GENERATING SUM ALARMS IN PROCESS CONTROL

FIELD OF THE INVENTION

The invention relates to Industrial Automation and Control Systems, in particular to Substation Automation systems, with a standardized configuration representation. More particularly, it relates to a method of presenting alarms of the system to an operator.

BACKGROUND OF THE INVENTION

Substation Automation SA systems supervise, monitor, protect and control the substation. This is done typically by protection and control devices allocated to the substation bays and primary equipment, and station level gateways and Human Machine Interfaces HMIs. The applications at station level need to be configured according to the substation layout and the requirements of the customer respective the operator.

Protection and control devices of the SA system close to the process generate events, warnings and alarm signals which are sent to the station level devices for logging, archiving and evaluation. In case of disturbances, an operator in charge has to investigate what exactly has happened when and at which location in the system, based on a tremendous amount of information available. For this purpose alarm evaluation applications provide some sort of support to the operator.

A first possibility often used includes filters configurable according to alarm and event lists to filter out certain aspects, e.g. alarms of a bay, a specific switch or transformer, or a specific secondary equipment device or function. These filters rely typically on the limited information available in the event and alarm lists like the names of the objects at which the alarm happened. A more elaborate variant includes filter category properties like priorities, alarm classes etc., which have to be engineered for each signal or at least signal type.

Another way to obtain a fast overview on the system alarm state includes sum alarms at different hierarchical levels, which allow a fast identification of the location or function of the switch yard or secondary system where the problem has occurred. Again, this requires manually pre-engineered alarm hierarchies according to switch yard structure and different functional categories like switch yard, protection, control, communication system, with sum alarms defined according to the switch yard structure, e.g. at substation, voltage level, bay and equipment level. Such hierarchical alarm structure enables the operator to gain a fast overview on the alarm situation at a higher level and to proceed downwards to the interesting lower levels, however need to be configured individually for each substation at signal or signal type level, i.e. for each alarm signal, the assignment of the functional category is done manually.

SA systems based on IEC 61850 are configured and described by means of a standardized configuration representation or formal system description called Substation Configuration Description (SCD). An SCD file comprises the logical data flow between the IEDs and the relation between the IEDs as well as the functionality which the IEDs execute on behalf of the substation. In addition to SA systems for substations in high and medium- voltage power networks, other process control systems for e.g. hydro power plants, wind power systems, and Distributed Energy Resources (DER), may likewise be described by a formal system description at least partly identical to the IEC 61850 SA description.

EP-A 2264967 is concerned with an interface description or structure of an inter-bay SA application. The interface of said application to other elements of the SA system, e.g. to a bay controller, IED, OPC server, HMI, and/or gateway, is needed in order to fully automate inter-bay SA application configuration and implementation. A formal description or structure of the base SA system as e.g. comprised in an IEC 61850 SCD file is used to generate a formal description of the interfaces of the inter-bay SA application to be engineered, i.e. to structure the interface data into Logical Nodes according to IEC 61850. The latter are further connected to the process single line diagram and integrated into the SCD file of the base SA system, thereby generating an enhanced SCD file. The interface- level Logical Nodes include control blocks and data set definitions that together define the data flow within the application, i.e. the communication links between the IED that hosts the interface function block and the IED hosting a basic SA functionality assigned to substation constituents on a hierarchically lower level. Preferably, this data flow is engineered automatically by a separate application engineering wizard, or a component of a system engineering tool. DESCRIPTION OF THE INVENTION

It is an objective of the invention to support the implementation of an alarm hierarchy and categorization for fast analysis of disturbances in an industrial plant or process. This objective is achieved by a method of generating a sum alarm and by an alarm interface according to the independent claims. Preferred embodiments are evident from the dependent patent claims, wherein the claim dependency shall not be construed as excluding further meaningful claim combinations.

According to the invention, alarms of a Process Control PC system for an industrial plant described by a standardized or formal system configuration description, in particular alarms of a Substation Automation SA system for a substation in a high or medium- voltage power network are embedded or consolidated, in an automated way, into a sum alarm for further processing or analysis. All alarms or other events requiring immediate operator intervention are identified and retrieved from the system configuration description and assigned to a plant or structural level according to the configuration description. Based on an alarm type, such as a Logical Node class and Data Object name according to IEC 61850, likewise retrieved from the system configuration description, and according to some preconfigured or user-defined rules, each identified alarm is assigned to an alarm category. Finally, consolidated sum alarms at a particular plant level and per alarm category are derived, or calculated, from all alarms assigned to the respective alarm category and all plant levels not hierarchically superior to the particular plant level.

In other words, the invention enables, based on the formal system configuration description of a PC system of an industrial plant, an automated generation of an alarm interface as part of a plant supervision process or of a Human Machine Interface. The alarm interface includes an alarm hierarchy according to plant level or process structure and an alarm categorization or classification according to pieces of equipment or process functions involved. Typical alarm categories in this context are related to primary equipment or secondary equipment, or to protection, control, or security functions. In this context, the category assignment may be ambiguous as e.g. a protection alarm may be assigned to both the "function" oriented category ("protection") and to the "equipment" oriented category ("transformer").

In a preferred embodiment, a sum alarm acknowledgment is defined for each implemented sum alarm. The corresponding acknowledgement extends to all alarms that contribute to the sum alarm, i.e. to all the alarms assigned to a same category and to inferior plant levels that are evaluated by the sum alarm in question. The former thus need not be acknowledged individually by the operator.

Specifically, in an alarm interface of an SA system, the sum alarms are presented in a hierarchical and structured way, where the structure is automatically derived from an IEC 61850 Substation Configuration Description SCD file as the formal configuration description of the SA system. A generic alarm application configured with the IEC 61850 SCD file of the SA system and pre-defined as well as user-defined alarm categories is executed as an application expert program, based on SCD external categorization rules. The SCD file allows automatically subscribing to the needed online data of the substation either via a standard interface like an OPC server, or directly to the IEDs as an IEC 61850 client. The plant level assigned is a substation hierarchy level out of (in hierarchically decreasing order) a Substation, Voltage, Bay, Primary Equipment, Sub-equipment level.

Classification is largely determined by rule-based definition of categories using the inherent semantics contained in the IEC 61850 data model from standardized Logical Node LN classes and Data Object DO names of the Data Objects comprising the alarm information, as well as from primary equipment structure and type as contained in the Substation section of the SCD file. Additionally, by means of user-defined rules, project- specific categorization into customer-chosen types of functional structures may be arranged for during engineering of a specific SA project, e.g. in order to reflect different preferences as far as the abovementioned ambiguities are concerned.

In preferred embodiments, the alarm is represented by a DO of a LN instance, with the alarm status or value being coded or given by an updated value of the DO. The alarm is generally assigned to the hierarchical level of the respective LN. However, if an alarm is represented by a DO of a LN relating to a property of a specific Intelligent Electronic Device IED which in turn hosts a plurality of LNs, the highest substation hierarchy level of the plurality of LNs is assigned to this alarm. As a consequence, a protection IED locally in a bay will be allocated to the bay, while a bus bar protection IED across several bays will be allocated to the voltage level of the bus bar.

The alarm hierarchy and the alarms in the different categories may be displayed to an operator in a tree or table view. Sum alarms may also be provided for graphical representation in an operator HMI, e.g. for optical display in a single line overview picture, equipment picture or graphical room layout. A suitable alarm application can automatically generate all sum alarms at the appropriate plant levels and categories and provide the sum alarms online, over a communication network of the SA system, as signals to gateways or other IEDs for further access and evaluation without any additional configuration or engineering effort. The access is enabled by means of a standard interface like OPC or as an IEC 61850 server providing CALH sum alarms as detailed in the next paragraph.

In a preferred variant of the invention, and in order to simplify the further access or interfacing to sum alarm status data, a sum alarm is defined via formal description terms as an instance of a CALH LN according to IEC 61850. Sum alarms or CALH LNs are instantiated per category on every substation hierarchy level. Each instance is further connected to the process single line diagram and integrated into the SCD file of the SA system as detailed in EP-A 2264967. Accordingly, the integrated SCD file with the sum alarm LNs includes automatically engineered control blocks and data set definitions that together define the data flow within the alarm application, e.g. the communication links between the IED that hosts the sum alarm LNs and the IEDs hosting the LNs that comprise the basic alarm information.

The present invention also relates to a computer program product including computer program code for controlling one or more processors of an IED adapted to be connected to an SA communication network and/or to host a sum alarm LN, particularly, a computer program product including a computer readable medium containing therein the computer program code.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Fig.l depicts a table view of an alarm hierarchy view at voltage level AAIEI showing the alarm state of the bays. The red circle denoted by an arrow indicates a control alarm in bay AA1E1Q05. By clicking on one of the objects at the left side, in this case the bay Q05, the next level of the hierarchy containing primary equipment like switches and protection functions is depicted in Fig.2. The red circle denoted by an arrow shows that the problem is at the circuit breaker QA1 within this bay. By selecting this object and then clicking the "control" category at the top, the appropriate signals in this level are shown, revealing that this breaker is blocked; c.f the two red circles denoted by arrows in Fig.3.

Fig.4 depicts an excerpt of an SCD file comprising the configuration part for the automatically generated application views depicted in Fig.l, especially the bay view for AA1E1Q05. In particular, the circuit breaker QA1 as an exemplary primary or conducting equipment is listed. It includes a Logical Node XCBR, of which the Data Objects BlkCls and BlkOpn are reported to have an active alarm status in Fig.3

The hierarchy of the sum alarms in a SA system follows the SCD file substation hierarchy Substation / Voltage level / Bay / Primary Equipment / Sub-equipment. Additionally a Function / Subfunction hierarchy can be added at each level as needed, wherein a restriction coming from IEC 61850 concerns the fact that an alarm can only be allocated to a single substation hierarchy level. The categorization is done by rules based on the inherent semantic of the IEC 61850 data model. Exemplary pre-defined rules for categorization are:

• Protection alarms: LN class starts with P and data item or DO name is Op or Tr or Blk or Health; LN class is RBRF and DO name is data Health, OpEx, Opln.

• Control alarms: LN classes are XCBR, XSWI, DO name is BlkOpn, BlkCls.

• Primary equipment alarms: LN classes starting with X (switching device), Y (transformer), Z (other primary equipment), T (instrument transformer) and DO name

EEHealth; LN classes SIMG, SIML and DO names EEHealth, InsAlm, PrsAlm; LN class is TVTR and DO name is FuFail; LN class MMXU or MMXN limit violations.

• Secondary system (IED) alarms: any subscribed data item with q='invalid'; LN class LPHD, data names PhyHealth, WacTrg, WrmStr, PwrDwn, PwrUp.

Individual alarm states are summed up or evaluated per category and across the hierarchy, according to some logic ensuring that the highest alarm state in terms of importance is prevailing over all other contributing alarms. On any change of an alarm value the state of all superior sum alarms in the category is recalculated. In other words, a generic, substation-level alarm application configured with the IEC 61850 SCD file of the SA system and preconfigured as well as user-defined alarm categories is executed repeatedly during operation in order to propagate any base alarm status change without delay.

In addition to the standard IEC 61850 alarm states "OK" (green), "Warning" (yellow; applicable e.g. if a maximum number of switching operations is approached/reached, or if one out of two redundant communication channels is out of order), "Alarm" (red) an additional state "Not communicated" (black) is introduced, which also represents an exemplary IED related alarm. In addition, the communication state of an IED can be derived from the quality of the signals exchanged. In this case 'blue' means OK, but derived, while 'red' at the IED and 'black' at the signal shows a not communicated signal. Alarm states of short duration like protection trips may also be handled, in which case a refined concept of alarm acknowledgement can be introduced, wherein an alarm stays pending until it is acknowledged AND its alarm state vanishes.

In an advantageous embodiment of the invention, the categories generated automatically respective by user defined rules could also be used to classify and filter, but not to graphically represent, events of an (archived) event list instead of the current alarm state.