Download SEQUENCE OF OPERATION:

CPCN for Bethesda Triangle, LLC
Prepared by South River Consulting, LLC
Bethesda Triangle
Description of Use of
On-site Electrical Generation System
Introduction
The Bethesda Triangle Project is a high rise apartment building located at 4835 Cordell
Ave., Bethesda, Maryland 20814. The building consists of 13 stories of apartments, 4
levels of garage parking, office space on the lobby level and retail space on the plaza
level. An analysis of the benefits of using the on-site standby generation equipment
required for building occupancy as a hedge for the market purchase of electrical power,
based on a residential profile and the projected loads for the Bethesda Triangle (BT)
Project, have indicated that the utilization of the 1800 kW generation unit will provide
savings on future electric purchases in a deregulated market. The on-site system will
operate under this scenario, whenever the market conditions indicate that it is more cost
effective to do so than purchase power on the open market. The generation system is
sized slightly larger than the peak consumption that is currently projected for the project.
Whenever the system comes on-line, any excess generation output may be sold back into
the market or to Bethesda Triangle’s retail supplier. When the system is not operational,
Bethesda Triangle will purchase its power from the market through a retail supply
agreement.
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CPCN for Bethesda Triangle, LLC
Prepared by South River Consulting, LLC
Generation System
The generation system, which was installed for the Project, is a Cummins Power
Generation 2000DQKC generator set with a Power Command Control System and utility
paralleling switchgear. The generator set has a prime power rating of 1825 kW at 60 Hz
and generates at 13.2 kilovolts. The scope of supply is detailed in the attachments.
Generator set data sheets and specifications are also included. A one-line diagram and an
interconnection protection scheme for the local distribution company (PEPCO) tie in is
also provided and the following includes the sequence of operation description for
utilization in the market. The system ties into the existing feed to the building from
PEPCO and therefore no transmission line is required. The generator and switchgear
equipment are located in an enclosed room on the G1 (garage) level of the building next
to the PEPCO vault as seen in the attached drawing, “G1 Gear Room”.
Generation Operational Strategy
The use of the generator to respond to market conditions is based on a two-part strategy
to minimize electric procurement costs and extract value from the market for sales of
excess generation. The generator dispatch is based on mitigation of fixed cost and
extreme energy cost avoidance. The unit will produce energy anytime the marginal cost
of delivered power exceeds the marginal cost of operating the unit. The energy charge
component of the electric cost will be displaced whenever the generator is operating.
Confidential and Proprietary
CPCN for Bethesda Triangle, LLC
Prepared by South River Consulting, LLC
The second element of the strategy is for the project to realize revenue from the sale of
the excess generation into the market as an energy resource. Utilizing existing market
algorithms, the market data will be analyzed to determine the appropriate time to selfgenerate and sell the excess power into the market.
Based on market conditions, operation of the generator will be limited to less than 1,000
hours per year. This limitation is driven by PJM market economics and any operation
beyond this limit other than for emergency use, would have a negative financial impact.
Electric Sales and Purchases
Bethesda Triangle’s electric service contract will be for the supply of electric service to
meet 100% of the project’s requirements. When utilizing the on-site generation, the
system will be treated as a behind the meter resource, which nets the load and generation.
Excess power sales for the energy will be marketed through the retail supplier or other
qualified market participant.
Bethesda Triangle
SEQUENCE OF OPERATION
Loss of Normal Power: System is given a signal to start by receipt of a start signal from
the transfer pair control voltage sensing or a remote device. On receipt of this signal, the
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CPCN for Bethesda Triangle, LLC
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generator set automatically starts, and accelerates to the rated frequency and builds up to
the rated voltage. The control system verifies that the generator set is at 90% of rated
voltage and frequency or more, and the breaker pair operates to connect loads to the
system bus.
Fail to Crank or Fail to Start: On receipt of a start signal, following a start time delay,
the control system issues a command to start the engine. The control verifies that the
engine is rotating when the start command is issued. If the engine does not rotate when
the start command is issued, the unit stops cranking, then tries again. If the engine still
does not rotate, the generator set is shut down and a “FAIL TO CRANK” shutdown
alarm is issued. If the generator set cranks but fails to start after the overcrank time delay
(in the generator set control) has expired, the unit will be shut down, and an alarm will
sound.
Fail to Synchronize: If the generator set fails to synchronize after a preset time delay an
alarm will sound, but the unit will continue to attempt to synchronize until signaled to
stop by manual operation of the control switches on the generator set.
Fail to Transfer: The control system continuously monitors the breakers as they are
issued signals to operate. If a breaker does not operate properly, the control system
provides fallback operation modes to prevent operation of the generator set in parallel
with the utility service for sustained periods of time.
Return of Normal Power: When all of the system start signals are removed from the
digital power transfer control, the system will begin a retransfer process in either an open
or closed transition mode, as selected by the operator. If running in the closed transition
mode, the system synchronizes the generator set to the utility, closes the utility breaker,
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CPCN for Bethesda Triangle, LLC
Prepared by South River Consulting, LLC
ramps down the load on the generator breaker to a minimum value, then opens the
generator bus breaker. If running in the open transition mode, the system transfers back to
the utility by opening the generator bus breaker, then closing the utility breaker at an
operator programmed time period later. When all loads have been transferred back to the
utility, the generator set operates at no load for a cooldown period. When the cooldown
period has been completed, the generator set shuts down. If a system start signal is
received during the cooldown period, the system immediately re-transfers to generator set
power, as described in “Loss of Normal Power”.
Automatic Operation - Peak Shave Mode:
The peak shave mode may be selected via dry contact or locally from the Operator
Interface Touchscreen. On receipt of this signal, the generator set starts, accelerates to
rated frequency, and builds up to rated voltage. The PowerCommand Control monitors
the generator set, and on finding the generator set at 90% of rated voltage and frequency,
and in synchronism, closes the unit to the bus. The UM breaker remains closed.
Once the generator set is connected to the utility, the Master Control PLC will calculate
the required generator KW level using a transducer input from the switchgear. The
generator will then ramp up to assume the load above the peak shave KW setting (set on
the operator touchscreen). This will allow the Utility to maintain a constant load while
the generator system adjusts to supply the load “peaks”.
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CPCN for Bethesda Triangle, LLC
Prepared by South River Consulting, LLC
Full Load Mode Selected: Once the generator set is connected to the utility, the
generator will ramp up to assume the load up to the full load setting of the generator
(adjusted on the generator set setup screen). If the building load is less than this setting,
excess power will be exported to the utility. The #32 reverse power relay is disabled in
this mode.
On receipt of an unload (Peak Shave / Full Load Off) signal, the generator will gradually
ramp down to a preset level, and 52-G will open. The generator set paralleling breakers
will open and the generator sets will then run unloaded for a cooldown period and shut
down.
If there is a power failure while in the Peak Shave Mode or Full Load Mode, the utility
protective relays on the UM breaker will activate a Lockout Relay which trips 52-UM.
The Lockout relay must be reset at the switchgear.
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