Using control systems to optimize microgrids with CHP - Thermo Systems

 
Using control systems to optimize microgrids with CHP - Thermo Systems
Using control systems to optimize
microgrids with CHP
Proper system integration is key in today’s increasingly complex projects.

Serge Zinger, Account Executive, Thermo Systems LLC; and Jason Wittkamp, PE, Director, Thermo Systems LLC

Photo Serge Zinger.

The microgrid/CHP system at the TWA Hotel.

          icrogrids are a focal point of dis-          Whether a district energy system is       tem (PMS). All of these will be used to

M         cussion in the district energy
          industry, and this trend does not
          appear to be going in any other
direction but up. As the demand for
microgrids has increased, so has their
                                                 considering a traditional microgrid, one
                                                 coupled with CHP, or a hybrid microgrid, a
                                                 major area of focus should be the supervi-
                                                 sory control and data acquisition (SCADA)
                                                 automation, balance-of-plant (BOP) con-
                                                                                                 integrate the OEM equipment and enable
                                                                                                 the microgrid to function as one coordi-
                                                                                                 nated system. This SCADA plant control
                                                                                                 system should be robust, reliable and
                                                                                                 responsive to make sure the entire
complexity. End users want to gain effi-         trol system and power management sys-           microgrid system works as designed.
ciencies from new technologies and
hybrid systems to optimize their micro-
grids. With the increasing complexity, it
is critical to incorporate robust, adapt-
able controls to ensure the successful
commissioning, operation and mainte-
nance of these systems. Whether the
project driver is a post-natural-disaster
recovery, the aftermath of wildfires or
an energy reliability/resiliency goal,
microgrid solutions are being discussed
and deployed.
      Microgrids are sophisticated systems
that can generate electrical energy in
parallel with or independent of the local
electrical utility (main grid). Microgrids
typically consist of a prime mover (com-
bustion turbine or reciprocating engine)
that can produce power/electrical energy,
and they are often utilized with combined
heat and power technology to produce
steam or hot water. There are also hybrid
microgrid systems – consisting of addi-
tional original equipment manufacturer
                                                    Photo Serge Zinger.
(OEM) components – which are gaining
popularity.                                      A microgrid/CHP system operator monitors hot water production at a SCADA workstation.

© 2020 International District Energy Association. ALL RIGHTS RESERVED.                            District Energy | Spring/Summer 2020   9
Using control systems to optimize microgrids with CHP - Thermo Systems
To illustrate the successful deploy-       The PMS is typically responsible for            mize the system’s efficiency and return
ment of microgrid systems, it is useful to      breaker control/interlocks, load man-           on investment. A BOP control system
explore three different customer types in       agement (automatic load shed and/or             can be installed within these facilities to
the New York, N.Y., metro area: Hudson          restore) and coordination of generating         coordinate and control the plant’s OEM/
Yards, a real estate megaproject; the TWA       resources. The PMS controllers require          BOP equipment and ensure the waste
Hotel at John F. Kennedy International          fast response times to handle unex-             heat is utilized effectively. The BOP will
Airport; and New York University. While         pected events and to ensure the cogen-          also provide control of all the miscella-
the considerations and needs driving each       eration facility is kept on line through        neous systems within the plant, which
of their decisions to implement a micro-        upsets. In addition, the PMS provides           is required to keep the electrical gen-
grid may have varied, one critical com-         remote monitoring/control and long-term         eration equipment operational. These
mon factor for all was the selection of         historical trending using an overlaying         systems typically include natural gas,
an industrial-grade SCADA solution with         SCADA system. The sequence-of-events            lube oil, gas detection, feedwater, cool-
a programmable automation controller-           reporting for analyzing alarms and deter-       ing water, plant HVAC, etc. Similar to the
based plant control system.                     mining trip root cause is also commonly         PMS, a SCADA is overlaid on top of the
                                                included. Utility companies require             BOP to provide remote control/monitor-
MAXIMIZING POTENTIAL                            access into the PMS to monitor critical         ing, long-term historical trending, and
      Regardless of who the microgrid user      microgrid information and to be able to         alarm management.
is, or what the drivers are, the key to a       trip generating resources offline should              See figures 1 and 2 for examples
successful project is the proper integra-       the need arise.                                 of SCADA human-machine interface
tion of OEM components and the intelli-              Many microgrids include cogenera-          screens depicting, respectively, the CHP
gent dispatch of energy, both electric and      tion or CHP equipment as the source of          system process equipment and the PMS
thermal.                                        on-site power generation. These cogen-          used for management and/or coordina-
      Microgrids with multiple generating       eration units typically utilize natural gas-    tion of electrical systems.
resources, energy storage, varying loads        burning engines or combustion turbines.               Effective coordination between the
and a connection to the utility company         Cogeneration facilities require use of the      PMS and BOP systems is essential for
require a power management system.              engine’s or turbine’s waste heat to maxi-       fully maximizing the cogeneration and

FIGURE 1. Screenshot of combined heat and power system overview.

Source: Thermo Systems LLC.

10     District Energy | Spring/Summer 2020                            © 2020 International District Energy Association. ALL RIGHTS RESERVED.
Using control systems to optimize microgrids with CHP - Thermo Systems
microgrid potential. Every site will have
a unique solution based on utility agree-
ments, electrical generating resources,
equipment capabilities and thermal load
profiles.

THREE SYSTEMS, UNIQUE SOLUTIONS
      The microgrid systems with cogen-
eration operating at the three sites in
New York – Hudson Yards, the TWA Hotel
and New York University – were each
established with different goals and driv-
ers. These included having the ability to
reliably keep the lights on and provide
heating and cooling to campus buildings,
use the microgrid as an infrastructure
enhancement to attract tenants, reduce
the site’s carbon footprint and be the
property’s sole source of power. These
customers are all achieving their goals
with microgrids that exemplify the effec-
tive use of control systems.

Hudson Yards                                        Courtesy Related Oxford.
    On Manhattan’s West Side, Hudson
Yards is New York’s newest neighborhood,         Restaurant view, the shops at Hudson Yards.

FIGURE 2. Screenshot of power management system overview.

Source: Thermo Systems LLC.

© 2020 International District Energy Association. ALL RIGHTS RESERVED.                         District Energy | Spring/Summer 2020   11
Using control systems to optimize microgrids with CHP - Thermo Systems
considered the largest private real estate        controller, the BOP collects information        son Yards CHP plant. The thermal and
development in the city since Rockefeller         from the chilled- and hot water-consum-         electric loads will likely never be equal.
Center. Comprising 28 acres, it will ulti-        ing residents and tenants on the prop-          As a result, an advanced control scheme
mately include more than 18 million sq ft         erty. The BOP utilizes this information         had to be developed to determine where
of commercial and residential space, along        to determine where to invest the waste          the output of the engines will be set.
with more than 100 shops, a collection of         heat energy from the engine generator.          This control scheme takes into account
restaurants, a public school, 14 acres of         The waste heat can be used to generate          the electric rate structure with the util-
public plazas and gardens, and more. The          hot water, chilled water or both via the        ity company, availability of other plant
microgrid/CHP system serving Hudson               use of an absorption-type chiller.              assets and criticality of the load consum-
Yards comprises four reciprocating                     Once the waste heat energy is prop-        ers. Additionally, the control scheme pro-
engines, four directly coupled absorption         erly allocated, the BOP can determine           vides the ability to limit some customers’
chillers and a free-cooling system.               whether it has too much or too little           consumption in extreme cases. Without
     Operation of the Hudson Yards micro-         waste heat available. If there is excessive     this control scheme and coordination,
grid system is financially driven. Depend-        waste heat, the plant will be required          the engines cannot run at an optimal
ing on conditions at the site, the system         to reject the heat using cooling towers,        output, and the Hudson Yards plant
may be either thermally or electrically           which is a waste of the electrical energy       would not meet the needs of its cus-
led. Regardless of which approach is              created from the generators. On the             tomers or could overproduce and nega-
selected, the objective is to ensure that         other hand, if there is insufficient waste      tively affect their efficiency and payback
the tenant/retail spaces receive the best         heat, then other boiler and chiller assets      period.
payback.                                          from the facility will need to be utilized.
     Once electrical demands are satis-           Based on the current state, the BOP will        TWA Hotel
fied, the electrical output of the engines        request that the generators increase or              In another case, the TWA Hotel –
may need to be increased in order to              decrease output in an attempt to balance        formerly the iconic Eero Saarinen-designed
produce more waste energy to satisfy              the waste heat with the thermal demand.         TWA Flight Center – at Kennedy Airport
the thermal demand (chilled or hot water)              In a similar fashion, the PMS pro-         in Queens was constructed without con-
of the site. The decision of where to set         grammable automation controller is              nection to the electrical grid. This was
the engine’s output is determined with            monitoring the demand of the electric           done to avoid the high utility prices and
input from both the BOP and PMS sys-              energy customers to determine the               costs for upgrading the old interconnec-
tems. Using a programmable automation             appropriate electric output of the Hud-         tion infrastructure that once provided

     Photo Shutterstock.

The new TWA Hotel opened to guests in May 2019.

12         District Energy | Spring/Summer 2020                          © 2020 International District Energy Association. ALL RIGHTS RESERVED.
Using control systems to optimize microgrids with CHP - Thermo Systems
power to this 1960s-era TWA terminal
building. With the aid of the microgrid,
all the electrical and thermal energy at
the TWA Hotel is generated on-site.
      The property’s microgrid includes
three reciprocating engines and an elec-
tric storage system consisting of two
batteries. The electricity and waste heat
generated by the engines is utilized to
produce the hot and chilled water for the
hotel and convention center. The electric
storage system provides the means to
allow the engines to baseload while the
battery maintains frequency and voltage.
The electric storage system also provides
a safety net to keep the lights on through
any unexpected interruptions of power
to the plant.
      The coordination between this sys-
tem’s BOP and PMS is intertwined on
many levels. In this case, both systems
were combined into a single program-
mable automation controller, allowing
for one central processor to monitor
conditions and instantaneously make
operating decisions. Without the grid for
reliability and inertia, the plant’s control
system must make decisions regarding
turning on and off engines, charging or
discharging the battery, and using either           Photo littleny, iStock.

gas-fired or electric chillers. Load shed-
                                                 New York University in Manhattan’s Greenwich Village.
ding of noncritical loads in the case of
an emergency is also utilized to main-
tain plant operations. Tight coordination        operate at maximum capacity, and the             COMBINING BOP, PMS
between the PMS and BOP enables reli-            duct burners of the heat recovery steam                Effectively integrating the BOP and
able, effective and efficient operation of       generators modulate to match the steam           PMS systems requires planning and con-
this plant.                                      demand of the steam turbine generators,          sideration upfront. The most streamlined
                                                 chiller and heat exchangers as needed.           and cost-effective means is to combine
New York University                              NYU utilizes energy from the utility com-        these systems into a single program-
     In Manhattan’s Greenwich Village            pany to make up the excess demands of            mable automation controller, as seen in
neighborhood, New York University (NYU)          the campus buildings. The plant operates         the TWA Hotel example. This is an indus-
operates a microgrid with CHP equip-             in this fashion 99 percent of the time.          trially hardened solution with varying
ment to provide heating, cooling and                   However, in 2012 when Superstorm           levels of redundancy applied to ensure
electricity to its classroom, office and         Sandy hit, and the electrical grid of lower      minimal disruptions to operations. This
dorm buildings. The CHP system includes          Manhattan went dark, the plant had to            approach of a single programmable auto-
two gas turbines coupled with heat               change operations to an electrical island        mation controller is not always practical,
recovery steam generators. The gas tur-          mode. With the safety net of the grid            especially for larger, more distributed
bines create electricity, and the heat           gone, the control systems of the plant           systems. In that case, ensuring that the
recovery steam generators produce                were relied on to manage campus elec-            controllers of the BOP and PMS systems
steam that feeds a steam turbine gen-            trical demand, ensuring it did not exceed        natively communicate with each other at
erator, a steam-driven chiller and steam-        the CHP system’s capacity and endanger           high speeds is imperative.
to-high-temperature-hot-water heat               its operations. In the end, the plant was              To ensure smooth integration, it is
exchangers.                                      able to remain on line during the extended       advisable to have a single provider of
     Under normal circumstances, the             grid outage, and NYU received praise for         the two systems with expertise in both
plant runs per design in a relatively            its vision and planning for an event such        microgrid and CHP applications. Devel-
simple control scheme; the gas turbines          as this.                                         oping an upfront design specification

© 2020 International District Energy Association. ALL RIGHTS RESERVED.                             District Energy | Spring/Summer 2020   13
Using control systems to optimize microgrids with CHP - Thermo Systems
for the control scheme makes sure that       and BOP plant control system. Early             in electrical engineering from Rensselaer
the systems can be put through exten-        engagement with an experienced con-             Polytechnic Institute. He can be reached
sive factory testing before they are         trols integration provider – one that can       at serge.zinger@thermosystems.com.
deployed on-site. Due to the critical        recommend the proper technology to
nature of the loads that microgrids and      apply and has the expertise to deploy it
CHP systems support, on-site testing         – can aid in achieving a successful out-                         Jason Wittkamp, PE, is a
would be disruptive or impossible.           come for the project.                                            director at Thermo Sys-
     Today’s microgrid/cogeneration sys-                                                                      tems LLC, where he has
tems are evolving into complex hybrid                                                                         worked for over 13 years.
systems. In addition to combustion tur-                     Serge Zinger currently                            He is an expert in the in-
bines, reciprocating engines and battery                    holds the position of ac-                         strumentation and con-
storage, these hybrid systems now                           count executive at Thermo        trols industry; his efforts have concen-
include photovoltaic arrays, fuel cells,                    Systems LLC, where he has        trated on utility systems and the efficient
flywheels, etc. – increasingly driven by                    worked for over 11 years.        operation thereof. Wittkamp has exper-
the desire for more sustainable systems.                    He has provided high-level       tise on a multitude of large projects, in-
These control systems, which make            expertise on projects in the district energy    cluding the New York University com-
complex electric and thermal microgrids      marketplace, including microgrids, com-         bined heat and power plant, Hudson
possible, also make it possible to inte-     bined heat and power, landfill gas-to-          Yards cogeneration plant and the TWA
grate renewables and waste heat, thus        energy, and chilled- and hot water distri-      Hotel microgrid, to name a few. A licensed
lowering carbon emissions.                   bution. His past work experience includes       professional engineer, Wittkamp has a
     As these systems grow in size and       the positions of general manager of engi-       Bachelor of Science degree in mechanical
complexity, so does their dependency         neering at Panasonic Electric Works and         engineering from Rutgers University. He
on being integrated into a robust, reli-     applications engineer at Deutsch Relays.        can be contacted at jason.wittkamp@
able and appropriately matched SCADA         Zinger has a Bachelor of Science degree         thermosystems.com.

14    District Energy | Spring/Summer 2020                          © 2020 International District Energy Association. ALL RIGHTS RESERVED.
Using control systems to optimize microgrids with CHP - Thermo Systems Using control systems to optimize microgrids with CHP - Thermo Systems Using control systems to optimize microgrids with CHP - Thermo Systems
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