CEC/NPT/SVP

Silicon Valley Power (SVP) is a municipal network of 850 buses serving the city of Santa Clara, California. It comprises two 115-kV main feeds, a 60-kV transmission system, and 48 or more distribution feeders of 12 kV, lightly loaded with about 422 customer locations. The SVP system has approximately 1,000 line segments with 106 switchable branches connecting them, 101 switchable capacitors, and six on-site generators with megawatt and megavar capability.

The project required development of a detailed electrical model of the SVP combined Transmission and Distribution system, wholly integrated into the surrounding Western regional transmission system, using a methodology developed by New Power Technologies. The study showed that the effort involved in developing the model was justified by GRIDfast’s speed and robustness in running the large model, and in producing detailed, bus-specific, ranked analytical outputs, and by GRIDfast’s ability to expedite the model-building activity.

GRIDfast was applied to the model, first, to optimize system performance under multiple load scenarios under specified conditions and constraints and system performance objectives, then, to determine the feasibility of GRIDiant locating (bus-specific locations) and right-sizing distributed energy resources (DER) on the distribution grid, as well as predicting the actual dollar value return for the utility company. DER included distributed generation (DG), capacitance (reactive power resources), and targeted, dispatchable load management (demand response, or DR).

Integrated T&D grid performance objectives included the following:

• Minimize real power losses

  
  

• Minimize reactive power consumption

  
  

• Minimize system voltage variability, with a target voltage of 1.05 per unit (PU)

  
  

• Increase system load serving capacity

  
  

• Reduce utility system costs

  
  

Study results included the following:

• Before considering distributed DG, reactive power, and dispatchable DR additions, GRIDfast “re-control” measures demonstrated that “limited resetting of a few localized controls can have a pervasive impact on voltage and performance across the network, with beneficial effects far less localized than conventionally thought.”

  
  

• GRIDfast identified and ranked hundreds of individual locations (buses) in the system under multiple load scenarios where incremental changes of active and reactive capacity and load management would yield significant improvement in performance, stability, and efficiency of the combined T&D system as defined by predetermined objectives.

  
  

• GRIDfast considered not only local system impacts, which might be predicted from an analysis of load flow results, but also impacts at locations in the system that were removed from the site of the capacity addition.

  
  

• Under an optimized DER portfolio, the Real power (P) losses within the SVP system were reduced by 33-40%, and reactive power consumption was reduced by 28-45%…There were significant loss reductions in the surrounding regional transmission system as well. The DEP projects could be deployed to eliminate low- and high-voltage buses, improve network voltage profiles, and reduce the amount of real power stress in the system. The benefits were not limited to peak load conditions. In some cases there were greater benefits under conditions other than the Summer Peak.

  
  

• In a real-world context, even relatively small DGs, averaging much less than 150 kW, can deliver disproportionate beneficial impact. In fact, one of the highest priority potential DG sites that GRIDfast flagged within the Distribution grid called for just 7 kW to support one customer’s 14 kW load. Notably, this locale was so critical to the grid that the additional capacity GRIDfast identified would benefit the entire interconnected T&D system.

  
  

• DER additions identified by GRIDfast increased the system load serving capability (LSC) of a summer-load SVP T&D system under a single-outage contingency scenario by 117.6 MW.

  
  

• A GRIDfast-produced GRIDiant DER Portfolio deployed in the SVP grid could also save the surrounding, connected Pacific Gas & Electric utility thousands of dollars per day during peak loads because of the interconnectivity of their grids. The study estimated that, “the dollar value of network benefits associated with GRIDiant DER Portfolio projects could be used to derive value-sharing financial incentives for real projects that yield network benefits.”