Automatic System for the Control of Stability of an HVDC link - Implementation in Red Eléctrica de España (REE)

Authors: J Martin, Red Electrica de España (REE), C. de Arriba, J. Rodriguez, GE Grid Automation, and E. Leon, Siemens, Spain

Factory and Site Acceptance Tests

A complete truth table checking was done for each system, with satisfactory results on both systems (Figure 8).
Several tests have been carried out to simulate every event and every power level affecting the HVDC stability, checking at the same time the response time of the complete system is below the specified operation time. Time obtained was in the range of 30 to 40 ms.
Site tests were carried out by synchronizing secondary injection sets in 4 substations by means of using IEEE1588 PTP synchronization protocol available in one ASPAS network.
In this way were more than 450 automated tests were carried out, with all possible conditions and combinations, to both redundant systems, all with satisfactory results giving an average actuation time of 70ms (Figure 9).

Solution Analysis
After the successful commissioning of the ASPAS System we can highlight the following:
Benefits produced by the ASPAS System in the Balearic Electric System:  
Economic: it is not needed to increase the generation in the Balearic system (greater cost than the peninsular one) due to the limitation of the HVDC link.
Environmental: prevents conventional generation in Balearic system to cover the limitations imposed by the HVDC, which contributes to a more sustainable Balearic energy mix.

Technical: after contingencies, prevents the HVDC link can be kept operating with low short-circuit power, which can cause damage to the converter station and the transmission network close to it.
Improvements added during the normal operation of the link that the ASPAS system: It increases the security in the operation of the link, by discriminating several cases with potential risk in the stability of the system, which the old stability function would have erroneously evaluated. It facilitates the operation of the system, by sending all the on-line status of the system from the PDC of Santa Ponsa to the CECOIB, which helps the operators to anticipate the performance of the HVDC link on critical contingencies and allows to take actions before the event occurs. It improved the knowledge of the protection and control system of the HVDC link.
The unavailability of the system and unscheduled interventions are reduced, along with the facilitation of the execution of maintenance activities.

Conclusions:  Electrical islanded AC systems which may be prone to be weak, where a main-land links is delivering power, needs to optimize the energy imported which is cleaner and cheaper compared with the energy self-generated in the Island.
This optimization is based on solutions that allow optimizing the possibilities offered by the insular network. It will be crucial to be able to quickly modify the operating conditions, and the economic benefits. The ASPAS System is a new development using synchrophasors in the operation of an electrical system, facilitating the decision making in emergency situations, where the speed of action can be a critical factor to maintain the grid integrity. The new application achieved with the ASPAS System based on phasor technology opens a large field of research and development to provide the system with the appropriate tools for the energy transition. We evolved from a network based on conventional generation with synchronous machines, to a network based on renewable generation dominated by power electronics.

 

Let?s start with organization in protection testing