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高比例新能源受端电网调频能力及频率安全域演化规律分析方法

Analysis on frequency regulation capability and frequency security domain evolution of high-proportion renewable energy receiving-end grid

  • 摘要: 高比例新能源受端电网中同步机组占比持续下降,系统固有调频能力不断弱化,频率安全风险日趋严峻。为掌握受端电网调频能力及频率安全域的演化规律,提出一种基于小样本时序数据的高比例新能源受端电网调频能力及频率安全域演化规律联合分析方法。首先,建立受端电网多机聚合频率响应模型,提取系统等效惯量和一次调频系数作为量化受端电网调频能力的关键参数,推导预想扰动下频率稳定指标的解析表达式,进而基于频率安全约束确定临界参数组,划定预想扰动下受端电网频率安全域边界;其次,采用分数阶多变量灰色模型(fractional-order multivariate grey model,F-MGM)对系统未来年份的等效惯量与一次调频系数进行联合预测,并评估其预测精度;同时,将多层感知机(multilayer perceptron,MLP)与Koopman算子相结合,从历史边界数据中学习安全域边界的演化规律,实现频率安全域边界的年际时序预测。在此基础上,通过比对预测的调频能力参数与安全域边界,可量化未来频率安全裕度。最后,利用华东电网2021—2026年历史实际数据、2027—2028年规划数据,对所提方法进行验证并推演未来电网的调频能力及频率安全域。结果表明:在调频能力参数组预测中,F-MGM优于传统模型;在频率安全域边界预测中,MLP-Koopman相比纯MLP方法能更准确捕捉频率安全域边界演化的长期特征,且从动力学角度揭示频率安全域演化的物理内涵,即在相同条件下,华东电网所需的调频与惯量支撑能力随时间推移而不断提高,系统的频率安全运行裕度呈现出逐年的衰减特性。

     

    Abstract: With the continuous decline in the proportion of synchronous units in receiving-end power grids with high penetration of renewable energy, the inherent frequency regulation capability of power systems is gradually weakened, leading to growing severe risks to frequency security. To investigate the evolution laws of frequency regulation capability and frequency security region for receiving-end power grids, this paper proposes an analysis method based on historical time-series data. Firstly, a multi-machine aggregated frequency response model of the receiving-end power grid is established. The equivalent system inertia and primary frequency regulation coefficient are extracted as key parameters for quantifying the system's frequency regulation capability. The analytical expressions of frequency stability indices under anticipated disturbances are derived. On this basis, critical parameter sets are determined subject to frequency security constraints, and the boundary of the frequency security region of the receiving-end grid under anticipated disturbances is delineated. Secondly, the fractional-order multivariate grey model (F-MGM) is adopted to jointly predict the equivalent inertia and primary frequency regulation coefficient of the power grid in future years, and the prediction accuracy is evaluated. Meanwhile, combining the multilayer perceptron (MLP) with the Koopman operator, the evolution law of the security region boundary is learned from historical boundary data to realize the annual time-series prediction of the frequency security region boundary. Furthermore, the future frequency security margin can be quantified by comparing the predicted frequency regulation capability parameters with the security region boundary. Finally, historical and planned data of the East China Power Grid from 2021 to 2028 are utilized to verify the proposed method and deduce the future frequency regulation capability and frequency security region of the power grid. The results demonstrate that F-MGM outperforms conventional models in the prediction of frequency regulation capability parameter sets. For the prediction of frequency security region boundaries, the MLP-Koopman method can capture the long-term evolution characteristics of boundaries more accurately than the pure MLP approach. In addition, this method reveals the physical connotation underlying the evolution of frequency security regions from the perspective of system dynamics.

     

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