1 Scope

The specification “Energy Consumption Management” defines a standardized information model on OPC UA for the purpose of defining interoperable interfaces and a standardized semantic for energy management systems in industrial automation and process automation industries. The purpose of an energy management system is to save overall energy consumption and energy costs, as well as the fulfilment of regulatory standards like ISO 50001 [1] and the protection of the climate.

As Figure 1 shows, the general approach to cut down overall energy consumption and energy costs is a step-by-step circular approach. Starting point is the analysis of today energy consumption. With awareness about energy consumption of sections, machines and devices in the production plant, in a next step potential energy savings are identified. After the definition of potential energy savings, the next step is the realization of the identified savings.

The specification Energy Consumption Management is on the communication of energy related measurement data, which is to be used in the task of “analyse energy consumption” and in the advertisement and control of energy savings in the task of “realize energy savings”. Existing OPC UA models for Energy Management (OPC 30141) together with other fieldbus energy profiles serve as the basis for this companion specification. Also, the universal energy information model out of the project results of the IGF research project 21329 N “Development of energy management interfaces for IoT technologies (IoT_EnRG) ” [3] was used here.

It will allow management of energy consumption by automated equipment in manufacturing and processing applications for discrete and continuous productions. The model is intended to be scalable from small stand-alone devices to complete machines to production cells or entire factories and plants.

2 Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments and errata) applies.

OPC 10000-1, OPC Unified Architecture - Part 1: Overview and Concepts

http://www.opcfoundation.org/documents/10000-1/

OPC 10000-2, OPC Unified Architecture - Part 2: Security Model

http://www.opcfoundation.org/documents/10000-2/

OPC 10000-3, OPC Unified Architecture - Part 3: Address Space Model

http://www.opcfoundation.org/documents/10000-3/

OPC 10000-4, OPC Unified Architecture - Part 4: Services

http://www.opcfoundation.org/documents/10000-4/

OPC 10000-5, OPC Unified Architecture - Part 5: Information Model

http://www.opcfoundation.org/documents/10000-5/

OPC 10000-6, OPC Unified Architecture - Part 6: Mappings

http://www.opcfoundation.org/documents/10000-6/

OPC 10000-7, OPC Unified Architecture - Part 7: Profiles

http://www.opcfoundation.org/documents/10000-7/

OPC 10000-100, OPC Unified Architecture - Part 100: Devices

http://www.opcfoundation.org/documents/10000-100/

OPC 10000-200, OPC Unified Architecture - Part 200: Industrial Automation

http://www.opcfoundation.org/documents/10000-200/

PE 3802 Common Application Profile PROFIenergy – Version 1.3MU1 – Date: October 2021 Order No.: 3.802

3 Terms, definitions and conventions

3.1 Overview

It is assumed that basic concepts of OPC UA information modelling are understood in this specification. This specification will use these concepts to describe the Energy Consumption Management Information Model. For the purposes of this document, the terms and definitions given in OPC 10000-1, OPC 10000-3, OPC 10000-4, OPC 10000-5, OPC 10000-6, OPC 10000-7, OPC 10000-100, and OPC 10000-200 as well as the following apply.

Note that OPC UA terms and terms defined in this specification are italicized in the specification.

3.2 OPC UA for Energy Consumption Management terms

4.2.1

EnergyProfile

standardized aggregation of energy variables with standardized semantic and predefined accuracy classes reflecting typical use cases and devices

3.3 Abbreviated terms

3.4 Conventions used in this document

3.4.1 Conventions for Node descriptions

3.4.1.1 Node definitions

Node definitions are specified using tables (see Table 2).

Attributes are defined by providing the Attribute name and a value, or a description of the value.

References are defined by providing the ReferenceType name, the BrowseName of the TargetNode and its NodeClass.

If the TargetNode is a component of the Node being defined in the table the Attributes of the composed Node are defined in the same row of the table.

The DataType is only specified for Variables; “[<number>]” indicates a single-dimensional array, for multi-dimensional arrays the expression is repeated for each dimension (e.g. [2][3] for a two-dimensional array). For all arrays the ArrayDimensions is set as identified by <number> values. If no <number> is set, the corresponding dimension is set to 0, indicating an unknown size. If no number is provided at all the ArrayDimensions can be omitted. If no brackets are provided, it identifies a scalar DataType and the ValueRank is set to the corresponding value (see OPC 10000-3). In addition, ArrayDimensions is set to null or is omitted. If it can be Any or ScalarOrOneDimension, the value is put into “{<value>}”, so either “{Any}” or “{ScalarOrOneDimension}” and the ValueRank is set to the corresponding value (see OPC 10000-3) and the ArrayDimensions is set to null or is omitted. Examples are given in Table 1.

The TypeDefinition is specified for Objects and Variables.

The TypeDefinition column specifies a symbolic name for a NodeId, i.e. the specified Node points with a HasTypeDefinition Reference to the corresponding Node.

The ModellingRule of the referenced component is provided by specifying the symbolic name of the rule in the ModellingRule column. In the AddressSpace, the Node shall use a HasModellingRule Reference to point to the corresponding ModellingRule Object.

If the NodeId of a DataType is provided, the symbolic name of the Node representing the DataType shall be used.

Note that if a symbolic name of a different namespace is used, it is prefixed by the NamespaceIndex (see 3.4.2.2).

Nodes of all other NodeClasses cannot be defined in the same table; therefore only the used ReferenceType, their NodeClass and their BrowseName are specified. A reference to another part of this document points to their definition. Table 2 illustrates the table. If no components are provided, the DataType, TypeDefinition and ModellingRule columns may be omitted and only a Comment column is introduced to point to the Node definition.

Each Type Node or well-known Instance Node defined shall have one or more ConformanceUnits defined in 11.1 that require the Node to be in the AddressSpace.

The relations between Nodes and ConformanceUnits are defined at the end of the tables defining Nodes, one row per ConformanceUnit. The ConformanceUnits are reflected in the Category element for the Node definition in the UANodeSet (see OPC 10000-6).

The list of ConformanceUnits in the UANodeSet allows Servers to optimize resource consumption by using a list of supported ConformanceUnits to select a subset of the Nodes in an Information Model.

When a Node is selected in this way, all dependencies implied by the References are also selected.

Dependencies exist if the Node is the source of HasTypeDefinition, HasInterface, HasAddIn or any HierarchicalReference. Dependencies also exist if the Node is the target of a HasSubtype Reference. For Variables and VariableTypes, the value of the DataType Attribute is a dependency. For DataType Nodes, any DataTypes referenced in the DataTypeDefinition Attribute are also dependencies.

For additional details see OPC 10000-5.

Components of Nodes can be complex that is containing components by themselves. The TypeDefinition, NodeClass and DataType can be derived from the type definitions, and the symbolic name can be created as defined in 3.4.3.1. Therefore, those containing components are not explicitly specified; they are implicitly specified by the type definitions.

The Other column defines additional characteristics of the Node. Examples of characteristics that can appear in this column are show in Table 3.

If multiple characteristics are defined they are separated by commas. The name or the short name may be used.

3.4.1.2 Additional References

To provide information about additional References, the format as shown in Table 4 is used.

References can be to any other Node.

3.4.1.3 Additional sub-components

To provide information about sub-components, the format as shown in Table 5 is used.

3.4.1.4 Additional Attribute values

The type definition table provides columns to specify the values for required Node Attributes for InstanceDeclarations. To provide information about additional Attributes, the format as shown in Table 6 is used.

There can be multiple columns to define more than one Attribute.

3.4.2 NodeIds and BrowseNames

3.4.2.1 NodeIds

The NodeIds of all Nodes described in this standard are only symbolic names. Annex A defines the actual NodeIds.

The symbolic name of each Node defined in this document is its BrowseName, or, when it is part of another Node, the BrowseName of the other Node, a “.”, and the BrowseName of itself. In this case “part of” means that the whole has a HasProperty or HasComponent Reference to its part. Since all Nodes not being part of another Node have a unique name in this document, the symbolic name is unique.

The NamespaceUri for all NodeIds defined in this document is defined in Annex A. The NamespaceIndex for this NamespaceUri is vendor-specific and depends on the position of the NamespaceUri in the server namespace table.

Note that this document not only defines concrete Nodes, but also requires that some Nodes shall be generated, for example one for each Session running on the Server. The NodeIds of those Nodes are Server-specific, including the namespace. But the NamespaceIndex of those Nodes cannot be the NamespaceIndex used for the Nodes defined in this document, because they are not defined by this document but generated by the Server.

3.4.2.2 BrowseNames

The text part of the BrowseNames for all Nodes defined in this document is specified in the tables defining the Nodes. The NamespaceUri for all BrowseNames defined in this document is defined in 12.2.

For InstanceDeclarations of NodeClass Object and Variable that are placeholders (OptionalPlaceholder and MandatoryPlaceholder ModellingRule), the BrowseName and the DisplayName are enclosed in angle brackets (<>) as recommended in OPC 10000-3.

If the BrowseName is not defined by this document, a namespace index prefix is added to the BrowseName (e.g., prefix '0' leading to ‘0:EngineeringUnits’ or prefix '2' leading to ‘2:DeviceRevision’). This is typically necessary if a Property of another specification is overwritten or used in the OPC UA types defined in this document. Table 69 provides a list of namespaces and their indexes as used in this document.

3.4.3 Common Attributes

3.4.3.1 General

The Attributes of Nodes, their DataTypes and descriptions are defined in OPC 10000-3. Attributes not marked as optional are mandatory and shall be provided by a Server. The following tables define if the Attribute value is defined by this specification or if it is server-specific.

For all Nodes specified in this specification, the Attributes named in Table 7 shall be set as specified in the table.

3.4.3.2 Objects

For all Objects specified in this specification, the Attributes named in Table 8 shall be set as specified in the table. The definitions for the Attributes can be found in OPC 10000-3.

3.4.3.3 Variables

For all Variables specified in this specification, the Attributes named in Table 9 shall be set as specified in the table. The definitions for the Attributes can be found in OPC 10000-3.

3.4.3.4 VariableTypes

For all VariableTypes specified in this specification, the Attributes named in Table 10 shall be set as specified in the table. The definitions for the Attributes can be found in OPC 10000-3.

3.4.3.5 Methods

For all Methods specified in this specification, the Attributes named in Table 11 shall be set as specified in the table. The definitions for the Attributes can be found in OPC 10000-3.

3.4.4 Structures

OPC 10000-3 differentiates between different kinds of Structures. The following conventions explain, how these Structures shall be defined.

The first kind are Structures without optional fields where none of the fields allows subtype (except fields with abstract DataTypes). Its definition is in Table 12.

The second kind are Structures with optional fields where none of the fields allows subtypes (except fields with abstract DataTypes). Its definition is in Table 13.

Structures with fields that are optional have an “Optional” column. Fields that are optional have True set, otherwise False.

The third kind are Structures without optional fields where one or more of the fields allow subtypes. Its definition is in Table 14.

Structures with fields that allow subtypes have an “Allow Subtypes” column. Fields that allow subtypes have True set, otherwise False. Fields with abstract DataTypes can always be subtyped.

4 General information to Energy Consumption Management and OPC UA

4.1 Introduction to Energy Consumption Management

Due to the climate and energy crisis, industrial companies are faced with the challenge of taking appropriate steps to efficiently manage their own energy requirements. The introduction of an energy management system according to the ISO 50001 standard [1] has proven to be a promising approach in the past. The introduction of such an energy management system provides the organizational framework for deriving energy efficiency actions based on recorded energy data, implementing them, and monitoring their effects. In this context, the procedure is continuously monitored and optimized through the application of a so-called Plan-Do-Check-Act cycle, so that energy inputs are constantly made more energy-efficient. In addition to the organizational part, an energy management system also needs a technical part that can be used to measure, provide, store, display and evaluate energy data. Furthermore, energy demands can be directly influenced by a load management system. With standby management functions, devices or entire plant sections can be ramped down to an energy-saving mode during production pauses, e.g. when cleaning of the production plant is required. The components of the required technical part can be termed as technical energy management system [2].

The functions of such a technical energy management system are clustered according to Figure 2 and show the basic functional submodels scoped by this specification. The cluster “Power Metering and Monitoring” functions provides energy related measurement values to cover the use case for energy consumption monitoring and metering and energy related measurement values to cover the use case power quality monitoring. The electrical measurement values in this cluster are based on the standards IEC 61557-12 [4] and IEC 61000-4-30 [6].

The cluster “Power Standby Management” addresses the switch down of components and devices to a power standby or power off mode in cases the component or device is temporarily not needed in the production process. This can be the case for planned pauses like lunchtime or maintenance or because of unplanned pauses caused by defects in the production line and temporary interruptions in the supply chain. The power standby management cluster contains basically two different modes for standby. The standby pause management assumes that the ethernet or fieldbus interface at the device is still operative and the device is able to receive commands for management of the standby pause states of the device. The device power off management causes a complete power down of the device, leaving only the ethernet MAC functionality operative in order to be able to receive an ethernet WOL magic package to conduct the standard ethernet wake on LAN functionality.

4.2 Introduction to OPC Unified Architecture

4.2.1 What is OPC UA?

OPC UA is an open and royalty free set of standards designed as a universal communication protocol. While there are numerous communication solutions available, OPC UA has key advantages:

A state of art security model (see OPC 10000-2).

A fault tolerant communication protocol.

An information modelling framework that allows application developers to represent their data in a way that makes sense to them.

OPC UA has a broad scope which delivers for economies of scale for application developers. This means that a larger number of high-quality applications at a reasonable cost are available. When combined with semantic models such as energy consumption management, OPC UA makes it easier for end users to access data via generic commercial applications.

The OPC UA model is scalable from small devices to ERP systems. OPC UA Servers process information locally and then provide that data in a consistent format to any application requesting data - ERP, MES, PMS, Maintenance Systems, HMI, Smartphone or a standard Browser, for examples. For a more complete overview see OPC 10000-1.

4.2.2 Basics of OPC UA

As an open standard, OPC UA is based on standard internet technologies, like TCP/IP, HTTP, Web Sockets.

As an extensible standard, OPC UA provides a set of Services (see OPC 10000-4) and a basic information model framework. This framework provides an easy manner for creating and exposing vendor defined information in a standard way. More importantly all OPC UA Clients are expected to be able to discover and use vendor-defined information. This means OPC UA users can benefit from the economies of scale that come with generic visualization and historian applications. This specification is an example of an OPC UA Information Model designed to meet the needs of developers and users.

OPC UA Clients can be any consumer of data from another device on the network to browser based thin clients and ERP systems. The full scope of OPC UA applications is shown in Figure 3.

OPC UA provides a robust and reliable communication infrastructure having mechanisms for handling lost messages, failover, heartbeat, etc. With its binary encoded data, it offers a high-performing data exchange solution. Security is built into OPC UA as security requirements become more and more important especially since environments are connected to the office network or the internet and attackers are starting to focus on automation systems.

4.2.3 Information modelling in OPC UA

4.2.3.1 Concepts

OPC UA provides a framework that can be used to represent complex information as Objects in an AddressSpace which can be accessed with standard services. These Objects consist of Nodes connected by References. Different classes of Nodes convey different semantics. For example, a Variable Node represents a value that can be read or written. The Variable Node has an associated DataType that can define the actual value, such as a string, float, structure etc. It can also describe the Variable value as a variant. A Method Node represents a function that can be called. Every Node has a number of Attributes including a unique identifier called a NodeId and non-localized name called as BrowseName. An Object representing a ‘Reservation’ is shown in Figure 4.

Object and Variable Nodes represent instances and they always reference a TypeDefinition (ObjectType or VariableType) Node which describes their semantics and structure. Figure 5 illustrates the relationship between an instance and its TypeDefinition.

The type Nodes are templates that define all of the children that can be present in an instance of the type. In the example in Figure 5 the PersonType ObjectType defines two children: First Name and Last Name. All instances of PersonType are expected to have the same children with the same BrowseNames. Within a type the BrowseNames uniquely identify the children. This means Client applications can be designed to search for children based on the BrowseNames from the type instead of NodeIds. This eliminates the need for manual reconfiguration of systems if a Client uses types that multiple Servers implement.

OPC UA also supports the concept of sub-typing. This allows a modeller to take an existing type and extend it. There are rules regarding sub-typing defined in OPC 10000-3, but in general they allow the extension of a given type or the restriction of a DataType. For example, the modeller may decide that the existing ObjectType in some cases needs an additional Variable. The modeller can create a subtype of the ObjectType and add the Variable. A Client that is expecting the parent type can treat the new type as if it was of the parent type. Regarding DataTypes, subtypes can only restrict. If a Variable is defined to have a numeric value, a sub type could restrict it to a float.

References allow Nodes to be connected in ways that describe their relationships. All References have a ReferenceType that specifies the semantics of the relationship. References can be hierarchical or non-hierarchical. Hierarchical references are used to create the structure of Objects and Variables. Non-hierarchical are used to create arbitrary associations. Applications can define their own ReferenceType by creating subtypes of an existing ReferenceType. Subtypes inherit the semantics of the parent but may add additional restrictions. Figure 6 depicts several References, connecting different Objects.

The figures above use a notation that was developed for the OPC UA specification. The notation is summarized in Figure 7. UML representations can also be used; however, the OPC UA notation is less ambiguous because there is a direct mapping from the elements in the figures to Nodes in the AddressSpace of an OPC UA Server.

A complete description of the different types of Nodes and References can be found in OPC 10000-3 and the base structure is described in OPC 10000-5.

OPC UA specification defines a very wide range of functionality in its basic information model. It is not required that all Clients or Servers support all functionality in the OPC UA specifications. OPC UA includes the concept of Profiles, which segment the functionality into testable certifiable units. This allows the definition of functional subsets (that are expected to be implemented) within a companion specification. The Profiles do not restrict functionality, but generate requirements for a minimum set of functionalities (see OPC 10000-7)

4.2.3.2 Namespaces

OPC UA allows information from many different sources to be combined into a single coherent AddressSpace. Namespaces are used to make this possible by eliminating naming and id conflicts between information from different sources. Each namespace in OPC UA has a globally unique string called a NamespaceUri which identifies a naming authority and a locally unique integer called a NamespaceIndex, which is an index into the Server's table of NamespaceUris. The NamespaceIndex is unique only within the context of a Session between an OPC UA Client and an OPC UA Server- the NamespaceIndex can change between Sessions and still identify the same item even though the NamespaceUri's location in the table has changed. The Services defined for OPC UA use the NamespaceIndex to specify the Namespace for qualified values.

There are two types of structured values in OPC UA that are qualified with NamespaceIndexes: NodeIds and QualifiedNames. NodeIds are locally unique (and sometimes globally unique) identifiers for Nodes. The same globally unique NodeId can be used as the identifier in a node in many Servers – the node's instance data may vary but its semantic meaning is the same regardless of the Server it appears in. This means Clients can have built-in knowledge of what the data means in these Nodes. OPC UA Information Models generally define globally unique NodeIds for the TypeDefinitions defined by the Information Model.

QualifiedNames are non-localized names qualified with a Namespace. They are used for the BrowseNames of Nodes and allow the same names to be used by different information models without conflict. TypeDefinitions are not allowed to have children with duplicate BrowseNames; however, instances do not have that restriction.

4.2.3.3 Companion Specifications

An OPC UA companion specification for an industry specific vertical market describes an Information Model by defining ObjectTypes, VariableTypes, DataTypes and ReferenceTypes that represent the concepts used in the vertical market, and potentially also well-defined Objects as entry points into the AddressSpace.

5 Use cases

5.1 Use cases for Energy Consumption Measurement

The following uses cases are addressed in this specification.

As a user, I want to know the electricity and piped resources consumption (per part or per output produced) to be able to determine key figures.

As a user, I want to know the electricity and piped resources consumption (per operating condition) to be able to determine key figures.

As a user, I want to measure the energy consumption over an external coordinated time period.

As a user, I want to see the change in energy consumption to assess the condition of the consumer. With regard to condition monitoring, the consumer may be a machine, component, system or process.

As a user, I want to see the energy consumption so I can relate it to a production phase.

As a user, I would like to know the energy consumption in the individual operating modes in order to be able to compare machines and minimize standby consumption, among other things.

As a user, I want to know the largest consumers in the facility in order to identify optimization potential.

As an energy manager, I want to know the energy consumption of individual functions so that I can compare machines and minimize standby consumption, among other things.

As a user, I want to know the energy consumption in order to optimize the production parameters.

As a user, I would like to determine the potential energy savings between existing and new equipment in order to apply for government funding and/or to reduce energy costs.

As a user, I would like to know the energy consumption of the individual machine components in order to be able to compare machine components, among other things, and to minimize the consumption of the components in the respective operating state.

As a user, I want to know the electrical load behaviour of my equipment in order to avoid expensive load peaks or overload shutdowns.

As a user, I want to know the load behaviour of all forms of energy in my equipment in order to avoid peak loads, for example, I would like to know the pneumatic load behaviour of my operating equipment, for example, in order to avoid inadmissible lowering of the pressure.

As a user, I want to know the energy consumption/load profile of the production (per component/per operating condition) in order to be able to cover the energy requirements of the machine with the production plan.

As a user, I would like to determine the CO2 emissions per unit produced/per operating condition in order to calculate component-specific carbon footprint (or product-specific carbon footprint).

As a user, I would like to determine the CO2 emissions per year in order to draw up the balance sheet for the machine.

As a user, I would like to receive information about the connected load of the machines and components in the facility in order to carry out energy network planning and, if necessary, increase production capacities.

As a user, I would like to record and compensate for the reactive power of the machine up to the total production in order to save costs and reduce internal losses.

As a user, I want to ensure voltage/network quality to avoid power and production outages.

As a user, I want to ensure voltage quality to avoid machine failure.

Note that not all use cases are directly addressed by the information model defined in this specification, but provide the base information so that clients can implement the use case.

5.2 Use cases for Standby Management and Sleep Mode

The following uses cases are addressed in this specification to support all scenarios of energy saving for planned or unplanned pauses:

As a user I want to request switching in energy saving modes by only requesting the pause period and the entity should go to a fitting energy saving mode. The entity shall select the best fitting energy saving mode from the perspective of energy savings and startup time.

As a user I want to interrupt an active energy saving mode.

As a user I want to change the duration of an active energy saving mode or switch to another energy saving mode.

6 Energy Consumption Management Information Model overview

6.1 Overview

The information model is separated into a part considering energy consumption measurements, one for standby management and one for sleep mode WOL functionality.

6.2 Energy Consumption Measurement

6.2.1 Base Concepts

In order to provide measured energy consumption, either current values or aggregated values (counters), the information model enables to create Objects of ObjectType EnergyMeasurementType with potentially several measurements measured at the same point in a system represented by Variables of VariableType EnergyMeasurementValueType. Those Objects may have a Method to reset the aggregated values. How those Objects are connected to other parts of an information model (e.g., for a device or a machine) is not addressed by this specification. The EnergyMeasurementValueType provides additional meta data of the measurement like the engineering unit.

In Figure 8, an overview of the EnergyMeasurementType and the EnergyMeasurementValueType is given. They are formally defined in 7.1.1 and 8.1.

In Figure 9, an example of the usage of those TypeDefinitions is given. The “X:SampleObject” contains two instances of EnergyMeasurementType, one measuring the electrical power and one the air extraction. Both contain different measurement values, like pressure, volume, and temperature.

6.2.2 Standardized Measurement Identifiers

6.2.2.1 Overview

Instead of defining the different type of measurements in a large variety of TypeDefinitions or InstanceDeclarations, this specification defines a container for measurement identifiers (MeasurementID) and a list of those standardized identifiers. In Table 15, the format of the table containing the standardized IDs is given. The file, as comma separated value file is published in addition to this document (see Annex A).

The MeasurementID is a unique numeric identification. The BrowseName (leaving out the NamespaceIndex, which is always the one of this specification (see Annex A)), is a unique identification that is used as BrowseName for instances of the EnergyMeasurementType. Those BrowseNames are also used for the interfaces (see 6.2.3). The Description (in English) may be used as the Description Attribute for those Nodes.

For all instances of EnergyMeasurementType using the BrowseName as defined in the table, the EngineeringUnits shall be used for the 0:EngineeringUnits Property, the DataType shall be used as DataType (Attributes DataType and ValueRank), and the MeasurementPeriod shall be used for the MeasurementPeriod. If no EngineeringUnits is provided in the table, the 0:EngineeringUnits Property shall not be provided as well. If no MeasurementPeriod is provided in the table, the MeasurementPeriod Property shall not be provided as well. The MeasurementPeriod is the interval of time over which the data is collected and at the end of the period being reported. If the MeasurementPeriod is defined as “user-defined”, the MeasurementPeriod Property shall be provided, but the value is not pre-defined. If it is defined to start in the full hour (see Description), a multiple of the value shall fit into one hour.

The HasStatisticComponent defines, if the 2:HasStatisticComponent ReferenceType shall be used to reference the Variable of EnergyMeasurementType (YES), or the 0:HasComponent ReferenceType shall be used (NO). Using 2:HasStatisticComponent indicates, that the Variable is aggregating values over time and may be reset, potentially using the 2: ResetStatistics Method (see 7.1.1).

Note that the referenced file is part of the specification, and changes in the file are considered as changes in the specification, requiring the normal update process.

6.2.2.2 Explanations to the defined measurements

In general, measurements of voltage and current are RMS values calculated over 3 seconds or 10 minutes as described in IEC 61000-4-30. Note: 3s corresponds to 150 cycles on a 50Hz system or 180 cycles on a 60 Hz system.

Energy values are calculated over a period of time, typically 15 minutes, as described in IEC 61577-12.

Values described as minimum or maximum values are calculated over the period since the last reset.

For measurements defined in this companion standard that do not have a specific measurement period, the system integrator or manufacturer may use any period that is appropriate or available.

The BrowseNames of the standardized measurement identifiers follow the following naming conventions:

AcPe: Phase to Neutral

AcPp: Phase to phase

Lp: Low Precision (Float DataType)

Hp: High Precision (Double DataType)

Total: concerns all phases

Sum: concerns the sum of all measured import and export parts (sum = import - export)

Some explanations to the Description text in the table:

Qtot is according to IEC61557-12 [4] the reactive power calculated by the triangle formula, also known as Fryze's definition (harmonics are specified vendor specific)

Qn is according to IEC61557-12 [4] the reactive power calculated according to the Budeanu's harmonic definition (harmonics are specified vendor specific)

Measurements defined to have the DataType Int16[5] represent values as defined in [8].

6.2.3 Standardized Interfaces for combinations of Measurements

Some combinations of measurement values are reasonably provided together. This specification standardizes some of those combinations by defining interfaces containing all those combinations. Applications may implement those interfaces and thereby provide the combinations of measurement values.

Standardized interfaces are defined in 7.1.3 An example, how standardized interfaces are used is shown in Figure 10. The interface can either be used directly on an instance, like on MyMeasurementPoint, or on a ObjectType like on MyEnergyMeasurementType.

6.2.4 Accuracy Domains and Classes

Individual measurements (Variables of EnergyMeasurementValueType) have a specific accuracy class defined by a specific accuracy domain. This specification defines accuracy domains in a way, that it is possible to add additional accuracy domains. Each accuracy domain is represented by an Object of AccuracyDomainType (see 7.1.2). The Objects can be browsed from the standardized AccuracyDomains Object (see 10.1), allowing a Client to receive all accuracy domains used by the Server (see Figure 11). This specification defines standardized accuracy domains in 10.

The Object representing an accuracy domain contains the EnumValues Property containing the different accuracy classes defined by the accuracy domain. Each measurement of EnergyMeasurementValueType references its accuracy domain by the Property AccuracyDomain of DataType NodeId. The accuracy class is provided in the AccuracyClass Variable. This Variable of MultiStateValueDiscreteType shall either reference the EnumValues Property of the referenced accuracy domain Object (see VariableA in Figure 12 as example) or it shall contain a copy of that Property containing the same values (see VariableB in Figure 12 as example).

6.3 Standby Management

Standby Management allows a device or parts of a device to switch into an Energy Saving Mode if not in operation or engaged. If a Standby Management Entity supports more than one Energy Saving Mode (with different levels of energy consumption), transitions from one Energy Saving Mode into another might be possible (see Figure 13). For the smooth integration of devices with Standby Management functionality into a production process, Standby Management offers commands to issue the transition into an Energy Saving Mode and the termination of an Energy Saving Mode with switchback to normal operation.

For further cutdown in energy consumption the functionality of Sleep Mode WOL, defined in 6.4, could be used.

Standby Management defines a state model determining the possible state transitions. Figure 14 shows the state model.

When in ‘Energy saving disabled’ state, the device is in normal operation and does not accept standby commands. In the ‘Ready to operate’ state the device accepts standby commands. When in transition to or from an Energy Saving Mode, the device has a ‘Moving to …’ transition state. Thus, the state model reflects the physical properties of a real-world device: Changes in energy consumption imply changes of some physical processes which will always be time consuming.

Standby Management is made available for OPC UA Clients with the ObjectTypes defined in 7.2.

Status information functionality of Standby Management provides information about the current state of a Standby Management Entity, the current energy consumption, the available Energy Saving Modes and their detailed characteristics.

The current state information of a Standby Management Entity is made available for OPC UA Clients with the EnergySavingModeStatusType (defined in 7.2.3) referenced by the EnergyStandbyManagementType.

Detailed information about a specific Energy Saving Mode is provided by the EnergySavingModeType defined in chapter 7.2.4.

6.4 Sleep Mode WOL

Devices might support Sleep Mode WOL functionality allowing to switch off a device almost completely. If this Sleep Mode WOL functionality is active, the device in Sleep Mode WOL is not reachable for network communication and can only be ‘awakened’ by receiving a ‘WOL magic packet’. The energy consumption of a device in Sleep Mode WOL is caused by the power to keep the network MAC controller alive while Standby Management demands an application on the device to monitor and control the Standby Management states. Therefore, Sleep Mode WOL typically consumes less power than Standby Management.

The transition to the Sleep Mode WOL state is initiated by invoking the SwitchOffWOL Method of the EnergyDevicePowerOffType defined in 7.3.1.

If the switched off device contains the OPC UA server, the connection of the OPC client to the server disconnects. The server will be reachable again after a wake up of the device by WOL (sending the WOL magic wake-up packet).

7 OPC UA ObjectTypes

7.1 ObjectTypes for Energy Consumption Measurement

7.1.1 EnergyMeasurementType ObjectType Definition

The EnergyMeasurementType provides various energy measurement values measured at the same point in a system and is formally defined in Table 16.

The ApplicationTag provides a string that is supposed to uniquely identify the functionality of the energy measurement. It is to be set by an end user or system integrator. Server-provider would typically initially set it to an empty string. It is marked as writable. However, applications may also provide other mechanism than the OPC UA interface to set the value, e.g. by some proprietary engineering environments.

The <MeasurementValue> Variable is a placeholder for all measurement values provided by the instance of the EnergyMeasurementType. At least one measurement value shall be provided. There are standardized measurement values defined (see 6.2.2).

The ObjectType implements the 2:IStatisticsType Interface as defined in OPC 10000-200 providing the optional 2:ResetStatistics and 2:StartTime.

The optional 2:ResetStatistics Method can be used to reset measurement values used as energy counter, i.e. aggregating the energy consumption over time. Details of its usage are defined in OPC 10000-200. Measurement values that can be reset are identified by being referenced using the 2:HasStatisticComponent (a subtype of 0:HasComponent).

The optional 2:StartTime indicates when the collection of aggregated data has started or was reset. Details of its usage are defined in OPC 10000-200.

7.1.2 AccuracyDomainType

The AccuracyDomainType is used to represent accuracy domains and contains the accuracy classes of the accuracy domain (see 6.2.4). It is formally defined in Table 17.

The EnumValues provides the accuracy classes of the accuracy domain.

7.1.3 Interfaces for Energy Consumption Measurement

7.1.3.1 IEnergyProfileE0Type

The IEnergyProfileE0Type contains the References to EnergyMeasurementValueType Variables needed for EnergyProfile E0.

7.1.3.2 IEnergyProfileE1Type

The IEnergyProfileE1Type contains the References to EnergyMeasurementValueType Variables needed for EnergyProfile E1.

7.1.3.3 IEnergyProfileE2Type

The IEnergyProfileE2Type contains the References to EnergyMeasurementValueType Variables needed for EnergyProfile E2.

7.1.3.4 IEnergyProfileE3Type

The IEnergyProfileE3Type contains the References to EnergyMeasurementValueType Variables needed for EnergyProfile E3.

7.1.3.5 IEnergyProfileD0Type

The IEnergyProfileD0Type Interface contains a Reference to a EnergyMeasurementValueType Variable representing direct current (EnergyProfile D0).

7.1.3.6 IEnergyProfileD1Type

The IEnergyProfileD1Type Interface contains the References to EnergyMeasurementValueType Variables representing measurements for equipment that produces or consumes direct current.

7.2 ObjectTypes for Standby Management

7.2.1 EnergyStandbyManagementType

7.2.1.1 Overview

The EnergyStandbyManagementType ObjectType provides access to the Standby Management functionality of one Standby Management Entity. Parallel access of Clients to the read only data shall be possible but write operations and Method invocation can be limited to one Client at a time with the Lock Object.

The StandbyManagementStatus Variable shall contain the current state of the Standby Management. The value of this Variable shall be consistent with the content of the EnergySavingModeStatus Object.

The mode IDs used in the EnergySavingModeStatus and the EnergySavingModes (IDSource and IDDestination) in correlation to the StandbyManagementStatus are described in Figure 15.

The values of the 0:EnumStrings of the StandbyManagementStatus shall follow the definition of Table 31. Each instance shall have the values 0 to 8. Element numbers 9-15 are reserved for future use. If vendors add specific elements, the range 9-15 shall be filled with ‘null’-strings.

The Variables of the EnergyStandbyManagementType have additional Attributes defined in Table 32.

The EnergySavingModes container Object contains References to EnergySavingModeType Objects representing the supported Energy Saving Modes.

Writing the PauseTime Variable can be used to update the pause time alternatively to the StartPause Method. Setting the PauseTime Variable with a value not equal to 0 shall have the same effect as invoking the StartPause Method passing the PauseTime value. Setting the PauseTime Variable with a value equal to 0 shall have the same effect as invoking the EndPause Method. An additional benefit is that the Variable PauseTime can be used in a PubSub communication scenario where the PauseTime is distributed by a central time management client using a broadcast telegram to which every Standby Management Entity subscribes.

The Lock Object ensures exclusive write access and Method call for one Client. Write access and Method calls from Clients shall be blocked unless the client has locked the Object by invoking the InitLock Method of the Lock Object. The LockingServicesType is defined in OPC 10000-100.

The StartPause Method starts the transition to an Energy Saving Mode. The SwitchToEnergySavingMode allows the transition into a specific Energy Saving Mode. The EndPause Method ends the Energy Saving Mode.

7.2.1.2 StartPause Method

This Method starts the transition into an Energy Saving Mode.

Signature

	StartPause (
		[in]  0:Duration		PauseTime
		[out] 0:Byte		ModeID
		[out] 0:Duration		CurrentTimeToDestination
		[out] 0:Duration		RegularTimeToOperate
		[out] 0:Duration		TimeMinLengthOfStay
		[out] 0:Byte		ReturnCode
		);
	

The Method Result Codes (defined in Call Service) are defined in Table 33.

ReturnCodes are defined in Table 34.

7.2.1.3 SwitchToEnergySavingMode Method

This Method initiates a switch to a certain Energy Saving Mode.

Signature

	SwitchToEnergySavingMode (
	[in]  0:Byte		ModeID
	[out] 0:Byte		EffectiveModeID
	[out] 0:Duration	CurrentTimeToDestination
	[out] 0:Duration	RegularTimeToOperate
	[out] 0:Duration	TimeMinLengthOfStay
	[out] 0:Byte	ReturnCode
		);
	

The Method Result Codes (defined in Call Service) are defined in Table 33.

ReturnCodes are defined in Table 34.

7.2.1.4 EndPause Method

This Method ends the current Energy Saving Mode.

Signature

	EndPause (
		[out] 0:Duration	CurrentTimeToOperate
		[out] 0:Byte	ReturnCode
		);
	

The Method Result Codes (defined in Call Service) are defined in Table 33.

ReturnCodes are defined in Table 34.

Table 33 shows the possible values for the Method call result codes.

Table 34 shows the possible values for the out parameter ReturnCode.

7.2.2 EnergySavingModesContainerType

The EnergySavingModesContainerType provides a grouping of different Energy Saving Modes.

7.2.3 EnergySavingModeStatusType

The EnergySavingModeStatusType provides information about the current status of the Energy Saving Mode.

The CurrentTransitionData Variable contains details for the state transition indicated by the StateInformation Variable.

The StateInformation Variable contains details for the actual Energy Saving Mode state.

7.2.4 EnergySavingModeType

The EnergySavingModeType provides detailed information for a specific Energy Saving Mode.

The BrowseName shall contain a unique name for the Energy Saving Mode.

The ID Variable shall contain a unique mode ID for the Energy Saving Mode. The mode ID’s 0x00, 0xF0, 0xFE and 0xFF are reserved for predefined states.

DynamicData shall indicate whether the time, energy consumption and power values can vary (slightly) during runtime.

The TimeMinPause Variable shall contain the minimum pause time for this Energy Saving Mode.

The TimeToPause Variable shall contain the expected time to switch to this Energy Saving Mode.

The TimeMinLengthOfStay Variable shall contain the time of minimum stay in this Energy Saving Mode.

The TimeMaxLengthOfStay Variable shall contain the time of maximum stay in this Energy Saving Mode.

The RegularTimeToOperate Variable shall contain the time value to reach ”Ready to operate” (see Figure 14) if this Energy Saving Mode will be regularly terminated.

The ModePowerConsumption Variable shall contain the energy consumption in this Energy Saving Mode. Unit: [kW].

The EnergyConsumptionToPause Variable shall contain the energy consumption from ”Ready to operate” to this Energy Saving Mode. Unit: [kWh].

The EnergyConsumptionToOperate Variable shall contain the energy consumption from this Energy Saving Mode to ”Ready to operate”. Unit: [kWh].

7.3 ObjectTypes for Sleep Mode WOL Functionality

7.3.1 EnergyDevicePowerOffType

7.3.1.1 Overview

The EnergyDevicePowerOffType type provides access to the Sleep Mode WOL functionality of the device if supported.

The RegularTimeToOperate Variable shall contain the time value to reach the state “Ready to operate” if the WOL sleep mode is terminated by a wake-up (see below).

The ModePowerConsumption Variable shall contain the energy consumption in the
WOL sleep mode. Unit: [kW].

The WOLMagicPacket Variable shall contain the 6 bytes MAC address to be used with the magic packet sent for wake-up (see PE 3802, chapter 7.3.4.9).

The SwitchOffWOL Method initiates the transition into the WOL sleep mode. In this mode the device is effectively switched off and unavailable for network communication. The device can be awakened using the magic packet (see PE 3802, chapter 7.3.4.9).

7.3.1.2 SwitchOffWOL Method

This Method starts the transition into the special WOL mode.

Signature

	SwitchOffWOL (
		[out] 0:Byte		ModeID
		[out] 0:Duration		CurrentTimeToDestination
		[out] 0:Duration		RegularTimeToOperate
		[out] 0:Duration		TimeMinLengthOfStay
		[out] 0:Byte		ReturnCode
		);
	

The Method Result Codes (defined in Call Service) are defined in Table 33.

ReturnCodes are defined in Table 34.

8 OPC UA VariableTypes

8.1 EnergyMeasurementValueType VariableType Definition

The EnergyMeasurementValueType is a subtype of BaseDataVariableType. It is used to provide an individual energy measurement value. It is formally defined in Table 39.

The AccuracyDomain defines the semantic how to interpret the AccuracyClass (see 6.2.4).