Secure and reliable operation of power systems with high wind and solar shares requires system flexibility. In this paper, an hourly-based market and grid simulation model is developed to assess security and reliability of a power system with high wind and solar energy share. The model is applied to Turkey as an emerging G20 country that aims to supply its rapidly growing electricity demand from local renewables and lignite as well as nuclear energy. The most ambitious scenario that covers the 2016–2026 period assumes half of all electricity demand is supplied from renewables (30% wind and solar and 20% other resources). This is achieved by ensuring system flexibility through system-friendly location of wind and solar capacity, energy storage, flexible thermal generators, and demand response. Without system flexibility, 3% of renewable power is curtailed and redispatch share required for system security and reliability doubles from current levels. Moreover, additional transmission grid investments are needed. Improving system flexibility ensures secure and reliable operation but increases system costs by 1%–5% with each flexibility option providing different scale benefits, indicating the need for system-wide planning. As gas-based generation declines below 10%, accounting for energy security benefits will be important. On the other hand, coal supply remains around 25% depending on nuclear energy development. At this crossroad, Turkey needs to make its choices to transition to a secure, clean and affordable energy system. The study addresses quantitatively how the flexibility options contribute to such a transition, providing learnings for countries with similar conditions.

具有高风能和太阳能份额的电力系统的安全可靠运行需要系统灵活性。在本文中，开发了基于小时的市场和网格仿真模型，以评估具有较高风能和太阳能份额的电力系统的安全性和可靠性。该模型适用于土耳其，是一个新兴的G20国家，旨在通过本地可再生能源，褐煤以及核能满足快速增长的电力需求。涵盖2016年至2026年的最雄心勃勃的情景是，假设所有电力需求的一半来自可再生能源（30％的风能和太阳能以及20％的其他资源）。通过对风能和太阳能容量的系统友好位置，能量存储，灵活的热力发电机和需求响应来确保系统灵活性，从而实现这一目标。没有系统灵活性，减少了3％的可再生能源，而系统安全性和可靠性所需的重新分配份额从目前的水平翻了一番。而且，需要额外的输电网投资。改善系统灵活性可确保安全可靠的操作，但由于每个灵活性选项都可提供不同的规模效益，因此将系统成本提高了1％–5％，这表明需要进行系统范围的规划。随着天然气发电量下降到10％以下，考虑到能源安全利益将非常重要。另一方面，取决于核能的发展，煤炭供应仍占25％左右。在这个十字路口，土耳其需要做出选择，以过渡到安全，清洁和负担得起的能源系统。该研究从数量上探讨了灵活性选项如何促成这一转变，