The lack of inertial response from non-synchronous, inverter-based generation in microgrids makes the power system vulnerable to a large rate of change of frequency (ROCOF) and frequency excursions. Energy storage systems (ESSs) can be utilized to provide fast-frequency support to prevent such large excursions in the system. However, fast-frequency support is a power-intensive application that has a significant impact on the ESS lifetime. In this paper, a framework that allows the ESS operator to provide fast-frequency support as a service is proposed. The framework maintains the desired quality-of-service (limiting the ROCOF and frequency) while taking into account the ESS lifetime and physical limits. The framework utilizes moving horizon estimation (MHE) to estimate the frequency deviation and ROCOF from noisy phase-locked loop (PLL) measurements. These estimates are employed by a model predictive control (MPC) algorithm that computes control actions by solving a finite-horizon, online optimization problem. Additionally, this approach avoids oscillatory behavior induced by delays that are common when using low-pass filters as with traditional derivative-based (virtual inertia) controllers. MATLAB/Simulink simulations on a test system from Cordova, Alaska, show the effectiveness of the MHE-MPC approach to reduce frequency deviations and ROCOF of a low-inertia microgrid.

中文翻译：

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基于优化的低惯量微电网快速频率估计与控制

微电网中基于逆变器的非同步发电缺乏惯性响应，使得电力系统容易受到较大的频率变化率（ROCOF）和频率偏移的影响。储能系统（ESS）可用于提供快速频率支持，以防止系统中发生如此大的偏移。但是，快速频率支持是一项功耗密集型应用程序，会对ESS寿命产生重大影响。在本文中，提出了一个框架，该框架允许ESS运营商提供快速频率支持即服务。该框架在考虑ESS寿命和物理限制的同时，保持了所需的服务质量（限制了ROCOF和频率）。该框架利用移动视界估计（MHE）从噪声锁相环（PLL）测量中估计出频率偏差和ROCOF。这些估计由模型预测控制（MPC）算法采用，该算法通过解决有限水平的在线优化问题来计算控制动作。此外，这种方法避免了像传统的基于微分的（虚拟惯性）控制器那样使用低通滤波器时常见的延迟引起的振荡行为。在来自阿拉斯加科尔多瓦的测试系统上进行的MATLAB / Simulink仿真显示，MHE-MPC方法可有效降低低惯性微电网的频率偏差和ROCOF。此外，这种方法避免了像传统的基于微分的（虚拟惯性）控制器那样使用低通滤波器时常见的延迟引起的振荡行为。在来自阿拉斯加科尔多瓦的测试系统上进行的MATLAB / Simulink仿真显示，MHE-MPC方法可有效降低低惯性微电网的频率偏差和ROCOF。此外，这种方法避免了像传统的基于微分的（虚拟惯性）控制器那样使用低通滤波器时常见的延迟引起的振荡行为。在来自阿拉斯加科尔多瓦的测试系统上进行的MATLAB / Simulink仿真显示，MHE-MPC方法可有效降低低惯性微电网的频率偏差和ROCOF。