 |
  |
  |
  |
|
 |
|
|
|
Small generation resources: Standards for interconnection and parallel operationThese standards apply to resources of 1,000 kW or less
1. Installation and Permitting
Minimum Standards
Without limiting the provisions of paragraph 22, the Interconnection Customer and the DGS must comply with all applicable National Electric Code (NEC), UL and IEEE requirements, including, but not limited to:
UL 1741-Standard (e.g., Standard for Static Inverters and Charge Controllers for Use with Photovoltaic Systems).
IEEE Standard 1547 (2003): Standard for Interconnecting Distributed Resources with Electric Power Systems.
Other organizations, such as the Canadian Standards Association (CSA), test to UL 1741. If the equipment is tested by an organization other than Underwriters Laboratories, the test data must be submitted to LPC.
System Construction
The Interconnection Customer or its contractor must construct the System as specified.
Power Quality Requirements
All power quality parameters (i.e., voltage, flicker, frequency, distortion) are specified at the point of common coupling (PCC) unless otherwise stated. The DGS shall not create power system disturbances that exceed the standards specified by LPC. When there is demonstrated, unreasonable interference to other customers and such interference exceeds LPC standards, LPC reserves the right, at its expense, to install test equipment as may be required to perform a disturbance analysis and monitor the operation of the DGS to evaluate the quality of the power produced. If the DGS is demonstrated to be the source of the interference, and the interference exceeds LPC standards or generally accepted industry standards, then the DGS will be disconnected and locked out from the LPC distribution system until corrections are made to remedy the interference. It is the customer's responsibility to eliminate the interference problem caused by the DGS. The following requirements must be met:
Voltage – the DGS must be capable of operating within normal or emergency voltage operating limits of 106-132 volts (88 to 110% nominal 120V). This range results in trip points at 106 volts and 132 volts. Response to abnormal voltages should be as follows:
Table 1:
Interconnection system response to abnormal voltages
Distributed Generation System < 30 KW
Point of Common Coupling
Voltage (V) Range
Clearing times
Seconds/Cycles% of Base (120)
Volts
V<50
V<60
0.17
10
50 =V< 88
60 =V< 106
2.0
120
88 =V< 95
106 =V< 114
Emergency Range
Normal Operating Range
Emergency Range95 =V< 105
114 =V< 126
105 =V< 110
126 =V< 132
110 =V< 120
132 =V< 144
1.0
60
V =120
V =144
0.17
10
Table 2:
Interconnection system response to abnormal voltages
Distributed Generation System = 30 KW
Point of Common Coupling (PCC)
Voltage (V) Range
Clearing times
Seconds/Cycles% of Base (120)
Volts
V<50
V<60
0.17
10
50 =V< 88
60 =V< 106
2.0
120
88 =V< 95
106 =V< 114
Emergency Range
Normal Operating Range
Emergency Range95 =V< 105
114 =V< 126
105 =V< 110
126 =V< 132
110 =V< 120
132 =V< 144
1.0
60
120 =V<130
144 =V<156
0.17
10
V =130
V =156
0.1
6
Flicker – The DGS shall not create objectionable flicker for other LPC customers. Flicker is considered objectionable when it either causes a modulation of the light level of lamps sufficient to be irritating to humans or causes equipment malfunction. See IEEE 519-1992.
Frequency – The DGS must operate in a fixed frequency range of 59.3 to 60.5 Hz. When the interconnected system frequency is outside this range, the DGS shall cease to energize the LPC connection per Table 3:
Table 3:
Interconnection system response to abnormal frequencies
DGS kW |
frequency range (Hz) |
Clearing times (secs) |
|
=30 kW |
f > 60.5 |
0.17 |
|
|
f <59.3 |
0.17 |
|
>30 kW |
f >60.5 |
0.17 |
|
|
f <57 |
0.17 |
|
>30 kW |
57 >DGS>59.8 |
Adjustable .17 to 300 |
|
Waveform Distortion (Harmonics) - The DGS must have low current-distortion levels to ensure that no adverse effects are caused to other equipment connected to LPC's electric system. When the DGS is serving balanced linear loads, harmonic current injection into LPC's network shall not exceed:
Harmonics h<11 11=h<17 17=h<23 23=h<35 35=h Percent 4.0 2.0 1.5 0.6 0.3 Maximum Total Demand Distortion (TDD) 5.0%
Even harmonics are to be limited to 25% of the odd harmonics shown above.
Power Factor – The DGS must operate at a power factor >0.85 (leading or lagging) when output is greater than 10% of full load.
Islanding Protection – The DGS must cease to energize the utility line when the generation equipment or inverter is subjected to islanding conditions. The DGS must immediately, completely and automatically disconnect from LPC's electric system in the event of a fault on the DGS or loss of source on LPC's electric system. LPC, at its own discretion and expense, may conduct periodic testing of anti-islanding. Anti-islanding is a means by which the DGS will cease to generate when it is still connected to the isolated (due to fault clearing or other switching) section of the LPC electric system.
DC Injection. The DGS shall comply with IEEE 1547 for direct current injection as measured at the PCC.
Customer Pays for Additional Equipment
The Interconnection Customer, at the Customer's expense, must pay for any additional equipment required to connect the DGS to LPC's electric system. This includes any modifications to LPC's electric system necessary to accommodate the DGS consistent with safety, reliability and power quality standards. At a minimum, the following protective functions are necessary to sense abnormal conditions and disconnect the customer's generation from the LPC distribution system:
1. over and under voltage functions
2. over current trip functions
3. ground fault protection
4. over and under frequency functions
5. anti-islanding function
With LPCs approval, the transfer switch or system used to transfer the customer's loads from LPC's distribution system to the customer's Distributed Generation may be used in lieu of the protective functions required for parallel operation.
Technology Specific Requirements
Different technologies may require unique designs for the operation of the generator. If the standards do not address the interconnection requirements for a particular generating facility or technology, LPC and the Customer may agree upon other requirements.
Aggregated Generation
LPC reserves the right to consider the effect of the DGS in combination with any other generation systems on the same circuit. This review and any appropriate remedy to the effect of the aggregated generation will be done on a case by case basis at the sole discretion of LPC.
Three Classes of Distributed Generation
Classes of Distributed Generation shall be based upon the generator (or inverter) nameplate rating(s). If the site incorporates more than one generator, the nameplate (for the purposes of determining class) shall be the sum of the nameplates.
Class 1 Generation - Distributed Generation of 10 kW or less - must meet the requirements and standards defined above.
Class 2 Generation - Distributed Generation of 50 kW or less but greater than 10 kW - must meet the requirements and standards defined above and be connected to LPC with a dedicated transformer.
Class 3 Generation - Distributed Generation of 1,000 kW or less but greater than 50 kW - must meet the requirements and standards defined above and:
a. Be connected to LPC with a dedicated transformer meeting LPC standards and design criteria.
b. Employ a fused disconnect switch for the disconnect switch.
c. Employ switchgear on the LPC side of the fused disconnect switch.
Written Authorization Required to Connect System
The Interconnection Customer may not connect the DGS to LPC's electric system until: 1) this Agreement has been fully executed by the parties, 2) the DGS has been tested, and 3) written authorization to connect the DGS, in a form substantially similar to Attachment B, has been given to the Interconnection Customer by LPC. LPC may have representatives present at the initial testing of the DGS and may perform (at its own expense) whatever testing of the DGS that LPC deems necessary.
After written authorization to connect the DGS to LPC's electric system has been given, the Interconnection Customer shall make no changes or modifications in the System or of its mode of operation without the prior written approval of LPC.
Location of System
The System will be installed at the Interconnection Customer's premises as defined in the Interconnection Agreement and located in the physical location specified or depicted in the Agreement. The Interconnection Customer cannot relocate and connect the DGS at another premises or physical location without filing a new interconnection application with LPC or requesting modifications to this Agreement allowing for connection at the alternate location. In the event that such approval is given, any relocation and installation of the DGS will be at the Interconnection Customer's sole expense.
Access to Premises
The Interconnection Customer will provide LPC access to the Customer's premises in accordance with section 14.32.220.J.1 of the Longmont Municipal Code:
1. to inspect the DGS
2. to read and to replace meters
3. to open the load-break disconnect switch
4. to disconnect the interconnection facilities at LPC's meter or transformer
Maintenance of Equipment
The Interconnection Customer, at the Customer's sole cost and expense, will maintain the DGS including, but not limited to, all over-current protective equipment, in a safe and prudent manner and in conformance with all applicable laws, codes and regulation, including, but not limited to, the requirements of Section 4 above. The Interconnection Customer must retain all records for such maintenance. These records must be available to LPC for inspection at all reasonable times.
Safety
The Interconnection Customer agrees to install, operate and maintain the DGS in a safe and prudent manner and in conformance with all applicable laws, codes and regulations including, but not limited to, those contained in Section 4 above.