The Transmission System must operate safely and reliably, to prevent overload and outages, whereas potential disruptions must be addressed in a safe manner with the goal of restoring the system to regular operation status while ensuring the proper functioning of the electricity market.
This goal requires precise coordination and use of all appropriate instruments and tools at all levels, from design to real-time operation. That is why rules have been introduced, which are implemented at all times.
At all times, the grid must operate in a manner so that interruption of an electrical connection, such as a transmission line between two nodes, does not cause a disruption in the power supply.
This can be ensured through a coordinated operational method or a different operational combination between various elements of the system. Important elements of the network, for example, are the transmission lines, cables or transformers. The system must be managed in a manner so that the load flow remains inside the safety limits despite the interruption of a connection.
If these measures are not sufficient for safe operation, the control of the system may also directly affect the load flow by reducing production from power plants or energy injection units in an area of the system, and increase production in other areas.
An important factor that ensures safe operation is the prompt implementation of the knowledge and skills of the specialised staff in different network statuses. To ensure that these skills are appropriate, a permanent procedure for the training and education of the personnel needs to be in place. The training and education procedure focuses on all matters related to network capacity from the inclusion of new elements and their behaviour to the new legal framework, and from implementation and use of new control tools and systems to analysis and evaluation of disruptions and critical system conditions.
Control of the technical failures of network elements, which cannot unfortunately always be avoided, as well as the effects that may be observed in the network area due to these failures, are also part of the system’s control. It is very important to have determined in advance the appropriate tools and their configurations, so that the respective protection and automation systems will disconnect from the network, with the necessary selectivity, speed and safety, the network elements which fail.
The system’s management must also ensure recovery of the supply after a generalized outage, quickly, safely and most of all in harmonious cooperation with the multiple participants in the electricity system. Recovery processes must be studied, planned and included in the training of the specialised staff.
Another requirement for the safe collaboration, with the purpose of supplying electricity to the various interconnected networks are the clear arrangements dictated by agreements concluded between IPTO with users and participants somehow connected to the HETS (power plants, Network Operator, Customers, Neighbouring Operators, etc.). Agreement with neighbouring operators in particular, and mainly the detailed annexes containing technical specifications and operating instructions are always updated with the latest information and are harmonised with European and Greek laws.
Another objective of the system's control is the continuous assessment and analysis of the system's status in terms of voltage control and inactive power demand. These analyses and assessments may be part of operating instructions, set out the requirements for the management of voltage and inactive power element control or even dictate the planning of the system.