This division is intended to provide for the orderly, safe and
effective interconnection and parallel operation of distributed generation
facilities within the city electric system by customers of the city
electric utility.
(Ordinance adopted 1/22/18, sec.
1.1)
The city is authorized to enact this article by the Tex. Util.
Code Ann. section 31.005, which authorizes and encourages electric
utilities to establish customer option programs that encourage the
reduction of air contaminant emissions including distributed energy
generation technology. Also, Tex. Util. Code Ann section 39.101(b)(3)
entitles all state electric customers access to on-site distributed
generation. Finally, Tex. Util. Code Ann section 39.916 authorizes
electric utilities to establish requirements for and allow the interconnection
and parallel operation of distributed renewable generation, and requires
the public utility commission of the state to promulgate rules and
regulations for the implementation of interconnection and parallel
operation of distributed renewable generation.
(Ordinance adopted 1/22/18, sec.
1.2)
As used in this article, the following words and terms shall
have the meanings as set forth below:
City contact person.
The person or persons designated by the city administrator
to serve as the city’s contact for all matters related to distributed
generation interconnection.
Commission.
The public utility commission of the state.
Customer.
A person or entity interconnected to the city’s electric
system for the purpose of receiving or exporting electric power from
or to the city’s electric system.
DG agreement.
An agreement between a customer and the city that sets forth
the contractual conditions under which a company and a customer agree
that one or more facilities may be interconnected with the city’s
electric system.
DG application.
The form of application of a customer seeking interconnection
and parallel operation of distributed generation with the city’s
electric system.
Distributed generation.
An electrical generating facility located at a customer’s
point of delivery (point of common coupling) of ten (10) megawatts
(MW) or less and connected at a voltage less than sixty (60) kilovolts
(kV) which may be connected in parallel operation to the city’s
electric system.
Distributed generation owner.
An owner of distributed generation, the customer on whose
side of the meter distributed generation is installed and operated,
regardless of whether the customer takes ownership of the distributed
generation, or a person who by contract is assigned ownership rights
to energy produced from distributed generation located at the premises
of the customer on the customer’s side of the meter.
ERCOT.
The Electric Reliability Council of Texas, Inc. or successor
independent organization under PURA section 39.151 for the power region
to which the city’s system is connected.
Interconnection.
The physical connection of distributed generation to the
utility system in accordance with the requirements of this article
so that parallel operation can occur.
Manual disconnect device.
A manual switch at the point of interconnection that provides
clear indication of the switch position, and when in the open position
isolates the distributed generation from load unrelated to generation
of electricity or operation of the facility.
Network service.
Two or more utility primary distribution feeder sources electrically
tied together on the secondary (or low voltage) side to form one power
source for one or more customers. The service is designed to maintain
service to the customers even after the loss of one of these primary
distribution feeder sources.
Parallel operation.
The operation of distributed generation while the customer
is connected to the city’s electric system.
Pre-certified equipment.
A specific generating and protective equipment system or
systems that have been certified as meeting the applicable parts of
this article relating to safety and reliability by an entity approved
by the commission.
Pre-interconnection study.
A study or studies that may be undertaken by the city in
response to its receipt of a completed DG application. Pre-interconnection
studies may include, but are not limited to, service studies, coordination
studies and utility system impact studies.
Stabilized.
The city’s electric system is considered stabilized
when, following a disturbance, the system returns to the normal range
of voltage and frequency for a duration of two minutes or a shorter
time as mutually agreed by the city and the customer.
(Ordinance adopted 1/22/18, sec.
1.3)
This division applies to all persons or entities that desire
to interconnect or operate in parallel a distributed generation system
within the city’s electric system.
(Ordinance adopted 1/22/18, sec.
1.4)
(a) Before a person or entity may interconnect or operate in parallel
a distributed generation system within the city’s electric system,
that person or entity must apply to the city by completing a city
DG application form and execute a DG agreement with the city that
establishes the terms and conditions for the interconnection and parallel
operation of the distributed generation system.
(b) The city administrator has the authority to execute agreements with
customers for the interconnection and parallel operation of distributed
generation within the city electric system in accordance with this
DG division, DG agreement and in accordance with all applicable city
codes and applicable state and federal laws and regulations.
(c) The interconnection shall not be energized prior to the execution
of the agreement.
(Ordinance adopted 1/22/18, sec.
1.5)
Distributed generation with installed capacity greater than
or equal to 1 MW, which exports energy into the city’s distribution
system, is required to be registered with ERCOT.
(Ordinance adopted 1/22/18, sec.
1.6)
(a) The city contact person or persons for all matters related to distributed
generation interconnection is provided on the city’s DG customer
information materials and the city’s website.
(b) The designated city DG contact person shall review applications for
distributed generation with attached technical documentation and determine
compliance with the city technical requirements for interconnection
and parallel operation of distributed generation.
(c) When the city is satisfied that the customer has complied with the
application requirements and that the DG system complies with the
technical requirements for interconnection and parallel operation
of distributed generation, the city DG contact person shall recommend
to the city administrator that an agreement be executed with the customer
for the interconnection and parallel operation of distributed generation.
(Ordinance adopted 1/22/18, sec.
1.7)
(a) All DG interconnections shall comply with PUC subst. R. 25.212 and
successors. In addition, all DG interconnections shall comply with
applicable state and federal laws and regulations.
(b) All DG interconnections shall comply with local building and electrical
codes. Building codes are enforced by the city code enforcement department.
Installation of all interconnections shall be inspected by city to
ensure compliance with city DG specifications and requirements. Inspection
and approval of the installation by the city is a condition of interconnection
and parallel operation of distributed generation.
(c) Variations from the technical requirements must be reviewed and approved
by the city prior to implementation. Variations in the point of interconnection
must be approved and included in the agreement approved by the city
administrator.
(Ordinance adopted 1/22/18, sec.
2.1)
The distributed generation facility must have an interrupting
device capable of interrupting the maximum available fault current,
an interconnection disconnect device, a generator disconnect device,
an over-voltage trip, an under-voltage trip, an over/under frequency
trip, and a manual or automatic synchronizing check (for facilities
with stand-alone capability).
(Ordinance adopted 1/22/18, sec.
2.2)
The customer shall provide and install a manual load break switch
that provides clear indication of the switch position at the point
of interconnection to provide separation between the city’s
electrical system and the customer’s electrical generation system.
The location of the disconnect switch must be approved by the city.
The disconnect switch shall be easily visible, mounted separately
from metering equipment, readily accessible to the city personnel
at all times, and capable of being locked in the open position with
a city padlock. City reserves the right to open the disconnect switch
isolating the customer’s electrical generating system (which
may or may not include the customer’s load) from the city electrical
system for the following reasons:
(1) To facilitate maintenance or repair of the city electrical system.
(2) When emergency conditions exist on the city electrical system.
(3) When the customer’s electrical generating system is determined
to be operating in a hazardous or unsafe manner or unduly affecting
the city electrical system waveform.
(4) When the customer’s electrical generating system is determined
to be adversely affecting other electric consumers on the city electrical
system.
(5) Failure of the customer to comply with applicable codes, regulations
and standards in effect at the time.
(6) Failure of the customer to abide by any contractual arrangement or
operating agreement with the city.
(Ordinance adopted 1/22/18, sec.
2.3)
(a) Voltage.
The city shall endeavor to maintain the distribution
voltages on the electrical system but shall not be responsible for
factors or circumstances beyond its control. The customer shall provide
an automatic method of disconnecting generation equipment from the
city electrical system within 10 cycles should a voltage deviation
greater than +5% or -10% from normal be sustained for more than 30
seconds (1,800 cycles) or a voltage deviation greater than +10% or
-30% from normal be sustained for more than 10 cycles. If high or
low voltage complaints or flicker complaints result from the operation
of the customer’s electrical generation, the customer’s
generating system shall be disconnected until the problem is resolved.
(b) Frequency.
The city shall endeavor to maintain a 60-hertz
nominal frequency on the electrical system. The customer shall provide
an automatic method of disconnecting generation equipment from the
city electrical system within 15 cycles should a deviation in frequency
of +0.5Hz or -0.7Hz from normal occur.
(c) Harmonics.
In accordance with IEEE 519, the total harmonic
distortion (THD) of voltage shall not exceed 5% of a pure sine wave
of 60-hertz frequency or 3% of the 60-hertz frequency for any individual
harmonic when measured at the point of interconnection with the city
electrical system. Also, the total current distortion shall not exceed
5% of the fundamental frequency sine wave. If harmonics beyond the
allowable range result from the operation of the customer’s
electrical generation, the customer’s generating system shall
be disconnected until the problem is resolved.
(d) Flicker.
The distributed generation facility shall not
cause excessive voltage flicker on the city electrical system. This
flicker shall not exceed 3% voltage dip, in accordance with IEEE 519
(section 10.5), as measured at the point of interconnection.
(e) Power factor.
The customer’s electrical generation
system shall be designed, operated and controlled at all times to
provide reactive power requirements at the point of interconnection
from 0.97 lagging to 0.95 leading power factor. Induction generators
shall have static capacitors that provide at least 97% of the magnetizing
current requirements of the induction generator field. The city may,
in the interest of safety, authorize the omission of capacitors. However,
where capacitors are used for power factor correction, additional
protective devices may be required to guard against self-excitation
of the customer’s generator field.
(Ordinance adopted 1/22/18, sec.
2.4)
The customer shall provide approved protective equipment necessary
to immediately, completely and automatically disconnect the customer’s
electrical generation equipment from the city electrical system in
the event of a fault on the customer’s system, a fault on the
city system or loss of source on the city system. Such protective
equipment shall conform to the criteria specified in UL 1741 and IEEE
1547. The customer’s generating system shall automatically disconnect
from the grid within 10 cycles if the voltage on one or more phases
falls and stays below 70% of nominal voltage for at least 10 cycles.
The automatic disconnecting device may be of the manual or automatic
reclose type and shall not be capable of reclosing until after the
city service voltage and frequency are restored to within the normal
operating range and the system is stabilized.
(Ordinance adopted 1/22/18, sec.
2.5)
The customer shall be solely responsible for coordination and
synchronization of the customer’s electrical generating system
with all aspects of the city electrical system, and the customer assumes
all responsibility for damage or loss that may occur from improper
coordination and synchronization of its generating system with the
city electrical system.
(Ordinance adopted 1/22/18, sec.
2.6)
(a) The actual metering equipment required, its voltage rating, number
of phases and wires, size, current transformers, number of input and
associated memory is dependent upon the type, size and location of
the electric service provided. Customer shall pay for the installation
of the data recorder (meter) that is capable of measuring the “KWh
Delivered” (energy delivered to the customer) and the “KWh
Received” (energy received by the city distribution system)
in intervals established by the city, using a single meter or two-meter
configuration.
(b) The city may waive this fee if a standard electric meter can be programmed
or configured to support the required measurements and functionality.
(Ordinance adopted 1/22/18, sec.
2.7)
(a) The city may perform interconnection studies, which shall include
service study, coordination study, and utility system impact study,
as needed and determined in the sole discretion of city. In instances
where such studies are deemed necessary, the scope of such studies
shall be based on the characteristics of the particular distributed
generation facility to be interconnected and the city’s distribution
system at the specific proposed location. The city may charge customer
fees for pre-interconnection studies that recover the costs of performing
such studies. Any modifications or additions to the city’s electric
system identified through the interconnection study as required for
the safe and reliable interconnection of customer’s facility
shall be solely at the customer’s expense. Customer shall not
acquire any ownership in such modifications or additions to city’s
electric system.
(b) City will determine whether an interconnection study is necessary,
based on relevant engineering factors including the output of the
system, the location of the system and other city distribution system
factors. If the interconnection study is deemed necessary, city shall
perform the study under reasonable terms and conditions agreed upon
by both the customer and the city and at the customer’s sole
expense. No study fee will be charged if the proposed generation site
is not on a networked secondary and if all of the following apply:
(c) Proposed generation equipment is pre-certified:
(1) Generation equipment that are less than 20 kW AC shall be considered
pre-certified if system meets appropriate codes and standards provided
by NESC (National Electrical Safety Code), ANSI (American National
Standards Institute), IEEE (Institute of Electrical and Electronic
Engineers), NEC (National Electrical Code), UL (Underwriter’s
Laboratory), technical requirements and local building codes and other
applicable ordinances in effect at the time of the installation of
the DG system.
(2) Proposed generation system does not expect to export more than 15%
of total load on the feeder.
(3) Proposed generation system does not contribute more than 25% of the
maximum possible short circuit current of the feeder.
(Ordinance adopted 1/22/18, sec.
2.8)
The distributed generation facility must have interrupting devices
capable of interrupting the maximum available fault current, an interconnection
disconnect device, a generator disconnect device, an over-voltage
trip, an under-voltage trip, an over/under frequency trip and a manual
or automatic synchronizing check (for facilities with standalone capability).
Facilities rated over 10 kW, three phase, must also have reverse power
sensing and either a ground over-voltage or a ground over-current
trip depending on the grounding system. Grounding shall be done in
accordance with UL 1741, IEEE 1547 and NEC article 250.
(Ordinance adopted 1/22/18, sec.
2.9)
(a) Synchronous machines.
(1) The distributed generation facility’s circuit breakers shall
be three-phase devices with electronic or electromechanical control.
(2) The customer is solely responsible for proper synchronization of
its generator with the city system.
(3) The excitation system response ratio shall not be less than 0.5.
(4) The generator’s excitation system shall conform to the field
voltage versus time criteria specified in ANSI Standard C50. 13-1989.
(b) Induction machines.
The induction machines used for
generation may be brought up to synchronous speed if it can be demonstrated
that the initial voltage drop at the point of interconnection is within
the flicker limits specified in this document.
(Ordinance adopted 1/22/18, sec.
2.10)
(a) Line-commutated inverters do not require synchronizing equipment.
(b) Self-commutated inverters require synchronizing equipment.
(Ordinance adopted 1/22/18, sec.
2.11)
The distributed generation equipment shall be designed, installed,
operated and maintained in accordance with, but not limited to, ANSI
standards, UL standards, IEEE standards, the National Electrical Code,
ERCOT Operating Guides and any other applicable local, state or federal
codes and statutes. In the case of a conflict between the requirements
in this document and any of those standards or codes, this document
shall prevail.
(Ordinance adopted 1/22/18, sec.
2.12)
Any person violating this DG policy by interconnecting distributed
generation to the city electric system without a complete application
and executed agreement shall have the DG system disconnected from
the city distribution system, until all violations have been corrected
to the satisfaction of the city.
(Ordinance adopted 1/22/18, sec.
2.13)