NZQA registered unit standard
15578 version 6
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Title
Maintain electricity system frequency and voltage within agreed
tolerances
Level
5
Credits
6
Purpose
People credited with this unit standard are able to: demonstrate
knowledge of electrical power systems and the control of
systems to maintain power output balance; identify and
communicate system status and conditions; maintain system
frequency and voltage dispatch; manage events which impact
on system frequency and voltage; and report control of
frequency and voltage.
Classification
Electricity Supply > Electricity Supply - Power System
Management
Available grade
Achieved
Entry information
Recommended skills
and knowledge
Unit 12390, Demonstrate knowledge of electricity supply
systems.
Explanatory notes
1
This unit standard is intended for, but not restricted to, workplace assessment. The
range statements across the unit standard can be applied according to industry
specific equipment, procedures, and processes.
2
Safety of personnel and plant must be a priority throughout the assessment. If the
safety requirements are not met the assessment must stop.
3
Performance and work practices in relation to the outcomes and evidence
requirements must comply with all current legislation, especially the Electricity Act
1992, and any regulations and codes of practice recognised under that statute; the
Health and Safety in Employment Act 1992; and the Resource Management Act
1991. Electricity supply industry codes of practice and documented industry
procedures include the current version of the Safety Manual – Electricity Industry
(SM-EI) (Wellington: Electricity Engineers’ Association). A full list of current
legislation and industry codes is available from the Electricity Supply Industry
Training Organisation, PO Box 1245, Waikato Mail Centre, Hamilton 3240.
4
The phrase in accordance with industry requirements is implicit in all outcomes and
evidence requirements in this unit standard.
Electricity Supply Industry Training Organisation
SSB Code 101813
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
15578 version 6
Page 2 of 6
5
Reference to procedures and specifications in this unit standard may be taken as
including documented procedures and specifications relevant to the workplace in
which assessment is carried out.
6
Industry requirements include all asset owner requirements; manufacturers’
specifications; and enterprise requirements which cover the documented workplace
policies, procedures, specifications, business, and quality management requirements
relevant to the workplace in which assessment is carried out.
7
Asset owner refers to the owner of an electricity supply network that takes its point of
supply from Transpower NZ and delivers electricity to industrial, commercial, and
residential customers.
8
Practical workplace exercises or simulations should be used for training and
assessment where possible.
9
Abbreviations related to this unit standard:
AC – Alternating current
DC – Direct current
SCADA – Supervisory Control and Data Acquisition system, a computer system that
is used to operate equipment and monitor the performance of the electrical power
system and/or network, gather data for analytical purposes, and generally assist the
operation and delivery of electrical network functions concerning the supply of
electricity to customers.
Outcomes and evidence requirements
Outcome 1
Demonstrate knowledge of electrical power systems and the control of systems to
maintain power output balance.
Evidence requirements
1.1
Theory of mechanical and electrical power and energy is described in terms of
potential and kinetic energy, moment of inertia, rotational energy, and electrical
active power.
1.2
The principles of electrical power systems and their operation are described.
Range
includes but is not limited to – AC systems, DC systems, voltage,
frequency, power balances, DC and AC generators, excitation
systems, prime movers, governors, unsynchronised and
synchronised generators, transmission efficiency, network
voltages, tap changers, reactive power sources – capacitor banks,
synchronous and static compensators, system capacitance.
Electricity Supply Industry Training Organisation
SSB Code 101813
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
1.3
The principles of system disturbance and recovery are defined and explained.
Range
1.4
15578 version 6
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may include but is not limited to – system response to active
power unbalance, rotational inertia and energy, prime mover
governing, reserve generation, types of spinning reserve – partial
loading, tailwater depression.
Frequency and voltage keeping limits are defined.
Range
may include but is not limited to – time error, transmission
voltages, supply voltages and contractual requirements,
monitoring plant loads against limits, power quality standards.
Outcome 2
Identify and communicate system status and conditions.
Range
includes but is not limited to – frequency, voltage, time error, on-line and other
available generating capacity, identified transmission constraints, operating
parameters and standards, weather conditions and forecasts.
Evidence requirements
2.1
Plant and equipment status is determined.
Range
2.2
Planned events which impact on plant and equipment status are identified and
their impact is determined and recorded.
Range
2.3
may include but is not limited to – current configuration of active
and reactive power flows in network, planned generating and High
Voltage Direct Current transmission transfer schedule for
frequency control period, nominated station or group of stations,
amount and location of active and reactive generating capacity
available for load following and voltage support, current
transmission constraints, forced reactive transmission.
may include but is not limited to – transmission constraints
planned to arise during frequency control period, weather
forecasts.
Controller handover procedures are completed, ensuring that all relevant
information is transferred to the new controller.
Outcome 3
Maintain system frequency and voltage dispatch.
Range
may include but is not limited to – active power, reactive power, frequency, time
error, nominated station or group for frequency keeping, on-line tap changers,
capacitor banks, rotating and static compensators, frequency control
responsibility period.
Electricity Supply Industry Training Organisation
SSB Code 101813
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
15578 version 6
Page 4 of 6
Evidence requirements
3.1
System frequency and/or voltage is maintained within set parameters.
Range
3.2
may include but is not limited to – frequency is maintained within
statutory limits, Electricity (Safety) Regulations 2010; voltages at
network injection and delivery points.
Reactive power flows in the network are minimised for the prevailing reactive
demands and available generation.
Range
may include but is not limited to – use of reactive generation
capacity close to reactive demand, reduction in transmission
losses.
Outcome 4
Manage events which impact on system frequency and voltage.
Range
may include but is not limited to – emergency, unscheduled event, abnormal
conditions, alarms, protective relay operations, forced outage, power system
faults.
Evidence requirements
4.1
System is stabilised.
Range
4.2
The event and/or cause of the event is identified using all available resources,
and the impact on frequency keeping and network voltages is determined.
Range
4.3
may include but is not limited to – alarms and protective relay
operation identified, events lists, event recording charts, alarms
and protective relay flaggings listed, SCADA displays, local
control, contingency plans, emergency operating plans.
The event is responded to.
Range
4.4
may include but is not limited to – indications, alarms and
protective relay operation acknowledged and reset, governor load
limiters, active and reactive power outputs stabilised, local
operating conditions.
may include but is not limited to – industry standards, reserve
generation schedule, local control, contingency plans, emergency
operating plans, power quality.
The event reporting is conducted.
Range
may include but is not limited to – post-event analysis, local
instructions, event reporting standards, logging, reporting, industry
standards.
Electricity Supply Industry Training Organisation
SSB Code 101813
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
4.5
15578 version 6
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The event is analysed to identify options to remedy or mitigate undesired
conditions and identify necessary actions.
may include but is not limited to – event reporting procedures, log
book, event lists, relay flag sheets, SCADA and Energy
Management System tools which include – system dynamic
modelling, governor droop settings, automatic voltage regulator
settings.
Range
Outcome 5
Report control of frequency and voltage.
Range
service report, log book, computer logging, test reports and results, customer
reports.
Evidence requirements
5.1
Recorded information is complete, concise, and legible.
5.2
Active and reactive power generation and control information is recorded in the
required format and filed within scheduled timeframe.
Planned review date
31 December 2014
Status information and last date for assessment for superseded versions
Process
Version Date
Last Date for Assessment
Registration
1
20 December 1998
N/A
Review
2
20 September 2002
N/A
Revision
3
11 February 2004
N/A
Rollover and
Revision
4
26 November 2007
Review
5
16 April 2010
N/A
Revision
6
15 September 2011
N/A
N/A
Consent and Moderation Requirements (CMR) reference
0120
This CMR can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
Please note
Providers must be granted consent to assess against standards (accredited) by NZQA,
before they can report credits from assessment against unit standards or deliver courses
of study leading to that assessment.
Industry Training Organisations must be granted consent to assess against standards by
NZQA before they can register credits from assessment against unit standards.
Electricity Supply Industry Training Organisation
SSB Code 101813
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
15578 version 6
Page 6 of 6
Providers and Industry Training Organisations, which have been granted consent and
which are assessing against unit standards must engage with the moderation system that
applies to those standards.
Requirements for consent to assess and an outline of the moderation system that applies
to this standard are outlined in the Consent and Moderation Requirements (CMR). The
CMR also includes useful information about special requirements for organisations wishing
to develop education and training programmes, such as minimum qualifications for tutors
and assessors, and special resource requirements.
Comments on this unit standard
Please contact the Electricity Supply Industry Training Organisation info@esito.org.nz if
you wish to suggest changes to the content of this unit standard.
Electricity Supply Industry Training Organisation
SSB Code 101813
 New Zealand Qualifications Authority 2016