UNIfying Grid-FOllowing And Grid-foRMing Control In Inverter-based Resources (UNIFORM)

英国和全世界雄心勃勃的脱碳能源目标将使基于逆变器的资源(IBR)(例如风能、太阳能、电动汽车)进入电力系统的水平达到前所未有的水平。该项目的合作伙伴国家电网ESO预测，IBR将从2020年的约10GW增加到2028年的约30GW，增长三倍。我们电力系统的这种快速转型带来了新的机遇，也带来了新的运营和稳定挑战。与传统发电厂的机器相比，IBR的电力电子设备(逆变器)允许更快、更可编程的运行，但它们在干扰(如线路故障、发电机跳闸)时的行为也非常不同。这种不同的动态响应导致了网络中大量由逆变器驱动的不稳定，国家电网ESO对2030年前由于电网薄弱而在苏格兰北部遥远的风力发电场出现这种复杂情况以及整个GB网络系统惯性迅速减少的情况发出了危险信号。不解决这些问题就等于限制了IBR对我们网络的渗透，使我们的净零目标落空。这些挑战主要与逆变器的动态行为有关。传统上，IBR一直运行在“网格跟随”(GFL)模式下，这就像网络中的一个电流源。最近，“网格形成”(GFM)作为一种模仿电压源特性的替代方法出现。然而，最近的研究结果表明，虽然GFL在弱电网中失败，但GFM在强电网中也失败，因此这两种技术都不是适用于所有电网和条件的灵丹妙药。作为对这一问题的妥协，系统运营商目前正在考虑在整个网络中以“正确的组合”分布GFL和GFM逆变器，这实际上是一种临时措施，不能完全解决这个问题。我们将在逆变器本身中结合这两种行为，而不是在网络中混合单独的电流源和电压源。通过将GFL和GFM模式统一到一个通用的“复合V-I源”中，每个逆变器都可以根据电网条件以可编程的比率仿真混合电压/电流响应。这本质上意味着一个通用控制器，它(I)稳健地与任何电网同步，(Ii)模拟逆变器输出，确保最好的稳定性结果。这将是释放IBR真正潜力的踏脚石，并增加任何IBR驱动网络的稳定裕度，从而为设想的100%IBR电力系统铺平道路。为实施这一想法，罕见的学术界和产业界形成了合作伙伴关系。南安普顿大学将领导该项目，利用PI在逆变器控制方面的专长，并与国际合作伙伴NTUA(Nikos Hatziargyriou教授)密切合作，NTUA是世界领先的电网稳定专家。国家电网ESO将分享GB网络的案例研究和实际经验，而智能电力网络将引导实验验证阶段走向工业开发。一个详细的知识交流和研究访问计划将建立一个强大的合作伙伴关系，拥有独特和互补的技能，将在新兴的“逆变器驱动的电力系统”领域进行创新。这些工具和知识不仅有可能促进我们实现能源目标，而且还可以提升我们在全球具有巨大工业和商业潜力的领域作为全球领导者的地位。

The ambitious decarbonisation energy targets of the UK and worldwide will lead to unprecedented levels of inverter-based resources (IBRs) (e.g. wind, solar, electric vehicles) into the power system. National Grid ESO, partner of the project, forecasts a threefold IBR increase from about 10GW in 2020 to approximately 30GW by 2028. This rapid transformation of our power system comes with new opportunities, as well as new operational and stability challenges. The power electronics (inverters) of IBRs allow for faster and much more programmable operation compared to the machines of conventional power plants, but they also behave very differently during disturbances (e.g. line faults, generator trip). This different dynamic response gives rise to a multitude of inverter-driven instabilities in the network, with National Grid ESO raising a red flag for such complications in distant wind farms in North Scotland by 2030 due to weak grid, and for the entire GB network with the rapid reduction of its system inertia. Not resolving these issues equals to limiting the IBR penetration into our network and failing our net-zero targets.These challenges relate primarily to the dynamic behavior of the inverters. Conventionally, IBRs have been operating in 'grid-following' mode (GFL), that is behaving like a current source in the network. Lately, 'grid-forming' (GFM) has emerged as an alternative that emulates voltage-source characteristics. However, recent findings show that while GFL fails at weak grid, GFM also fails at strong grid, hence neither technology is a silver bullet for all grids and conditions. As a compromise to this, system operators are currently looking into distributing GFL and GFM inverters across the network in the "right mix", which is really a makeshift measure and cannot address the issue fully.UNIFORM approaches this problem from an entirely new perspective. Instead of mixing individual current and voltage sources within the network, we will combine these two behaviors within the inverter itself. By unifying the GFL and GFM modes into a universal 'Composite V-I source', every single inverter can emulate a hybrid voltage/current response at a programmable ratio depending on the grid conditions. That essentially means a universal controller that (i) synchronizes robustly to any grid, and (ii) emulates an inverter output that ensures the best possible stability outcome. This will be the steppingstone in unlocking the true potential of IBRs and increase the stability margin of any IBR-driven network, thus paving the way for the envisioned 100%-IBR power system.A rare academia-industry partnership is formed to implement this idea. The University of Southampton will be leading the project, leveraging on the PI's specialization on inverter control, and closely working with the international partner NTUA (Prof Nikos Hatziargyriou), world-leading expert in grid stability. National Grid ESO will be sharing case studies and real-life experience from the GB network, while Smart Power Networks will be guiding the experimental validation phases towards industrial exploitation. An elaborate knowledge exchange and research visits plan will establish a strong partnership with unique and complementary skillsets that will innovate in the emerging area of 'inverter-driven power systems'. These tools and knowledge have the potential to not only facilitate meeting our energy targets, but also boost our position as a global leader in a field with tremendous industrial and commercial potential worldwide.