R&D Nester (the energy research center from the Portuguese TSO REN and SGCC) will be presenting its work at the bi-annual CIGRÉ meeting 26-31 august 2018.

With mainly TSOs, utilities and DSOs, international influential decision makers and technology experts as its regular attendees, 3000+ international delegates and 8000+ participants from 93 countries, CIGRÉ is the international leading event for the Power Systems Industry.

R&D Nester succeeded to submit 3 publications to the exclusive list of accepted papers for the technical sessions, aiming at contributing to a more robust, sustainable and efficient power system.

Below is a short description of the work being presented, which results from the cooperation between R&D Nester, REN and CEPRI experts.

1)Demonstration of new solutions for provision of ancillary services: Frequency and Voltage control

Study Committee C2 - Power System Operation and Control

With the increasing penetration of wind and solar photovoltaic, the system operator may not rely on the remaining synchronous generators to guarantee the frequency and voltage control. These renewable sources of energy must take part in the frequency and voltage control in order to contribute to the electricity grid safety. In the scope of the project "Renewable Dispatch Tool", R&D Nester researched this topic leading to real frequency and voltage tests, on site and in factory environment. The goal of this paper is to show the tests results for wind and PV technology regarding frequency and voltage control tests. Regarding the frequency control tests, frequency-droop-control and inertia emulation tests were conducted for wind and two tests for solar (including the simulation of a real frequency incident in the European electricity grid). The simulation of the feature f-return was also addressed. In the voltage control tests, a test with a real wind farm was performed and a simulation test in factory environment was done for solar. The conclusions are that wind and solar can comply with the "voltage-droop-control" system service; they can also comply with the primary frequency control for over-frequency, by limiting the output power. For under-frequency control, only wind has demonstrated the capability to provide synthetic inertia. For solar PV, local storage might be required to fulfil this requirement. These new solutions will also require a new market design in which the system will have to pay for all system services.

2)The impact of shorter intraday market gate closure on regulation reserves

Study Committee C5 - Electricity Markets and Regulation

This work quantifies the variation of regulation reserve requirements by reducing the time span between gate closure of intraday markets and physical power delivery in Portugal. Intraday markets and regulation reserves are means of readjust the grid balancing against deviations from the day-ahead market schedule. While the first works ex-ante to the physical power delivery, the second is a real-time mechanism used by the System Operator to secure the energy supply and avoid the curtailment of wind and solar power generation.

The work reviews the new intraday market design in connection with the system services' market. Quantitative analysis identifies a significant increase in the activation of regulation reserves for real-time technical restrictions relief when the physical delivery is more than 7 hours away from the end of the intraday negotiation. This happens in two of the sessions of the intraday market. With the integration of the European continuous market model in the MIBEL intraday market design, it is expected these sessions will lose their weight in the system management.

3)Laboratorial assessment and scalability analysis of protection and automation functions supported by a smart substation process bus network

Study Committee B5 - Protection and Automation

As the IEC 61850 standard is increasingly being adopted as the communication and configuration standard by IED manufacturers, utilities are deploying more Process Bus networks in their substations. Despite all the advantages broadly analyzed in literature, these networks shall be carefully designed, in order to get the maximum benefit without compromising the current levels of reliability, dependability and security of Protection, Automation and Control (PAC) systems.

This paper presents a laboratorial assessment of a Process Bus network architecture suitable to be applied in transmission size substations. A testbed with physical, simulated and virtual IEDs and real-time simulation of Portuguese transmission system was used, where one Portuguese transmission substation was simulated and interacted with real IEDs installed in the testbed through hardware-in-the-loop (HIL) simulation.

For more information please see www.rdnester.com and http://www.cigre.org/Events/Session/Session-2018.