Document Number: EDS 05-9600
Version: 1.0
Date: 07/12/2017
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ENGINEERING DESIGN STANDARD
EDS 05-9600
RTU LOGIC FOR ANM SCHEMES
Network(s): EPN, LPN, SPN
Summary: Document describing UK Power Networks substation logic and the interface with the SCADA network and ANM systems for flexible connections.
Author: Miguel Bernardo Date: 07/12/2017
Approver: Barry Hatton Date: 20/04/2018
This document forms part of the Company’s Integrated Business System and its requirements are mandatory throughout UK Power Networks. Departure from these requirements may only be taken with the written approval of the Director of Asset Management. If you have any queries about this document please contact the author or owner of the current issue.
Applicable To
UK Power Networks External
☒ Asset Management ☒ G81 Website
☒ Capital Programme ☐ UK Power Networks Services
☒ Connections ☐ Contractors
☐ Health & Safety ☒ ICPs/IDNOs
☐ Legal ☐ Meter Operators
☒ Network Operations
☐ Procurement
☐ Strategy & Regulation
☐ Technical Training
RTU Logic for ANM schemes Document Number: EDS 05-9600
Version: 1.0
Date: 07/12/2017
© UK Power Networks 2018 All rights reserved 2 of 14
Revision Record
Version 1.0 Review Date 16/11/2020
Date 13/12/2017 Author Miguel Bernardo
New document describing UK Power Networks substation logic and the interface with the SCADA network and ANM systems for flexible connections.
RTU Logic for ANM schemes Document Number: EDS 05-9600
Version: 1.0
Date: 07/12/2017
© UK Power Networks 2018 All rights reserved 3 of 14
Contents
1 Introduction ............................................................................................................. 5
2 Scope ....................................................................................................................... 5
3 Glossary and Abbreviations ................................................................................... 6
4 Overview .................................................................................................................. 7
4.1 Control Scheme Designs ........................................................................................... 7
4.2 Interface between Systems ....................................................................................... 8
5 RTU Logic Functional Requirements ..................................................................... 9
5.1 Operation Modes ....................................................................................................... 9
5.1.1 Local Mode ................................................................................................................ 9
5.1.2 Remote ANM Mode ................................................................................................... 9
5.1.3 Remote NMS Mode ................................................................................................... 9
5.1.4 Orphaned Mode ........................................................................................................ 9
5.1.5 Decoupled Mode ....................................................................................................... 9
5.2 Logic Functions ....................................................................................................... 10
5.2.1 Failsafe Block and Failsafe Actions ......................................................................... 10
5.2.2 Monitor and Compare .............................................................................................. 10
5.2.3 Orphaned ................................................................................................................ 10
5.2.4 Decouple ................................................................................................................. 10
6 RTU Non-Functional Requirements ..................................................................... 11
6.1.1 RTU and other UK Power Networks Systems .......................................................... 11
6.1.2 RTU to DER control systems ................................................................................... 11
7 NMS and ANM Functional Requirements............................................................. 12
7.1 RTU Interface through NMS To ANM ...................................................................... 12
7.1.1 NMS Functional Requirements ................................................................................ 12
7.1.2 ANM Functional Requirements ................................................................................ 12
7.2 RTU Interface to NMS And to ANM ......................................................................... 13
7.2.1 NMS Functional Requirements ................................................................................ 13
7.2.2 ANM Functional Requirements ................................................................................ 13
8 References ............................................................................................................. 14
8.1 UK Power Networks Standards ............................................................................... 14
Figures
Figure 4-1 – Scheme Designs ............................................................................................... 7
Figure 4-2 – System Interfaces ............................................................................................. 8
Figure 6-1 – RTU Interfaces ................................................................................................ 11
RTU Logic for ANM schemes Document Number: EDS 05-9600
Version: 1.0
Date: 07/12/2017
© UK Power Networks 2018 All rights reserved 4 of 14
Figure 7-1 – Standard System Interface .............................................................................. 12
Figure 7-2 – Existing design (non-standard) ........................................................................ 13
RTU Logic for ANM schemes Document Number: EDS 05-9600
Version: 1.0
Date: 07/12/2017
© UK Power Networks 2018 All rights reserved 5 of 14
1 Introduction
The proliferation of generation connected at distribution level, as well as the requirements for the electricity industry to become more flexible in accommodating new connections has driven the necessity to better utilise the existing distribution network assets. Since the distribution network has been built to accommodate firm connection during the worst-case conditions, albeit a diversity factor being applied, there is little control over the impact of these connections to the network and assets.
The development of better intelligence on the network management systems combined with a new model of connections for customers allows distribution networks to defer traditional reinforcement therefore reducing the cost of customer connections, maintenance and operation costs. The development of the intelligence at the field devices is key to the safe operation of the network and manage customer’s connections.
Active Network Management (ANM) systems and other logic schemes are used to resolve the emerging requirement to rapidly and effectively manage network assets depending on network conditions. The RTU logic detailed in the document is a virtual component which resides on the RTUs and provides functions for such systems to operate.
2 Scope
This document details the design specification of the UK Power Networks RTU logic that will integrate with the centralised smart applications such as the ANM systems and the distributed controllable devices such as the DER controllers. This document shall be used as a supporting tool and reference document for the implementation, integration and testing of ANM systems with the NMS, IS operational systems and customer PLCs. This document encompasses the whole UK Power Networks system view as well as a detailed description for the assets directly interfacing with the “RTU logic”.
The document does not cover the technical feasibility of customer connections to existing or new schemes.
RTU Logic for ANM schemes Document Number: EDS 05-9600
Version: 1.0
Date: 07/12/2017
© UK Power Networks 2018 All rights reserved 6 of 14
3 Glossary and Abbreviations
Term Definition
ANM Active Network Management, term is loosely used to refer to autonomous systems with the authority to operate network assets.
APRS Automatic Power Restoration System, automation scheme.
DER Distributed Energy Resource
DSR Demand Side Response
HMI Human Machine Interface
IED Intelligent Electronic Device
IP Internet Protocol
NMS Network Management System, referring to the system used to monitor and operate an electrical network.
NTP Network Time Protocol
Orphaned When a component of a logic scheme becomes disassociated or no longer participates in the logic scheme.
Outstation Field device with the capability of providing measurement or operating assets.
PLC Programmable Logic Controllers, are field devices, mainly aimed at the control of local systems.
RTU Remote Terminal Unit (RTU) are field devices, usually ruggedized computing units, interfacing with sensors and controllable assets and the SCADA network
SCADA Supervisory Control and Data Acquisition
UK Power Networks UK Power Networks (Operations) Ltd consists of three electricity distribution networks:
Eastern Power Networks plc (EPN).
London Power Network plc (LPN).
South Eastern Power Networks plc (SPN).
RTU Logic for ANM schemes Document Number: EDS 05-9600
Version: 1.0
Date: 07/12/2017
© UK Power Networks 2018 All rights reserved 7 of 14
4 Overview
4.1 Control Scheme Designs
UK Power Networks applies different control schemes to manage the distribution network safely and with the least interruption of supply to customers. The majority of the schemes have been implemented with the purpose of restoring supply after a fault has occurred (post-fault automation)
The “RTU Logic” aims to manage the distribution network assets and DERs to prevent the occurrence under various running arrangements of operating above the safe operational limits (pre-fault automation).
Figure 4-1 – Scheme Designs depicts the design architectures of control schemes. All schemes design types in Figure 4-1 shall use the “RTU Logic”. The principles for the designs are based on the exchange of information and control decision authority. Scheme designs are divided into three main categories.
Standalone: Both the sensing/triggers and decision making process occur in the same device;
Field to Field: Sensing or triggers are from one or more field devices and the decision making process takes place in one or more of the field devices. Technically, there is no requirement for communications to the central system and the communications network can be restricted to the participating field devices.
Field to Central: As per the Field to Field for the sensing. However, the decision-making process takes place in a central system.
Although the schemes definition in this document are based on their exchange of information and decision-making. All RTUs participating in schemes should be able to cope with being orphaned from the scheme in which they participate. Therefore, being able to operate in a local standalone mode.
Figure 4-1 – Scheme Designs
Control Scheme Designs
Standalone
Outstation “controlled”
by its local
measurements, signals,
algorithms.
Use cases:
Timed
Turn down/up
Field to Field
One or more outstations
“controlled” by one or
more outstations other
than itself.
Use cases:
Operational Trip
Turn down/up
DSR
Field to Central
Outstations “controlled”
by central systems
Use cases:
Central Constraint
Mgmt
DERMS
APRS*
*APRS like system can interface with the RTU logic functionality even though they are not ANM
RTU Logic for ANM schemes Document Number: EDS 05-9600
Version: 1.0
Date: 07/12/2017
© UK Power Networks 2018 All rights reserved 8 of 14
4.2 Interface between Systems
UK Power Networks’ RTUs use multiple types of SCADA protocols such as DNP3, WISP+, TC3, etc. Any logic schemes under the scope of this document will exchange data using the DNP3 SCADA protocol. Figure 4-2 – System Interfaces represents the minimum typical IP based WAN network required for all three control schemes designs referenced in Figure 4-1 – Scheme Designs as well as the interaction between the different participants of the schemes.
The logic resides in all UK Power Networks RTUs that have been approved for network use. Please refer to appendix for approved devices documents.
Figure 4-2 – System Interfaces
Customer Site
NMS ANM
WAN (IP Based)
Historian
RTU
LAN Sensors
IEDs & Relays
CB control
RTU
CB control
Substation
UK Power Networks Owned Equipment Customer Owned Equipment RTU Logic for ANM
PLC
DNP3
DNP3
60870 DNP3 Hardwired
MODBUS 60870 DNP3
MODBUS
IEDs & Relays Sensors
Hardwired DNP3
DNP3 Analogues
Hardwired
Hardwired
Pi Hist Pi Hist PI Hist DNP3
DNP3
Logic Logic
ICCP
Design Alternative design
RTU Logic for ANM schemes Document Number: EDS 05-9600
Version: 1.0
Date: 07/12/2017
© UK Power Networks 2018 All rights reserved 9 of 14
5 RTU Logic Functional Requirements
The logic is designed in a modular approach to enable resources and functionalities to be shared and to allow for future modifications. All of the functions that the logic provide have the ability to be disabled within the logic configuration tool and/or remotely, if not in use. Please refer to EDS 05-9600a and EDS 05-9600b for detailed information on behaviour and data.
5.1 Operation Modes
The RTU shall operate in the following modes.
5.1.1 Local Mode
The logic will only receive inputs from the RTU configuration menu or HMI. Set points will be synchronised from the previous mode until replaced by an operator to prevent significant step increases passed to the DER. A local mode signal shall be relayed to the NMS and ANM. This mode can only be enabled locally. When leaving this mode, the logic shall revert to the previous operation mode.
5.1.2 Remote ANM Mode
The logic will receive inputs (dynamic) from an ANM system or use pre-configured inputs (static). Only during this mode, shall the DER be considered in the pool for ANM services. An ANM mode signal shall be relayed to the NMS and ANM. This mode can be enabled locally or from the NMS by an operator. This mode will be the default operation mode for the centrally managed ANM schemes.
5.1.3 Remote NMS Mode
The RTU logic will receive inputs from PowerOn (entered by an operator). Inputs will be latched from the previous mode until replaced by an operator to prevent significant steps passed to the DER. A NMS mode signal shall be relayed to the NMS and ANM. This mode can be enabled locally or from the NMS by an operator. This mode enables intervention from the control room.
5.1.4 Orphaned Mode
The mode cannot be manually selected. The RTU will only enter it once the integrity with the central systems (ANM or NMS) is impaired. During this mode, the RTU logic will read input values from memory. The DER may be required to comply with the Orphan Operational limits based on the design of the scheme. If the limits are breached or the Orphan Timer expires an Orphan Alarm and Failsafe action will occur.
5.1.5 Decoupled Mode
The mode can occur simultaneously with any of the previous four modes. The purpose is to detect if a DER is not acknowledging the effective operational limits or the integrity of the communication link is impaired. A decouple alarm will be raised if acknowledgement is not received or the link is impaired and a Decouple Alarm and Failsafe action will occur.
RTU Logic for ANM schemes Document Number: EDS 05-9600
Version: 1.0
Date: 07/12/2017
© UK Power Networks 2018 All rights reserved 10 of 14
5.2 Logic Functions
The RTU shall have the following logic functions. Detailed information regarding the interaction and functionality of the logic can be found in the documents in the appendix section. The response to the instructions to manage DERs is defined by the planning and design standards.
5.2.1 Failsafe Block and Failsafe Actions
The logic has the capability to issue five failsafe actions. These are single bit signals and represent when a predefined action needs to occur. The failsafe actions are automatically triggered once the measured values breach the configured effective operational limits; or a combination of a set of conditions; or directly triggered by Control room operators; or an ANM system.
The logic has the capability for escalating from one failsafe action to other failsafe actions. Each of the trigger output from the “Monitor and Compare” can have an independent sequence of failsafe states and timers when a non-compliance occurs.
5.2.2 Monitor and Compare
The logic monitors a set of data points against certain criterion or a combination of criteria. DERs shall follow a number of dynamic set points to comply with the DNO instructions and to prevent a failsafe action from occurring. These shall be set in accordance with the safe operational limits of the constraint asset.
5.2.3 Orphaned
This logic function shall be used when there is a requirement for the RTU to make decisions when the integrity of the link to the central systems is impaired. The logic block allows the detection of the following occurrences, NMS integrity through watchdog function and ANM integrity through expired active set points. An orphan alarm is raised if any of the conditions previously described is met and an orphan action will be requested if a non-compliance occurs during “Orphan mode”
5.2.4 Decouple
This function shall be used when there is a requirement for the RTU to make decisions when the integrity of the link to DERs is impaired. The logic block allows the detection of the occurrences of a DER failing to acknowledge active set points or a failed watchdog. The decouple alarm will be raised when either of the above conditions occur and a decouple action will be requested if a non-compliance occurs during a “Decoupled” condition.
RTU Logic for ANM schemes Document Number: EDS 05-9600
Version: 1.0
Date: 07/12/2017
© UK Power Networks 2018 All rights reserved 11 of 14
6 RTU Non-Functional Requirements
The RTU requirements shall be set as per the standard SCADA documentation and as per additional following requirements:
6.1.1 RTU and other UK Power Networks Systems
Interface with UK Power Networks systems using IP;
Support multiple IP-based protocols (IEC 61850, DNP3, Modbus, etc);
One channel set up per master/slave relation;
RTU must cope with multiple DNP3 master/slave interfaces for the ANM, NMS and other RTUs;
Controls and measurements restricted to only specific data points;
RTU Local/Remote button to allow data points to be received from HMI or NMS respectively;
DNP3 secure for connections;
DNP3 file transfer (receive and send);
Capability to store and pass file values as inputs to logic;
Simulation mode, the RTU shall be capable of simulating DER acknowledgement values and watchdogs.
6.1.2 RTU to DER control systems
Interface with customer systems using IP and serial interfaces (selectable);
RTU to be a DNP3 master for the customer control system (PLC)/Other RTUs or IEDs;
The functionality for all signals to be able to be configurable as restricted or un-restricted;
Interface to use RTU serial port through Ethernet/fibre converter or a dedicated isolated port;
Support of DNP3 secure protocol;
Hardwired signal to be provided for the tripping functionality if required by scheme;
Capability to act as NTP server to allow DER time synchronisation;
Figure 6-1 – RTU Interfaces
RTU
NMS
Substation and Customer Logic
PLC
Customers Control System
Master
Slave
Master Slave
Serial to Ethernet
ANM
Master
Slave
RTU
Slave/Master
Master/Slave
RTU Logic for ANM schemes Document Number: EDS 05-9600
Version: 1.0
Date: 07/12/2017
© UK Power Networks 2018 All rights reserved 12 of 14
7 NMS and ANM Functional Requirements
The interfacing with the DER through the RTU will require arbitration and synchronisation between central systems as well as functionality to enable an override of the actions instructed to the DER by the RTU logic. There are two design approaches for the interface with the RTU from the central systems. The second design approach will not be used for new system deployments wherever possible. The requirements for both design approaches are reflected in the existing company requirements for the NMS or ANM.
7.1 RTU Interface through NMS to ANM
In this approach all datapoints are passed through the NMS (PowerOn) avoiding duplication. This will also allow the benefit of the dual communication system to be realised.
Figure 7-1 – Standard System Interface
7.1.1 NMS Functional Requirements
Passing of values between the ANM and RTU;
Use of values to allow the correct functionality and information to be made available to NMS users;
Adequate alarms and information displayed;
7.1.2 ANM Functional Requirements
Use of values to allow the correct functionality and information to be made available to NMS users.
NMS ANM
RTU
Con
tro
l & C
onfi
g si
gnal
s
AN
M d
atap
oint
s
NM
S d
atap
oin
ts
Fails
afe
dat
apo
ints
Mea
sure
d v
alue
sC
usto
mer
issu
ed d
atap
oin
tsW
eat
her
dat
a
Sta
tus
sign
als
Control & Config Signals: RTU remote sel Selection flags Enables & disables Timers Tolerances Time to live
Status Signals: RTU Operating mode Triggered failsafe M&C breaches
ANM Datapoints: Setpoints Direct failsafe triggers ANM watchdog
Measured values, Customer issued datapoints & weather data: Setpoints Measured setpoint Weather
NMS Datapoints: Setpoints Direct failsafe triggers
Failsafe Datapoints: Setpoints
DER
Control Signals
Customer issued datapoints & measured values
Customer ack & weather data(optional)
Control Signals: Triggered failsafes Alarms
Customer issue datapoints & measured values: Setpoints Measured values@POC Time sync signal
Customer ack & weather data (optional): Setpoints A set of analogues:
*Weather data *Customer measured values
Status signals
Measured values
ANM Datapoints
ANM Datapoints: Setpoints Direct failsafe triggers ANM watchdog
Measured values: Measurements
Status signals: RTU Operating mode Triggered failsafe M&C breaches
Loca
l/R
emot
e
Loca
l Dat
apoi
nts
Local/Remote: Set local or remote
Local Datapoints: Setpoints
Remote sel: Set “remote manual” or
“remote anm”
NMS Datapoints: Setpoints Direct failsafe triggers
Rem
ote
sel
NM
S D
atap
oin
ts
RTU Logic for ANM schemes Document Number: EDS 05-9600
Version: 1.0
Date: 07/12/2017
© UK Power Networks 2018 All rights reserved 13 of 14
7.2 RTU Interface to NMS and to ANM
In this approach both NMS and ANM can directly interact with the RTU. This is not the approach for central system ANM designs but can be used for substation based ANM systems and legacy systems where the preferred design is not viable.
Figure 7-2 – Existing design (non-standard)
7.2.1 NMS Functional Requirements
Passing of values between the ANM and RTU
Use of values to allow the correct functionality and information to be made available to NMS users.
7.2.2 ANM Functional Requirements
Use of values to allow the correct functionality and information to be made available to NMS users.
NMS ANM
RTU
Con
tro
l & C
onfi
g si
gnal
s
ANM datapoints
NM
S d
atap
oin
ts
Fails
afe
dat
apo
ints
Mea
sure
d v
alue
sC
usto
mer
issu
ed d
atap
oin
tsW
eat
her
dat
a
Sta
tus
sign
als
Control & Config Signals: RTU remote sel Selection flags Enables & disables Timers Tolerances Time to live
Status Signals: RTU Operating mode Triggered failsafe M&C breaches
ANM Datapoints: Setpoints Direct failsafe triggers ANM watchdog
Measured & Customer issued datapoints & weather data: Issued Measured Weather
NMS Datapoints: Setpoints Direct failsafe triggers
Failsafe Datapoints: Setpoints
DER
Control Signals
Customer issued datapoints & measured values
Customer ack & weather data(optional)
Control Signals: Triggered failsafes Alarms
Customer issue datapoints & measured values: Setpoints Measured values@POC Time sync signal
Status signals
Measured values
ANM Datapoints: Setpoints Direct failsafe triggers ANM watchdog
Measured values: Measurements
Status signals: RTU Operating mode Triggered failsafe M&C breaches
Loca
l/R
emot
e
Loca
l Dat
apoi
nts
Local/Remote: Set local or remote
Local Datapoints: Setpoints
Remote sel: Set “remote manual” or
“remote anm”
NMS Datapoints: Setpoints Direct failsafe triggers
Rem
ote
sel
NM
S D
atap
oin
ts
RTU Logic for ANM schemes Document Number: EDS 05-9600
Version: 1.0
Date: 07/12/2017
© UK Power Networks 2018 All rights reserved 14 of 14
8 References
8.1 UK Power Networks Standards
EAS 05-9000 Approved Equipment List – RTU and Control Equipment
EDS 05-5001 MW and MVAr Transducer Connection
EDS 05-9003 UKPN RTU Specification
EDS 05-9007 SCADA Numbering System
EDS 05-9600a RTU Logic for ANM Schemes Diagram
EDS 05-9600b RTU Logic for ANM Schemes Data Point Mapping