The Open Model for Exchanging Power System Simulation Data (ODM) schema is formally defined in this document. The ODM Schema is based on XM Schema standard published by W3C. Eclipse, an open-source free IDE, is used to create and edit the schema. The schema and its associated Java API library are hosted at the InterPSS Project on Github, open and freely accessible.
Please Note: The ODM Schema is still under development. Therefore the information presented here might be not 100% accurate. We intend to make regular updates to make it as currently as possible.
ODM Schema currently is hosted at InterPSS Github Code repository and the ODMSchema.xsd is the main schema file.
There is two main XML data structures used in ODM, in addition to standard data types defined in XML schema.
The ODM Schema target namespace is "http://www.ieee.org/odm/Schema/2008". All types defined in the ODM Schema are "qualified" with a namespace prefix pss.
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://www.ieee.org/odm/Schema/2008"
xmlns:pss="http://www.ieee.org/odm/Schema/2008"
elementFormDefault="qualified">
...
<element name="PSSStudyCase" type="pss:StudyCaseXmlType"></element>
...
</schema>
Please see Namespaces in XML for more in depth discussion about namespace.
The Schema root element type StudyCaseXmlType has a attribute schemaVersion for indicating schema version number.
Actual units, such as KV, MVA, and PU could be used in the ODM Model. All PU values in the model are based on the base case base Kva and bus base voltage, unless otherwise specified.
ODM is designed to be extended. The extension folder is for ODM extension by any interested party. Currently, it has a folder containing extension by InterPSS. The following namespace has been introduced in InterPSS extension.
xmlns:ipss="http://www.interpss.org/Schema/odm/2008"
The ODM schema root element PSSStudyCase is of type StudyCaseXmlType.
<schema xmlns="http://www.w3.org/2001/XMLSchema" ...>
<element name="PSSStudyCase" type="pss:StudyCaseXmlType"></element>
...
</shema>
The StudyCaseXmlType has the following elements:
The information are organized in the Schema using the record concept.
A ID record has an id of Type xsd:ID, which guarantees its uniqueness in an ODM xml file. It is the parent of all searchable records, such BusRecord, BranchRecord.
The base case element is of type PSSNetworkXmlType. It is intend to describe a power network for simulation purpose. Currently, it our focus is on Loadflow study information. The structure has been designed in such a way that it could be extended to include more simulation information, such as short circuit, transient stability.
Bus record has a unique id and a set of attributes inherited from the BaseRecordXmlType. It also holds bus related simulation data. Now it only covers Loadflow study information. It will be extended to cover other simulation concepts, such as short circuit.
Bus Loadflow Data
By analysis different data formats, we believe the above bus model captured all possible permutations of a local bus model for loadflow analysis purpose. Bus generation Q some times is used to control voltage of a remote bus.
Bus Loadflow data is described by the LoadflowBusDataXmlType.
Generation Loadflow Data
Load Data
Remote Voltage Adjustment
Some times, generator Q is used to control voltage of a remote bus, for example, the high-voltage side of generator output transformer.
Branch record has an unique id, an id reference to a from bus record, an id reference to a to bus record, a circuit id, and a set of attributes inherited from the BaseRecordXmlType. The tereiayBus is optional, which could be used to define a 3-winding transformer. It also holds branch related simulation data. Now it only covers Loadflow study information. It will be extended to cover other simulation concepts, such as short circuit.
Loadflow Branch Data
Branch Loadflow data is described by the LoadflowBranchDataXmlType.
Loadflow Line Data
By analysis different data formats, we believe the above line model captured all possible permutations of a local transmission model for loadflow analysis purpose.
Loadflow Transformer Data
By analysis different data formats, we believe the above transformer model captured all possible permutations of a local transformer or a logical phase-shift transformer model for loadflow analysis purpose. Adjustment could be applied to transformer tap to adjust bus voltage or Mvar flow, or to phase-shifting transformer angle to adjust Mw flow.
Transformer Data
In the transformer data schema definition, only transformer impedance z are required elements. The fromTurnRation and toTurnRatio should be set to 1.0 if not defined. The other optional elements should be set to zero if not specified.
Please Note: When transformer Z and Y are specified in actual value, in Ohm or Mho, the side where the value is measured need to be specified. ODM assumes that the value is measured at the high voltage side.
Transformer Tap Adjustment
Transformer Tap Adjustment for Bus Voltage
Transformer Tap Adjustment for MVar Flow
Loadflow PhaseShift Transformer Data
PhaseShift transformer inherits from transformer. In addition it has the following fields
Phase Angle Adjustment
Branch Rating Limit
Three mva rating limits and a current rating limit could be defined
A list of modifications could be defined in a StudyCase, as shown in the following figure:
The modification element is of type ModifyRecordXmlType, which is abstract. In actual application, it needs to be replaced with a concrete Xml type, for example, the NetModificationXmlType, in the following figure:
In contingency analysis, there is a need to define a list of contingencies which might be applied to the base case. Here we present one possible ways to define contingencies.
A studyScenario could be defined in a StudyCase, as shown in the following figure: