NZQA registered unit standard 15578 version 6 Page 1 of 6 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 Page 3 of 6 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 Page 5 of 6 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