POWER October 2020 - 22

TOP PLANT
Upgrades and Interconnection
Make Gas-Fired Plant a Winner
Courtesy: Raffineria de Milazzo S.C.p.A
The Termica Milazzo cogeneration combined cycle power plant completed an extensive
upgrade and integration project with a nearby refinery in Sicily, Italy. The
successful project, which spanned about three years and included more than
100,000 man-hours of work, makes it a worthy POWER Top Plant award winner.
Aaron Larson
E
ni S.p.A. and Kuwait Petroleum Italia
S.p.A. own equal shares of Raffineria
di Milazzo S.C.p.A. (Refinery
at Milazzo, RaM). RaM, which is located in
Sicily, operates within the Italian and international
refining system to produce fuels
and raw materials for petrochemicals.
In 2016, RaM acquired Termica Milazzo
(TEM)-a cogeneration combined
cycle gas turbine (CCGT) power plant
located about 500 meters from the refinery-assuming
full management of
maintenance activities and energy production
for the facility. The plant had previously
sold power only to the national
grid. RaM, however, had other objectives.
It intended to use the facility to
supply the refinery's entire electrical load
demand by integrating the electrical network,
thereby increasing the reliability of
RaM's power system.
The TEM facility operates a single GE
frame 9E GT (Figure 1) arranged in a singleshaft
configuration with a combined cycle
ISO nominal energy output of 155 MW.
When acquired by RaM, the flexibility of
the power plant was limited to a steam cogeneration
flow of about 80 tons/hr to 100
tons/hr and a minimum emissions-compliant
power turndown of 110 MW.
Melding Facilities
As part of RaM's long-term vision for the
power plant, it wanted to improve power
and steam generation flexibility by reducing
the minimum turndown of the GT,
while maintaining emissions compliance
and optimizing potential energy market
trading opportunities. The company also
wanted to upgrade the existing control
system, which included multiple separate
22
components, into a single, advanced and
integrated system. RaM hoped by doing
so, it would gain some enhanced features
and innovative functions, including Industry
4.0 and Internet of Things (IoT) aspects.
Despite being located so close to each
other, the refinery and TEM were totally
separate from both an electrical and automation
standpoint prior to the acquisition.
So, RaM embarked on a complex
project, which included engineering and
technology solutions to achieve industrial
integration between the CCGT and the refinery
plant. The multidisciplinary project
consisted of the following main activities:
■ Installing a high-voltage (HV) electrical
cable interconnecting the separate HV
substations of RaM and the TEM plant.
■ Upgrading and modifying the GE GT
(frame 9E) combustion system.
■ Upgrading the electrical control system
and cogeneration plant with a more integrated
distributed control system (DCS).
RaM's Technology and Engineering departments
conducted important research
during the design phase. The groups investigated
and evaluated available products
and technologies to determine the
most innovative solutions for the project.
Due to the various competencies
involved, a classic turnkey model was
adopted. Three main contracts were coordinated:
Terna Rete Italia was responsible
for electrical interconnections, ABB
for general control system work, and GE
for GT upgrades. The remaining balanceof-plant
and ancillary system tasks were
carried out by RaM with the support of
other minor subcontractors.
The first step of the project-assigned
www.powermag.com
to Terna with ABB as a subcontractor-
was to connect TEM's electric production
directly to refinery loads, reaching a complete
self-production configuration, with
capability to export the energy surplus to
the national grid. To accomplish the task,
a new HV electrical cable was installed,
interconnecting the two separate HV substations.
The distance between the substations
was about 300 meters, requiring
various modifications at both sides in order
to provide start/arrival feeders.
With this new interconnection cable,
the existing TEM HV grid feeder was
added to two existing refinery HV lines.
The new configuration significantly improved
electrical reliability and flexibility
of the RaM-TEM and 150-kV national grid
connection. Furthermore, with Terna and
ABB cooperation, an additional synchronization
system was studied and implemented
at the interface with the national
grid battery limit switch breaker, with direct
control of the 9E GT MARK VIe frequency
governor in TEM.
The HV electrical protection and DCS
strategy had to be thoroughly reviewed
and checked in order to guarantee the
approval of the Transmission System
Operator (TSO) grid code. It also had
to comply with several specific requirements
related to the detection of possible
electrical faults, and potential
blackout and islanding events.
Regarding HV control system architecture,
an extensive integration and upgrade
based on IEC 61850 bus protocol was
completed through the application of a
specific ABB family of products (REx600
series) for electrical protection relays.
This architecture enabled an easier signal
interchange and integration of HV assets,
POWER | October 2020
http://www.powermag.com
POWER October 2020

Table of Contents for the Digital Edition of POWER October 2020
