IEEE Electrification Magazine - March 2014 - 8

technology leaders

xx
identify applicable interconnec-

tion standards and practices,
including interoperability and
control of distributed resources.
xx
explain how traditional contracting, risk assessment, and financing practices apply to microgrids
and analyze minnesota policies
that affect microgrid development.
xx
research and model potential
electric loads available to microgrids in minnesota, and segment those loads by user groups.
xx
identify renewable resources in
the state potentially accessible in
microgrid applications and
examine economic and operational factors for possible renewables-based microgrids.
xx
recommend policy steps that
would capture microgrid benefits
for minnesotans and assist in the
safe, cost-effective implementation and integration into the utility system.
my charge, the focus of this article, can be articulated at slightly
greater length. The importance of
interconnection standards and policies in this context was viewed as a
fundamental, pragmatic matter. so
the team was tasked with identifying
minnesota's applicable interconnection standards and practices, including interoperability and control of
distributed resources. The team was
also directed to compare and contrast minnesota's standards and
practices with current federal and
industry standards and articulate differences that might affect microgrid
development and optimization in
utility systems.
The reference to standards
regarding "optimization in utility systems" in this element of the scope (as
well as a similar reference in the final
point listed previously) underscores
that minnesota is exploring microgrids
for the benefit of its citizenry, with a
clear intent to work with utilities.
minnesota public policy regarding
microgrids reflects a commitment to
make this innovation workable and

I E E E E l e c t r i f i cati o n M agaz ine / MARCH 2014

even beneficial from a utility standpoint. This wisely recognizes utilities'
prerogatives as well as the practical
issues surrounding interconnections
between microgrids and utility grids.
identifying mutual benefits makes
sense because minnesota's current
regulatory approach, which is based
on cost-of-service rate making and volumetric pricing, initially puts investorowned utilities and microgrids
"squarely at odds," as the white paper
put it. As minnesota clearly recognizes,
utilities' concerns about microgrids'
potential impact on their business
model as well as impacts on operational matters based on interconnection issues are well founded and need
to be addressed.

Utility Concerns on
Microgrid Control, Safety
The interconnection of a utility grid
with dg systems is governed by a finite
number of industry standards issued
by the usual suspects, including the
ieee, Underwriters Laboratories, the
international electrotechnical commission, and the Federal energy regulatory
commission (Ferc). All applicable
standards are intended to address utilities' concerns, for the simple reason
that utilities operate the grid to which
microgrids would interconnect and
they have significant, regulated public
responsibilities. Those concerns can be
summarized in four categories:
1) Anti-islanding features are needed to prevent the unintentional
flow of current from grid-connected dg onto a circuit that otherwise should not be energized,
as in an outage.
2) distribution systems do not all
have protection equipment to
safely prevent short circuits from
dg running in synchronous,
parallel interconnection to the
utility grid.
3) synchronized generators that
fluctuate to follow microgrid
loads or intermittent renewable
energy sources can cause voltage
instability, forcing the utility to

install expensive capacitor banks
and voltage regulators to maintain voltage stability.
4) Utility grid operators often have
little or no visibility into customer-owned dg, resulting in suboptimal operations for both parties.
recent developments in interconnection technologies and new
approaches to microgrid control have
provided cost-effective solutions to
many utility concerns. And new
methods of testing and simulation
can rapidly prove the safety of
microgrid-related technologies and
practices. (The white paper's appendices offer case studies in support of
this statement.) That said, it certainly
behooves utilities to have an active
testing program to assess how new
technology affects their systems, a
precaution that can benefit their customers. However, cultural factors
must be addressed as well. Power
systems engineers' experience has
bred mistrust of new systems until
exhaustive field testing has concluded that they are effective and safe.
given utilities' public obligations and
the danger of high-voltage power,
caution is justified. And, as we shall
see, in minnesota as elsewhere, current policies may give utilities the
upper hand in facilitating or inhibiting microgrid development. Thus, the
onus is on microgrid sponsors to
demonstrate the safety, reliability,
and cost-effectiveness of their system to the utility-if utility cooperation is to be expected.

Applicable Standards
and New Amendments
For microgrid development in minnesota, the most important standard is
ieee 1547, Standard for Interconnect-

ing Distributed Resources with Electric Power Systems . ieee 1547,
approved in 2003, aims to provide a
uniform set of criteria and requirements for interconnecting the grid
with dg. its requirements relate to
the testing, operations, maintenance,
and safety of the grid-to-dg

Table of Contents for the Digital Edition of IEEE Electrification Magazine - March 2014