1.
Manual Disconnect
A manual load break disconnect switch that
provides clear indication of the switch position and is appropriate to the voltage
level shall be available at the customer's main service point to provide a separation
point between the customer's electrical generation system and Bryan Texas Utilities’
(BTU) electrical system.
BTU will coordinate
and approve the location of the disconnect switch. The disconnect switch shall be easily visible, mounted separately from the
metering or inverter equipment, readily accessible to BTU personnel at all times, and capable
of being locked in the open position with a BTU padlock. Bryan Texas Utilities 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 BTU’s electrical system for the following reasons:
a.
To facilitate maintenance or repair of BTU’s electrical
system;
b.
When emergency conditions exist on BTU’s electrical system;
c.
When the customer's electrical generating system is determined
to be operating in a hazardous or unsafe manner or unduly affecting BTU’s voltage
waveform;
d.
When the customer's electrical generating system is determined to be adversely affecting
other electric consumers on the BTU system;
e.
Failure of the customer to comply with applicable codes,
regulations and standards in effect at that time;
f.
Failure to abide by any contractual arrangement or operating
agreement with Bryan Texas Utilities.
2.
Voltage
BTU 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 BTU’s electrical system within 10 cycles should a voltage
deviation greater than +5% or -10% from nominal be sustained for more than 30 seconds
(1800 cycles) or a voltage deviation greater than +10% or -30% from nominal 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.
3.
Frequency
BTU 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 BTU’s electrical system within
15 cycles should a deviation in frequency of +0.5Hz or -0.7Hz from nominal occur.
4.
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 BTU’s 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.
5.
Flicker
The distributed generation facility shall
not cause excessive voltage flicker on BTU’s 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.
6.
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 0.95 lagging to 0.95 leading power
factor.
Induction generators shall
have static capacitors that provide at least 95% of the magnetizing current requirements
of the induction generator field.
BTU
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.
7.
Loss of Source
The customer shall provide UL approved protective
equipment necessary to immediately, completely and automatically disconnect the
customer’s electrical generation equipment from BTU’s electrical system in the event
of a fault on the customer's system, a fault on BTU’s system or loss of source on
BTU’s system.
Such protective equipment
shall conform to the criteria specified in UL 1741. 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 BTU’s service voltage and
frequency are restored to within the normal operating range and the system is stabilized.
8.
Coordination and synchronization
The customer shall be solely responsible
for coordination and synchronization of the customer's electrical generating system
with all aspects of BTU’s 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 BTU’s electrical system.
9.
Metering
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.
In situations
where power may flow both in and out of the customer's electrical system, power
flowing into the customer's electrical system will be measured separately from power
flowing out of the customer's electrical system.
BTU will provide, subject to existing rate schedules at the time of application,
the metering equipment necessary to measure capacity and energy delivered to and
from the customer. This includes a
separate PV meter for the purpose of measuring the total system output.
10.
Interconnection Study
If BTU determines that an interconnection
study is necessary, BTU shall perform (or have performed by an outside engineering
firm) the study under terms and conditions agreed upon by both the customer and
BTU and at the customer's sole expense.
No interconnection study shall be necessary and no study fee will be charged if
all of the following apply:
a.
The proposed generation equipment is pre-certified
i.
Generation equipment with capacity less than 100 kW AC
shall be considered pre-certified if a UL 1741 listed inverter is used as well as
UL 1703 listed PV modules;
b.
The proposed generation system does not export more than 15% of total load on the
feeder serving the proposed facility; and
c.
The proposed generation system does not contribute more
than 25% of the maximum possible short circuit current of the feeder serving the
proposed facility.
11.
Protection requirements
The distributed generation facility must
have an interconnection disconnect device and a generator disconnect device, both
capable of interrupting the maximum available fault current supplied by the generator
and BTU; 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).
Facilities rated over 10kW, 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 and NEC Article 250.
12.
Additional requirements for three-phase generators
a.
Synchronous
machines
i.
The distributed generation facility’s circuit breakers
shall be three-phase devices with electronic or electromechanical control.
ii.
The Customer is solely responsible for proper synchronization of its generator with
BTU’s system.
iii.
The excitation system response ratio shall not be less than 0.5.
iv.
The generator’s excitation system shall conform to the field voltage versus time
criteria specified in ANSI Standard C50.13-1989.
b.
Induction
generator
i.
The induction generator 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.
c.
Inverters
i.
Line-commutated inverters do not require synchronizing
equipment.
ii.
Self-commutated inverters require synchronizing equipment.
13.
Conformance to standards
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.
Adopted: 4-07-08