Red Eléctrica, a subsidiary of the Redeia group, has notified this Wednesday the Ministry of Ecological Transition and the National Commission of Markets and Competition (CNMC) of recent sudden variations in voltage in the Spanish peninsular electrical system after the blackout of the April 28“although within the established limits, even with a high number of conventional groups connected,” reported the department headed by Sara Aagesen.
Consequently, the Ministry has asked the system operator to act according to its functions and the CNMC to strengthen supervision and take “the necessary measures to ensure that all agents comply with their obligations for the proper functioning of the system”. As a result, the CNMC has begun the processing of some temporary and time-limited measures, while it continues its supervisory work and finishes deploying the new operating procedure that will allow all technologies to provide voltage control.”
However, he assured that “there has been no supply risk in recent days”, but that “some situations of sudden voltage variations” have been observed in the system “always within the established margins”, as company sources have indicated to Europa Press.
In the proposed resolution of the body chaired by Cani Fernández, it is detailed that on the date On October 7, 2025, a letter from the system operator was entered into the CNMC requesting the introduction of modifications urgent in various electrical operating procedures.
Impact on security of supply
Red Eléctrica highlights in its writing the observance In the last two weeks of “sudden” voltage variations in the Spanish peninsular electrical system, “such that they may have an impact on security of supply if the proposed changes are not implemented.”
One day later, The CNMC began the hearing process, sending the Electricity Advisory Council la proposed resolution temporarily modifying several electrical operating procedures for the introduction of urgent measures to stabilize the voltage in the Spanish peninsular electrical system.
Likewise, on that same date, in compliance with the public information process, the aforementioned proposed resolution was published on the organization’s website so that the subjects could formulate their allegations within 5 business days. Likewise, that same day the proposed resolution was sent to the General Directorate of Energy Policy and Mines for comments on the matter.
How to manage sudden changes
The modifications requested by Red Eléctrica are aimed at mitigating sudden voltage variationswhich the company relates to sudden program changes, in particular, of renewable generation, as well as the response time of the generation providing dynamic voltage control.
The proposed changes would have implications for operating procedures: PO 3.1 Programming Process, PO 3.2 Technical RestrictionsPO 7.2 Secondary Regulation and PO 7.4 Voltage Control.
In view of this proposal, A public hearing process is agreed, which will be open until October 15in order to gather the opinion of the subjects and be able to adequately assess its impact.
According to the information provided to the CNMC by the system operator, the rapid voltage variations registered in these last two weeks, even though the voltages are always within the established margins, potentially can trigger demand and/or generation disconnections that end up destabilizing the electrical system, the agency considers.
The “stepping stone” effect
The evolution that the system has had in recent years has caused these dynamics to now begin to appear. This occurs due to different factors, such as significant growth of connected facilities through power electronics to the system and the high concentration in certain points of it. According to REE, these installations can modify their power in very few seconds, practically in “steps”.
Another factor is that the active participation of these technologies in the different segments market increases the probability of ever greater variations in its production. It should be remembered that these technologies do not regulate voltage continuously. Furthermore, it is observed that a part of the connected groups that have continuous voltage control “they do not have the speed of response that the system requires given the dynamics of variation of the parameters that have been recorded in recent days”.
Proliferation of small power installations
Just as there has been a very strong increase in large installations connected to the system, there has also been a strong growth of small power installations connected at low voltages, a good part of them associated with self-consumption. The system operator claims to have no “observability” of these facilities, so he cannot anticipate their behavior.
Besides, The increase in self-consumption in distribution has caused net demand in transportation to be much lower when there is a high solar resource. This causes the transport networks to be unloaded, bringing the system to an operating point where variations in active power have an increasingly greater impact on the variability of the system variables, the most important of which is the network voltage.
Conclusions
The system operator concludes that the appearance of rapid variations in voltage in recent dayss, in periods of low demands, high solar resources and observance of a slow response of the generation that has continuous control of the voltage “makes it necessary to take measures as a matter of urgency.”
For this reason, and taking into account the valuation of Red Eléctrica and, in particular, its consideration of the impact of the proposed measures on security of supplythe CNMC considers it appropriate to proceed with the urgent processing of the requested changes in the operating procedures, prior to a public hearing in order to gather the opinions of the subjects and be able to adequately assess their impact.
The CNMC warns that the requested measures could have a “significant” impact on balance, restrictions and tension control services as well as on the negotiation possibilities of production facilities in all markets.
Notice of a possible cost increase
Specifically, the tightening of the conditions for providing services “could result in a reduction in supply and, with it, competitiveness in the marketsand/or result in an increase in the cost borne by the demand,” he warns.
Therefore, understanding the need to take these measures immediately in the current context, It is considered that they must have an exceptional and temporary naturewaiting to carry out a more in-depth analysis of the causes and solutions to resolve the voltage variations recorded.
In this sense, it is worth remembering that Currently, the process of enabling the generation facilities is being carried out. to regulate voltage dynamically in response to Red Eléctrica instructions, “which will contribute to significantly improving the safety of the system and, in particular, the rapid response of the facilities.”
Consequently, The CNMC orders the “immediate” implementation of the requested modifications by the system operator in the operating procedures but on a temporary basis. Its application may be extended if the persistence of the need is confirmed and taking into consideration the observed impact on markets and services.
