Stability and Control of Power Networks with Energy Storage (STABLE-NET)

摘要：互联电网的运行正面临着前所未有的挑战，这主要是由于新的间歇性发电正在取代集中式灵活发电。这种发电的间歇性不可避免地给实现可靠运行带来困难。中国现有的弱高压交流系统存在与稳定性相关的问题，因此，2010年中国十大风电基地17%的发电量被削减，其中甘肃省的削减率高达25%。2011年2月24日的单网故障导致西北地区598台风机断网，导致系统频率下降0.178 Hz，凸显了目前控制技术的不足。2010年9月2日，英国发生了类似的停电事件，导致频率迅速下降，通过频率变化率（RoCoF）保护的作用，大约350兆瓦的嵌入式发电（主要是风能）断开。这是许多事件中的两个，突出表明需要在快速系统监测中采用新的方法来增强稳定性和控制。储能对于解决不同时间尺度的发电和需求之间的平衡至关重要。然而，储能系统在不同负荷下的动态性能描述、充电状态和健康监测是目前尚未解决的问题。复杂的动态行为，如迟滞，可能在存储系统中表现出来。因此，目前尚不清楚储能如何影响电力系统的运行，特别是在稳定性方面。由于间歇性发电和电网之间的电源转换器接口控制不足，已经出现了发电损失的情况。当现有的电源转换器技术被复制作为存储和电网之间的接口时，如果不提高对局部和全局动态的理解，性能差是不可避免的。另一个关键障碍是缺乏强大的监视和控制技术，无法以时间关键的方式集成存储功能。利用能量函数法对电力系统进行了快速动态安全评估，但由于电力系统动态特性的复杂性，现有工具无法计算出真正的稳定裕度。所有这些障碍都可以通过对储能监测、建模和控制的基础研究来克服，以稳定互联电网的运行。挑战在于存储与网络接口的快速计算、故障检测和鲁棒控制设计。本文提出的方法是对网络进行分散的稳定性监测、评估和控制。现有的网络操作实践严重依赖于通过大型SCADA/EMS的缓慢和集中控制架构。因此，正在提出的方法将很少需要依赖全系统的通信基础设施。此外，动态系统监测的分布式方法、系统范围扰动的分散方法和通过分布式能量函数进行动态安全评估都是新的方法。这些创新包括高功率低能量存储的前沿表现；能源功能包括异步和同步发电与电阻元件存储，突破性分散故障检测的实际应用以及间歇性发电与系统其余部分之间的强大可靠控制。由于互联电网的成功运行需要快速的计算和控制，以及储能领域的知识，因此该联盟的电力系统和储能专家由一些具有电网经验的领先控制理论专家加入，这无疑是一个非常独特的团队力量。

Summary:The operations of interconnected power networks are facing unprecedented challenges which are primarily driven by new intermittent sources of generation that are replacing centralised flexible generation. Such intermittency in generation inevitably leads to difficulties in achieving reliable operation. The existing weak high voltage AC system in China suffers from stability-related problems and as a result, in 2010 17% of the electricity produced in China's top 10 wind power bases was curtailed with curtailment reaching as much as 25% in the Gansu province. A single grid fault on the 24th of February 2011 caused the disconnection of 598 wind turbines in Northwest China, resulting in a system frequency dip of 0.178 Hz, highlighting the inadequacy of the control technology currently used. A similar incident of generation outage in the UK on the 2nd of September 2010 led to a rapid decline in frequency, which disconnected about 350 MW embedded generation (mainly wind) through the action of the rate of change of frequency (RoCoF) protection. These are two of the many incidents that highlight the need for new approaches in fast system monitoring for enhanced stability and control. Energy storage is essential to address the balance between generation and demand at different time scales. However, the description of the dynamic performance of energy storage under varied loading, and their state of charge and health monitoring are currently open problems. Complex dynamic behaviour, such as hysteresis, may manifest in storage systems. Therefore it is not clear how storage may impact power system operation, particularly with respect to stability. There have been instances of loss of generation because of the inadequate control of the power converter interface between intermittent generation and network. When the existing power converter technology is duplicated to act as an interface between storage and the grid, the poor performance is inevitable without improved understanding of local and global dynamics. Another key barrier is the lack of robust enabling technology for monitoring and control that can integrate the capabilities of storage in a time critical manner. Fast dynamic security assessment has been attempted through the energy function approach - but existing tools fail to compute the true stability margin because of the complexity of power system dynamic characteristics. All these barriers may be overcome through underpinning research in monitoring, modelling and control of storage to stabilise interconnected power network operations. The challenges lie in fast computation, fault detection and robust control design of the interface between storage and the network. The approach proposed here is decentralised stability monitoring, assessment and control of the network. Existing network operation practice relies heavily on slow and centralised control architectures through large SCADA/EMS. The methodologies that are being proposed will thus need to rely little on system wide communication infrastructure. In addition, distributed approach to dynamic system monitoring, decentralised approaches to system wide disturbances and dynamic security assessment through distributed energy function are novel approaches. The innovations include cutting edge representations of high power low energy storage; energy functions to include asynchronous and synchronous generation with storage with resistive elements, practical applications of ground breaking decentralised fault detection and robust and reliable control between intermittent generation and the rest of the system.Because the successful operation of interconnected power grids requires fast computation and control, as well as energy storage domain knowledge, the power system and energy storage experts in this consortium are joined by a number of leading control theory experts with experience in power networks - definitely a very unique strength of the team.