Document ID: EPA-HQ-OAR-2009-0491-4686
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2011-10-14T04:00Z

F. Local Reliability Rule

      The local reliability rule for Northport Gas Burn (IR-5) for 2011 remains the same as last year and are provided as a guide for unit commitment. Use of information from the 2010 Summer Operating Study are still valid since there have been no significant system changes in the area. For the 2010 period an analysis was conducted to determine the Long Island load level up to which Northport units can be permitted to burn gas depending on how many units are online as well as the number of cables in service.  Power flow simulations were prepared to represent the instantaneous loss of fuel, with those units continuing to produce MVAR output for 20 minutes.  During this time, operators would be able to put quick start GTs online, increase remaining steam units to their DMNC capabilities, adjust phase shifters, and switch on capacitor banks as needed.

                                 TABLE II-F-1
                    Steam Generation Resources at Northport
                                     Unit
                                 Ratings (MW)

DMNC
Continuous
Northport Steam 1
                                                                          395.0
363
Northport Steam 2
                                                                          381.7
363
Northport Steam 3
                                                                          395.2
363
Northport Steam 4
                                                                          399.2
363
Total
1571.1
1452

	
      1. Assumptions
      
         Several base assumptions, depending on the case, were made to observe conservatism and to make a stressed case.  These assumptions are as follows:
          91% System Power Factor (note: it does vary by bus location)
          Northport Units online at DMNC 
          One Barrett Steam Unit online
          Caithness CC online
          Dunwoodie and Sprainbook series reactors in service (Y49 series reactor bypassed)
          Four (4) shunt reactors in service on Y49 and Two (2) shunt reactors in service on Y50
          Northport Norwalk Harbor (NNC)
                    i.  In service
                        1. Importing 100 MW with only 2 Cable in Service
                        2. Importing 200 MW with 3 Cables in service
          Neptune import of 660 MW with 0 MVAR flow
          Contractual MVAR flow split on Y49, Y50 & NNC
          Capacitor banks and generation were adjusted based on load level
            
            
            
      1. Analysis
      
         Attached Tables and Diagrams:
          Diagrams II-F-2 (a-c) show the results of this analysis for two, three, and four Northport units, 
          Tables II-F-2 (a-c) list the generation dispatch assumed to obtain operating limits
          Table II-F-2d is the listing of the reactive resource dispatch assumed 
          Table II-F-2e is the guideline for how many units must be run on oil at various load levels depending on how many Northport units are online
         All charts included in the following section, assume 2 NNC cables in-service with 100 MW of imports.  Additional tests were performed with 3 NNC cables in-service and 200 MW of imports but are omitted here as the results are very similar.
         
         
         Additional Comments:
          At each load level, the loss of gas supply was simulated by reducing the MW output of the Northport steam units to zero and fixing their MVAR output to pre-fault levels.
          The point at which the voltage on the 138 kV system crossed 0.95 p.u. on contingency (violates criteria) was used as the operating limit.  Using a 5% safety margin from that point is the recommended Long Island system load level for running Northport units on gas.
          With the new NNC cables and LTE/STE ratings in place, the LTE overloads on the NNC for loss of three Northport units have been reduced from prior years.  With 2 cables in-service there is a small LTE overload and completed eliminated with 3 cables in-service.[,]   Adjusting inter-ties and on-island generation can be used to rebalance loadings if needed.
          For the loss of Northport units, turning on quick start GTs at Barrett and Holtsville and/or reducing the Con Edison wheel helps compensate for the MW loss.  After the quick start GTs are online, system voltages are within criteria.  Load flow simulations confirm that after the MVARs from the Northport units are lost, system voltages recover to acceptable levels.
          Installation of Caithness in 2009 provided additional voltage support on contingency since the unit has more MVAR capability than other on-island generators and with its higher efficiency, it is expected to be in operation.  This allowed for Northport units to burn gas at slightly higher load levels.
                                DIAGRAM II-F-2A
         Transmission Voltages for the Loss of Gas Supply at Northport
                   L/O 2 Northport Units with 2 Units Online
                       2 Cables In-Service 100 MW on NNC
                                       
                                       
                                 TABLE II-F-2A
                   Generation Dispatch for Diagram II-F-2A 
                                DIAGRAM II-F-2B
         Transmission Voltages for the Loss of Gas Supply at Northport
                   L/O 3 Northport Units with 3 Units Online
                       2 Cables In-Service 100 MW on NNC
                                       
                                       
                                 TABLE II-F-2B
                    Generation Dispatch for Diagram II-F-2B
                                DIAGRAM II-F-2C
         Transmission Voltages for the Loss of Gas Supply at Northport
                   L/O 3 Northport Units with 4 Units Online
                       2 Cables In-Service 100 MW on NNC
                                       
                                       
                                 TABLE II-F-2C
                   Generation Dispatch for Diagram II-F-2C 
                                  TABLE II-F-2D
           MVAR Reactive Resource Dispatch for Loss of Northport Units
                         2Cables In-Service 100 MW on NNC
                                   Bus Name
                                     Max 
                                   Dispatch 
BARRETT1    138.00
                                                                            -75
                                                                              0
NRTHPT2     138.00
                                                                            -75
                                                                              0
PILGRIM     138.00
                                                                            104
                                                                              0
HOLBROOK    138.00
                                                                            104
                                                                              0
HOLTS GT    138.00
                                                                            104
                                                                              0
RVRHD       138.00
                                                                            -27
                                                                              0
FARRCK1     69.000
                                                                             54
                                                                             54
VLYSTRM2    69.000
                                                                             54
                                                                             54
E.G.C.2     69.000
                                                                             54
                                                                              0
GLNWD SO    69.000
                                                                             54
                                                                             54
MASPEQUA    69.000
                                                                             54
                                                                             54
NEWBRGE1    69.000
                                                                             54
                                                                             54
NEWBRGE2    69.000
                                                                             54
                                                                              0
FLWRFLD     69.000
                                                                             27
                                                                             27
INDIANHD    69.000
                                                                             27
                                                                              0
PILGRM      69.000
                                                                            108
                                                                            108
RULND RD    69.000
                                                                            108
                                                                             54
WOLFHILL    69.000
                                                                             27
                                                                              0
BRGHTWTR    69.000
                                                                             54
                                                                              0
BRNTWOOD    69.000
                                                                             54
                                                                              0
STERLING    69.000
                                                                             54
                                                                              0
WATSON      69.000
                                                                             54
                                                                             54
HOLBRK1     69.000
                                                                             54
                                                                             54
HOLBRK2     69.000
                                                                             54
                                                                              0
JAMESPRT    69.000
                                                                             14
                                                                              0
MORICHES    69.000
                                                                           28.8
                                                                           28.8
PECONIC     69.000
                                                                             14
                                                                             14
PTCHOGUE    69.000
                                                                             27
                                                                              0
RIDGE       69.000
                                                                           28.8
                                                                              0
SOUTHOLD    69.000
                                                                         -23.31
                                                                              0
WILDWOOD    69.000
                                                                           28.8
                                                                              0
BRGHMPTN    69.000
                                                                             14
                                                                              0
BUELL       69.000
                                                                             14
                                                                              0
EHAMP       69.000
                                                                             14
                                                                              0
RIV 1       69.000
                                                                             27
                                                                             27
RIV2        69.000
                                                                             27
                                                                              0
SOHMPTN     69.000
                                                                          22.55
                                                                             14
TEMPLE      69.000
                                                                           24.5
                                                                           24.5
TIANA       69.000
                                                                             27
                                                                             27
GRN ACRE    34.500
                                                                             12
                                                                             12
MONTAUK     23.000
                                                                            7.2
                                                                              0
TOTAL
                                                                        1641.65
                                                                          714.3

                                                                            %On
                                                                            43%

                                                                           %Off
                                                                            57%
                                       
                                         
                                TABLE II-F-2E [6]
                   Guideline for Running Northport Units on Oil
                                         
                                  NNC In-Service
                       2 Cables In-Service 100 MW Import or
                        3 Cables In-Service 200 MW Import 
                                         
                                  Load Level
                            Northport Units Online
                                       
                                      One
                                      Two
                                     Three
                                     Four
                                    0-2950
                                       0
                                       0
                                       0
                                       1
                                   2951-3250
                                       0
                                       1
                                       1
                                       1
                                   3251-5450
                                       0
                                       1
                                       1
                                       2
                                   5451-6000
                                       0
                                       1
                                       2
                                       3
         Note1: Differences between 2 and 3 cable operation are not significant
         Note2: Northport Gas Burn Rule Guideline for NNC In Service in 2011 was provided as a guide and are based on the 2010 Summer Operating study since there have been no significant system changes.
         
         
         6 - Values in table II-F-2E above indicate the number of units that can be run on oil.  For example, with NNC In-Service, if three Northport units are online, none have to be run on oil (all three can be on gas) up to a load level of 2950 MW.  Starting at 2951 MW, only one of the three units must be on oil (2 on gas) up to a load level of 5450 MW after which 2 units must be on oil.