Developing Wide Area Protection, Automation and Control (WAMPAC) solutions for the optimal exploitation of Greek HV transmission lines

Work Package 6 of FARCROSS Project has the primary goal to deploy a pilot in Greece to demonstrate and evaluate the Implementation of a Wide-Area Protection, Automation and Control system (WAMPAC) applied to Cross-Border transmission Systems.

Today, the WAMPAC system is successfully installed and running.

Two PDCs from different vendors in the project consortium (SEL and STER) are installed in demonstrator. In Figure 1, a general diagram of FARCROSS WAMPAC architecture is shown.

Figure 1 General Diagram of FARCROSS WAMPAC System architecture.

14 Greek locations were selected for PMU installation. In Figure 2 a map of Greece is presented, where the locations are represented. The PMU locations were proposed by IPTO based on its requirements and experience.

General Diagram of FARCROSS WAMPAC System architecture


14 Greek locations were selected for PMU installation. In the next figure, a map of Greece is presented, where the locations are represented. The PMU locations were proposed by IPTO based on its requirements and experience.

Greek Power System, PMUs Location

Detailed information on the design of the FARCROSS WAMPAC system has been presented in the following paper:

In the next figures,  some pictures of the PMUs installed for WAMPAC System can be found.

Installed STERPMU-R1 in the Greek power system

Portable STER PMU in the Greek power system

SEL PMU installed in Substation Acharnon

Pictures of SEL PDC and STER PDC can be found in the following images, respectively




The services implemented in the WAMPAC system are: Voltage Stability, Power Oscillation Monitoring, Low Frequency Oscillation Monitoring, Dynamic Line Rating, Islanding Detection and Loss of Synchronism, Rate of change of active power, MPFC control for Power Oscillation Damping and Zone IIA Protection. All the services are supervised by FARCROSS SCADA.

The main window of FARCROSS SCADA can be observed below:


Through the SCADA system it is possible to monitor the PMU measurements and communication status. This service shows the measurements of voltages and currents of all the installed PMUs and can also detect fails in PMU communications and store them in a list for later analysis.

FARCROSS SCADA, PMU Overview, List of Communication fails


FARCROSS SCADA, PMU Overview, Measurements

In SCADA is implemented a tool that lists all the events generated by the FARCROSS WAMPAC system. The list is always presented to the operators of the system in all the SCADA windows. If an event is generated by the WAMPAC system, an alarm will appear in the SCADA window, and the system operator will be able to quickly locate the origin of the event clicking on the “eye” icon associated to that event presented in the list. The “eye” icon changes automatically the SCADA window to the one related to the service that generated the alarm.

FARCROSS SCADA, Tab List of WAMPAC services events

The outputs of Voltage Stability service include a Voltage Instability Index in each PMU location and also is monitored the angle difference between two locations to compare the difference with a threshold angle of voltage stability previously defined.

SCADA visualization of Voltage Stability Service

The Low Frequency Oscillation Monitoring (LFO) service can detect Low frequency oscillations in all PMU locations, this service is applied in all cross-border interconnection between Greece and neighboring countries.


Each event detected by LFO service contains information about event triggered UTC time (system time), event start UTC time, trigger frequency, average-minimum-maximum frequency, maximum amplitude, trigger parameter and end UTC time of event.

A detailed description about testing of LFO service can be found in the following paper:

The Power Oscillation Monitoring (POM) service is able to detect low damped local or inter-area electro-mechanical oscillation modes of relevant amplitudes and frequencies, before the amplitudes become critically high, triggering warnings and alarms in FARCROSS SCADA. Therefore, the power system operator can act to prevent growing oscillations that can cause system instability or collapse, or before the local protection trip of a heavily loaded line.

SCADA visualization for POM Service

Dynamic line rating service will be applied to supervise the temperature of the 150kV submarine/underground cable between Cyclades islands and Greek Mainland. With the DLR warnings and alarms, and all the real-time information displayed by the DLR services, the operator of the power system can monitor and control the power transfer through the cable line to avoid reaching the maximum conductor temperature thresholds.

SCADA visualization for DLR Services

The Islanding detection and Loss of synchronism service is implemented in the interconnection lines between Molaoi – Chania. Specifically, the interconnection line consists of two submarine cables – each 135 km long – making this the longest sub-sea alternating current connection in the world. The output of this service is an “Islanding Condition or Loss of Synchronism” alarm to the Control Center when islanded operation or loss of synchronism is detected. With this information, the power system operator can decide to decouple the two electrical systems, and/or other remedial actions to reduce the loss of synchronism.

SCADA visualization of Islanding Detection and Loss of synchronism Service

The Rate of Change of Active Power service (RCAP) is applied also in the interconnections between Greek mainland and the Island of Crete. The goal of this service is the fast detection of active power swings transferred through the interconnection that could appear with a sudden load or generation imbalance, or after a cable line trip. With these alarms, the system operator can take remedial actions to preserve the interconnection, e.g., load shedding or curtailment, generation shedding or runback, and/or the activation of power system stabilizers (PSS) or other power oscillation damping controllers. The RCAP service complements the Power Oscillation Monitoring (POM) service, because the RCAP is designed to detect fast oscillations arising from disturbances or switching events in the power system, whereas the POM have an slower detection because is designed to calculate the oscillation modes parameters during normal or post-disturbance conditions, and to alarm only events defined as critical if they have an oscillation mode with a low damping ratio, high amplitude, and relevant frequency.


SCADA visualization, Rate of change of Active Power service

The Zone IIA Protection service is implemented the interconnection lines between Greek mainland and the Island of Crete. The output of this service is an Alarm to the control center when an internal fault is detected within the protected zone. In the future this signal could be used to trip the faulty zone as a backup protection.

The protection method is explained in detail in the following paper:

SCADA visualization Line IIA/Zone IIA Service

About the use of MPFC for Power Oscillation Damping service, the final scope is to damp power oscillations, using as control inputs the frequency, amplitude and damping of active power oscillation detected. The control actions will be executed by SmartValve, the MPFC developed by SmartWires. This service aims to investigate the possibilities of using active elements to damp oscillations and its action is limited to the physical limitation of the active device.

It was not possible to implement this service in the real demonstrator due to limitations in communication’s hardware of the MPFC installed in field. For this service were executed simulations in DIgSILENT Power Factory and also using Hardware in the loop testing using an RTDS. Obtained results were very hopeful about the feasibility of the implementation. In the following figure can be observed some results of DIgSILENT Power Factory simulations.

Results of DIgSILENT Power Factory simulations of MPFC for power oscillation damping service

Before field implementation of WAMPAC services in Greek Demonstrator, each service were tested using a PMU Real-Time Laboratory that was designed and assemble in CIRCE (Spain).

Overall view of the PMU real-time Laboratory

Examples of the use of the PMU real-time Laboratory can be found in the following papers:

Detailed analysis of the behaviour of WAMPAC services will be done during the next months in order to fine tune the algorithms and examine which of the alarms represent actual critical situations in the transmission system and which are false.

About the detection of communication fails between the PMUs and the PDCs, 55,808 communication fails were detected and reported in the SCADA system (time period between 17/11/2022 and 01/03/2022). 98% of the communications fails were concentrated in two substations. The communication between the PDCs with one of the substations has already been upgraded and the upgrade with the other one is expected to be completed soon. The communication with the other substations where PMUs are installed has been operating sufficiently based on WAMPAC requirements.