Risk Assessment for the Latvian Power System and Recommendations for Risk Mitigation

2021
VPP Enerģētika projekts FutureProof, Andrejs Utāns, Dmitrijs Guzs, Zane Broka, Antans Sauļus Sauhats

This deliverable (D4.1) considers the power system risks induced by the energy transition processes, both already implemented and expected in the future. Particular attention is given to the desynchronization of the Baltic power systems from the IPS/UPS and consequent synchronization with the continental Europe power system in 2025, which is the most topical development in the Baltic states energy sector in the imminent future. Considering the close interconnectivity of the Estonian, Latvian and Lithuanian power systems, for assessment purposes, they are modelled together, in some specific instances focusing more on the Latvian electricity network in particular. As a result of the research carried out, a novel load shedding method has been proposed which can aid in reducing foreseeable power system stability risks. The report has three main chapters. The first chapter is devoted to the ongoing energy transition induced by the fight against adverse climate change, and related power system risks therein identifiable. The chapter also provides theoretical background on risk management in general, and also in terms of power systems in particular. For power system risk assessment, two types of models have been considered: static (as used, for instance, in capacity adequacy evaluation in WP1) and dynamic. The latter takes into account transient processes inherent in power systems and thereby is paramount for ensuring their stability and blackout prevention. The second chapter focuses on the reliability and stability of the Baltic power system. Two main emerging factors affecting it are the desynchronization project and the expected significant increases in electricity production from intermittent (and non-synchronous) RES. Additionally, conventional factors influencing the stability of Baltic power systems like large generator and interconnector outages also are addressed. Guidelines for asynchronous mode prevention are briefly summarized. The third chapter is devoted to the identified stability risks and their mitigation measures. It also takes into account the regional TSO plan to install nine synchronous condensers (SCs) for inertia provision, while also assessing the consequences should this decision be rescinded. Consequently, the stability loss risks in a system without SCs were modelled simulating disconnection of the largest power generating unit in the region (Riga CHPP-2) and short-circuits is critical transmission lines. The most dangerous situations arise if the single planned synchronous connection with Continental Europe (Lithuania-Poland) disconnects. In this instance, even in the presence of SCs any additional outage or short-circuit can lead to asynchronous mode, frequency drop and system blackout. In general, after the desynchronization project, the stability loss risk in the Baltic power system will be increased and thereby it is recommended to use state-of-the-art fault-prevention automation systems and maintain sufficient fast reserve capacities. Moreover, to improve the speed of post-contingency frequency response, a new load-shedding method is proposed to be used in the Baltic power system after the desynchronization and installation of SCs. The novel approach is tested on two modelled case studies, which show that the proposed load-shedding method based on the active power injections by SCs provides considerable system stability improvements. To develop the proposed concept further and apply it in practice, the actual locations of the planned SCs in the high-voltage grid need to be determined, so that the design and operation parameters of the algorithm can be estimated.

Keywords
energosistēma; riski; stabilitāte; drošums; pārejas procesi; modelēšana; energosistēmas atslodze

Utāns, A., Guzs, D., Broka, Z., Sauhats, A. Latvijas energosistēmas risku novērtējums un rekomendācijas to mazināšanai: Valsts pētījumu programma “Enerģētika”, projekts “FutureProof” VPP-EM-INFRA-2018/1-0005. Rīga: Rīgas Tehniskās universitāte, 2021. 46 p.

Publication language
Latvian (lv)