Sacramento Municipal Utility District

A municipal utility serving a metropolitan area of over a million people asked GRIDiant to demonstrate how GRIDfast could improve the load serving and import capability of its system. Specifically, GRIDfast’s objectives were as follows:

• To evaluate all cases and Critical Contingencies to determine the effect of additional DG and capacitance resources on the system’s load serving and import capabilities

  
  

• To determine the optimum locations and size for placement of additional distributed generation (DG) and capacitors within the system

  
  

• To optimize the system voltage profile to reduce system voltage variations

  
  

• To develop a new planning tool for measuring and verifying the correctness and effectiveness of DG and capacitor placements relative to the load serving and import capability of the system.

  
  

GRIDiant was supplied with several High Load Power Factor and Low Load Power Factor planning cases. The utility also specified 13 critical system contingencies that included 7 single (N-1) and 6 double (N-2) contingencies. All of the standard control devices, such as generator reactive power and voltage settings, Tap Changers Under Load Controls (TCULs), and SVDs were assumed active during the optimization.

GRIDfast analysis of GRIDiant DG placement and Capacitor Placement resulted in increased system load serving and import capability:

• The addition of 145 MW DG (approximately 4.15% of the total system load) with limited reactive power capability to the High Load Power Factor case increased load serving capability by 150 to 180 MW (4.3% to 5.7% of total load). The import capability increased by 5 to 65 MW (0 to 3% of import capability).

  
  

• The addition of 158 MW DG (approx. 4.51% of the total load) with limited reactive power capability to the Low Load Power Factor case increased the load serving capability by 200 MW to 230 MW (5.5% to 7.8%). Significantly, the import capability increased by 182 MW to 311 MW (9.9% to as much as 17.67% of import capability).

  
  

• The addition of 175 MVAR of capacitors to the transmission system for the High Load Power Factor cases increased the load serving capability by 16.7 MW to 66.7 MW (0.5% to 2.12% of the load). The import capability increased by 30 MW to 90 MW (1.5% to 4.55% of the import capability).

  
  

• The addition of 300 MVAR of capacitors to the Low Load Power Factor cases increased the load serving capability by 135 MW to 250 MW (3.85% to 8.49% of the total load). Significantly, the import capability increased by 240 MW to 300 MW (13.09% to as much as 16.96% of the import capability).