IEEE Power & Energy Magazine - March/April 2020 - 75

contingency reserve, the EMS will send the MW set point
to the ESS.

Integration of the ESS With
System Operation Platform
To achieve the full benefit of the SSPC ESS in support of the
utility's day-to-day system operation needs, the ESS must be
incorporated as a resource in its system operation platform
so that the EMS could dispatch the ESS as needed. However,
fully integrating the ESS is not a trivial task. It requires an
understanding of the system operation scheme and the customization of software platforms to incorporate the ESS. The
following sections provide several system operation aspects
and discuss a potential option for including the ESS within
the company's operational platform.

Day-to-Day System Operation

ing the necessary feasibility tests and optimizing across the
larger EIM footprint, sends signals to PGE that are then used
by the BAO to dispatch the resources through the utility's
EMS. The overall system operation process is outlined
in Figure 7.

Pathway to Integration With
System Operation Platform
To integrate the SSPC ESS with PGE's day-to-day operation platform, the ESS must be modeled using the utility's
resource modeling tool. The major parameters used to model
the ESS with this tool are listed in Table 1 as are the sources
of information used for determining parameter values.
Once the ESS is modeled using the resource modeling
tool, it will be available for daily allocation into various services. The allocation schedule produced will eventually be
used for the day-ahead scheduling of ESS operations.
The utility is also building an EMS interface for dispatching
its ESS assets (SSPC and future units). An illustrative version

BAOs

Real-Time Scheduling

PowerOps

Day-Ahead Scheduling

Power operations (PowerOps) and balancing authority operators (BAOs) are the main groups involved in the day-to-day
operation of the utility's system.
There are two functions of PowerOps: day-ahead and real-time
scheduling. The day-ahead schedResource Modeling
uling function uses an optimizaDay-Ahead Schedule
tion tool to model generating
* Heat Rate
* Load Forecast
resources using parameters, e.g.,
* Ramp Rate
* Resource Availability
* Min/Max Generation
heat rate, ramp rate, min/max
* Gas Purchase
generation, and the allocation of
Contract
Resource Allocation
resources to a variety of services,
* Long-/Short-Term
e.g., baseload, frequency response,
Hydro Contract
* Base Load
and reserves. This function then
* Wind Forecast
* Frequency Response
creates hourly day-ahead sched* Reserve
ules via software, using data on
load forecasts, the availability of
resources, gas purchase contracts,
short-/long-term hydro contracts,
and wind forecasts. The day-ahead
Execution of Day-Ahead Schedule
schedule is then transferred to the
* Several Hours to Under an
real-time function for execution.
Hour Ahead
Depending on any changes in
* Accommodate Change in System
the forecast and system condiCondition and Forecast
tion, the real-time group modifies
* Communicates With CAISO for
the day-ahead schedule within a
EIM Participation
period of under an hour to several
hours ahead. The real-time function also sends hourly plans and
schedules to the BAO and California Independent System Operator
(CAISO) for participating in the
EMS
energy imbalance market (EIM).
* Dispatch Resources
Plans for each hour are sent about
* Manage Real-Time
60 min before the hour, while
Changes
revisions are sent (by the BAO)
40 min before the hour. The CAISO
EIM market engine, upon perform- figure 7. The day-to-day system operation scheme. min/max: minimum/maximum.
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IEEE Power & Energy Magazine - March/April 2020

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