GUIDE FOR MICROGENERATION INTERCONNECTION TO CITY OF MEDICINE HAT ELECTRIC DISTRIBUTION SYSTEM

Transcription

1 GUIDE FOR MICROGENERATION INTERCONNECTION TO CITY OF MEDICINE HAT ELECTRIC DISTRIBUTION SYSTEM Page 1 of 19

2 Table of Contents 1.0 SCOPE PURPOSE LIMITATIONS GENERAL INTERCONNECTION AND PROTECTION REQUIREMENTS Distribution System System Frequency System Voltage Micro Generation Equipment Inverter Operational Settings Sheet Synchronism Voltage Regulation and Power Factor Frequency Control Interconnection Facility Safety Point of Common Coupling (PCC) Point of Disconnection Interconnection Grounding Phase and Ground Fault Protection Over-Voltage and Under-Voltage Protection Over-Frequency and Under-Frequency Protection Anti-Islanding Special Interconnection Protection Flicker Harmonics Typical Interconnection Requirements Single-Phase Inverters Three-Phase Inverters Mitigation of Protection Scheme Failure Maximum Generator Power to be Exported Interconnection Protection Approval CONSTRUCTION General METERING General Meter Requirements Net Billing INSPECTION TESTING Type Testing Verification Testing Protective Function Testing INFORMATION REQUIREMENTS MARKING AND TAGGING...13 Page 2 of 19

3 11.0 MAINTENANCE...13 TABLE 1 RECOMMENDED SERVICE VOLTAGE VARIATION LIMITS...14 TABLE 2 SINGLE PHASE INTERCONNECTION PROTECTION FUNCTION REQUIREMENTS..15 TABLE 3 THREE PHASE INTERCONNECTION PROTECTION FUNCTION REQUIREMENTS...16 APPENDIX 1 DEFINITIONS...17 APPENDIX 2 SINGLE LINE DIAGRAM FOR GRID-DEPENDENT MICRO-DG SYSTEMS...18 APPENDIX 3 SINGLE LINE DIAGRAM FOR GRID-INTERACTIVE MICRO-DG SYSTEMS...19 Page 3 of 19

4 GUIDE FOR MICROGENERATION INTERCONNECTION TO CITY OF MEDICINE HAT ELECTRIC UTILITY DISTRIBUTION SYSTEM 1.0 SCOPE The intent of this Guide is to establish the interconnection requirements of microgeneration with the City of Medicine Hat Electric (City Electric) distribution system. While every precaution has been taken in the preparation of this Guide, it may contain inaccuracies or inconsistencies. The authors of this Guide assume no liability for errors or omissions, or damages resulting from the use or reliance upon the information contained herein. This Guide has been developed without regard to whether its adoption may involve patents on articles, materials, or processes. Such adoption does not assume any liability to any patent owner, nor does it assume any obligation whatsoever to parties adopting this Guide. 2.0 PURPOSE This document is an interconnection application guide that applies to grid dependent and grid interactive microgeneration systems. It establishes minimum uniform requirements relevant to the performance, operation, testing, safety considerations, and maintenance of the interconnection of microgeneration systems with the City Electric distribution dystem and is based on the following principles: The addition of microgeneration systems to the distribution system will not appreciably change the distribution system and its characteristics. The microgeneration inverter must meet the requirements of this Guide. Users, owners, and operators of microgeneration systems need not have any technical expertise. The installation shall meet the requirements of the latest version of the Canadian Electrical Code. Microgeneration systems are deemed to be operating unattended. Microgeneration installations shall require a permit from the City of Medicine Hat Safety Code Services or the authority having jurisdiction in the City of Medicine Hat Electric service area outside the corporate boundaries of Medicine Hat. City Electric personnel will need to be aware of the microgeneration system specifications, operating characteristics, and installed location. Page 4 of 19

5 3.0 LIMITATIONS The criteria and requirements in this guide are applicable to microgeneration facilities with a rated generation capacity of 5 kw or less per service that use a single phase or three phase inverter to generate AC electricity that is in parallel with the City Electric distribution system and have a nominal operating voltage of 600 volts phase to phase AC or lower. 4.0 GENERAL INTERCONNECTION AND PROTECTION REQUIREMENTS The Microgenerator s interconnection installation must meet all applicable national, provincial and local construction and safety codes. The Microgenerator is required to install, operate and maintain in good order and repair at all times, in conformity with good electrical practice, the equipment required by this Guide for the safe parallel operation with the City Electric distribution system. 4.1 Distribution System A Microgenerator's inverter shall be certified to meet this Guide's provisions as detailed in Section 4.1 which defines the power quality and characteristics of the City Electric system to which the Microgenerator is interconnecting. It is the manufacturer's responsibility to ensure that the inverter operates in this environment System Frequency The distribution system operates at 60 hertz. Frequency deviations are typically 59.7 hz to 60.2 Hz System Voltage See Table Micro Generation Equipment Inverter Operational Settings Sheet The Microgenerator owner needs to ensure that the inverter has an Inverter Operational Settings Sheet (IOS) document. The IOS document must certify that the inverter operates within the ranges specified in Section Synchronism Inverters will automatically restart following automatic re-closing of distribution facility electrical equipment as per CSA 22.2 #107.1 (or other equivalent and recognized standard such as UL 1741).It will not be possible for City Electric to co-ordinate inverter Page 5 of 19

6 restart. A synchronizing scheme does not need to be submitted for grid-dependent inverters Voltage Regulation and Power Factor The Microgenerator shall be responsible for ensuring that the voltage levels at the point of interconnection are maintained within the guidelines prescribed by City Electric and/or at least equal to the voltage levels, at all feeder load conditions, prior to the interconnection. City Electric will decide if voltage regulation is expected to be a concern and identify possible solutions at time of application. The Microgenerator is not required to be capable of adjusting the power factor but shall operate in the range of ±0.9. City Electric will not require the inverter to operate in a power factor control mode Frequency Control A Microgenerator's operating frequency must lie between 59.5 and 60.5 Hz. Underfrequency over-frequency protection that automatically disconnects the Microgenerator from City Electric shall not operate for frequencies in the range of 59.5 to 60.5 Hz. The Microgenerator is not required to remain synchronously connected for any frequency excursions beyond this range. 4.3 Interconnection Facility Safety Safety of personnel, the public and of equipment is of primary concern in the design of the interconnection Point of Common Coupling (PCC) The PCC will be considered to be the service entrance unless otherwise stated Point of Disconnection Low Voltage Disconnecting Means To enable City Electric s personnel to work on their facilities, a manual disconnecting means is required between City Electric s facilities and the Microgenerator's inverter. The Microgenerator is responsible for installation of the disconnecting means. The characteristics of this disconnecting means must meet the following requirements and be subject to the approval of the authority having jurisdiction enforcing the Canadian Electrical Code: must provide safe isolation for City Electric s personnel from the inverters. not required to have a lockable, direct, visible means to verify contact operation. do not need a City Electric switch number, and do not need to undergo annual inspections and maintenance. Page 6 of 19

7 All low voltage disconnecting means must: Be adequately rated to break the connected generation/load; Allow simultaneous disconnection of all ungrounded conductors of the circuit; Be externally operable without exposing the operator to contact with live parts; Be capable of being closed without risk to the operator when there is a fault on the system; Be capable of being energized from both sides; Plainly indicate whether in the open or closed position; and Meet all applicable CSA Part II standards and all applicable codes. No switching, clearance, and tagging procedures will be required of the Microgenerator. For all grid-interactive inverters, the manual disconnecting means must also: Be within 5 meters horizontal walking distance of the PCC, unless otherwise approved by City Electric; Be readily accessible to City Electric Interconnection Grounding Single-phase generating systems must be grounded as per the manufacturer s recommendations and the Candian Electric Code Part 1. The inverter manufacturer shall certify that their inverter isolates all sources of fault contribution from a faulted line or distribution element, blocks the transmission of harmonic currents and voltages; and protects the low voltage side from high fault current damage Phase and Ground Fault Protection The Microgenerator shall use an inverter that detects faults or power outages occurring on all ungrounded conductors to which it is connected and then promptly ceases to energize such conductors and does not re-energize until at least 5 minutes after the normal voltage of the City Electric system is restored. The Microgenerator shall employ over-current protection in their interconnection equipment if the inverter is capable of producing current greater than the ratings of the interconnection equipment Over-Voltage and Under-Voltage Protection Provided that the inverter utilized by the Microgenerator is certified to CSA 22.2 #107.1 (or other equivalent and recognized standard such as UL 1741), the Microgenerator will not be required to install additional relays to trip the circuit breaker when the voltage, measured phase to ground is outside the predetermined limits in Page 7 of 19

8 This recognizes: a) that the certification to CSA 22.2 #107.1 (or other equivalent and recognized standard such as UL 1741) guarantees and tests the appropriate protection functionality to operate on abnormal voltage; b) the Microgenerator's generating equipment operates automatically and unattended; c) the generating facility is not manually controlled nor operated by the Microgenerator beyond being turned off and on; and d) it is acceptable that the under-voltage and over-voltage setpoints and reaction times are not adjustable for Microgenerator inverters. The inverter manufacturer shall indicate the time delay for reconnection after City Electric s distribution system voltage and frequency return to normal range and are stabilized. Minimum time for reconnection to be 5 minutes as per CSA C22.2 No The Microgenerator and City Electric will work together to arrive at a solution to any concerns about the voltage levels on the distribution facility. The Microgenerator's automatic reconnection will not be governed by any local operating orders that require manual reconnection upon authorization from City Electric Over-Frequency and Under-Frequency Protection City Electric recognizes that the Microgenerator's generating equipment disconnects on manufacturer preset over-frequency and under-frequency conditions and at manufacturer preset delay times. Additional frequency selective relays to separate the inverter(s) from the electric system in cases of extreme variations in frequency will not be required Anti-Islanding The Microgenerator s generation facility must be equipped with protective hardware and software designed to prevent the generator from being connected to a deenergized circuit owned by City Electric. Certification of the Microgenerator's inverter by an accredited certification organization shall be deemed to meet the anti-islanding requirements of this Guide without any further assessment requirements The Microgenerator is responsible for any damage caused to his equipment or City Electric s infrastructure resulting from improper operation of the Microgenerator s anti-islanding protection. In spite of the above certification of inverters, it is recognized that the effect on antiislanding schemes used by different inverters may require on site testing and/or further evaluation when there is a mixture of generation connected to the same feeder. Page 8 of 19

9 4.3.9 Special Interconnection Protection No special inverter-specific protection and controls, such as out-of-step or loss of synchronism, will be required. City Electric recognizes that the Microgenerator's inverter and its manufacturer preset protection limits are the prime protection mechanism that the Microgenerator will be employing. No additional protection other than the already specified will be required Flicker The microgeneration system shall not cause objectionable flicker on the distribution system. It is recognized that flicker is a site-dependent condition. See CAN/CSA- C and City Electric for specific site requirements Harmonics The microgeneration system employing an inverter certified to CSA C22.2 No is assumed to comply with harmononic distortion limits of City Electric. It is recognized that voltage harmonics is a site-dependent condition. Exceeding the limits may require the Microgenerator or City Electric to take compensatory measures the cost of which would be borne by the Microgenerator. Current harmonics are specified in CSA C22.2 No Typical Interconnection Requirements An Inverter Operational Settings document shall be made available by the Microgenerator to the City Electric to determine if the interconnection equipment and settings are acceptable to its system requirements. The City Electric will work closely with customer to determine whether interconnection and operation within a specific distribution facility is possible. The interconnection equipment shall meet the required protective functions specified in Table Single-Phase Inverters Table 2 of this Guide shows the protective functions required to meet this Guide. Inverters must be certified to CSA 22.2 #107.1 (or other equivalent and recognized standard such as UL 1741) Three-Phase Inverters Table 2 of this Guide shows the protective functions required to meet this Guide. Inverters must be certified to CSA 22.2 #107.1 (or other equivalent and recognized standard such as UL 1741) Mitigation of Protection Scheme Failure If the protective device functions required in Table 2 and Table 3 are performed by the microgeneratoration s control, then the microgeneration shall be designed to have self-diagnostic and fail-safe features. In case of failure of the Page 9 of 19

10 microgeneration s protection function, the microgeneration shall automatically cease to operate in parallel with the City Electric s system Maximum Generator Power to be Exported A Microgenerator's microgeneration system output shall never exceed 5.5 kilowatts (10% above nominal rating). 4.5 Interconnection Protection Approval The Microgenerator shall provide to City Electric complete inverter documentation for review against the requirements of this Guide and for potential impacts on the City Electric distribution system. The documentation should include: a completed application form, an overall description of the inverter and its protection functions, including the manufacturer, model, and Inverter Operational Settings document along with Independent Testing Laboratory certification documentation or equivalent documentation provided by the inverter manufacturer that describes its protection settings, a detailed single line diagram if the system is different than shown in Appendix 2 or Appendix 3. the disconnecting means details (i.e., manufacturer, model and associated certification). The Microgenerator shall revise and re-submit the inverter or protection information for any proposed modification. 5.0 CONSTRUCTION 5.1 General The Microgenerator s generation facility must be constructed and installed to meet all applicable regulations. All permitting and safety code requirements must be completed and copies of inspection reports must be provided to City Electric. All Single Line Diagrams provided to the City Electric shall be drawn in accordance with IEEE standards and conventions. Professional stamps shall only be required where required by permitting authorities. Page 10 of 19

11 6.0 METERING 6.1 General Metering must comply with Measurement Canada requirements and the latest revision of City Electric s By-law Bi-directional metering shall be installed so that kwh (delivered) and kwh (received) are separately recorded. 6.2 Meter Requirements For microgeneration systems the bi-directional billing meter will be supplied and installed by City Electic. Cost of metering equipment will be borne by City Electric, but labor, equipment and material associated with the installation of the metering equipment will be charged to the customer. 6.3 Net Billing Customers are given credit for the excess power generated from their microgeneration system up to a maximum of their energy usage in any twelve month period. Customers are still charged the non-energy variable charges based on their usage of the distribution system. 7.0 INSPECTION The Microgenerator shall maintain a quality control and inspection program according to the recommendations of the inverter manufacturer. In addition to the Microgenerator's normal inspection procedures, the City Electric reserves the right to witness any part of work that concerns the subject equipment; to inspect materials, documents and installation procedures, to witness tests and to evaluate results of non-destructive examinations. The Microgenerator shall supply the City Electric with a complete set of detailed drawings, which will be used by the City Electric to assist in the inspection during the testing of equipment. 8.0 TESTING 8.1 Type Testing Is performed or witnessed once by an independent testing laboratory for a specific protection package. Once a package meets the type testing criteria described in this section, the design is accepted by City Electric. Page 11 of 19

12 8.2 Verification Testing Prior to completion of commissioning of a microgeneration system, or when interconnection system hardware or software is changed, a verification test shall be performed. City Electric reserves the right to witness verification testing or to require written certification that the testing was performed. All verification tests relating to the interconnection system prescribed by the manufacturer or developed by the Microgenerator that are agreed to by City Electric shall be performed prior to interconnection. The Microgenerator shall maintain verification test reports for inspection by City Electric. Any system that depends upon a battery for trip power shall be verified to be of fail-safe design by disconnecting the battery and verifying that the system ceases to energize the distribution system. 8.3 Protective Function Testing If microprocessor-controlled protective functions are used, and production line testing has been done according to section 8.1, then a repeat of the production line testing (subject to item (ii) below) in the field is not required. The non-islanding function shall be checked by operating a disconnecting means to verify that the inverter ceases to energize its output terminals and does not restart for the required time delay after the disconnecting means is closed. 9.0 INFORMATION REQUIREMENTS The following table identifies the drawings and information the Microgenerator is required to submit to the City Electric when applying for interconnection to City Electric s distribution system. Page 12 of 19

13 Drawing/Data Proposal Acceptance * Verified Manufacturer s equipment data sheet including the Inverter Operational Settings (IOS) document Single line diagram (not required if as per Appendix 2 or Appendix 3) Commissioning report c/w protection settings Plot plan showing location of disconnecting means X X X X X X X X X X Operating Manual X X X *The minimum time requirement for review of information is generally 20 working days MARKING AND TAGGING The disconnecting means shall be clearly marked in accordance with the Canadian Electrical Code Part 1. City Electric may choose to place warning tags or labels on parts of the Service Entrance MAINTENANCE The Microgenerator has full responsibility for routine maintenance of the Microgenerator's complete system, control and protective equipment up to and including the PCC in accordance with the manufacturer's recommendations, and the keeping of records for such maintenance. The Microgenerator must maintain the equipment to accepted industry standards. Failure to do so may result in disconnection of the microgenerator at the PCC. Page 13 of 19

14 TABLE 1 RECOMMENDED SERVICE VOLTAGE VARIATION LIMITS Nominal system voltages Single phase 120/ Recommended voltage variation limits for circuits up to 100 V, applicable at service entrance Extreme operating conditions Normal operating conditions 106/ / / / Three phase 4-conductor 120/208Y 240/416Y 277/480Y 347/600Y 110/ / / / / / / / / / / / / / / /635 Three phase 3-conductor Source: CSA CAN3-C235, Table 3. Page 14 of 19

15 TABLE 2 SINGLE PHASE INTERCONNECTION PROTECTION FUNCTION REQUIREMENTS Notes: 1. Exporting to the City Electric's system may require coordination of operations with the City Electric. 2. This is as required in Section Function # Protection Function Required Inverter AC disconnect means X 59T Over-voltage trip X 27 Under-voltage trip X 81/O, 81/U Over/Under frequency trip X 25 Automatic Synchronizing (1) X Anti-islanding (2) Page 15 of 19

16 TABLE 3 THREE PHASE INTERCONNECTION PROTECTION FUNCTION REQUIREMENTS Function # Protection Function Inverter Size 5kW or less # of Phases 2 Inverter Disconnect Means X (3) 25 Automatic Synchronizing 1 X (1) 27 Under-Voltage Trip X (3) 50/51 Inst/Timed Over-Current X (3) 59 Over-Voltage Trip X (3) 81/O, 81/U Over/Under-Frequency Trip X (3) Anti-islanding 5 X (3) Note: 1. For inverters with standalone capability. 2. Number of phases to be monitored shown in parentheses, e.g., (3). 3. X designates functions that are a protection requirement. 4. To be in accordance with the Canadian Electrical Code. 5. As required in Section Page 16 of 19

17 APPENDIX 1 DEFINITIONS The following terms are defined here to assist in the understanding of microgeneration. Though some of these terms are not used in this Guide, they may arise in discussions of microgeneration systems and so would be useful to understand. 1. Microgenerator Distributed generation up to 5 kw typically installed in a residential or small business building. It is deemed to be operating unattended using untrained personnel. 2. Inverter An electronic device that converts DC electricity to AC electricity. 3. Voltage-following inverter An inverter in which the output follows the waveform of an external device. 4. Stand-alone mode An inverter which operates in isolation from the City of Medicine Hat Electric Distribution System (City Electric). 5. Grid-interactive mode An inverter which operates in parallel with City Electric and contains provision for synchronizing with City Electric. 6. Grid-dependent mode An inverter which automatically ceases to operate upon loss of voltage from City Electric and resumes operation when City Electric voltage is restored. 7. Single phase inverter An inverter that generates a single phase electrical output. 8. Point of common coupling (PPC) The point where City Electric is connected to the Microgenerator s facility. 9. Disconnecting means A device which disconnects a circuit from its source of supply. 10. Islanding A condition in which a portion of City Electric is energized by a Microgeneration facility thru a PCC while that portion of City Electric is separated from the rest of City Electric distribution system.. Page 17 of 19

18 APPENDIX 2 SINGLE LINE DIAGRAM FOR GRID-DEPENDENT MICRO-DG SYSTEMS PROTECTION LEGEND: AI - Anti-Islanding 27 - Under-Voltage 59 - Over-Voltage 81O - Over-Frequency 81U - Under-Frequency Micro-DG Source Wire Owner distribution system Interconnection Protection Functions AI /O 81/U [Note 3] Local loads Point of Common Coupling Service entrance Label: Two power source, parallel system [Note 1] 120/240 VAC [Note 1] [Note 1] Outdoor Indoor NOTES: 1. This shows all possible locations of meters. The number and location of metering points are given by commercial agreement. 2. Some inverters may not contain internal disconnects. 3. Protection schematic shown is for micro- DG systems. Refer to Table 2 for requirements on specific systems. 4. Location and specification of S1 and S2 are given by requirements of Wire Owner and CE Code. [Note 4] S1 Label: DG Source Disconnect Internal disconnects DC = ~ Grid-Dependent Inverter [Note 2] AC 1φ [Note 4] S2 Label: DG Inverter Disconnect [Note 1] New installation Main AC breaker panel Breaker with no line and load markings. Label: DG System Disconnect Single-Phase, Grid-Dependent, Micro-Distributed Generator Single Line Diagram for Interconnection through Wire Owner Distribution Transformer Submitted by: Date: Site Description: This single line diagram is intended for use during the application for interconnection. It is not intended to be used for system design or installation. DRAWING NO. SCALE: NOT TO SCALE REV 1 SHEET Site Location: Page 18 of 19

19 APPENDIX 3 SINGLE LINE DIAGRAM FOR GRID-INTERACTIVE MICRO-DG SYSTEMS PROTECTION LEGEND: AI - Anti-Islanding 25 - Synchronism Check 27 - Under-Voltage 59 - Over-Voltage 81O - Over-Frequency 81U - Under-Frequency Electrical Storage Device Micro-DG Source DC S1 Label: DG Source Disconnect [Note 4] Wire Owner distribution system Interconnection Protection Functions [Note 3] S3 Label: Electrical Storage Device Disconnect AI /O 81/U DC Essential loads AC breaker panel = ~ Grid-Interactive Inverter [Note 2] Internal transfer switch AC 1φ S2 Label: DG Inverter Disconnect [Note 4] Point of Common Coupling Service entrance Internal disconnects Label: Two power source, parallel system Local loads [Note 1] Single-Phase, Grid-Interactive, Micro-Distributed Generator Single Line Diagram for Interconnection through Wire Owner Distribution Transformer 120/240 VAC [Note 1] [Note 1] Outdoor Indoor Submitted by: Date: Site Description: NOTES: 1. This shows all possible locations of meters. The number and location of metering points are given by commercial agreement. 2. Some inverters may not contain internal disconnects. 3. Protection schematic shown is for micro- DG systems. Refer to Table 2 for requirements on specific systems. 4. Location and specification of S1 and S2 are given by requirements of Wire Owner and CE Code. New installation Main AC breaker panel Breaker with no line and load markings. Label: DG System Disconnect This single line diagram is intended for use during the application for interconnection. It is not intended to be used for system design or installation DRAWING NO. SCALE: NOT TO SCALE REV 1 SHEET Site Location: Page 19 of 19