EDS 05-9600 RTU Logic for ANM schemeslibrary.ukpowernetworks.co.uk/library/asset/5f003e...The logic will receive inputs (dynamic) from an ANM system or use pre-configured inputs (static)

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.


Version: 1.0

Date: 07/12/2017


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


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Figure 7-1 – Standard System Interface .............................................................................. 12

Figure 7-2 – Existing design (non-standard) ........................................................................ 13


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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.


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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).


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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


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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


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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.


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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.


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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


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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

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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


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”


Rem

ote

sel

NM

S D

atap

oin

ts


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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


7.2.2 ANM Functional Requirements


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


Measured & Customer issued datapoints & weather data: Issued Measured Weather


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


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”


Rem

ote

sel

NM

S D

atap

oin

ts


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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

Documents

EDS 05-9600 RTU Logic for ANM schemeslibrary.ukpowernetworks.co.uk/library/asset/5f003e...The logic will receive inputs (dynamic) from an ANM system or use pre-configured inputs (static)