Monitoring

Introduction

PFM image Unbundling of electricity supply systems and the introduction of new technologies in all areas of generation, transmission and distribution has made power system operation more complex. Supervision of generator performance according to Grid Codes and Connection Conditions, the stability supervision of large transmission networks at specific locations, verification of power quality criteria in distribution as well as the determination and analysis of key system parameters has generated the need for power system monitoring and grid supervision beyond classical fault recording and SCADA based trending systems. Under those aspects, wide area monitoring (WAM) via phase measurement units (PMU) is just one special feature out of all monitoring applications.

The PowerFactory Monitor fully integrates with DIgSILENT PowerFactory software offering easy access to recorded data, analysis of trends, verification of system upset responses and test results.


Typical PowerFactory Monitor Applications

  • Generation outage, load rejection and system frequency response analysis
  • Voltage stability monitoring and steady-state instability supervision
  • Power oscillation detection and analysis
  • System frequency control supervision, analysis and classification
  • Tie-line power exchange and network control characteristics
  • Control performance supervision and identification
  • Voltage dip classification and analysis
  • Power quality monitoring
  • Load parameter identification
  • Supervision of Connection Conditions and Ancillary Services
  • Frequency response tests of primary and secondary controllers
  • Wide Area Monitoring (WAM) via coordinated Phasor Measurement Units (PMU)

In addition to on-line grid supervising functions, the PowerFactory Monitor is an excellent high-end general purpose measurement instrument for all kind of plant tests typically performed to support device and plant modelling as well as parameter identification to allow for precise power systems simulation tasks.

Among these applications are:

  • Generator, motor and general feeder load tests and parameter identification
  • Power plant measurements and identification (AVR, exciter, PSS, turbine, boiler, hydraulic systems)
  • Determination of wind turbine characteristics and control behaviour
  • Optimal tuning of Power System Stabilizers (PSS)

The PowerFactory Monitor interacts perfectly with the DIgSILENT power system analysis software PowerFactory featuring seamless integration of system and plant tests, plant modelling and parameter identification.

Functional Overview

PFM image 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

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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

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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

General Characteristics
Overview
  • Up to 288 analogue and 336 digital input channels
  • Up to 7 relay outputs for alarms
  • Scan rates up to 15.15 kHz, 16 bits resolution. (optional: 30.72 kHz, 20 bits resolution)
  • Self-diagnostic, watch-dog and auto-boot
  • Alarm contacts: 1 alive and 6 programmable (optional)
19" Enclosure
  • SU32: 3*HU
  • SSU15-C: 4*HU
  • SSU32, SSU32-C, SSU32-C/E: 7*HU
Supply Voltage
  • 100-360 VDC and 90-240 VAC
Analogue Channels
  • 15/32 analogue channels / SU / SSU, flexible input configuration
Current Input
  • Input: 3x 1 or 5 A (nominal)
  • Range: 4x In
  • Accuracy: 0.1%
  • Overload: 150 A, 1s; 4x In cont.
Voltage Input
  • Input: 3x 150V p-n
  • Range: 2x Vn
  • Accuracy: 0.08%
Small Signals Input
  • 1mV, 10mV, 1V, 10V, ±20mA
Communication
  • Ethernet / optional modem
  • PFM2PFM communication via TCP/IP based PFM-DsProtocol
  • IEEE C37.118 PMU protocol
  • IEC 61850 (Optional)
  • IEC 60870-5-101, IEC 60870-5-104
  • Modbus TCP
  • Digital status input/outputs
  • Relay outputs
Recording Functions
Sampling Rate
  • Scan rate: 15.15 kHz
  • 50 cycle/s: 303 samples per cycle
  • 60 cycle/s: 252 samples per cycle
  • GPS time stamping (1µs)
20 Bit Sampling Rate (Optional)
  • Up to 512 samples per cycle
  • 50 cycles/s: up to 25.6 kHz
  • 60 cycles/s: up to 30.72 kHz
Fault-/Event/Fast Transients Recording Stream
  • Pre-fault time: user selectable (typical: 0.1-5s)
  • Post-fault time: user selectable (typical: 0.1-5s)
  • Re-trigger: supported, various setting options
RMS-/Phasor/PQ/Mid-Term Transients Recording Stream
  • Pre-fault time: user selectable (typical: 1-60s)
  • Post-fault time: user selectable (typical: 10-600s)
  • Re-trigger: supported, various setting options
Continuous RMS/Phasor/PQ Monitoring/Slow Transients Recording Stream
  • Sampling rate: 0.1-100 samples per second
  • Recording interval: 24x7 over several years
  • Variables: Full flexibility (user defined)
Triggering
  • Threshold and gradient on any input and user defined signal (voltage, power, frequency, phase, sequence quantity, etc.).
  • Dynamic triggering on calculated quantities (signal oscillation, PQ-criteria, step changes, etc.).
  • Manual triggering on visually observed signals and test commands.
SSU15-C Basic Module Details
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IPC Controller Unit
  • Intel Embedded Celeron
Main Memory
  • 2 GByte, DDRam
Hard Disk
  • 32 GB SSD memory (default)
Networking
  • 2 x Gigabit LAN (10/100/1000), 1 x Front LAN (10/100) for diagnostics
Time Synchronisation
  • GPS / 1µ signal synchronization (optional)
  • IRIG-B (optional)
  • IEEE 1588 PTP protocol (optional)
Analogue Input Channels
  • 15
Digital Input Channels
  • 16
SSU32-C Basic Module Details
PFM image
IPC Controller Unit
  • Intel Embedded i7
Main Memory
  • 4 GByte, DDRam
Hard Disk
  • 128/256 GByte SSD Storage
Networking
  • 2 x Gigabit LAN (10/100/1000), 1 x Front LAN (10/100) for diagnostics
Time Synchronisation
  • GPS / 1µ signal synchronization (optional)
  • IRIG-B (optional)
  • IEEE 1588 PTP protocol (optional)
Analogue Input Channels
  • 32
Digital Input Channels
  • 16

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