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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>View-based and Model-driven Outage Management for the Smart Grid</article-title>
      </title-group>
      <contrib-group>
        <aff id="aff0">
          <label>0</label>
          <institution>Erik Burger, Victoria Mittelbach, Anne Koziolek Institute for Program Structures and Data Organization, Chair for Software Design and Quality Karlsruhe Institute of Technology</institution>
          ,
          <addr-line>Karlsruhe</addr-line>
          ,
          <country country="DE">Germany</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>-The integration of renewable energy resources is Thus, the contribution of this paper is twofold: We have created challenging the traditional electricity network. To manage this, a unified model of the smart grid that makes cross-domain the smart grid has been defined as a cyber-physical system analyses possible, and in addition, we have created view types caonndsiasticnogmopfuatatpihonysailcaclomcopmopnoenntencto,nwsihsitcinhgisofthae ceolemctmriucnitiycagtrioidn, that implement these analyses. They offer insights into the network, metering network, and software components. Therefore, smart grid that can only be gained by combining information the smart grid can not just be seen as an electrical grid, but also from heterogeneous systems of the grid. as a system of software systems. Currently, control centers of the For the evaluation of the prototype, we have evaluated the smart grid use an outage management software system to react system using historical data of the the German electricity grid. to Irneptohritsedpaopuetar,gews.e present an extended outage management We have used the SAIDI index to demonstrate how the outage system that solves one main problem of the smart grid: software management systems shortens the outage time per person per systems of the different domains are using different standards. year. The results show that the average annual outage duration Consequently, cross-domain data exchange and analysis are diffi- can be reduced by at least 2 min 28 s if our approach is applied. cult. Therefore, we use the model-driven view-based VITRUVIUS approach to build a unified model of the smart grid. We then II. FOUNDATIONS combine it with system stability analysis methods presented as views on the model. The result is a model-driven run-time A. Smart Grid monitoring, analysis and control framework to increase the reliability of power supply. The evaluation with statistical data of the German power grid shows that outage time can be reduced with our approach.</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>I. INTRODUCTION</title>
      <p>The smart grid is a cyber-physical system that spans the
physical structures of the electricity network and the system of
software systems that monitor, control, and repair the system
in case of outages. Currently, many heterogeneous systems and
standards have to interoperate to achieve the desired reliability,
stability, and efficiency of the electricity network. Many of
these standards are based on UML and other metamodeling
standards, or can at least be expressed as such. Thus, model
management systems that were originally designed mainly
for the development of software can be used to integrate
information from these heterogeneous systems.</p>
      <p>
        In this paper, we present a concept for an extended outage
management system (OMS) for the smart electricity grid. The
extended OMS is used during run-time to monitor and control
the smart grid, as well as for simulation. The goal of the
introduction of the OMS is to increase the reliability of the grid
by detecting outages and by preventing outages by detecting of
instabilities and imbalances. The extended OMS is realized with
the view-based and model-driven VITRUVIUS approach [
        <xref ref-type="bibr" rid="ref1 ref2">1, 2</xref>
        ]
and uses its capabilities for runtime analysis and control of the
electricity grid. The system is prototypically implemented in the
Eclipse Modeling Framework using the description languages
for model correspondences and view generation of VITRUVIUS.
      </p>
    </sec>
    <sec id="sec-2">
      <title>The smart grid [3] integrates modern IT infrastructure into</title>
      <p>
        the traditional physical infrastructure of the electricity network.
It is thus a cyber-physical system. The motivation behind its
introduction are the integration of renewable energy resources
into the network, improvement of efficiency, and the reduction
of transmission losses. Furthermore, new load profiles, such
as electrical vehicles and smart homes, shall participate in
balancing the grid and its self-healing abilities [
        <xref ref-type="bibr" rid="ref4 ref5">4–6</xref>
        ].
      </p>
      <p>Control centers manage the grid via the supervisory control
and data acquisition system (SCADA), which monitors and
controls the technical processes of the electricity system.
Smart meters are electronic devices that are installed at the
consumers’ places. They measure electricity production and
consumption, and are connected in the advanced metering
infrastructure (AMI), which can also receive commands to
shape electricity consumption. The wide area monitoring
system (WAMS) connects metering data in real-time. The</p>
      <sec id="sec-2-1">
        <title>WAMS consists of Phasor management units (PMU), which</title>
        <p>are high-precision sensors that measure electrical waves with
a frequency of 10 to 30 times per second. A power outage is
a longer interruption in the electricity supply that can either
be planned or unplanned. The causes for unplanned outages
can be categorized into the following types [7]:</p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>Atmospheric Interferences are caused by events of nature,</title>
      <p>such as thunderstorms, sub-zero temperatures, avalances,
etc.</p>
      <p>Internal Failures are caused by maloperation of systems,
malfunction of network internal systems and all other
VT3
MM1
MM2</p>
      <p>MM3</p>
      <p>VT4</p>
      <p>VT1</p>
      <p>Legend:
VT
MM</p>
      <sec id="sec-3-1">
        <title>View Type</title>
      </sec>
      <sec id="sec-3-2">
        <title>Metamodel MIR</title>
      </sec>
      <sec id="sec-3-3">
        <title>ModelJoin</title>
        <p>causes that are directly related to the operations of the
network.</p>
        <p>Outside Influences are not caused by network operators,
but, e.g., by construction work, traffic accidents, etc.</p>
        <sec id="sec-3-3-1">
          <title>Supply Failures/Cascading Outages are caused by a</title>
          <p>network other than the one controlled by a specific energy
supplier, but have an effect on the supplier’s network.
In case that despite the monitoring and control systems, a
disturbance causes a power outage, an outage management
system (OMS) becomes active to restore the power supply.</p>
          <p>From an architectural viewpoint, the smart grid can be
seen as a system of software systems that is connected by
a communication network. A large number of standards exists,
which cover the various aspects of the smart grid systems. The
key standards will be presented in the following.</p>
          <p>IEC 61970/61968: The IEC 61970 standard defines the</p>
        </sec>
        <sec id="sec-3-3-2">
          <title>Common Information Model (CIM), which is used to describe</title>
          <p>the physical components, measurement data, control and
protection elements, and the SCADA system. It is defined
in UML notation. The IEC 61968 standard is an extension
of the CIM for the distribution network [8]. It is also called
distributed CIM (DCIM)</p>
          <p>IEC 61850: This is a series of standards for substations
with the purpose of supporting interoperability of intelligent
electronic devices (IED) in substation automation systems. It
defines the Abstract Communication Service Interface with a
mapping to concrete communication protocols, the XML-based</p>
        </sec>
        <sec id="sec-3-3-3">
          <title>Substation Configuration Description Language (SCL), and</title>
          <p>the Logical Node (LN) model, which describes power system
functions [9].</p>
        </sec>
        <sec id="sec-3-3-4">
          <title>IEC 62056: COSEM (Companion Specification for Energy</title>
          <p>Metering) is the international standard for data exchange for
meter reading, tariff and load control in the domain of electricity
metering. It works together with the Device Language Message
Specification (DLMS). Together, they provide a communication
profile to transport data from metering equipment to the
metering system and to define a data model and communication
protocols for data exchange [10].</p>
        </sec>
        <sec id="sec-3-3-5">
          <title>B. Vitruvius</title>
        </sec>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>VITRUVIUS [1, 2] is a view-based, model-driven framework</title>
      <p>for the mangement of heterogeneous models, i.e., models
that are instances of different metamodels. It is based on
the concept of a single underlying model (SUM) [11], which</p>
    </sec>
    <sec id="sec-5">
      <title>Control Center</title>
      <p>Operator
view
view . . .
uses
view
«instance-of»
operate on</p>
    </sec>
    <sec id="sec-6">
      <title>Algorithms</title>
      <p>«instance-of»
view
uses</p>
    </sec>
    <sec id="sec-7">
      <title>Operator Viewtypes</title>
    </sec>
    <sec id="sec-8">
      <title>System Viewtypes</title>
    </sec>
    <sec id="sec-9">
      <title>Extended OMS</title>
      <p>show information from</p>
    </sec>
    <sec id="sec-10">
      <title>Smart Grid SUM Metamodel</title>
      <p>show information from
view
view . . .</p>
    </sec>
    <sec id="sec-11">
      <title>Smart Grid Software systems</title>
      <p>represents all the information that is available about a system.
The metamodel for this model is specific to the domain in
which the VITRUVIUS approach is used. It combines several
metamodels to form a modular SUM metamodel (see Figure 1).
The metamodels are included non-intrusively and do not have
to be adapted. To express the semantic relations between the
elements of the metamodels, VITRUVIUS defines the
consistency description language MIR (mapping/invariant/response).
Since VITRUVIUS is a view-based approach, all information in
the SUM can only be retrieved or manipulated via specialized
views. A view is a special kind of model and conforms to
a view type, i.e., its metamodel. For the definition of view
types and views, VITRUVIUS uses the ModelJoin language
[12]. VITRUVIUS has been implemented as a prototype1
in the Eclipse Modeling Framework and can thus be used
with any Ecore-conforming metamodel. So far, it has been
applied to software architecture models [13] and model-based
representations of programming languages [14].</p>
    </sec>
    <sec id="sec-12">
      <title>III. AN EXTENDED OUTAGE MANAGEMENT SYSTEM</title>
    </sec>
    <sec id="sec-13">
      <title>In this section, we present the elements of the extended outage management system that are developed with VITRUVIUS.</title>
      <sec id="sec-13-1">
        <title>A. Concept of the extended OMS</title>
        <p>The Extended Outage Management System is a model-driven
analysis and control framework, which is used during run-time
of the electrical system to monitor and control the smart grid,
as well as for simulations. The framework enables network
stability analysis, grid balance analysis, failure detection and
location analysis, and direct controlling interactions with the
electricity system to correct faulty sections of the network.</p>
        <p>The structure of the system, displayed in Figure 2, can
be seen from two perspectives: From an inside perspective,</p>
      </sec>
    </sec>
    <sec id="sec-14">
      <title>1https://sdqweb.ipd.kit.edu/wiki/Vitruvius, retrieved 2016-09-13</title>
      <p>VT
VT</p>
      <sec id="sec-14-1">
        <title>Generator</title>
        <p>Monitoring VT
Viewtype
for the electricity system provide possibilities for the grid to
provide new measurement data, and make system changes to
keep the smart grid model of the extended OMS system always
up to date. Consequently, system and operator viewtypes are
defined based on the smart grid SUM metamodel, and, in case
of the operator viewtypes, on the analysis algorithms. Instances
of the operator viewtypes are the result of the evaluation of
the viewtypes on the instance of the smart grid model. These
views are presented to the operator and the smart grid system
for them to interact with the smart grid model.</p>
        <p>This leads directly to the structure as seen from the outside by
the operators and the electrical system. They see the complete
analysis framework as a ‘black box’, and never interact directly
with the models and algorithms inside, but only with the views
presented to them. The operators can request certain views that
they need for monitoring, analysis, and controlling purposes,
which are delivered to them by the extended OMS system. The
extended OMS system presents them the data and results from
the smart grid system in a compact and consistently modeled
view, which contains only the information that they need at that
special moment, to reduce the complexity for the operators.
developers can see the inner structure of the system, whereas
operators and existing software systems only have and outside
perspective on the system.</p>
        <p>The inner structure of the system consists of three elements: B. The Smart Grid SUM Metamodel
The first one is the Smart Grid SUM Metamodel, which is The modular SUM metamodel of the extended OMS consists
displayed in detail in Figure 3. Following the VITRUVIUS of the IEC smart grid standards to model the four required
approach, it is a modular metamodel that combines four elements. The necessary elements are the advanced smart meter
separate elements of the electricity system: the physical network infrastructure modeled by the IEC 62056 COSEM standard, the
topology, the SCADA control system, the WAMS for grid wide area monitoring system for phasor measurements from
monitoring, and the AMI for customer monitoring. In the the grid modeled by a part of the IEC 61850 standard, the
metamodel, these elements are modeled using the IEC smart substation control functions modeled by another part of the
grid standards introduced in section II: The network topology IEC 61850 standard, and the network topology and overview,
model is based on the CIM and DCIM standards; the SCADA modeled by the two standards IEC 61970 and IEC 61968, also
control system uses the logical node model of the IEC 61850 known as the CIM and DCIM standards.
standard; the data collected from the WAMS are modeled COSEM for the Smart Meter System: The smart meter
applying the logical nodes for system measurements from the metamodel is not freely available as a digital UML model, so
IEC61850 standard; finally, the AMI smart metering data are we built it manually as an Ecore model in Eclipse, based on
modeled using the COSEM standard. Since these metamodels the IEC 62056 standard. An excerpt of the smart meter Ecore
overlap at certain points, they are complemented by MIR model can be seen in Figure 4: The smart meter is represented
correspondence rules to specify the relationships between them. by the PhysicalDevice class, which is identified by its ID. It is
Together, the four metamodels of the elements of the electricity associated with the ManagementLogicalDevice class and the
system and the correspondence rules form the modular SUM LogicalDevice class. The logical device class has a relation to
metamodel. The framework uses an instance of this metamodel each electricity-related COSEM object class. Each COSEM
as a basis for all further analysis and control actions. object class implements its interface class. For example, the</p>
        <p>The second important element are the different outage and class ElectricityValues contains the attributes for current and
instability detection and location algorithms, which are used voltage measurement data of the power import and export. For
for the different types of failure and stability analysis. later modeling and containment purposes, the physical device</p>
        <p>The third important element are the viewtypes, which define also references each COSEM object class.
the different possible perspectives on the smart grid model. CIM/DCIM (IEC 61970/61968): To use the CIM and DCIM
The viewtypes need to be differentiated between viewtypes standard as a part of the SUM metamodel, they both need to
for the system operator and such for the electricity system. be in the format of an Ecore model. The CIM User Group2
The viewtypes for the operator implement the algorithms for provides the two metamodels as an integrated Sparx Enterprise
balancing input and output of the network to stabilize the Architecture Model ready to download as an xmi file. These
voltage, and for failure detection analysis. They define views metamodels are based on the most current release of the two
on the network topology and control regions. Furthermore, standards in 2014. The CIM User Group offers the metamodel
they define views for the interaction with and control of the
physical equipment of the electrical system. The viewtypes 2http://cimug.ucaiug.org, retrieved 2016-09-13
COSEM interface classes</p>
      </sec>
      <sec id="sec-14-2">
        <title>COSEM object classes . . . . . .</title>
        <p>LogicalDevice
ID: EString
name: SAPAssignmentCurrent
. . .</p>
        <p>ManagementLogicalDevice
0..*
0..1</p>
        <p>PhysicalDevice
ID: EString
. . .
together with the open source Eclipse plugin “CIMtool”3. With
this tool, it is possible to browse through the models and to
export them as an Ecore model, which can then be directly
imported into the VITRUVIUS environment.</p>
        <p>IEC 61850 for Substation Control and PMU: Analogous to
the CIM/DCIM metamodel, the IEC 61850 logical node model
needs to be in the format of Ecore in order to be integrated into
the SUM. Our Ecore-based metamodel of the standard realizes
parts 5 and 7 of the IEC 61850 standard. The metamodel
has been created by adapting an Enterprise Architect UML
model by ABB. ABB has donated this metamodel to the IEC
technical committee (TC) 57. It is accessible as a web-based
UML model on their website.4 The web-based model can
be browsed, but unfortunately, it cannot be downloaded. To
integrate the metamodel into the SUM Metamodel as an Ecore
model, we have rebuilt it manually in Eclipse. Since the ABB
model is not completely compatible with Ecore, a few changes
had to be made, which are described in detail in [15].</p>
        <sec id="sec-14-2-1">
          <title>C. Correspondence Rules</title>
          <p>map CIM.CIM.IEC61970.Wires.Breaker as Breaker
and substation.substationStandard.LNNodes.LNGroupX.</p>
          <p>XCBR as XCBR {
when-where {</p>
          <p>Breaker.mRID == XCBR.NamePlt.IdNs</p>
          <p>Breaker.mRID = XCBR.NamePlt.IdNs
}
}</p>
        </sec>
      </sec>
      <sec id="sec-14-3">
        <title>Listing 1. Example Mapping Rule for Breaker</title>
      </sec>
    </sec>
    <sec id="sec-15">
      <title>The correspondence rules for the extended Outage Management</title>
      <p>System (OMS) have been defined in the MIR language of
VITRUVIUS. They describe the semantic overlaps between the
metamodels of the modular SUM metamodel. Since it is not
mandatory in the VITRUVIUS approach to define rules for
all binary combinations, and since there were no semantic
correspondences between IEC 61850 and COSEM, rules have</p>
    </sec>
    <sec id="sec-16">
      <title>3http://wiki.cimtool.org/HowToValidateCPSM.html, retrieved 2016-09-13</title>
      <p>4http://www.nettedautomation.com/download/std/61850/uml/, retrieved
201609-13
only been defined for the combinations IEC 61850/CIM and
CIM/COSEM (see Figure 3). An example for such a rule can
be seen in Listing 1, where the correspondence is defined for
metamodel elements that describe circuit breakers in both the
CIM and the IEC 61850 metamodel, which has the package
name “substation”. For a complete listing of all rules, we refer
the reader to [15].</p>
      <sec id="sec-16-1">
        <title>D. Viewtypes</title>
        <p>The second part of the extended OMS are the viewtypes
designed for the interaction with operators and the smart grid
software systems (cf. Figure 2). Each of the three metamodels in
the modular SUM metamodel is exposed as a legacy viewtype
to support existing software and visualization methods, and for
data exchange with the systems of the smart grid. In addition,
nine specific view types have been defined using the declarative
ModelJoin language. Each viewtype combines information of
either a single or multiple sub-metamodels of the modular
SUM metamodel, as displayed in Figure 3.</p>
        <p>For network monitoring, the Network Topology Viewtype
defines a view on the electricity system elements and their
topology. The Control Area Viewtype focuses on the
segmentation of the electricity system into control areas, where each
area is regulated by one control center.</p>
        <p>Four viewtypes have been defined to support balancing of
the electricity grid: The System Balance Analysis Viewtype
compares production and consumption with predicted values to
detect fluctuations. The Generator Monitoring and Consumer
Monitoring view types observe the current situation of
generators and consumers. They serve as a basis of decision-making
on how to react to imbalances in the system. After this decision,
operators use the Generator and Consumer Control Viewtype
to control the production and demand of electricity.</p>
        <p>The Consumer Reachability Viewtype is used to detect
outages. The detection algorithm exploits the fact that when
a smart meter is cut off from power supply, it cannot send
any data. Together with the network topology viewtype, it is
possible to see the system in a tree structure, and to mark the
nodes that failed by searching for the failed consumers in the
topology view. Thus, it is possible to detect the outage, and to
locate the area of its origin. If a failure is detected, the Grid
Control Viewtype can be used to stabilize the situation again.</p>
      </sec>
      <sec id="sec-16-2">
        <title>Finally, the Three Phase Measurement Matrix Viewtype</title>
        <p>combines measurement data from phasor measurement units
and smart meters. Thus, instabilities and disturbances in the
transmission and distribution network can be detected, so that
outages can be prevented before they occur. For a complete
definition of all view types, we again refer the reader to [15].</p>
      </sec>
    </sec>
    <sec id="sec-17">
      <title>IV. EVALUATION</title>
      <sec id="sec-17-1">
        <title>A. The SAIDI Index as Benchmark</title>
      </sec>
    </sec>
    <sec id="sec-18">
      <title>The overall goal of the extended Outage Management System (OMS) is to reduce the outage duration and to lower the amount of outages. To evaluate how well the system is performing in doing this, the SAIDI index is used.</title>
      <sec id="sec-18-1">
        <title>Atmospheric</title>
        <p>Interferences
Internal Failures
Outside Influences
Supply Failures,
Cascading Outages
Perc.
45:1 %
29:51 %
22:59 %
2:8 %
Outages
Low
Voltage
66 658</p>
        <sec id="sec-18-1-1">
          <title>Definition 1. The SAIDI (System Average Interruption Dur</title>
          <p>ation Index) index is the average outage duration for each
served customer. It is an indicator for the reliability of power
supply of an electricity system. It is calculated as:</p>
          <p>C Kj
SAIDI = å å j j;k NNj;k</p>
          <p>j=1 k=1
where C is the amount of areas the grid is divided into, K j
is the number of annual outages in area j, and j j;k is the
duration of the k-th outage in area j, and N j;k is the number
of consumers in area j affected by outage k, and N is the total
number of consumers in the system [16].</p>
        </sec>
        <sec id="sec-18-1-2">
          <title>B. Datasets used for the Evaluation</title>
        </sec>
      </sec>
      <sec id="sec-18-2">
        <title>Consumers</title>
        <p>Outages Low-Voltage
Outages Medium-Voltage</p>
        <p>SAIDI Low-Voltage
SAIDI Medium-Voltage</p>
        <p>SAIDI Total
49 600 000
147 800
26 000
2:19
10:09
12:28
the faulty section. In this case, the outage is repaired after 2
minutes. If this is not the case, the detection and restoration
of the failure takes up to one hour. Since these two cases
cannot be differentiated here, an average outage restoration
duration is calculated based on them. Since this evaluation is
conducted in a modern smart grid, it is assumed that the first
case happens slightly more often than the second one (60:40).
Consequently, the average outage restoration duration is about
30 minutes (using 7.5 minutes for the outage reporting time):
0:6 2 min + 0:4 60 min + 7:5 min = 31:5 min.</p>
        <p>Besides these, some more general assumptions are made for
all of the following evaluations.</p>
        <p>The percentages of the types of outages from the Austrian
report will be used for the German system, since they
are neighbors with similar infrastructure and weather (see
Table I).</p>
        <p>The outage restoration duration is 30 minutes.</p>
        <p>Based on this duration and the SAIDI values in Table II,
the average number of people affected by an outage in the
low and medium voltage network is 24 in the low-voltage
network and 640 in the medium-voltage network.</p>
      </sec>
    </sec>
    <sec id="sec-19">
      <title>To evaluate the extended outage management system in the</title>
      <p>German smart grid, four main datasets are used:</p>
      <p>1) Germany: Each year, the federal electricity agency of
Germany releases a monitoring report about the electricity
system. Besides data about production, renewable production C. Evaluation Views
and consumption, it includes numbers about the reliability of
power supply and the amount of outages per year. The report For the evaluation of our approach, we have analysed several
is freely available and will be used as a basis to calculate the properties of a smart grid using model and the views as
SAIDI index and for comparison, since it includes the SAIDI described in subsection III-D.
index for the current German system. For this evaluation, the 1) Grid Balancing: The main purpose of the viewtypes
report from 2014 will be used [17]. for grid balancing is to prevent outages by keeping electrical
2) Austria: Similar to the German report, E-Control pub- inflows and outflows at balance. We have recalculated the
lishes the outages and disturbances statistic for Austria each SAIDI index to measure the improvement gained from using the
year. The report includes data about the number and type of viewtypes. The calculation is based on the numbers from 2014
outages in Austria in 2014, together with the SAIDI index. in Germany and Austria and makes some specific assumptions:
Since the German and Austrian systems are neighbours, we The fourth outage type Supply failures and cascading
will assume for the evaluation that the types of outages (as outages combines two kinds of outages, of which only
introduced in section II) are the same [7]. the supply failures are of interest. For this evaluation, it
3) entsoe: To analyze balancing the grid, statistical data is assumed that they have each a share of 50 % of the
about the actual and forecasted production and consumption for total 2:8 % of their appearance. This is 2069 outages in
2015 provided by entsoe is used. The dataset includes quarter the low-voltage network and 364 in the medium-voltage.
hourly data for every day and can be used to detect differences Since the views currently only focus on production and
between forecasted and actual production and consumption. consumption and no models for the electricity market</p>
      <p>
        The duration of the system restoration after an outage is an and special forecasts are included it is assumed that the
important aspect. According to literature [
        <xref ref-type="bibr" rid="ref4">4, 16</xref>
        ], two cases need views will not perform very well in preventing imbalance
to be differentiated: In both cases, the detection of an outage outages that currently occur. Therefore it is assumed, that
relies on customer feedback. On average, an outage is reported only 30 % of the outages can be prevented. This makes
after 5 to 10 minutes. In the first case, the system has an 629 prevented outages in the low-voltage network and
implemented infrastructure to automatically detect and restore 109 in the medium voltage. The total amount of outages
w25o8u9ld1 tihnetnhebem1ed4i7u1m5-1voinltatghee. low-voltage network and Outage Type VLOooulwttaa-ggees VOMouelttdaaiggueems - TOouttaalges
STAhIeDrIelsouwlt=s foå4r t1h4å7e4151lo3w0-mainnd m49e6d0204iu0m00-=vol2t:a1g4emsiyns,tem are: IIAnntttmeerrofnesarplehnFecareiiclsures 6261 685088 113782367 7285 368445
j=1 k=1 Outside Influences 33 388 5873 39 261
SAIDImedium = å4 25å8491 30 min 49660400000 = 10:02 min SCuapscpalydinFgailOuruetsa,ges 2061 364 2425
Thus, the total isj=112:k1=61 min with an improvement of 0:16 min. OUTAGES OF THETaTbOlTeAILIIEXTENDED OMS
2) Outage Detection: The main objective of these views
is to detect outages automatically and faster, since currently,
this relies on customer feedback, which can take up to 10
minutes. Since in the modern smart grid with automatic remote is 2069 outages in the low-voltage network and 364 in
control, it is possible to restore the power supply after an the medium-voltage.
outage already after two minutes, it is important to reduce the It is assumed that the external system to compare the
time for detection in order to lower the total outage restoration values from the views with historic data has been built.
duration. Internal failures, especially if a device is broken, cannot
The evaluation is based on the following assumptions: always be prevented even if the disturbance is detected.
However, due to the N-1 criterion it should be guaranteed
The low-voltage networks attached to a medium-voltage in most of the cases that the outage can be prevented. But
network do all have the same amount of customers. to estimate it carefully it is assumed, that only 50 % of
Each smart meter sends data once every 30 minutes. the internal outages can be prevented.
The smart meters in a medium-voltage network segment Concerning cascading outages, since they can be prevented
do not send all at the same time, but are distributed equally by separating the faulty section from the rest of the grid,
over the 30 minutes. They are rotating through the low- it is assumed that 70 % of them can be prevented.
voltage networks attached to the medium-voltage.
aTnoddlioffnegrepnetiramteanbeentwteoeuntasgheosr,t ttheemdpeotreacltioountatgimese(&lt;nee1dms itno) STAhIeDrIelsouwlt=s foå4r t1h2å4e453l9o3w0-mainnd m49e6d02i04u0m00-v=ol1ta:8g1emsyins,tem are:
be longer than 1 minute. j=1 k=1
soyustWategemeu:dse3etetch6t24ei5o0nfotr3im0m64mu0eilnab=aosfe3d:[61om5n,itnsh.eecAtnisounmexb5pe.l3ra.io4nf]ecdtuoisntcoatmlhceeurlsgaetiennettrhhaeel STAhuIDs,Itmheedituomta=lisjå=41102:k12å=499019m3i0nmwinith a4n966i0m4000p0r0ov=em8:e4n8tmofin1.:99 min.
assumptions, there are now two cases of outage restoration. D. The SAIDI Index of the overall extended OMS
The same restoration times will now be combined with the new
detection time. With 60 %, the restoration time is 2 minutes, The different views evaluated above are all used together
and with 40 %, it is 60 minutes, which gives an average outage in the extended outage management system. Therefore their
detection and restoration time of 0:6 2 min + 0:4 60 min + functionalities can be combined to combine outage detection
3:6 min = 28:8 min. This duration will become lower the higher with prevention. This will further improve the SAIDI index of
the share of remote controls in the grid gets. the extended OMS, since the single improvements are added
The results for the low- and medium-voltage system are: up. In order to do that, this section summarizes the single
SAIDIlow = å4 14å74800 28:8 min 4960204000 = 2:06 min, icmo mprboivneemdeSnAtsIDfIroimndetxh.e Tphreevmioauins ascehciteiovnesmeanntds acrael:culates a
j=1 4k=126000 Reduction of supply failure outages by 30 %, which are
SAIDImedium = jå=1 kå=4 1 28:8 min 49660400000 = 9:66 min. 160299 ipnrethveenmteeddiouumtagvoesltaigne.the low-voltage network and
Thus, the total is 11:72 min with an improvement of 0:56 min. Detection of outages in 3.6 minutes with a total reduction
3) Instability and Cascading Blackouts detection: The main of average outage detection and restoration time to 28.1.
objective of these views is to prevent outages due to instabilities Reduction of internal failure outages by 50 %, which
in the system and to detain cascading outages. It is the goal to means 21 808 prevented outages in the low-voltage
netprevent outages of two types: internal outages and cascading work and 3837 in the medium voltage.
outages. To evaluate the functionality of these views, some Reduction of cascading outages by 70 %, which are 1448
further assumptions have to be made: prevented outages in the low-voltage network and 255 in
The fourth outage type Supply failures and cascading the medium voltage.
outages combines two different kinds of outages of which This results are displayed in Table III. The results for the
only the cascading outages are of interest for these views. extended OMS are:
sFhoarrethoisf 5e0va%luaotfiothneittoitsala2s:s8um%eodf tthhaetirthaepypeeaaracnhceh.avTehias SAIDIlow = jå=41 1k2å3=49115 28:8 min 4960204000 = 1:72 min
SAIDImedium = jå=41 2k1å=48010 28:8 min 49660400000 = 8:10 min. Smientcheodcsu.rTrehnistlycanthbee mfoaupnpdinsgeveorfalstiigmneaslsinbelittwereaetunreth[e30C–3IM3].
      </p>
      <p>In total, this is 9:82 min with a total improvement of 2:46 min, and IEC 61850 standards needs to be performed manually,
which is 2 minutes and 28 seconds. these papers suggest a mapping between the SCL and the</p>
      <p>This means if the extended OMS is used in the German smart CIM configuration file with ontology matching. This approach
grid, the average annual outage duration for each consumer follows the same purpose like the model-driven approach
could be reduced by at least 2 minutes and 28 seconds. presented in this research, however using a different method.
Consequently, the analysis and control framework built can
indeed help to improve the reliability of power supply. VI. CONCLUSION</p>
    </sec>
    <sec id="sec-20">
      <title>V. RELATED WORK</title>
    </sec>
    <sec id="sec-21">
      <title>Related work on improving the reliability of the power supply</title>
      <p>using model-driven methods can be grouped in two categories:
Approaches that treat the problem of improving the reliability
of power supply, and approaches that examine the problem of
combining information of the smart grid using model-driven
or related methods.</p>
      <p>There is quite an extensive amount of research about the
reliability of electrical systems, also in connection with the
smart grid. E.R. Brown [18] examines the challenge of a reliable
power distribution system, and D. Elmakias introduces in his
book methods to examine and improve the reliability of an
electrical system [19]. Chowdhury et al. [20] and Waseem et al.
[21] focus especially on the impact of distributed generation on
system reliability, since the integration of distributed generation
is a new challenge for the power system. Related to power
distribution, Russell et. al [22] work on improving the reliability
of the distribution system equipment in their research.</p>
      <p>
        Since the unification of different smart grid elements in
one model has been identified early in the NIST smart grid
roadmap [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ], different approaches have been developed:
      </p>
      <p>The Electric Power Research Institute (EPRI) has harmonized
the CIM model with the IEC 61850 substation equipment with
a CIM-based unified UML model that includes the physical
elements of both standards [23–27]. In contrast, the approach
presented in this paper leaves the existing smart grid models
unchanged and builds mappings to combine them. The EPRI
approach includes only the substation equipment from the IEC
61850 SCL model, while our research focuses on the substation
functions in the LN model.</p>
      <p>Andrén et. al. use model-driven QVTo transformations to
transform IEC 61850 LN models into IEC 61499 models, a
standard for process automation. This is done to automate the
substation processes. The authors use model transformations
to combine the two standards, like it is done in this research.
However, they focus on those two standards and do not have
the goal to enhance smart grid integration [28].</p>
      <p>Byunghun et. al. present in their work mappings between
datatypes from the CIM and the IEC 61850 standard. The two
standards can only be unified if their datatypes match. The
IEC 61850 however defines special datatypes for the standard
that need to be mapped onto the datatypes defined in the CIM
model. For deeper research about the mapping of the two
standards, this paper is of importance [29].</p>
      <p>Another different approach to map the two standards CIM
and IEC 61850 is the use of ontologies and semantic web</p>
    </sec>
    <sec id="sec-22">
      <title>In this paper, we have presented a model-driven and view</title>
      <p>based framework, called the extended outage management
system, for run-time analysis and control of the smart grid.</p>
      <p>The main purpose of the system is to increase the system
reliability by faster detection of outages and by preventing
the outages through the detection of system instabilities and
imbalances. The system is built in VITRUVIUS, a model-driven
and view based model management framework, which was
originally created for software development purposes, but can
be used with any kind of metamodel-based data. This paper
has shown that the mechanisms and languages of VITRUVIUS
for defining correspondences and viewtypes can successfully
be applied to domains that do not purely concern software.</p>
      <p>The framework has been evaluated using the SAIDI index.</p>
      <p>Using statistical data of the German power grid, a possible
improvement of 2 minutes and 28 seconds in annual outage
time. The system could be further improved by including further
data sources, such as real-time data from the energy market.
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