一种将PMU支路电流量测引入非线性状态估计的方法

A New Method to Lead PMU Branch Current Measurement Into Nonlinear State Estimation

针对同步相量测量单元(phasor measurement unit,PMU)的电流量测难以直接引入到传统加权最小二乘状态估计的问题,提出一种在极坐标下引入PMU支路电流量测的快速分解状态估计方法。采用旋转量测变换法,利用PMU的电压相角量测信息,将电流量测转化成为旋转量测,减小了副对角元素,实现了状态量在极坐标下的解耦,从而解决了电流量测与SCADA量测的融合计算问题。同时采用了动态更新相角的方法,在每次迭代过程中更新量测旋转所用的相角值,减小了因相角量测中的不良数据带来的误差。最后通过IEEE39节点算例对旋转量测方法与直接分解法、量测变换法这3种方法进行了仿真对比。结果表明,旋转量测方法改善了状态估计的精确性,计算速度较快,能够为调度中心的决策提供精确的数据支持。

In allusion to the difficulty of directly leading the current measurement by synchronous phasor measurement unit （PMU） into traditional weighted least square based state estimation, a fast decomposition state estimation method, which leads in the PMU branch current measurement in polar coordinates, is proposed. Adopting rotated transformation and utilizing the information of voltage phase measurement by PMU, the current measurement is turned into rotated transformation to achieve the decoupling of state variables in polar coordinates and reduce the counter-diagonal elements, thus the calculation integrating branch current measurement by PMU with the measurement of supervisory control and data acquisition （SCADA） is realized. Meanwhile the dynamic updating of phase angle, by which the phase angle value used in the rotated transformation is updated during each iteration, is proposed, thus the error brought about by the bad data during the phase angle measurement can be reduced. Taking IEEE 30-bus system as the case, three methods, namely the proposed method, the direct decomposition method and the transformation measurement method, are compared by simulation results. Comparison results show that using the proposed method the accuracy of state estimation can be improved and the calculation speed of the proposed method is faster, thus the proposed method can provide accurate data to support the decision-making in dispatching center.