Using multiple Feature Models to specify configuration options for Electrical Transformers
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Jaime Chavarriaga, Carlos Rangel, Carlos Noguera, Rubby Casallas, Viviane Jonckers. Using Multiple Feature Models to specify configuration options for Electrical Transformers: An Experience Report. SPLC 2015. pp 216-224. 2015 http://doi.acm.org/10.1145/2791060.2791091
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Using multiple Feature Models to specify configuration options for Electrical Transformers
- 1. Jaime Chavarriaga, Uniandes Carlos Rangel, Siemens Colombia Carlos Noguera, VUB Rubby Casallas, Uniandes Viviane Jonckers, VUB 1 Using multiple Feature Models to specify configuration options for Electrical Transformers
- 3. SIEMENS produces electrical transformers in Colombia
- 4. There is a facility located at 8,5 kms of the center of Bogotá
- 5. +350 persons +15000 units/yr. Siemens Transformers
- 6. Multiple standards and norms must be supported … just for Colombia, there many national and proprietary standards for each single family. Clients across all America
- 8. Bid Process Customer Customer Requests Sales Engr Bid Engr Bids Proposals I want an electrical transformer with Power of 15KVA a Low Voltage of 214V and a High Voltage of 4160V To be installed in Buenos Aires
- 9. Bid Process Customer Customer Requests Sales Engr Bid Engr Bids Proposals I want an electrical transformer with Power of 15KVA a Low Voltage of 214V and a High Voltage of 4160V To be installed in Buenos Aires Gotcha !! Will it be pad- mounted or pole-mounted?
- 12. Some Issues to tackle Accessories Packing Shipping … Electrical Design Mechanical Design
- 13. … for the Sales Engineers • Detect inconsistencies in the client’s requests • Identify inconsistencies with standards • Identify already designed similar transformers • Complete the specification
- 14. Electrical Design Mechanical Design … for the Engineering Design Groups Accessories Packing Shipping … • Detect inconsistencies with decisions in other domains
- 15. Approach: Feature-Based Configuration Process (using a single feature model)
- 16. Our First Attempt: A Single Feature Model Catalog of Products Variability Reverse Engineering
- 17. Our First Attempt: A Single Feature Model Catalog of Products Variability Reverse Engineering This model represents the existing products… but we want to represent options to specify customized electrical transformers
- 18. Our First Attempt: A Single Feature Model Modelers Domain Related Constraints Standard Related Constraints Standard Additional constraints must be included to represent domain- and standards-related constraints
- 19. Our First Attempt: A Single Feature Model For a single family, with a single standard, we ended with +400 features and +120 cross-tree constraints ? ? Modelers Domain Related Constraints Standard Related Constraints Standard
- 20. Our First Attempt: A Single Feature Model Because each standard imposes different constraints on branches, adding a new standard was a challenge Any Standard ? ? Modelers Domain Related Constraints Standard Related Constraints Standard
- 21. Trying to create a single feature model did not help us to define, review and analyze the features in each domain, the inter-domain constraints and the cross-cutting constraints defined by the diverse standards.
- 22. A Revisited Approach: Using Multiple Feature Models to represent the configuration options
- 23. A Revisited Approach ❶ Separation of Domains ❷ Model each domain ❸ Model inter-domain relationships ❹ Model standards ❺ Merge the Models ❻ Analysis and User Validation
- 24. ❶ Separation of Domains System Type Installation Electrical, Thermal and Acoustic Mechanical ETA Accessories Mechanical Accessories
- 25. ❷Model each domain 27They were easier to build, understand and review by modelers
- 26. ❸Model Inter-domain relationships 28 Sealed_tank => ~buchholz_relay
- 27. ❹Modeling of Standards 29 Ntc_3997 => pad_mounted Ntc_3997 => Power = 15KVA ⋁ 30KVA Ntc_3997 => High Voltage = 4160V ⋁ 11400V Ntc_3997 => Low Voltage = 214V ⋁ 228V Ntc_3997 => ONAN Ntc_3997 => NEMA_TR1 Ntc_3997 => sealed_tank
- 28. ❺Merge Feature Models - Domains 30 + + +
- 29. ❺Merge Feature Models - Domains 31 + + + Root (Electrical Transformer)
- 30. ❺Merge Feature Models - Standards 33 Ntc_3997 => pad_mounted => Power = 15KVA ⋁ 30KVA => High Voltage = 4160V ⋁ 11400V => Low Voltage = 214V ⋁ 228V => ONAN => NEMA_TR1 => sealed_tank +
- 31. ❺Merge Feature Models - Standards 34 Ntc_3997 => pad_mounted => Power = 15KVA ⋁ 30KVA => High Voltage = 4160V ⋁ 11400V => Low Voltage = 214V ⋁ 228V => ONAN => NEMA_TR1 => sealed_tank + Add an standard
- 32. ❺Merge Feature Models - Standards 35 Ntc_3997 => pad_mounted => Power = 15KVA ⋁ 30KVA => High Voltage = 4160V ⋁ 11400V => Low Voltage = 214V ⋁ 228V => ONAN => NEMA_TR1 => sealed_tank + Introduce constraints
- 33. ❺Merge Feature Models - Standards 36 Ntc_3997 => pad_mounted => Power = 15KVA ⋁ 30KVA => High Voltage = 4160V ⋁ 11400V => Low Voltage = 214V ⋁ 228V => ONAN => NEMA_TR1 => sealed_tank + Add values and constraints
- 34. ❺Merge Feature Models - Standards 37
- 35. ❻Analysis and User Validation – Peer-review – Automated analysis – Tests using products from the existing catalogs Continuous Validation/Testing of the Models
- 36. Tool Support Our tools use/extend SPLOT… – Create Feature Models from standards – Merge Feature Models – Analyze single and merged Feature Models – Configure multiple feature models – Perform tests and validations http://www.splot-research.org/
- 37. Some Lessons Learned and Conclusions
- 38. Lesson Learned ❶ Modeling – Using a single feature model is tough – Multiple feature models facilitates the modeling – The separation of domains is an iterative process – Each standard can be modeled independently – Incremental modeling facilitates the work 41
- 39. Lesson Learned ❷ Models Validation – Incremental modeling Continuous Testing – We can test the models using product catalogs and reviews ❸ Tools – Existing tools has limited support to multiple FMs – Partial configurations can be used to lead the process ❹ Impact on other Processes – This allowed engineers to define and enforce standards in the company 42
- 40. Questions? Jaime Chavarriaga, Uniandes ja.chavarriaga908@uniandes.edu.co Carlos Rangel, Siemens Colombia Carlos Noguera, VUB Rubby Casallas, Uniandes Viviane Jonckers, VUB 43
Editor's Notes
- Here we are presenting some results of a collaborative project between Siemens Colombia and the Universidad de los Andes. We are currently working in how to use configuration processes for early detection of conflicts when a customer requests a new electrical transformer. I will present today our experience on using multiple feature models to specify configuration options.
- Electrical transformers are devices used in distribution networks to transport electricity from sources to buildings and houses that consume it. There are several families depending on the power they have to support and the type of installation among other things.
- Simens has been producing Electrical Transformers
- Siemens Transformadores is established at Bogotá * More than 1200 empleyees * Manufactures more than 2400 transformers per year * Sells and producess transformers for almost all the countries in North, Central and South America
- Siemens Transformadores is established at Bogotá * More than 1200 empleyees * Manufactures more than 2400 transformers per year * Sells and producess transformers for almost all the countries in North, Central and South America
- These transformers are sold across all America
- Therefore they must support standards and norms defined for each of these countries. For instance, for a single family, SIEMENS supports more than seven different national and proprietary standards in Colombia. Each power transmission and distribution network owner may define its own set of standard specifications for electrical transformers. Currently, many countries have different standards (e.g., IEEE Std C57.12 [13] is the standard in USA, IEC 60076[12] applies in Europe and ICONTEC NTC819[10] in Colombia). In addition, private portions of the networks owned by industries can also define their own standards. Furthermore, these standards are constantly evolving (e.g., the Ecodesign 548/2014 [8] takes effect in Europe starting in 2015). Each of these standards imposes constraints such as valid values for voltage or the prohibition of some accessories. For a technical sales expert, the diversity of standards makes more difficult to be aware of the constraints imposed by all of them and detect possible conflicts with customerprovided specifications. Some of the conflicts can be only detected by
- The processes to Bid, Design and manufacture the electrical transformers depend on the requirements provided by the client.
- Everything starts with a request of a client - Usually, a client provides an specification of a few properties and features of the electrical transformer. - A Sales Expert obtains that requests and provides an offer
- That is an iterative process where the sales expert discuss with the client and clarifies the features that must be included in the transformer. Usually, the sales expert must complete the specification.
- The sales expert send the transformer specification to multiple design groups in the factory Diverse groups are focused on creating an electrical design and a mechanical design for the transformer. These groups or other people also work to define the accessories to include, the packing and shipping of the transformer. In turn, each group defines additional specifications and features for the transformer. The transformer is then designed based on these specifications.
- The sales expert send the transformer specification to multiple design groups in the factory Diverse groups are focused on creating an electrical design and a mechanical design for the transformer. These groups or other people also work to define the accessories to include, the packing and shipping of the transformer. In turn, each group defines additional specifications and features for the transformer. The transformer is then designed based on these specifications.
- Considering the process before manufacturing, there are some issues to tackle
- First, the sales experts is in charge of detect inconsistencies in the requests from the client. She must detect inconsistent properties and requirements, detect inconsistencies with standards and complete the specification.
- Additionally, each of the design groups must also detect inconsistencies. They must review their decisions and the decisions from other groups and detect inconsistences resulting from decisions on multiple domains.
- In order to improve the process and support early detection of conflicts, we proposed a feature based configuration process. Our plan was focused on creating a single feature model that represented the diverse transformers that the factory can build.
- We started reviewing the large catalog of already produced transformers in Siemens.
- We used that catalog to create a model that represented the existing products. However, that inconsistencies tend to exist in custom-defined transformers instead of the standards.
- Some domain experts were involved into the project to define domain-related constraints. For instance, to specify constraints related to electrical or mechanical properties of the transformers that the factory can build.
- However, when these experts tried to specify these constraints the main obstacle was the complexity of the feature model. For example, the feature model for a small family, considering only a single standard ended with more that four hundred features and on hundred of constraints. The modelers found that model hard to understand and validate. Furthermore, they found many problems to check existing and introduce new constraints.
- Additionally, because we want to detect inconsistencies with the diverse standards in the different countries, the definition of constraints based in the standard becomes a real challenge. They did not found an efficient way to create these constraints. They ended with large constraints harder to understand and verify.
- As an initial conclusion, we detect that using a single feature model did not help us. We had to find an easier way to create the models and define the constraints with the domain experts.
- We proposed a new approach. Basically, instead of creating a single feature model where all the domain experts introduce new elements, we propose the creation of feature models for each domain.
- Our approach comprises six steps: First, we define a set of domains, Then, we model these domains, the constraints among these domains and the standards, And, finally, we merge and test these models.
- For instance, for the electrical transformer, we defined seven domains: Some related to the distribution network and the location where the transformer will be installed: there are System, Installation and Type. Others related to the Electrical Thermal and Acoustic properties and accessories: The ETA and ETA accessories And others related to the Mechanical properties and accessories. Originally, we have defined a different set of domains. These domains resulted after many iterations of the modeling process.
- Once the domains were defined, we worked with the domain experts to model each domain. For instance, here are excerpts of the models of type, ETA, Mechanical an ETA Accessories. The models we created resulted shorter than the single feature model we tried to create. These models were easier to build, understand and review by the modelers.
- After the models for each domain was created, we proceeded to create constraints and relationships between the features in each domain. Here we present a constraint relationships between a mechanical feature and an electrical accessory.
- Additionally, we define the standards as feature models and constraints. Here I present some constraints from an standard from Colombia. That standard defines some values for power and voltage, and defines some mandatory features and accessories in the different domains.
- When the different domains were modeled, we proceeded to merge the models and standards to detect problems and errors.
- The first process merges the feature models for the domains. We are using techniques proposed by Mathieu Acher to do it. Basically we define the models for each domain as a branch of the model for electrical transformers.
- An additional process merges the standards.
- First the standard is introduced as a feature in the model.
- Then, the diverse constraints in the standard are added to the model
- And finally, standard-specific values are included in the model as features, adding the corresponding constraints too.
- The main objective of merging the models was the validation of them. We performed several activities to continuously validate the models. The models were reviewed by multiple domain experts. We used solvers to detect errors in the models. And, additionally, we use the information of the existing products to validate if the constraints allow us to configure them.
- These tasks were performed with some tools we created. Because existing tools provide limited support for multiple feature models, we extend SPLOT to create and merge the models. Specially, create the models from the standard. In addition, we defined tools to configure multiple feature models and perform tests and validations.
- Now, I will summarize some lessons we learned.
- Regarding the modeling, using a single feature model is hard. We found that a single feature model was harder to understand and validate by the modelers. Instead, the use of multiple feature models was easier. In our case, we did an iterative process to define the domains and create the models incrementally. Very important, we found that many problems were caused when people tried to include the constraints imposed by some standard in the features of a large feature models. We consider that each standard can be modeled independently and that eases the work.
- Regarding the validation, incremental modeling was possible because we performed continuous testing. Each time a new version was proposed by a domain expert that was validated using automated tools. About the tools, existing tools has a limited support for multiple models. We have to extend them to perform the tasks we want. Additionally, we found that clients usually provide partial configurations and we are interested on defining tools that exploit these partial configurations. Finally, the project we are doing had an interesting impact on other processes in Siemens Because we have been working on products and standards, engineers in Siemens enriched their discussions on how to define and enforce the diverse standards in a more efficient way . And also discuss on the product portfolio.
- Here I presented our experience using multiple feature models to represent configuration options in electrical transformers. If you have some question, I can try to answer it.