the advanced distribution management...
Post on 04-May-2018
222 Views
Preview:
TRANSCRIPT
The Advanced Distribution Management System
The indispensable tool of the Smart Grid era
Telvent utilities group
August 2010
©2010 Telvent. All rights reserved. www.telvent.com/smartgrid | 1.866.537.1091
IntroductionThe Smart Grid era is the result of a shift in focus within the electricity
industry — a shift away from the older, familiar approach of large
power stations and reliance on transmission systems to move bulk
power. Our Smart Grid future is more likely to be focused on smaller
distributed electricity generators, a growth in renewable resources,
eliminating overloads, and reducing peak demand through demand
response options.
In addition to the focus on evolving management of distribution
networks, the electricity consumer is being asked to change long-
standing habits and manage growing appetites for energy. Regulatory
organizations and utilities are trying to cope with this issue all over the
world, blending advanced metering and communications technologies
to bring new options. Dynamic, time of use, and other pricing
alternatives are under consideration to reduce electricity network
congestion and energy costs.
With these changes, the need to more effectively plan, engineer,
and manage the distribution network is a critical requirement. In
addition, there is a rush to implement the core software to support this
responsibility — the advanced distribution management system (DMS).
This paper will provide an overview of the advanced DMS software,
including its diverse, complex portfolio of functionality, as well as its
benefit to the distribution network owner and the energy consumer.
The advanced DMS For more than 40 years, utilities have used the strength and speed
of computers to model electricity networks. For the most part, that
focus has been on transmission networks, and there are many mature
software products on the market that provide strong functionality for
bulk power transmission networks.
Modeling distribution networks is a different, and in many ways, more
complex problem.
The Advanced Distribution Management System
The indispensable tool of the Smart Grid era
1
What makes a DMS advanced?
Distribution Management Systems
(DMS) are software applications
with basic capabilities. When a
DMS has advanced functionality —
including volt/VAT control, FLISR
support, advanced forecasting and
planning functions, and others
— that tightly integrates with an
OMS and SCADA, it is considered
to be “advanced.”
©2010 Telvent. All rights reserved. www.telvent.com/smartgrid | 1.866.537.1091
2
Instead of the need to model static, meshed, and balanced transmission
networks, today’s advanced DMS technology must model radial,
unbalanced distribution networks with rapidly-changing topologies
and demand profiles. Instead of consistent and frequent telemetry
from the transmission network, advanced DMS technology must be
able to coordinate unsynchronized data for management of these
network models. Advanced DMS must also deal with the possibility
of “islanding” portions of the distribution network — creating the
potential for management of multiple and independent distribution
networks.
The advanced DMS must also deal with the evolving use of electricity,
supporting variable, localized demand profiles created by changing
consumption habits, and by new electricity-powered devices such as
battery-powered vehicles and high-tech devices. Further, the advanced
DMS must deal with shifting consumption patterns and customer
demand for higher levels of service for their devices. Not only must
service levels improve, but also the service must be high quality,
including voltage levels that operate within regulatory norms.
The advanced DMS is the tool that enables the power system engineer
and dispatcher to effectively and efficiently engineer, plan and operate
the distribution network. It analyzes unbalanced and dynamically
changing distribution networks in real-time, while providing a study
capability for both backward and forward review to identify options to
improve network reliability while lowering electricity costs.
The advanced DMS is the critical tool for management of the
distribution network, and enables the acquisition of many of the
benefits utilities and consumers expect from their Smart Grid
investments.
The foundation of the advanced DMS At the core of the advanced DMS is the ability to precisely define the
network model, and to process an unbalanced load flow algorithm
based on that model with telemetered data taken from the network.
• The network model
The advanced DMS must be able to represent all aspects of
the distribution network, including a variety of conductor
types, transformers, switches (both manual and motorized),
fuses, and other permanent and temporary devices used
©2010 Telvent. All rights reserved. www.telvent.com/smartgrid | 1.866.537.1091
3
in distribution system operations. The model must provide
connectivity based on the position of switches, and be able
to determine how individual demand points are connected
to the energy supply.
• The dynamic data
To enable functioning of the advanced DMS load flow
algorithm, it requires data telemetered from the distribution
network. That data is generally made available through
supervisory control and data acquisition (SCADA) systems
and their associated telemetry, through AMI networks, and
from the outage management system (OMS). This manages
the flow of information regarding “lights-out” events on the
distribution network.
The amount of data to be telemetered and stored is
significant and changes frequently, suggesting that great
care must be taken to manage the flow of data to the
advanced DMS — enabling it to process quickly and
efficiently. The data provides a variety of information (e.g.
voltage, current) and device status (e.g. open/closed) to
enable the load flow algorithm to function.
The advanced DMS must also be able to store copies of the
data for future study and training purposes. Historical data
copies can be very helpful in planning for situations that
develop on the network as demand profiles and energy costs
change.
• The unbalanced load flow algorithm
The advanced DMS must have a very fast load flow
algorithm that can solve unbalanced distribution networks
based on data telemetered from the field.
Visualization of advanced DMS results With a complex network model, significant quantities of data (both
telemetered and calculated) and the wide variety of advanced DMS
users (planning and design engineers, operations management,
and distribution system dispatchers, etc.), providing visualization of
advanced DMS results is an important consideration. An advanced
DMS should be able to display network data in a geographic view (e.g.
©2010 Telvent. All rights reserved. www.telvent.com/smartgrid | 1.866.537.1091
4
maps), a schematic view, and in single-line diagrams. Further, the end-
user should be able to easily manage the level of information displayed
in these views.
Individual utilities have developed different means to view their
network information over time, and the advanced DMS must be
flexible enough to support the format desired by the utility. Done
correctly, the advanced DMS will be able to drive full-scale power
network projections in system operations centers, both at dispatcher
workstations and projected on larger screens to inform those in the
control center or elsewhere.
State estimation — ensuring the accuracy of advanced DMS results One dictionary defines state estimation as “a branch of probability
and statistics concerned with deriving information about properties of
random variables, stochastic processes, and systems based on observed
samples.” In power networks, state estimation takes observable data
from the field and derives a model of what is actually happening, by
processing the data to identify bad readings or to estimate missing
data.
The quality of data telemetered from various points on the distribution
network is typically imperfect. Problems in devices or in the
telecommunications networks associated with those devices suggest
that prior to conducting an advanced analysis, the data must be pre-
processed to eliminate bad data points, estimate non-telemetered
points, and resolve any issues with “time skew” for unsynchronized
telemetry systems.
The tool that performs this quality analysis is known as state estimation,
a critical feature of the advanced DMS. To trust the results of the
analytical software, the inputs must be quality checked, and either
adjusted or eliminated to avoid bad results.
Advanced DMS analytical functionality The advanced DMS has functionality that supports several functional
areas:
• Operations planning and analysis, loss minimization
One of the primary uses for the advanced DMS is the real-
time analysis that enables optimization of the distribution
network. The advanced DMS continually runs real-time
©2010 Telvent. All rights reserved. www.telvent.com/smartgrid | 1.866.537.1091
5
analysis, identifying problems and suggesting approaches to
better balance load, suggest switching to minimize losses,
and identify other potential and real problems, as well as
likely solutions.
The advanced DMS enables utilities to reduce energy waste
on their distribution networks through a more detailed
understanding of losses — and through reconfiguration and
network optimization — to minimize those losses.
• Supporting outage management activities
The advanced DMS provides analytical support to ensure
that outage causes are identified and resolved more quickly.
Integrated with an OMS, it provides a “next generation”
level of functionality, which that can use to improve network
reliability.
The advanced DMS has a strong level of functionality around
fault location, identification, and service restoration (FLISR).
The FLISR functionality already present at most utilities is
enhanced with the advanced DMS’s ability to locate faults
(based on telemetry and analysis) and to provide ranked
switching options to a dispatcher (e.g. prioritization based
on connected load, connected customers, etc.) based on
the dynamic state of the network. The advanced DMS can
extend the capability of traditional self-healing network
automation by allowing it to operate on the as-switched
network model in any arbitrary configuration.
Because the advanced DMS maintains information about
the as-switched state of the network, it facilitates and
automates the creation of switching orders, for planned
and unplanned work that dispatchers or field operators can
execute according to traditional procedures, or which can be
executed automatically in the presence of field automation.
This can all be accomplished while managing tagging
functionality as needed, and ensuring that the state of the
network is well represented at all times — including the
incorporation of temporary elements that may be used to
support outage restoration.
©2010 Telvent. All rights reserved. www.telvent.com/smartgrid | 1.866.537.1091
6
• Volt/VAR Control
The volt/VAR control functionality contained in the advanced
DMS enables utilities to ensure power quality in all parts
of the distribution network. It also provides a transparent
approach to demand response that utilities can exercise
without any need or expectation of customer involvement.
To this end, volt/VAR management supported by the
advanced DMS enhances overall network stability and
reliability.
Performing analysis and control for volt/VAR optimization
on a distribution network may require additional field
telemetry and control. It may also require the identification
of feeder segments where additional capital infrastructure
investments may be needed to enable the creation of a
more “level” voltage profile. The strengthening of the
distribution network for maximum use of advanced DMS
functionality may therefore require additional time and
capital expenditures for the utility.
Demand response Demand response is a key function that drives utilities to Smart Grid
programs and to the implementation of advanced DMS software. The
complex world of demand response suggests many options can be
exercised to reduce demand in the face of increasing demand, and the
potential of surging costs and network instability. The advanced DMS
understands that there are multiple approaches to demand response,
and the software can direct the implementation of demand response
options that are created by Smart Grid programs.
Some demand response actions depend on customers to react on
their own. Utilities and governments routinely request for electricity
consumers to change their consumption patterns when supply is
short. Regulators can also create rate structures that encourage similar
conduct through normal attention to energy costs. However, since
these approaches do not provide sufficient reduction, additional
demand response options are provided, and the advanced DMS can
support the prioritized application of these options.
©2010 Telvent. All rights reserved. www.telvent.com/smartgrid | 1.866.537.1091
7
In general, the available options fit into three categories, which are
listed in order of customer impact (lowest to highest):
1. Conservation voltage management (CVR) — also
known as Distribution System Demand Response
(DSDR)
This functionality utilizes volt/VAR management functionality
to reduce demand through reduced voltage on the
distribution network. The voltage reduction (usually
between 3 percent and 7 percent) results in reduction
in the power delivered by a similar amount, all without
customer awareness. Further, voltage management can be
accomplished on a feeder or feeder segment basis to resolve
a local overload (perhaps as a result of electric vehicles or
other infrequent demand anomalies) instead of on a system-
wide basis. This surgical use of demand response and its
lack of impact on customers is often the critical reason to
implement an advanced DMS.
2. Direct load control
Most utilities have implemented some form of direct load
demand response, generally through radio-controlled devices
located on water heaters, air conditioners and pool pumps.
Using this form of demand response, utilities can turn off
these devices for a short period of time (perhaps 15 to 20
minutes) to reduce demand on the distribution network. The
direct load programs already in place rotate the “turn-offs”
around the service territory to reduce customer impact. Since
there is some amount of customer impact, while minimal,
utilities must generally ask customers to “opt-in” to such a
program, and often trade a rate advantage or discount to
customers who choose the program.
Direct load control will continue to increase in complexity
with the evolution of home area network (HAN) technology
and the continued roll-out of AMI systems. The advanced
DMS is designed for integration with these end-of-network
systems, supporting direct load control by identifying
appropriate feeders segments and timing in a prioritized
manner.
©2010 Telvent. All rights reserved. www.telvent.com/smartgrid | 1.866.537.1091
8
3. Load interruption/islanding
When other demand response options fail, utilities
disconnect some demand to maintain the ability to serve the
rest. Again, most utilities have “opt-in” programs for such
interruption, including interruptible rates that are supported
by regulators and governments. However, depending on
the nature of the overload and danger to the health of
the distribution network, utilities may have to exercise
interruption options with little or no advance notice — even
to customers who have not elected this option. Once again,
the advanced DMS makes recommendations and prioritizes
options for utility dispatchers to enable decision making in
situations where it is unavoidable.
Distributed generation The Smart Grid was initially intended to support the addition of
environmentally-renewable energy resources to the distribution
network, including wind, solar, biomass, and others. However,
managing a distribution network with hundreds or thousands of
potential energy sources requires an advanced DMS.
The advanced DMS can help maintain the balance needed to reliably
operate a diverse supply environment in the face of dynamic changes in
demand and in the topology of the distribution network.
As distributed generation becomes more prominent, distribution
networks may tend to become small “islands” of energy that can
operate while connected to the rest of the distribution network. They
may also operate independently as a “micro-grid” in a disconnected
manner. The advanced DMS can manage the network through these
operating approaches, optimizing it for losses, reliability, or cost of
operation, while maintaining a secure distribution network.
• Distribution network planning and demand forecasting
Since utilities must take a forward look in planning their
distribution networks, the advanced DMS must provide
functionality to enable planning and budgeting for
maintenance of reliability and quality of service. Advanced
planning functionality must start with demand forecasts
for the time frames required. The advanced DMS includes
demand forecasting (short, medium, and long-term)
contributing to the planning process.
©2010 Telvent. All rights reserved. www.telvent.com/smartgrid | 1.866.537.1091
9
Dispatcher training simulatorIn addition to the diverse real-time and off-line analytical functionality
contained in the advanced DMS, it is also possible to take a “snapshot”
of the distribution network — including the network model and
associated telemetry. This snapshot can then be used to train
distribution system dispatchers. The advanced DMS can also support
the storage of past forecasted models.
To be effective, the dispatcher training simulator must also have the
ability to move through time (typical demand and supply changes),
with events that can be programmed by an instructor. In this manner,
the simulator enables training cases based on experience or in advance
of anticipated events.
SummaryThe advanced DMS is an indispensable tool of the Smart Grid era.
Starting with the foundation of a fast, unbalanced load flow engine
and the ability to validate data via state estimation, the advanced
DMS provides complete functionality to help utilities optimize their
distribution networks. The software also provides dispatchers,
engineers, and others who operate and manage the network with easy
network visualization.
The advanced DMS includes significant functionality to manage
outages and perform FLISR operations. It also has the tools to support
volt/VAR optimization, which enables voltage-based demand response
functionality (DSDR), the form of demand response that has the least
impact on customers. The software supports distributed generation,
enabling the utility to grow and accommodate the renewable
generation expected of the Smart Grid era, while optimizing the
network for reliable service.
Lastly, the advanced DMS supports short, medium and longer term
planning, and also enables the capture of “cases” to support the
training of dispatchers who operate the distribution network.
Advanced DMS — the indispensable tool of the Smart Grid era.
Telvent (NASDAQ: TLVT) is a global IT solutions and business information services provider
that improves the efficiency, safety and security of the world’s premier organizations. The
company serves markets critical to the sustainability of the planet, including the energy,
transportation, agriculture, and environmental sectors. (www.telvent.com)
The concept of the virtual power plant
Virtual power plants (VPP) come
from a utility’s ability to dispatch
(set appropriate output levels) an
amount of power that exists in the
form of distributed generation and
demand response, instead of as a
physical power plant.
Using a variety of demand
response approaches (e.g.
direct load control, volt/AVR
management, etc.) and distributed
energy resources (e.g. energy
storage, renewable generation,
etc.), a utility can create a profile
of a virtual power plant, and use
it in its energy dispatch algorithms
when balancing demand and
supply.
This also requires critical analytics
and controls, such as those
provided by the advanced DMS —
using SCADA, DMS, and other tools
as needed — to create the VPP
and the forward operational plan
a utility would expect in a power
plant environment.
The advanced DMS is the tool that
enables the VPP concept.
top related