=Paper=
{{Paper
|id=Vol-2220/18_CONFWS18_paper_12
|storemode=property
|title=Towards Knowledge Infrastructure for Highly Variant Voltage Transmission Systems
|pdfUrl=https://ceur-ws.org/Vol-2220/18_CONFWS18_paper_12.pdf
|volume=Vol-2220
|authors=Mathias Uta,Alexander Felfernig
|dblpUrl=https://dblp.org/rec/conf/confws/UtaF18
}}
==Towards Knowledge Infrastructure for Highly Variant Voltage Transmission Systems==
https://ceur-ws.org/Vol-2220/18_CONFWS18_paper_12.pdf
Towards Knowledge Infrastructure for Highly Variant
Voltage Transmission Systems
Mathias Uta and Alexander Felfernig
Abstract. The high voltage transmission business uses very breakers separate the faulty part of the grid to prevent blackouts.
mature technical solutions to transport electrical energy over large Additionally, current transformers and voltage transformers give
distances. New developments in the information technology sector transmission utilities the possibility to measure the transported
are now promising opportunities to revolutionize the traditional energy. The collection of all main parts concentrated in one
processes within the business. In this paper the opportunities to
physical spot is called electric power transmission substation.
implement a sophisticated knowledge infrastructure to improve the
efficiency and quality of high voltage product manufacturers will
be outlined. Therefore, possible solutions have been assessed to
establish a non-redundant data structure and create an advanced
database system architecture with respect to business specific
requirements, considering in particular product configurators.
Based on the proposed master data system, the possibility to create
as well as integrate a knowledge system has been evaluated.
Accordingly, the introduction of a global knowledge manager is
proposed to organize inquiries of product configurators to expert
systems and introduce a company-wide framework for rules and
constraints. To assure communication between all parts of the
software architecture, the implementation of a universally
understandable format is discussed. Finally, possibilities to
integrate recommendation system mechanisms into the suggested
system architecture are highlighted.
1 INTRODUCTION
The market of high voltage transmission business is highly
competitive. The differentiation through up to date processes, high
quality and fast response times is highly desirable to manage the Figure 1. Electrical components in the energy grid [3]
increasingly complex and fast changing customer requirements.
This effect is intensified by general technical developments in Since each of the main modules has to correspond with many
measurements initiated by the energy transition from fossil to diversified customer requirements, the big suppliers in the business
renewable energy sources. such as Siemens, ABB or Alstom have separated their energy
Due to an increasing share of renewable energy into the grid and transmission business in many smaller segments [4] [5]. Each of
their decentralized physical arrangement compared to huge power these segments is concentrated on one of the main components in
plants, an extension of the electrical grid has to be provided. the grid. Customers expect suppliers to offer solutions for
Additionally, the weather dependency of the new energy sources specifications including a complete electric power transmission
intensifies this effect. As a result, the utilities are confronted with a substation. As a result, very complex projects with many internal
fast changing energy market and need to react to the new energy stakeholders have to be managed. This includes the decentralized
mixture [1]. Not only a transformation has to be managed on the data storage of in many cases identical information. In each of the
supplier side but also consumers are starting to adopt new involved business segments a unique tool infrastructure is installed
technologies with huge electrical energy demand like electrical and requires varying processes. In particular it is possible that, each
cars. Therefore, the only solution to assure a secure energy supply business segment uses one or more individual configuration
in the future seems to be an extension of the transmission grid [2]. solutions to determine the bill of material derived from individual
The structure of the electrical grid and the main components are configuration rules and constraints. These configuration rules are
shown in Figure 1. The renewable and non-renewable based power cross segmental on a higher level and do not differ until a finely
plants convert several energy sources to electrical energy and are granulated level of configuration is reached. Furthermore,
connected via transformers to the grid. The overhead lines and the individual pricing and quotation tools are used which are
cables transport the energy over large distances to consumers. The sometimes integrated with the configuration tool, resulting in so
switchgears integrate many of these lines on one conductor called configuration prizing and quotation solutions (CPQ). As a
(busbar) and build nodes in the grid. In case of failures circuit consequence, very complex processes and redundant actions are
decreasing competitiveness in a cost driven market environment. 2 DATABASE EVALUATION
Additionally, data and knowledge maintenance cause
disproportional effort leading to human and hardware resource Data modelling plays an important role. To create a ubiquitously
binding. applicable database, one has to consider a data structure which
To tackle the above described challenges, the introduction of a allows multiple views and possibilities to manipulate the stored
well-designed data and software infrastructure is necessary. A data via interfaces from manifold applications. Graeme C. et al.
completely integrated data and software landscape which provides characterize this situation as follows ‘The data model is a relatively
necessary information via interfaces to all quotation related tools small part of the total systems specification but has a high impact
should provide synchronization of all involved stakeholders and on quality and useful life of the system’ [6]. Data modelling is
improve the maintainability of data and knowledge. concentrated on achieving completeness, non-redundancy, and
In an environment which utilizes several ERP (enterprise resource reusability in databases. Additionally, stability, flexibility, and
planning), PDM (product data management) and CRM (customer performance have to be taken into account. The implemented
relationship management) tools, in future one company-wide database should be capable of modifications and extensions to
integrated database should be implemented to deliver one data integrate requirements arising in the future. Nonetheless, the data
source for all configuration, pricing and quotation tools. The goal modeler has to start with the given information to create a so called
is to enter the information only once into the system so that the ‘conceptual schema’ which can be accomplished by different
characteristic is passed on to all connected business segments and course of action like the process-driven, data-driven, or object-
their CPQ tools. In consequence, all related objects rely on the oriented approach to name only the most important ones. Based on
same data input. This assures cross segmental consistency of data the ‘conceptual schema’ a ‘logical schema’ can be deducted by
in all offer documents, technical descriptions and technical using entity-relationship modelling (ERM) or unified-modelling
calculations. language (UML) approaches. Finally, a physical design of the
Moreover, the integrated representation of data delivers the database can be created.
opportunity to implement consistent connections between objects Typically used database types are relational databases (RDBs),
in form of rules and constraints. This leads to the extension of data object-oriented databases (OODBs) and a hybrid form which is
to knowledge and should support users by preventing false called object-relational database (ORDB). Consistency in RDBs is
configurations and incorrect data input, i.e., to contract relevant achieved by using normalization methods for tables as proposed in
documents. These relations between the objects need to be non- [7]. The objective of OODBs is to create an abstract view on the
redundant as per the data itself. Supplemental to the rules and reality which is easily adaptable to object oriented programming
constraints describing simple relationships, interfaces to expert languages. Dependencies between objects are provided by pointers
systems capable of very specific and complex calculations need to which allow m:n relationship representations. Therefore, OODBs
be established. Mechanical calculations due to earthquake are often adapted for computer aided design (CAD) or technical
requirements or ferroresonance calculations of the grid are two calculation programs (expert systems) since these programs deal
examples of these expert systems. usually with high complexities and many variants [8] [9].
Finally, based on the achieved integrated data and knowledge, an Unfortunately, OODBs lack query performance compared to
analysis of the utilized materials, parameter characteristics and all RDBs, which is why they are still not able to replace traditional
other objects during the configuration, prizing, and quotation relational databases for query focused applications [10]. ORDBs
process can act as a basis for a self-learning system to improve the try to combine both approaches to achieve an improved
CPQ-tools. This system should be able to recommend technical performance and are often adapted by CPQ-tools. Michael
solutions and parameter input based on previously chosen solutions Stonebreaker evaluated all three options in [11] and classified them
in distinctive situations as customer specific requirements or as depicted in Table 1. The table points out ORDBs combine the
special environmental conditions. The user in this scenario still has advantages of RDBs and OODBs in comparison of the most
the opportunity to neglect the recommended solution which is important properties for databases, ‘fast queries’ and ‘complex data
consequently used to improve the recommendation logic. management’. But ORDBs implicate some issues as well which is
Overall, a complex system composition consisting of domain most importantly a low performance in web applications [10].
specific and integrated databases with direct interfaces to
Table 1. A classification of database management systems (DBMS) [11]
configuration, pricing, and quotation tools has to be established.
Further, the user of the quotation tools is supported by knowledge
bases inheriting logical connections between relevant parts and an
adaptive artificial intelligence which analyses user decisions.
The remainder of this paper is organized as follows. In section 2
we discuss the possibility of a holistic database and point out that
different use cases lead to contradicting database types. Conducted
from this perception we propose system architecture assuring data
consistency for the high voltage transmission business. Based on
this data consistency section 3 emphasizes the advantages of
knowledge integrity. This is followed by a general survey on an
approach to implement a global knowledge manager on basis of the
proposed system architecture in section 4. Section 5 suggests a A very detailed analysis of the given requirements is precondition
concept of a recommendation system in which the knowledge base for implementation of the most appropriate database and data
is constantly extended using the results of configuration structure. Since full integration of the whole value chain, including
applications used by experts.
PLM (product lifecycle management), ERP (enterprise resource 3 SYSTEM ARCHITECTURE
planning), CRM (customer relationship management),
configuration, pricing, quotation and technical calculations with The data used along the value chain can be described most likely as
expert systems, has to be realized, a solution with one centralized ‘master data’ of a company. Master data is defined as ‘data held by
database seems with respect to deviating requirements difficult to an organization that describes the entities that are both independent
implement. Table 2 shows adapted from Alejandro Vaisman’s et al. and fundamental for that organization, and that it needs in
a holistic comparison between these tools and their resulting reference in order to perform its transactions’ [13]. By other
utilized database types [12]. means, master data is all the data stored about customers,
employees, products, materials, suppliers. The management of this
Table 2. Requirement comparison between ERP, CRM, PDM, CPQ and data is called master data management (MDM) and can be
expert systems provided by mainly four different architectures as shown in Figure
Aspect ERP / CRM / CPQ Expert system 2.
PDM
User type Operators, Customer, sales Engineers
office employees
employees
Content Current, Current, Current,
detailed data detailed detailed
knowledge knowledge
Data According to According to According to
organization operational operational and operational
needs analysis needs needs
Data structures Optimized for Optimized for Optimized for
small complex queries complex queries
transactions
Access High High Medium
frequency
Access type Read, insert, Read, insert, Read, insert,
update, delete update, delete update, delete
Number of Few Many Many
records per
access
Response time Short Short Can be long
Concurrency High High From medium
level to low
Update High From medium From medium
Figure 2. Classification of architecture approaches [14]
frequency to low to low
Data Low Medium Can be high (no
redundancy (normalized (normalized normalization
The architecture in this approach is classified by two major
tables) tables and methods and categories:
objects) inheritance) ∂ Are global master data attributes defined or has each
Resulting Relational Object Object involved application its own master data definitions?
database type database relational oriented ∂ Where is data created and maintained – in a
(RDB) database database centralized system or decentralized in each connected
(ORDB) (OODB) application?
In the centralized master data system (1) all global master data
Whereas ERP, CRM, and PDM tools are designed for fast access to attributes are created and maintained in one database. Associated
distinctive data to satisfy operational queries, CPQ and expert applications receive these attributes directly from this centralized
systems are focused on very complex queries that require system via identical primary keys whereas additional specific
combinations between many data sources. Additionally, CPQ-tools attributes can be defined individually in the single applications.
are facing a high access frequency with expected short response The leading system methodology (2) instead has no global master
times which leads to an even higher level of complexity in the data attributes but a system which is responsible for data creation and
structure. maintenance. These attributes are transmitted to connected
In conclusion, based on these manifold requirements it seems more applications where the primary key of the attribute is mapped to the
likely to implement a sophisticated system architecture including corresponding attribute in the application.
several customized databases for each application instead of Decentralized data creation and maintenance approaches on the
establishing one ubiquitous database. The system architecture of other hand rely on company-wide standard definitions (3) or an
such a conglomeration of databases is closer examined in the next implementation of a repository (4). Company-wide standards do
chapter. not assure consistency in each dataset of the applications. Instead
they focus on the ability to create the same understanding of each
attribute which leads to easier manageable comparisons between
those datasets. A physical connection between applications is in
this approach not mandatory. The installation of a repository In another scenario a company-wide leading system located in at a
follows the idea of metadata storage to connect applications with distinct place is established to create and maintain all master data.
each other whenever an interaction is necessary. Therefore, This leading system is additionally used as basis for connected
primary keys of all involved applications for a certain attribute are central master data systems installed in distributed factories of the
stored in the repository and matched for cross-program query company. These centralized master data systems receive the
events with each other. company-wide master data from the leading system and can be
In case of the high voltage transmission business, an extended with manufacturing side specific master data as basis for
implementation of one integrated MDM solution seems, equivalent connected applications.
to the result of the second chapter for databases, not feasible. Two
reasons are mainly responsible for implementation of a more
complex structure. First of all the structure of the business
includes, as already pointed out, several different independent
departments responsible for distinct parts of the substation. These
departments are not necessarily located at the same location but are
distributed over the world to assure an increased satisfaction of
locational requirements. Consequentially, one centralized system
located, for instance, in Europe will lead to performance issues
when it comes to queries from an application located in Asia. Live
connections over long distances and many servers are due to the
congestion control of the transmission control protocol not
advisable [15]. A system which synchronizes independent and
asynchronous to operational tasks is therefore preferable. Secondly,
each department has sometimes not only one factory but several
production sides each with their own portfolio. The main structure
of the portfolio is same as per the department. The differences can Figure 4. Two layer leading master data system approach
be found on a more detailed layer of the products as, for instance,
in the differentiation of high-end products and cost-optimized Further combinations are imaginable as well and have to be
products which serve generally the same technical requirements evaluated based on several reference values in further publications.
but are differentiated in more sophisticated configuration options Based on these results and taking all requirements for the high
as better operation monitoring or increased maintainability of the voltage transmission business into account finally a decision on the
electrical component. From these considerations follows, a solution system architecture can be reached. Another important decision is
incorporating combinations of the previously presented options the selection of the tool used as master data management system.
seem more feasible to encounter the high complexity in the high The use of the ERP, CRM or PDM tool is imaginable since the
voltage transmission business and causes the introduction of more most data is created in these databases. Additionally, the adaption
than one MDM layer. of the CPQ-tool as main input tool for data might also be a
Figure 3 shows an option where a centralized master data system is reasonable choice.
implemented storing master data of one manufacturing location Up to that point we focused on data structure and system
whereas the centralized database is connected to other locations via architecture neglecting the value which can be created out of
a repository to assure a synchronization of all business relevant integrated, non-redundant data. The following chapters will discuss
data independent from daily operational tasks. Furthermore, the possibilities given by such a dataset.
standards across the whole company are defined to realize a
homogenous creation of new data since each master data system is
allowed to create and maintain its data by itself. 4 KNOWLEDGE INTEGRITY
A well-known use case for master data management systems is the
implementation of data warehouses. Operational data is put
through an ‘extraction, transformation, integration, and cleansing
process (to) store the data in a common repository called data
warehouse’ [13]. Data in the data warehouse is in reference to
W.H. Inmon saved ‘subject-oriented, integrated, time-variant,
nonvolatile (to) support management’s decision making process’
[16]. This means an OODB is implemented that saves data over a
long time to enable analysis of developments in the observed
business. Besides the data itself metadata – data about the stored
data – is stored in the data warehouse. In big organizations, data is
not directly used by queries to the data warehouse. Instead, data
marts are introduced as an additional layer between the user and
the data warehouse. Similar to the already analyzed central master
data systems data is transmitted from the data warehouse (central
master data system) to the data mart (application database) which
fits to the requirements of a specific department. The user of the
Figure 3. Three layer repository - master data system – standards approach
data mart is finally able to create reports, perform data analysis and technical realization of this requirement can be established by
to mine data. introducing interfaces between the product configurators and the
The restriction of this concept is already given in the definition of PDM system. However, with this step an integrated data
the data warehouse. The data warehouse should ‘support administration can be introduced but the knowledge administration
management’s decision making process’ [16]. The area which is still redundantly managed in each configuration tool.
besides the management decisions is widely neglected in To achieve knowledge integrity - a major target formulated in the
centralized data and knowledge storage is the configuration and visions at the beginning of this paper - we propose steps connatural
engineering sector. While huge effort is put into preparation of to the actions necessary to reach data integrity [7] [8] and which
management reports and supporting management decisions, are also related to frameworks as formulated in [19]. First a
configuration tasks, technical calculations and dimensioning ‘conceptual schema’ of the knowledge base has to be created using
decisions are left completely to engineers and expert departments. the object-oriented approach since several connections between the
This leads to a complete dependency of the company on their team given objects have to be considered. Data in the PDM system is
of experts. The problem worsens if the dependence is only on a most likely stored, as analyzed in chapter 2, in RDBs and has to be
single expert. Attempts to consolidate the knowledge of addressed to objects in an OODB or ORDB. These objects have to
engineering experts to more than one employee usually collapse be connected via rules and constraints on a level applicable for all
because of budget and time restrictions. The experience of the product configurators to implement a ‘logical scheme’. Therefore,
expert cannot be transferred to other colleagues within in short normalization methods comparable to data normalization need to
period of time [17]. It sometimes requires years to reach the level be formulated. In other words, a framework for product
of an expert and could result in loss of knowledge in case the configurators needs to be established ‘making the common parts
expert retires. common’ [19] and making general rules and constraints applicable
Another issue which is more and more visible to companies arises for all configuration tools to prevent redundant code
with the implementation of more than one configuration software. implementation. Due to the generalization of rules and constraints
Since the beginning of the new millennium a rising number of on a higher level, a non-redundancy of the knowledge in the
companies implement product configurators to treat a phenomenon separated specialized configuration solutions is achieved and
called ‘mass customization’ [18]. ‘Mass customization’ is an therefore, a centralized maintainability of the knowledge.
oxymoron referring on the one hand to the growing production Redundancy detection algorithms as proposed in [20] can
charges of companies to serve the market and on the other hand the consequentially be applied under these conditions to assure
increasing amount of individualization requirements by customers. continuous knowledge integrity. Furthermore, the knowledge of
The configuration technology relies on a subject-oriented, experts can be transferred in incremental steps into the knowledge
integrated, time-variant, nonvolatile dataset similar to the data base avoiding redundancy in several tools and decreasing
warehouse. Combinations of entities and their attributes are dependency on single persons in the company. Finally, a ‘physical
configured according to combination and configuration rules to scheme’ of the system architecture has to be created and is
create a producible bill of material. investigated in more detail in the next chapter.
This technology was immediately adopted by the high voltage
transmission business since the modular design of its products is
predestinated to realize product configurators. Unfortunately, the 5 A GLOBAL KNOWLEDGE MANAGER
degree of standardization in the business does not allow a full An initial approach to set up a system architecture analog to the
switch from CAD (computer aided design) applications to product requirement formulated above was made in the paper ‘On
configuration solutions. Special-purpose solutions define the high Knowledge-Base System Architectures’ and is illustrated in Figure
voltage transmission market up to fifty percent. The result is an 5 [21]. The paper introduced a unit called global knowledge
increasing redundancy in the configuration data and knowledge. manager (GKM) to centrally handle inquiries by other knowledge-
While the CAD system inherits engineering data accomplished by based systems and data type processors (e.g. traditional databases).
rules and constraints for the product with a high degree of freedom To assure common semantics a translator or interface was
to support the engineering expert, the product configuration proposed. A request incoming to the GKM is first scheduled and
application is designed for sales people or even for the customer optimized by using the GKM’s knowledge base and information
and includes a separated engineering dataset complemented by delivered by the source of the request. The result is an access plan
even more sophisticated rules, constraints and methods to prevent a stored in the GKM’s internal database. The monitor/interpreter
wrong configuration. Nevertheless, a redundancy of engineering uses this plan to process the request by applying the GKM’s
data and knowledge is introduced; leading to a high maintenance knowledge base rules, constraints and methods. The outcome is
effort and complicated processes whenever the research and returned to the original source using common semantics.
development department (R&D) releases technical innovations or This approach presumes a fully centralized inference of all
the product lifecycle management department (PLM) disables the inquiries. Any information in the system is gathered in the GKM,
use of certain parts of the product. scheduled and interpreted. In consequence, a centralized expert
Based on these evaluations, a centralized engineering database has system is introduced responsible to create and maintain all business
to be implemented as foundation for all product configurators. relevant rules, constraints and methods irrespective of the
PDM systems fortunately inherit all relevant product information complexity and domain of the request. A configuration task to
and can, as the major tool for PLM and R&D departments, be calculate the mechanical forces on a circuit breaker in case of an
utilized as a centralized engineering database. The result is a earthquake would as well be processed as a simple request for
database valid for all configuration applications which are no earnings before interest and taxes (EBIT) calculation. The
longer maintained decentral by each product configurator but are consequence would be a very complex set of knowledge
centrally maintained by the product responsible departments. The
representations neglecting all domain specific requirements.
Therefore, a master data and master knowledge approach assuring
consistency between all connected tools might be a more feasible
solution.
Figure 6. Three layer repository – global knowledge management –
standards approach
In Location 1, which is in shown in Figure 7, a system architecture
including two CPQ-tools and the usual databases is established.
CPQ-tool 1 is responsible for very standardized configuration tasks
while CPQ-tool 2 is an expert tool to configure specialized
customer requirements. Simple if-then relationships which
generally describe a part of the substation are maintained in the
GKM. For instance: ‘If product A is chosen then the cross section
of the rectangular conductor cannot exceed 2400 mm².’ The
information about the product is received via an interface to the
PDM database and is maintained in a fast accessible RDB
Figure 5. Architecture with global knowledge manager [21] database. In the GKM two objects (product A and rectangular
conductor) are described by parameters (cross section, ambient
Figure 6 shows, based on the system architecture presented in temperature, body temperature, rated current) matched to the
Figure 3, an overview of the system architecture we propose to information delivered by the PDM database and are connected via
provide the requirements of an easy maintainable, integrated the above mentioned relationship. This general rule is
system for the high voltage transmission business. A company- accomplished by a more specific rule in CPQ-tool 1 by the
wide standard or framework for creation of data, rules and following relationship: ‘If the rated current exceeds 2500 A at a
constraints is defined to assure semantic consistency between all ambient temperature of 35 °C then a rectangular aluminum
locations. The master data system is accomplished by the global conductor needs at least a cross section of 2400 mm² to not exceed
knowledge manager to facilitate data and knowledge integrity in 65°C body temperature.’ [22].
one location. While the master data management part is responsible A user of CPQ-tool 1 is in consequence not allowed to choose
for the data integrity of all databases, the global knowledge product A if the rated current exceeds 2500 A and an ambient
manager is comparably responsible for knowledge integrity in all temperature of 35°C is given. Contradicting to this rule, an expert
connected configuration applications and expert systems. in CPQ-tool 2 is not restricted by this constraint. An expert could
Additionally the global knowledge manager organizes special decide to use product A if the current exceeds 2500 A at a ambient
calculation inquiries by CPQ-tools to expert tools. Therefore, a temperature of 35 °C knowing that the conductor is allowed to
universally understandable format (e.g. extensible markup exceed 65 °C if the conductor is not touchable by humans. This
language – XML) is introduced to enable communications between expert knowledge includes besides product knowledge as well
the GKM and all connected tools. Knowledge integrity during knowledge about spatial constraints and human interactions with
operation is assured by redundancy detection algorithms the product and is with its complexity not easily describable in a
considering all knowledge bases of the software infrastructure. non-expert configuration tool. Nevertheless both configuration
Additionally, a repository is tracking comparable data, rules and systems will lead to a correct solution. CPQ-tool 1 will lead to the
constraints of the separately operating locations by defining costlier product B but is operable by the customer herself while
company-wide primary keys. Changes in the master data and CPQ-tool 2 with a higher degree of freedom will deliver a cheaper
global knowledge management system are synchronized solution of the configuration task but needs expert knowledge.
asynchronous to operational inquiries to maintain consistency Therefore, two options for the customer are established, a slightly
between all local data and knowledge sets by utilizing the costlier but very fast configuration or a very accurate solution with
repository primary keys. The behavior of the system is illustrated a more time consuming configuration.
in more details by the two following examples.
beginning of this paper also includes recommendation mechanisms
and possibilities to implement self-learning algorithms the
proposed system architecture needs to be accomplished by
continuative considerations.
6 CONSTRAINT-BASED RECOMMENDER
SYSTEMS
Recommender systems are since the 1990s an increasingly used
service in mainly e-commerce applications to recommend simple
products to users [23]. The user gets recommended products based
on previously taken buy decisions (individual information), social
background information and a knowledge base that proceeds given
user input in form of determined attribute and using concerned
domain and contextual knowledge. But according to Felfernigs et
Figure 7. Multiple CPQ-tool system architecture al. definitions recommender systems could be used in a much more
general way: ‘Any system that guides a user in a personalized way
Location 2 is in detailed visible in Figure 8 and includes the to interesting or useful objects in a large space of possible options
standard databases, CPQ-tool 1 and an expert system. The or that produces such objects as output.’ [24].
previously mentioned configuration task to calculate the Besides the possibilities given for e-commerce sellers, a second
mechanical forces on a circuit breaker in case of an earthquake is very large field of application opens with the usage in expert
given. This calculation task requires information which is not systems. Mainly product configuration applications are adopting
stored in the PDM database or any other standard available master recommendation techniques which can be classified in:
data. Additionally, very specific calculation methods have to be
applied not handled in the CPQ-tool. An expert system is necessary 1. collaborative recommendation – relying on the choices
to solve the calculation task. The calculation inquiry is sent from made previously by other users with the same social and
the CPQ-tool via the universally understandable format to the demographical background
GKM that interprets schedules and finally processes the request to 2. content-based recommendation – relying on choices
the correct expert tool. In consequence, the GKM inherits besides made previously by the user herself
generalized rules and constraints also information about the expert 3. knowledge based recommendation – relying on user
tools in the system and administrates access to them. The inquiry is requirements and domain knowledge
handled by the expert system using the information received via 4. hybrid forms – try to combine the other types to avoid
the interface and by utilizing additional information like specific disadvantages of each stand-alone solution
knowledge on the occurring earthquake forces in the concerned
region to calculate the forces on the circuit breaker. The result is With respect to the high voltage transmission business the only
processed back to the GKM and further to the CPQ-tool where the reasonable choice for recommender systems is the knowledge
resulting values trigger rules and constraints to decide which circuit based recommendation technique since electric power transmission
breaker has to be chosen. substations do not rely on choices or preferences of single users but
on very detailed requirement specifications delivered by the
customers (utilities). Even if the requirement specifications of
utilities do not change frequently and a content-based
recommendation could be possible in terms of parameter input to a
configuration application an important circumstance, a unique
feature of substations has to be taken into account – the
environmental conditions. Unlike other typically configurable
products like cars or kitchens substations are crucially impacted by
the locations they are assembled.
For example, the Russian ministry of electricity announces in a
tender a high voltage transmission substation with the same
topology (electrical circuit diagram) and electrical requirements as
five years before. One might conclude that the same electrical
requirements lead to the same bill of material and same physical
topology of the substation. But taking the new location near the
Baltic Sea compared to the previous one in Novosibirsk into
account this paradigm is false. The environmental conditions
Figure 8. CPQ-tool – expert system architecture including temperature, air pollution, earthquake requirements and
altitude of side have an essential impact on the physical
These two simplified examples are only supposed to give an arrangement of the substation. This set of conditions to be
overview about the working-principle to be established with the considered can be depicted as a very complex conglomeration of
introduction of a GKM and need to be further researched in constraints and is in conclusion applicable for recommendation
following publications. But since the vision formulated at the
systems. However, the complexity of the configuration task is ∂ Knowledge integrity – how should knowledge
probably too high to be provided with all features in one product normalization methods look like to build the base for a
configuration application which is why the example in the previous global knowledge manager and a framework for rules
chapter has been chosen. and constraints?
To achieve the best configuration solution many specialized ∂ System architecture – which system architecture allows
systems have to give input to the configuration process. the highest performance, best maintainability, and
Mechanical calculations, waste heat, ferroresonance and further security with respect to the requirements given by a fully
calculation applications are delivering valuable information and integrated knowledge system?
need to be addressed to receive a feasible solution. The expert ∂ Global knowledge manager – how should the global
systems outcome is involved as input for the existing knowledge manager be designed?
recommendation constraints to create a solution for the given ∂ Universally understandable format – how should a
configuration task. The user of CPQ-tool 1 in the example format look like which is processible by all databases and
illustrated for Figure 7 as a non-expert gets one feasible solution programs in the system, including expert systems and
recommended without any repair mechanism. The solution will be product configurators?
rather conservative, but is in line with the given rules and ∂ Recommender system – how can rules and constraints be
constraints. On the other hand the expert using CPQ-tool 2 in the improved by analyzing decisions of experts in a product
example has the possibility to neglect the recommended solution configurator to improve the recommended solutions to
and choose a more efficient one. The changes are recognized by non-experts?
the system and adapted to the existing constraints in the GKM. A
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