Feasibility Study Shaw Environmental, Inc. 12MW Landfill Gas Generation Interconnection J.E.D. Solid Waste Management Facility Holopaw Substation September 2013 1 of 12
Table of Contents GENERAL... 3 SHORT CIRCUIT STUDIES... 4 CASES STUDIED... 4 AVAILABLE FAULT CURRENTS... 4 IMPACT OF SHAW ENVIRONMENTAL GENERATION ON FEEDER... 4 LOAD FLOW STUDIES... 5 CASES STUDIED... 5 VOLTAGE CONDITIONS... 5 POWER FLOW CONDITIONS... 5 IMPACT OF SHAW ENVIRONMENTALADDITIONAL GENERATION ON FEEDER... 5 SYSTEM PROTECTION AND GROUNDING REVIEW UNINTENTIONAL ISLANDING... 6 FEEDER PROTECTION... 6 GROUNDING... 6 STABILITY ANALYSIS... 7 RECOMMENDED CONFIGURATION... 8 INTERCONNECTION... 8 Primary facilities... 8 System protection: Unintentional islanding... 8 System protection: other functions required... 8 VOLTAGE REGULATION... 9 Shaw Environmental Generation... 9 M0629 feeder... 9 HOLOPAW SUBSTATION UPGRADES... 10 Feeder protection... 10 INTERCONNECTION FACILITIES... 11 PRIMARY FACILITIES... 11 PROTECTION & CONTROL FACILITIES... 11 INTERCONNECTION FACILITIES ESTIMATES... 12 PRIMARY FACILITIES... 12 SUBSTATION, PROTECTION AND CONTROL... 12 FEEDER W0629... 12 COST SUMMARY... 12 2 of 12
General Shaw Environmental has submitted to Duke Energy Florida (DEF) a Generator Interconnection Service Request for its Landfill Gas to Energy Project. Shaw Environmental intends to interconnect 12 MW of generation with the Duke Energy Florida (DEF) distribution system. Connection will be to feeder W0629 out of DEF s Holopaw substation and near the JED Landfill located in Osceola County, Florida. Interconnection of the Shaw Environmental proposed 12 MW generation to the DEF W0629 feeder at the JED Landfill is feasible, provided the generation is operated within certain parameters, specific Interconnection Facilities are installed and certain necessary System Upgrades are completed. This document contains applicable study results, based on initial studies of the proposed interconnection configuration and equipment specifications per the July 22, 2013 scoping meeting. The estimated cost of the Interconnection Facilities and any necessary System Upgrades to allow interconnected operation of the facility are also included but may not be all inclusive. Determination of a definitive in-service date as well as the associated cost of upgrades and equipment will require further study. 3 of 12
Short Circuit Studies Cases studied Short circuit studies were run in which the DEF system and Shaw Environmental s generation were considered as sources able to contribute fault current for faults on the Holopaw Substation W0629 feeder. All faults are modeled as bolted faults with zero fault impedance. Shaw Environmental s generation fault contributions were modeled using transient reactances. The results of the studies are at the end of this section. Available fault currents In the planned configuration (delta/wye-grounded step-up transformer), Shaw Environmental s generation facility will increase fault currents on the feeder at certain locations. At the Holopaw substation bus the available three phase fault current will increase by 45% and the phase to ground fault current will increase by 38%. At the point of interconnection the available three phase fault current will increase by 110% and the available phase to ground fault current will increase by 156%. Impact of Shaw Environmental generation on feeder Interrupting ratings of protective devices are affected by the addition of the 12 MW generation. Approximately six (6) existing recloser installations will have their fault current rating exceeded with the addition of this generation and will need to be upgraded to reclosers with a higher fault duty rating. 4 of 12
Load Flow Studies Cases studied Load flow studies were performed for multiple cases of Holopaw Feeder W0629 in order to determine system conditions with and without the 12 MW Shaw Environmental s generation under various circumstances. Voltage conditions Studies indicated that acceptable voltage levels (between 95% and 105% of nominal) and load flows would be maintained with the Shaw Environmental s generators operating at unity (1.00) power factor, provided that the required system upgrades are completed. The only exception is at the generator s metering point where voltage was calculated at 105.2% of nominal. Power flow conditions For purposes of this analysis a minimum load on the W0629 Feeder of 41, 47 and 48 amps (~ 2 MW), on A, B, and C phase respectively, was used. A maximum load on the W0629 Feeder of 173, 202 and 197 amps (~8.2 MW), on A, B, and C phase respectively was used. Both of these cases are without any contribution from the Shaw Environmental generator. Feeder W0629 is the only feeder connected to the Holopaw substation bank #2 transformer, which consists of 3 single phase 3.33/4.166/4.666 MVA, 230 kv to 25 kv transformers. Impact of Shaw Environmental generation on feeder It is important to note that the Shaw Environmental generation (12 MW) at the JED landfill shall cause reverse power flow situation at the substation for all periods of operation. This was expected and planned for and shall not cause any operational problems provided the generation maintains a 1.00 Power Factor at all times. The maximum calculated reverse power flow on feeder W0629 (at Bank #2 in the substation) was an export (to transmission) of 9.7 MW with an import (from transmission) of 1.4 MVAR. The minimum calculated reverse power flow on feeder W0629 (at Bank #2 in the substation) was an export (to transmission) of 3.2 MW with an import (from transmission) of 3.1 MVAR. Recloser 6156648 (located on 441 just south of 17/92) is located between the substation and the generator and thus will experience reverse current flow when the generators are operating. The maximum reverse current will be about 235 amps. This will need to be studied in more detail to ensure appropriate operation of this device during abnormal situations. 5 of 12
System Protection and Grounding Review Unintentional islanding Due to the capacity of the generation as compared with the feeder load, unintentional islanding is of significant concern. A transfer trip protection scheme from Holopaw substation to the Shaw Environmental generation site (at JED Landfill) shall be required. Feeder protection The existing regulator control is being evaluated by Duke Protection and Control Department. The Recloser 6156648 (located on 441 just south of 17/92) is currently a Cooper VWE and will need to be upgraded to a G&W Viper. A new recloser (G&W Viper) will need to be installed at the start of the new tap line for the generators at the Landfill entrance and 441. Approximately six (6) existing recloser installations (type E) will have their fault current rating exceeded with the addition of this generation and will need to be upgraded to reclosers with a higher fault duty rating (type 4E). Grounding Grounding specifications supplied by Shaw Environmental for the generators and step-up transformer have been reviewed with no DEF objections. All Shaw Environmental sowned equipment will be expected to comply with all applicable codes regarding grounding. 6 of 12
Stability Analysis Due to the size and nature of this feeder and generating facility, stability analysis was not performed. The use of transfer trip with other appropriate backup relay functions should assure quick separation of Shaw Environmental s generation from the DEF system. 7 of 12
Recommended configuration The recommended configuration required for the Holopaw W0629 feeder in order to allow operation of Shaw Environmental generation is as follows. Interconnection Primary facilities The Shaw Environmental generation can be connected at the proposed location, with the following modifications: 1. New 795 AAC three phase overhead line from generator interconnection (primary meter) point to Landfill entrance on SR 441 (approximately 3 miles) 2. Reconductor existing 336 AAC overhead three phase line from Landfill entrance on SR 441 North to intersection of SR 441 with US 17/92 (approximately 9 miles) 3. Installation of new recloser (G&W Viper) on new line to generator at Landfill entrance and SR 441. 4. Installation of Primary Metering at generator location. System protection: Unintentional islanding 1) Isolate Plant during loss of Transmission Voltage or Distribution Bus voltage at Holopaw Substation. A Direct Transfer Trip will be send to isolate the plant in order to avoid unintentional islanding. 2) Actual Step Up Transformer at Plant is 10/12/14 MVA, Duke Energy Distribution Transformers are 3 single phase units with total of 10 MVA. The excess generation towards Transmission System shouldn t exceed 10 MVA. 3) Loss of feeder W-629 will result in loss of auxiliary power (Station Service) for the plant. 4) Additional sources of auxiliary power at the plant shouldn t back feed into feeder W-629 to provide an ungrounded system source. System protection: other functions required Although transfer trip should clear Shaw Environmental generation off line for most abnormal feeder conditions, any protection scheme utilizing remote communications as a primary protection scheme requires backup protection functions. The interconnection relaying referenced earlier will be used, at a minimum, for the following functions: 27 59 81O/U 51V 46 8 of 12
Voltage regulation Shaw Environmental generation DEF will require Shaw Environmental Generation to not actively regulate the voltage at the interconnection point. Rather, Shaw Environmental generation shall operate at unity (1.00) power factor. Shaw Environmental generation could potentially run at the maximum KW allowed by the generators capability curve while maintaining the prescribed power factor. DEF will specify the power factor at which to operate in order to minimize the effects of the generation on the voltage levels for DEF retail customers on the W0629 feeder. DEF may require Shaw Environmental generation to change its power factor from time to time as changes in the DEF system warrant. W0629 feeder Since there will be reverse power flow through the Holopaw substation transformer, existing 25 KV voltage regulation at the substation may require equipment modifications to handle this reverse power flow. Further review via the more detailed System Impact Study will be needed. 9 of 12
Holopaw substation upgrades 1) Since Holopaw Distribution Bank # 2 (230/25KV) is tapped off the West Lake Wales 230KV circuit, a 230KV Breaker will be installed in place of circuit switcher 1122. Protection and Control devices (for this breaker) will be required to help determine generation input. 2) Install potential transformers at feeder location to monitor load side of the feeder breaker W-629. 3) Install SEL-351S6 Control relay at the Feeder W-629. 4) Fiber Optic communication media between JED plant and Holopaw Substation must be installed to interface devices between Feeder protection and JED plant protection relays. This allows control and data exchange between Duke and JED. 10 of 12
Interconnection Facilities Estimates Primary facilities New 795 AAC three phase overhead line from generator interconnection (primary meter) point to Landfill entrance on SR 441 (approximately 2 miles) Reconductor existing 336 AAC overhead three phase line from Landfill entrance on SR 441 North to intersection of SR 441 with US 17/92 (approximately 9 miles) Installation of new recloser (G&W Viper) on new line to generator at Landfill entrance and SR 441. Installation of Primary Metering at generator location. The cost estimate for these facilities is $1,800,000. Protection & control facilities 1) Substation- 230 KV Breaker, Slab extension, Grounding Labor, Conduits, Splice box, Removal of existing Circuit switcher. 2) P&C Potential transformers, Protection relays, Communication Materials, Cables, Relay panels, Communication Interface devices, Control wiring, Relay settings and Commissioning. 3) Fiber Optic Cable (ADSS) and installation for 12 miles. The cost estimate is $ 900,000 11 of 12
W0629 feeder The Recloser 6156648 (located on 441 just South of 17/92) is currently a Cooper VWE and will need to be upgraded to a G&W Viper. Approximately six (6) existing recloser installations (type E) will have their fault current rating exceeded with the addition of this generation and will need to be upgraded to reclosers with a higher fault duty rating (type 4E). The cost estimate for these facilities is $85,000. Feasibility Study Cost Estimate Summary 25 kv Feeder reconductor and new line section $1,800,000 construction Protection, Control, Communications and new 230 kv $900,000 breaker New 25 kv Reclosers $85,000 TOTAL $ 2,785,000 12 of 12