random communication faults between the PMUs and the grid
controller. The scheme is tested on the IEEE 118-bus test model.
Yadykin, et. al., [
5], analyze power grid stability using finite and infinite Gramians to solve the
differential and algebraic Lyapunov equations in the time and frequency domains which are used to
model the power grid. The proposed scheme is applied to the Kundur four machine two area system
model.
Tedesco and Casavola, [
6], presents distributed supervisory control strategy for load and
frequency set point distribution for the power generators in a power grid. This solution
accommodates unexpected changes in the power balance in the grid, by changing the set points
for the active generating units. The scheme is evaluated with a model of a four area power grid.
Zhang, et. al., [
7], suggest a distributed fault detection and isolation method for detecting and
isolating islanding faults in smart (power) grids. It is a distributed approach in which each power
generating unit in the grid detects andisolates thefaults, based on local measurements.It is evaluated
on simulation study of a two machine power grid.
Wu, et. al., [
8], propose an active fault detection and isolation scheme for islanding faults. It is a
distributed scheme, in which each generating unit in the grid introduces the active detection signals
and detects and isolates the faults in the grid, which is obtained using a Set-Membership filter. The
scheme is evaluated with a simulation study.
Knuppel, et. al., [
9], present a structural approach for fault detection and isolation in a power grid.
The scheme is designed to adjust itself to changes in the grid, such that the most efficient analytical
redundancy relations are used. The scheme is evaluated by using PowerFactory simulation tools.
REFERENCES
1. Simani S, Castaldi P. Active actuator fault tolerant control of a wind turbine benchmark model. International Journal
of Robust and Nonlinear Control 2013; .
2. Segundo Sevilla FR, Jaimoukha B I and;Chaudhuri, Korba P. Fault-tolerant control design to enhance damping of
inter-area. International Journal of Robust and Nonlinear Control 2013; .
3. Juelsgaard M, Wisniewski R, Bendtsen J. Fault tolerant distributed portfolio optimization in smart grids.
International Journal of Robust and Nonlinear Control 2013; .
4. Huang J, Wu E. Minimum cost upgrade of pmu networks for synchrophasor availability. International Journal of
Robust and Nonlinear Control 2013; .
5. Yadykin I, IskakovA, Ahmetzyanov A. Stability analysis of large-scale dynamical systems by sub-gramian approach.
International Journal of Robust and Nonlinear Control 2013; .
6. Tedesco F, Casavola A. Fault-tolerant distributed load/frequency supervisory strategies for networked multi-area
microgrids. International Journal of Robust and Nonlinear Control 2013; .
7. Zhang X, Zhang Q, Polycarpou M, Parisini T. Distributed sensor fault detection and isolation for multimachine
power systems. International Journal of Robust and Nonlinear Control 2013; .
8. Wu Z, Yang F, Han QL. A novel islanding fault detection for distributed generation systems. International Journal
of Robust and Nonlinear Control 2013; .
9. Knuppel T, Blanke M, Oestergaard J. Fault diagnosis for electrical distribution systems using structural analysis.
International Journal of Robust and Nonlinear Control 2013; .
Copyright
c
2014 John Wiley & Sons, Ltd. Int. J. Robust. Nonlinear Control (2014)
Prepared using rncauth.cls DOI: 10.1002/rnc
ResearchGate has not been able to resolve any citations for this publication.
Article
In this paper, passive and active approaches for the design of fault-tolerant controllers (FTCs) are presented. The FTCs are used to improve the damping of inter-area oscillations in a power grid. The effectiveness of using a combination of local and remote (wide area) feedback signals is first demonstrated. The challenge is then to guarantee a minimum level of dynamic performance following a loss of remote signals. The designs are based on regional pole placement using linear matrix inequalities. First, a passive FTC is proposed. It is shown that the computation of the controller reduces to the solution of bilinear matrix inequalities. An iterative procedure is then used to design the controller. Next, as an alternative to active, time-varying controllers, one for each fault scenario, we propose an approach for the design of a ‘minimal switching’ FTC in which only one controller is designed, but where a simple switch is incorporated into the controller structure. A case study in a linear and nonlinear Nordic equivalent system is presented to show that the closed-loop response using a conventional control design could deteriorate the performance or even destabilize the system if the remote signals are lost and to demonstrate the effectiveness of the proposed FTC designs.
Article
This work considers a portfolio of units for electrical power production and the problem of utilizing it to maintain power balance in the electrical grid. We treat the portfolio as a graph in which the nodes are distributed generators and the links are communication paths. We present a distributed optimization scheme for power balancing, where communication is allowed only between units that are linked in the graph. We include consumers with controllable consumption as an active part of the portfolio. We show that a suboptimal, but arbitrarily good power balancing, can be obtained in an uncoordinated, distributed optimization framework, and we argue that the scheme will work even if the computation time is limited. We further show that our approach can tolerate changes in the portfolio, in the sense that increasing or reducing the number of units in the portfolio requires only local updates. This ensures that units experiencing faults or need for maintenance can be removed from the graph without affecting the overall performance or convergence of the optimization. The results are illustrated by numerical case studies. Copyright © 2014 John Wiley & Sons, Ltd.
Article
This paper proposes a novel islanding fault detection method for distributed generation systems. Islanding fault detection of distributed generation systems in microgrids and smart grids is an essential security technology. The existing methods for islanding fault detection can be classified as passive methods (such as under/over voltage detection, under/over frequency detection, and voltage phase jump detection, based on natural effects of islanding) and active methods (impedance measurement, slip mode frequency shift, Sandia frequency shift and so on). Once the power consumed by a local load matches the power generated by a local inverter, the islanding phenomenon will be not obvious, and traditional passive methods may fail. In contrast, the active methods can overcome this disadvantage. However, active methods create extra disturbances that may degrade the quality of power generated by the inverter. By reducing the harmonics of the inverter output, coupled with the use of a novel filtering method, the proposed approach can be achieved without additional disturbance and does no nondetection zone islanding detection. In this paper, current harmonic compensation is applied to inverter control to minimize the inverter output harmonics, highlighting on the grid harmonics. Set-membership filter is developed to estimate the voltage harmonics. Islanding condition is detected by the changes of the specific order harmonics. The effectiveness of the proposed method is demonstrated by simulations. A Kalman filter contrast experiment is presented to confirm that the set-membership filter can more effectively detect islanding. Copyright © 2013 John Wiley & Sons, Ltd.
Article
This paper describes the design of an active fault-tolerant control scheme that is applied to the actuator of a wind turbine benchmark. The methodology is based on adaptive filters obtained via the nonlinear geometric approach, which allows to obtain interesting decoupling property with respect to uncertainty affecting the wind turbine system. The controller accommodation scheme exploits the on-line estimate of the actuator fault signal generated by the adaptive filters. The nonlinearity of the wind turbine model is described by the mapping to the power conversion ratio from tip-speed ratio and blade pitch angles. This mapping represents the aerodynamic uncertainty, and usually is not known in analytical form, but in general represented by approximated two-dimensional maps (i.e. look-up tables). Therefore, this paper suggests a scheme to estimate this power conversion ratio in an analytical form by means of a two-dimensional polynomial, which is subsequently used for designing the active fault-tolerant control scheme. The wind turbine power generating unit of a grid is considered as a benchmark to show the design procedure, including the aspects of the nonlinear disturbance decoupling method, as well as the viability of the proposed approach. Extensive simulations of the benchmark process are practical tools for assessing experimentally the features of the developed actuator fault-tolerant control scheme, in the presence of modelling and measurement errors. Comparisons with different fault-tolerant schemes serve to highlight the advantages and drawbacks of the proposed methodology. Copyright © 2013 John Wiley & Sons, Ltd.
Article
This paper considers the problem of placing additional phasor measurement units (PMUs) and communication links into a PMU network in a power system. The objective is for the synchrophasors (PMU outputs) across the power system to meet a prescribed availability profile with fewest new PMUs and links among them. Achieving a required synchrophasor availability profile is critical in supporting wide area monitoring, protection, and control in a power system. In our recently reported work, synchrophasor availability is solved from a controlled Markov chain where binary variables indicating placement decisions are embedded as stationary control variables. In this paper, the assumption that communication links are always available wherever needed is removed. Random interruptions in PMU communications are modeled in such a way that the reformulated placement problem remains Boolean-convex, and the computational complexity with respect to the number of buses remains O(n2). The solution to placement of PMUs and communication links into the Institute of Electrical and Electronics Engineers (IEEE) 118-bus test system is presented. Copyright © 2013 John Wiley & Sons, Ltd.
Article
Fault-tolerance in electrical distribution relies on the ability to diagnose possible faults and determine which components or units cause a problem or are close to doing so. Faults include defects in instrumentation, power generation, transformation and transmission. The focus of this paper is the design of efficient diagnostic algorithms, which is a prerequisite for fault-tolerant control of power distribution. Diagnosis in a grid depend on available analytic redundancies, and hence on network topology. When topology changes, due to earlier fault(s) or caused by maintenance, analytic redundancy relations (ARR) are likely to change. The algorithms used for diagnosis may need to change accordingly, and finding efficient methods to ARR generation is essential to employ fault-tolerant methods in the grid. Structural analysis (SA) is based on graph-theoretical results, that offer to find analytic redundancies in large sets of equations only from the structure (topology) of the equations. A salient fea
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This paper presents a distributed sensor fault detection and isolation (FDI) scheme for multimachine power systems. Each generator is interconnected with other generators through a transmission network, where the interactions between directly interconnected generators are nonlinear. In the distributed FDI scheme, a local FDI component is designed for each generator excitation system in the power system based on local measurements and certain communicated information from other FDI components associated with generators that are directly interconnected to the local generator. In each FDI component, adaptive thresholds for distributed FDI are derived, ensuring robustness with respect to nonlinear interconnection and unstructured modeling uncertainty under certain conditions. Furthermore, the fault detectability and isolability properties are investigated, characterizing the class of sensor faults that are detectable and isolable by the distributed FDI method. In addition, the stability and learning capability of the local adaptive fault isolation estimators designed for each generator is derived. A simulation example of a two-machine power system is used to illustrate the effectiveness of the proposed method. Copyright © 2014 John Wiley & Sons, Ltd.
Article
SUMMARYA distributed supervisory strategy for addressing load/frequency set-point reconfiguration problems in networked multi-area microgrid is presented. The aim is at finding a distributed coordination strategy able to reconfigure, whenever necessary in response to unexpected load changes and/or faults, the nominal set-point on frequency and generated power to the generators of each area so that viable evolutions arise for the overall power system during transients and a new post-fault sustainable equilibrium is reached. In order to demonstrate the effectiveness of the strategy, an example on a four-area power system is presented. Copyright © 2014 John Wiley & Sons, Ltd.
Article
SUMMARY In this paper, we consider two methods for solving differential and algebraic Lyapunov equations in the time and frequency domains. Solutions of these equations are finite and infinite Gramians. In the first approach, we use the Laplace transform to solve the equations, and we apply the expansion of the matrix resolvent of the dynamical system. The expansions are bilinear and quadratic forms of the Faddeev matrices generated by resolvents of the original matrices. The second method allows computation of an infinite Gramian of a stable system as a sum of sub-Gramians, which characterize the contribution of eigenmodes to the asymptotic variation of the total system energy over an infinite time interval. Because each sub-Gramian is associated with a particular eigenvector, the potential sources of instability can easily be localized and tracked in real time. When solutions of Lyapunov equations have low-rank structure typical of large-scale applications, sub-Gramians can be represented in low-rank factored form, which makes them convenient in the stability analysis of large systems. Our numerical tests for Kundur's four-machine two-area system confirm the suitability of using Gramians and sub-Gramians for small-signal stability analyses of electric power systems. Copyright © 2013 John Wiley & Sons, Ltd.