Monitoring

Functional Overview

The DIgSILENT PowerFactory Monitor is an integrated, multifunctional data acquisition system that covers recording, monitoring and analysis of signals in all relevant time frames. It is especially designed to cover all needs of Transmission, Distribution and Generation on all voltage levels. Flexible hardware and software components allow for the configuration of portable systems, stand-alone cabinet mounted installations as well as LAN based multiple units, multiple location systems being coordinated and supervised via Master Stations

Key functions which could be operated simultaneously are:

• Fast and slow fundamental frequency signals recording (triggered and continuous)
• Triggered instantaneous value recording
• Phasor measurements
• Event recording and power quality monitoring
• Condition supervision and monitoring

Any quantity deviating from normal conditions is recorded and analysed. In addition, on-line analysis of signals is provided featuring the detection of inherent problems like system and control oscillations, deviations from connection conditions or power quality aspects. The PowerFactory Monitor is a stand-alone system including all necessary hardware and software functions for signal conditioning, signal conversion, data storage and processing, calculation and documentation. In addition, remote access is possible via modem, TCPI/IP networks, WWW and special SCADA interface techniques. Several monitoring systems can be synchronized to 1ms using GPS clock for precise parallel sampling, e.g. a basic requirement for system wide area phasor measurements.

Technical Overview

Hardware Configuration

Option 1 - Distributed Smart Signal Units (SSU)
The PowerFactory Monitor (PFM) can be configured as per specific user requirements. Most flexible operation is provided when accessing the CMU via the multi-user Master Station featuring full flexible analysis of all readings collected from the various locations. Independent of the operation and supervision of the various PFM systems installed at several locations in a power system, the Web Interface can be used for commissioning and unit-wise supervision of the various PFM components. The Smart Signal Unit (SSU) shall be applied when signals from various locations within a substation, power plant or from different other locations shall be collected. Typical applications would be dedicated SSUs per bay, large substation with several voltage levels, collection of data of individual generation units (conventional power plants with several units, wind turbines and wind park substation, large PV installations with many central inverters).
Option 2 - Centrally connected Signals Units (SU)
Shall a huge amount of analogue or digital signals be considered that are brought to a central place, the most cost effective PFM configuration is then based on a number of centrally installed Signal Units (SU) being connected via USB communication to the SSU. Respective setup is typically mounted in a cabinet with all infrastructure required. Access to recorded data for backup and processing is again made via the PowerFactory Master Station supporting multi-user operation as well as the optional interaction with the DIgSILENT PowerFactory software. For configuration, commissioning and maintenance service direct access via Web Interfaces is again possible independently of the Master Station.
Option 3 - Portable PFM System
Limited to 15 analogue and 16 digital signals, a CMU and SSU can be combined in one single portable 19" rack (PFM300 SSU15-C, 4 HU). Optionally, a larger system being able to handle 32 analogue and 16 digital signals is also available (PFM300 SSU32-C, 7 HU). The 32 channels system can be expanded with further portable SUs or SSUs as required. Operational access to the portable PFM system, e.g. for PFM setup und mobile recording applications is offered via Web Interface. The PowerFactory Master Station software is also available for mobile applications along with the PowerFactory functions.

Multi-time Frame Recording

Based on high speed signal data acquisition the PowerFactory Monitor generates a number of different data streams that allow for fault and disturbance recording, event recording, power system performance supervision, power quality recording as well as special on-line signal generation such as real time phasors and frequency monitoring.

Power System Performance Supervision

Fundamental frequency and phasor quantities (RMS) are determined on basis of high precision soft transducers with scan rates of up to 2-4 samples per cycle being time tagged with a 1µs resolution. High-speed recording of large amount of quantities is typically triggered via threshold criteria on primary signals or on basis of any criteria being derived from flexible equations or analysis functions incl. oscillation detection. Intelligent re-trigger functions are provided to guarantee capturing of disturbance sequences which may occur during catastrophic and extended network upset conditions. Triggering is reported to the Master Station initiating automatic upload of data should this be requested by the overall monitoring setup.

Real Time Phasors

Based on the flexible setup of the PowerFactory Monitor, frame and high level slot function definitions, various specific measuring devices can be configured. A typical application of such flexibility would be the real time phasor measurement where various phasor quantities are derived from local information, stored, analysed or passed on to remote systems for coordinated stability evaluation.

Power Quality Recording

Capturing of voltage sags and high voltage conditions along with the continuous monitoring and recording of harmonic distortion, phase unbalance and other quantities of interest, continuous power quality monitoring is provided. Any recording such as captured voltage sags or daily 24 hours power quality records can be kept locally at the PFM or may be transferred automatically to the Master Station for centralized storage and review.

Automatic Analysis

On the basis of standard PowerFactory DPL or Python scripts, the PowerFactory Monitor features the automatic analysis of monitoring data streams as well as recorded, event triggered data sequences. This will allow a pre-processing of the many recordings to determine its severity and relevance for further expert analysis. A typical standard feature of the automatic event and monitoring analysis would be the performance of automated printing of all recorded data sequences.

Technical Specifications

FCAS Background

The Australian Energy Market Operator (AEMO) operates a market for the delivery of Frequency Control Ancillary Services (FCAS) under agreements with service providers. These providers bid their services into the FCAS markets based on a combination of Fast, Slow, and/or Delayed services, as described by the AEMO guide.

Payments for ancillary services include payments for availability and for the delivery of the services. The market participant or participants responsible for a situation that requires ancillary services pay for individual services whenever regulation FCAS are needed to automatically raise or lower frequency to within the normal operating band of 49.9 Hertz to 50.1 Hertz.

The PowerFactory Monitor (PFM) hardware can assist service providers by the following:

• On-site or off-site access of the PFM and the data recorded
• Monitoring of analogue and/or digital signals required to demonstrate compliance with their agreements

FCAS Requirements

A summary of the AEMO measurement requirements for FCAS and the capabilities of the PowerFactory Monitor can be found below.

Requirement	Fast Raise and Fast Lower services Specification	Requirement	Slow Raise and Slow Lower services Specification	Requirement	Delayed Raise and Delayed Lower services Specification	PFM capability
2.5(a)(i) measurement point	At or close to connection point	3.5(a)(i) measurement point	At or close to connection point	4.5(a)(i) measurement point	At or close to connection point	Capable
2.5(a)(ii) local frequency	At or close to connection point	3.5(a)(ii) local frequency	At or close to connection point	4.5(a)(ii) local frequency	At or close to connection point	Capable
2.5(a)(iii) recording intervals	<= 50 ms, same time scale as power measurement	3.5(a)(iii) recording intervals, power, frequency	<= 4 s	4.5(a)(iii) recording intervals, power, frequency	<= 4 s	Compliant
2.5(a)(iv) switching controller	Up to 4 second intervals provided Power measured at <= 50 ms					Compliant
2.5(a)(v) accuracy for power flow	<= 2% error over range <= 0.2% resolution of measurement range	3.5(a)(iv) accuracy for power flow	<= 2% error over range <= 0.2% resolution of measurement range	4.5(a)(iv) accuracy for power flow	<= 2% error over range <= 0.2% resolution of measurement range	Compliant
2.5(a)(vi) range, error and accuracy requirements for frequency	Range = 49.0 to 51.0 Hz Error <= 0.01 Hz Resolution <= 0.0025 Hz	3.5(a)(v) range, error and accuracy requirements for frequency	Range = 49.0 to 51.0 Hz Error <= 0.02 Hz Resolution <= 0.01 Hz	4.5(a)(v) range, error and accuracy requirements	Range = 49.0 to 51.0 Hz Error <= 0.02 Hz Resolution <= 0.01 Hz	Compliant
2.5(a)(vii) settling time	99% of final value within 50 ms	3.5(a)(vi) settling time	99% of final value within 4 s for analogue signals			Compliant
2.5(a)(viii) frequency disturbance time	<= 10 seconds	3.5(a)(vii) frequency disturbance time	<= 10 seconds	4.5(a)(vi) frequency disturbance time	<= 10 seconds	Compliant
2.5(a)(ix) Trigger conditions	df/dt >= 0.05 Hz/s 49.8 Hz > f > 50.2 Hz	3.5(a)(viii) Trigger conditions	df/dt >= 0.05 Hz/s 49.8 Hz > f > 50.2 Hz	4.5(a)(vii) Trigger conditions	df/dt >= 0.05 Hz/s 49.8 Hz > f > 50.2 Hz	Settable, Compliant
2.5(a)(x)event recording	Pre-trigger >= 5 s Post-trigger >= 60 s	3.5(a)(ix)event recording	Pre-trigger >= 20 s Post-trigger >= 300 s	4.5(a)(viii)event recording	Pre-trigger >= 20 s Post-trigger >= 600 s	Settable, Compliant
2.5(a)(xi) format	Digital format suitable for spread-sheet analysis	3.5(a)(x) format	Digital format suitable for spread-sheet analysis	4.5(a)(ix) format	Digital format suitable for spread-sheet analysis	Settable, Compliant
2.5(a)(xii) retention	>= 12 calendar months	3.5(a)(xi) retention	>= 12 calendar months	4.5(a)(x) retention	>= 12 calendar months	Settable, Compliant
2.5(a)(xiii) alternatives	Make case to AEMO	3.5(a)(xii) alternatives	Make case to AEMO	4.5(a)(xi) alternatives	Make case to AEMO	Not required - PFM is compliant
2.5(a)(xiv) aggregation	Generator response can be aggregated	3.5(a)(xiii) aggregation	Generator response can be aggregated	4.5(a)(xii) aggregation	Generator response can be aggregated	PFM can be configured for individual units or aggregated units