Aricent Electrical Utility Whitepaper
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Transcript of Aricent Electrical Utility Whitepaper
1Electrical Utility Secondary Substation Automation
ELECTRICAL UTILITY SECONDARY SUBSTATION AUTOMATION The Electrical utility industry is going through a difficult evolution
battling issues like balancing high energy demand/consumption
with low energy generation while reducing their carbon footprint.
This has led to modernization of the grid and further proliferation
of smart devices like synchrophasors, sensors, smart meters,
and actuators that provide real-time assessment of power-
system health and control of utility assets like transformers
and capacitor banks.
Of the numerous activities that initiate a smart grid, automating
primary (HV/MV) and secondary (MV/LV) distribution
substations is perhaps the the most challenging activity, with
distribution substations distributed across a vast geography.
In order to introduce optimized automation algorithms into these
distribution substations, utilities use wireless technologies like
WirelessHART, LTE, ZigBee, etc.
Most utilities have automated their primary distribution
substations by using WirelessHART as a wireless sensor network
(WSN) technology between the sensors/actuators and the
automation controller. Even though the technologies used
in the primary substation can be adopted with the activities of
the secondary distribution substation, the secondary substation’s
proximity to residential homes and distributed energy resources
(DER) necessitates defining a secondary substation node (SSN)
that supports orchestration of IEC 61850-based devices as
well as devices supporting ZigBee SEP.
This paper highlights some of the considerations for a SSN as
defined by EU smart energy projects OpenNode and INTEGRIS,
and introduces Aricent’s approach to defining SSN through
our solution accelerators.
IntroductionMany countries across the world are modernizing their power
grids into smart grids in order to increase reliability and energy
efficiency, enable transition to renewable sources of energy,
reduce greenhouse gas emissions, and build a sustainable
economy. Enabling smart grids entails on adding and integrating
many varieties of digital computing and communication
technologies and services with the power-delivery infrastructure.
Bidirectional flows of energy and two-way communication
and control capabilities enable an array of new functionalities
and applications that go well beyond smart meters for homes
and businesses. Smart grids can provide predictive power
information (e.g., meter reading data, charges, and power usage
recommendations) to both utilities and consumers. It can also
diagnose power disturbances and outages to avoid equipment
failure and accidents in generation, transmission, and distribution
within the utility network.
Various standards bodies and national regulatory organizations
are working to define the interoperability of devices used in
smart grids. NIST is one such prominent standards body that
has defined detailed conceptual reference architecture for
smart-grid information networks. NIST’s concept model provides
a high-level, overarching perspective of major relationships
across different domains of power-grid systems like generation,
transmission, distribution, and energy sources, as well as users
with the capability to make decisions and exchange information
with other users. This concept model defines information flow
between different domains and users within the smart grid.
2Electrical Utility Secondary Substation Automation
and breakers), a network that connect all the devices (via wired
Ethernet or wireless connections), and software that receives
input from, and manages, the field devices. Fast and efficient
intercommunication between these devices is achieved
through substation automation system. Advanced distribution
optimization algorithms utilize exchange of information between
the devices and the device that coordinates all substation
devices. An example of this is the acquiring of empty or load
voltage values in order to assess whether they are within the
limits and to acquire medium-voltage distribution line states.
Additional information about the substation, such as door
position, transformer temperature, switch-gear position, and
voltage readings, is also used when making real-time adjustments
for changing loads, generation, and failure conditions within
the distribution system.
Newer microprocessor-based relays and other intelligent devices
provide unprecedented flexibility and rich functionality which,
in turn, provide low-cost monitoring analysis and diagnosis of
electrical faults in the power network. Many newer IEDs provide
optional network interfaces such as distributed network
protocol (DNP) 3.0 or IEC 61850 over transmission control
protocol (TCP)/Internet protocol (IP)/Ethernet.
Distribution Substations and AutomationSubstations in the power grid system are described by their voltage
class and application within a power system. A distribution
substation transfers power from the transmission system to the
distribution system of an area. A typical distribution substation
contains a switch and low-voltage transformer. Many large
cities feature complicated distribution substations containing
both high-voltage switching and low-voltage switching and backup
systems. More typical distribution substations have a switch,
one transformer, and few low-voltage facilities.
Distribution automation (DA) optimizes a utility’s operations
and directly improves the reliability of its distribution power
system. The success or failure of an automation program
hinges on proper selection of equipment and communications
to seamlessly integrate data into the utility control room.
Functions necessary for substation automation and application
are protection, control, measurement, and monitoring.
Typical distribution automation solutions consist of three main
components: an - IED (including reclosers, capacitor controls,
switch controls, faulted circuit indicators, voltage regulators,
Overview of Distribution Domain (Reference: NIST Smart Grid Framework)
Operations
Transmission Substation
Reclosers and Relays
DistributedStorage
CapBank
Customer
N.O. Switch
Sectionalizer
DistributedGeneration
Markets
CL200 2474 JNV JO4
ElxtNet
Control Measure Protect Record Optimize
External Communication Flows Internal Communication Flows Electrical Flows Domain
3Electrical Utility Secondary Substation Automation
substation takes higher priority compared to the secondary
substation automation. However, with increased focus on
power quality in the distribution network and with secondary
substation providing connection points for a wide variety of
loads as well as a growing number of unpredictable renewable
power sources, there is an increased focus on secondary
substation automation. The introduction of distributed
generation in distribution networks requires protection and
control systems that can reliably locate and isolate faults.
With rising demand for electricity, decentralized power
production (rooftop solar panels and household windmills),
and new loads (heat pumps and EVs), utilities, today more
than ever, are looking for ways to enable a smarter, secure
grid that delivers uninterrupted power supply to consumers
at reasonable prices. To achieve this, utilities face various
challenges to keep their substations up and running. Problems
like power outages, costly unplanned maintenance, and rising
operational costs often get in their way and then cascade into
a whole series of problems. Normally, electricity utilities with
SCADA systems have extensive control over transmission-level
equipment, and increasing control over distribution-level
equipment via distribution automation. However, they are
often unable to control smaller entities such as distributed
energy resources (DERs), buildings, or homes.
A micro grid is a cluster of various DERs like solar, wind, fuel
cell, micro-turbine, diesel generator, battery systems, Electrical
Vehicles (EV), etc. With the number of DERs bound to rise quickly,
the ability to monitor these new power inputs into the grid,
balancing grid demand with generation, and coordinating
generation from these micro grids as more generators are
connected to the distribution grid all become increasingly
critical. Seamless two-way communication plays an important
role in the operational and control functions of a micro grid,
such as optimal control, protection, monitoring, metering,
self-healing, etc. Because these DERs may have a grid
interconnection to feed excess power, it is important to
orchestrate their activities with those of the main grid for an
optimal utilization of the micro grid.
Secondary substation automation is used to increase efficiency
of grids. Recently, OpenNode, funded through European
Community’s Seventh Framework Program (FP7/2007-2013),
has begun addressing challenges in increasing efficiency of the
distribution grid through creation of a secondary substation
node (SSN) as an essential component of the smart distribution
grid. This node addresses the functionality required by the
grid to cope with massively distributed embedded systems in
the distribution grid. The SSN allows aggregation of status
monitoring and metering management, as well as running
third-party applications (e.g., advanced grid control algorithms
Until now, many of the sensors used in automation activities
were connected with wires, severely limiting their size and
scope of coverage. Wires and the required conduits are expensive
to install and become fixed installations that are difficult to
change. As a result, many installations find it necessary to
limit the number of sensors simply to control costs, which
restricts the flexibility to adjust these networks to meet new
uses. When not required for critical infrastructure, wired solutions
are often summarily dismissed as being a “luxury.” But with
the growing trend of minimizing technical and commercial
losses by moving from distribution automation to smart
distribution that supports self-healing (i.e., isolation of faults
for faster service restoration) and autonomous restoration,
distributed energy resource deployment, bi-directional flow
of energy and information, enhanced supply security, and
power quality, there is a greater focus on automating the
controller activities in a distribution substation through either
wired or wireless communication technologies.
The use of wireless sensor networks (WSNs) for automation and
monitoring has several benefits over wired systems, including
reduced cost, ease of reconfiguration, and deployment
convenience. There have been significant developments recently
in terms of WSN standardization, with the HART Communication
Foundation and International Society of Automation (ISA)
being particularly influential in the field of wireless industrial
automation systems and ZigBee Alliance in developing ZigBee
wireless standards.
However, WSNs also bring cyber security and privacy challenges
to smart grids. For example, a number of security, privacy, and
reliability issues can appear during electric power delivery.
Competitors can compromise selected nodes and thus fail the
critical mission of supervisory control and data acquisition
(SCADA) systems. Any of these can cripple a grid, resulting in
millions of homes and business establishments losing electrical
power. Security of WSNs is therefore a critical concern when
designing networks for usage within a substation or a mesh
network across substations.
Secondary Distribution Substations and AutomationBased on the voltage handled, a distribution substation is
divided into primary and secondary substations. A secondary
unit substation is typically MV/LV (with input of 1 kV up to 35
kV and output of 1 kV). Principal areas of application include
use in industrial plants, electric power generating stations, and
commercial buildings. With higher voltages involved in the
hierarchy of the network, automation of the primary distribution
4Electrical Utility Secondary Substation Automation
or critical value monitoring like monitoring busbar voltage
and split current across multiple transformers by activating
circuit breakers) that can be dynamically installed during live
operation to enable the controlled shift of grid intelligence
from centralized systems in the utility control center to lower
echelons of the grid hierarchy.
The SSN uses an IEC 61850-based data model that represents
all data points in its canonical tree structure. Thus, all logical
operations in SSN happen solely on the data model, completely
abstracting underlying automation hardware and higher-tier
system architectures. This architecture also proposes to use
IEC 60870-5-104 as standard for exchanging information for
electrical device monitoring and control as the protocol supports
real-time and synchronous data transfer.
The OpenNode requirements specification captures SSN
functional requirements that cover areas related to smart-meter
management and data acquisition, measurement of MV/LV
side of transformer, clock synchronization, fault detection and
isolation, alarm reporting, line restoration (open and close orders
to the MV switches in order to restore the power after an
interruption), auto test, power supply backup management,
fraud detection, autonomous load shedding, manage energy
storage devices, and integration with IEC 61850 procedures
and data model.
Another EU project, INTEGRIS (INTelligent Electrical Grid Sensor
communications), proposes the development of a novel and
flexible ICT infrastructure based on a hybrid Power Line
Communication (PLC) wireless integrated communications
system able to completely and efficiently fulfill the predicted
communications requirements of Smart Electricity Networks
in the future. This includes all-encompassing applications such
as monitoring, operations, customer integration, voltage control,
quality of service control, control of DERS, and asset management
and can enable a variety of improved power system operations,
some of which are to be implemented in field trials that must
prove the validity of the developed ICT infrastructure.
Secondary Substation
SSN
Transformer
IEDS Sensors Actuators
Control Centre Other Companies
Retailers
Traders
Power Supplies
Meter Operators
Others
Utility Systems
Technical Systems
Billing Systems
Workforce Management
Business Intelligence
SCADA
GIA
AMM
Millions Thousands One
CriticalInformation
UtilityFinal Customer
Middleware
Device Management
Events Processing
Software Provisioning
Measure Management
Network Supervision and Monitoring
Administration System
Distributed Process Management
GridTopology
Events Measures
Virtual SSN
Ente
rpri
se S
ervi
ce B
us
SM
SM
SM
SM
MV-LVSubstation
MV-LVSubstation
HV-MV Substation
Sensor RFID Reader
RFID Tag
PLC CPEPLC HEPLC Repeater
OpenNode and INTEGRIS serve as excellent references for
developing the SSN that will enable automation activities in a
secondary substation utilizing different WSNs (wireless sensor
networks) technologies as well as the DA protocols like IEC
61850 and DNP3.
Source: INTEGRIS
OpenNode overall framework (Source: OpenNode EU project)
5Electrical Utility Secondary Substation Automation
voltage, power factors, and harmonics). This, however, requires
connectivity to distribution management systems with the
intelligence needed to calculate the active power (P) and/or
reactive power (Q) requirements according for the actual situation
and the available P and/or Q in energy storage systems.
As well as implementing proper protection, control, and
monitoring, renewable sources are important. In order to
address this need, ZigBee SEP 2.0 has included a distributed
energy resources function set that provides an interface to
manage DER. Client devices of this function set include intelligent
solar inverters, fuel cells, EV, generation units, and battery
storage systems. Server devices of this function set include
energy management systems that can be part of a secondary
substation node. Servers expose energy transfer control events
called DER Controls (DERC) to client devices e.g., active power
derating setpoint indicating a percentage reduction to be
applied to a DER output. As SEP 2.0 resource representations
are built to be compatible with the IEC Common Information
Model (CIM), there is a greater harmonization among substation
automation standard IEC 61850 and ZigBee.
Secondary Substation Automation and AricentAricent’s SSN Framework is designed to help vendors accelerate
time to market with rapid prototyping and commercialization
of applications necessary for the secondary substation
automation. This framework consists of Aricent Data
Concentrator Application Framework (DCAF) and Aricent
Energy Manager Framework (EMF).
Aricent DCAF provides a Web services-based interface layer
that exposes most common functions related to smart-meter
management (e.g., meter read (ondemand plus periodic),
remote connect/disconnect, alarm management, fraud
detection, and meter administration (including meter registration,
remote software updates, clock synchronization, etc.)). The
framework has been designed in a platform and protocol-
agnostic manner and can be used on both DLMS/COSEM
and other protocols like ANSI C12. Aricent also brings in a
DLMS/COSEM stack on SSN node to connect with smart
meters over PRIME/G3 PLC.
Aricent EMF is an energy management framework that provides
an application environment to develop distribution automation
algorithms. As a first step, Aricent has implemented a demand
response (DR) algorithm wherein it handles events from utility
demand response application server and converts to multiple
ZigBee SEP and HA events. Aricent intends to extend this EMF
to include additional algorithms for secondary substation
automation as well as to enable DER management.
Role of ZigBee in Secondary Substation AutomationAs discussed earlier, use of WSNs based on IEEE 802.15.4
(WirelessHART, ISA 100.11a or ZigBee) are intended for
monitoring and control using analog and digital input/output.
They and they meet the requirements of less power, and also
transmit data a lower rate for automation and monitoring of the
secondary substation. Since WSN-based automation is not new
and there is a large installed base of HART/WirelessHART and
ISA-based automation networks, it is quite natural to select
these technologies for secondary substation automation. At the
same time, ZigBee has evolved as into being WSNs’ cheapest
and easiest solution for controlling and automating small network
devices. Research has shown no significant adverse impact
on the performance of ZigBee by the electromagnetic
environment of the substation and therefore can be used for
automation purposes inside a secondary substation.
All ZigBee networks must have a coordinator to set up the
network, be aware of all its constituent nodes, handle and store
information, act as a repository for security keys, and manage
the information transmitted and received within the network.
Core specification defines ZigBee’s smart, cost-effective and
energy-efficient mesh network as a self-configuring and self-
healing system of redundant, low-cost, very low-power nodes.
In mesh networks, each wireless node communicates with the
one adjacent to it. In the event of node failure, information
gets automatically rerouted to allow devices to continue
communicating.
Unlike ZigBee-enabled devices, all WirelessHART devices must
have routing capabilities (i.e., no reduced functionality).
WirelessHart networks are self-organizing, with all devices being
treated equally in terms of networking capability, installation,
formation, and expansion. This functionality may be necessary
for primary substations, but is overkill for secondary substations.
To maintain a focus on carbon reduction and effective utilization
of energy resources, it is important to balance energy generation
and demand through well-defined demand response (DR)
systems. Generation can be plagued by factors like fluctuation
(over/under) as well as duration of such fluctuation. These
factors have to be matched with demand-side parameter (e.g.,
under-generation to be managed through DER, over-generation
to be handled through storage, and time variability to be
handled through faster DER/short-term usage. To do this, it is
essential to get the data of the demand side and act on it.
ZigBee enables capture of the information either through
request/response method or last-gasp methods.
More energy sources connected to secondary distribution
networks play an important role in balancing peaks of supply
and demand as well as contributing to supply quality (controlling
6Electrical Utility Secondary Substation Automation
ConclusionAs utilities create their roadmap to build a resilient smart-grid
network, along with providing insight, choice, and control of the
energy usage at the demand side, orchestration of the distributed
generation with the grid network becomes of utmost importance
in maintaining stability of the utility network.
With secondary substation as the perfect position in the grid
network to handle distributed grid management functions
through a substation node that aggregates different
communication technologies to orchestrate activities of the
IED in substation, distributed energy resources, and smart
meters. Aricent, with its expertise in building smart-home
automation frameworks around ZigBee, building data
concentrator products in the substation, building routing
platforms that can work in harsh environments, and enabling
remote controlling of substation networks through backhaul
technologies like LTE and Ethernet, will be a trusted partner
to ODMs/OEMs and utilities that need to build such solutions.
DistributedGeneration,
EVs
DemandResponse,
Load Control
Home EnergyReports,
Web andMobile App
Building Energy ScienceB
ehav
iora
l Sci
ence
Orchestration
Control
Pricing,
Devices,
UtilityPrograms
Choice
Insight
Source: ZigBee Alliance
PRAKASHA M. RAMACHANDRA
is one of the system architects
in the Aricent’s smart energy
practice. He has more than 17
years of experience in architecting
applications & ICT back office
platforms in telecommunication,
media and smart energy domain.
prakasha.ramachandra
@aricent.com
B. VENKAT S. R. SWAMY
Venkat is one of the system
architects in the Aricent’s M2M
and Wireless practice. He has
more than 16 years of experience
in Product Conceptualization,
Architecture and Development in
next Generation Convergent and
wireless technologies and smart
energy domain.
REFERENCES
(1) U.S. NIST, “NIST framework and roadmap for smart grid interoperability standards, release 2. 0,”http://www.nist.gov/smartgrid/upload/NIST_Framework_Release_2-0_corr.pdf
(2) MSA Ghayum, “Comparative Study of Wireless protocols: WiFi, Bluetooth, ZigBee, WirelessHART and ISA SP100, and their Effectiveness in IndustrialAutomation”, University of Texas Master Thesis
(3) Q Shan, et al., “ZigBee Performance in 400 KV Air Insulated Power Substation”, Technological Developments in Education and Automation 2010, pp 15-18
(4) RAP Faria, “A Wireless Sensor Network for Electrical Distribution Substations”, Master Thesis, 2011
(5) M Alberto, et al., “OpenNode: A Smart Secondary Substation Node and its Integration in a Distribution Grid of the Future”, Proceedings of the FederatedConference on Computer Science and Information Systems pp. 1277–1284
The Aricent Group is a global innovation and technology services
company that helps clients imagine, commercialize, and evolve
products and services for the connected world. Bringing together the
communications technology expertise of Aricent with the creative
vision and user experience prowess of frog, the Aricent Group
provides a unique portfolio of innovation capabilities that seamlessly
combines consumer insights, strategy, design, software engineering,
and systems integration. The client base includes communications
service providers, equipment manufacturers, independent software
vendors, device makers, and many other Fortune 500 brands.
The company’s investors are Kohlberg Kravis Roberts & Co.,
Sequoia Capital, The Family Office, Delta Partners, and The Canada
Pension Plan Investment Board.
INNOVATIONSERVICESFOR THECONNECTEDWORLD
aricent.com © 2013 Aricent Group. All rights reserved.All Aricent brand and product names are service marks, trademarks, or
registered marks of Aricent Inc. in the United States and other countries.