交直流并联输电系统实用动态安全域研究

STUDY ON PRACTICAL DYNAMIC SECURITY REGIONS OF AC/DC PARALLEL SYSTEMS

通过改变发电机节点有功功率、电压幅值以及负荷节点有功功率、无功功率可得到满足暂态功角稳定性的临界点。在给定事故、直流功率及控制方式下,交直流并联输电系统的保证暂态功角稳定性的实用动态安全域边界,由描述各节点有功功率及无功功率或电压幅值(对应于发电机节点)上、下限的垂直于坐标轴的平面和极少数几个分别对应于不同失稳模式的临界点的超平面(简称为临界面)围成。在相同故障、失稳模式、直流控制方式下,分别对应于不同直流功率的临界面间具有近似平行性,并且它们的空间几何距离与直流功率的改变量成正比。因此直流功率可以作为临界面方程的一个有功功率变量。通过观察拟合得到的临界面方程系数可以看出,临界群中各节点的有功功率、发电机节点的电压幅值的变化将显著影响系统的暂态功角稳定性,而负荷节点的无功功率变化对系统的暂态功角稳定性影响很小。

A study on dynamic security regions （DSR） of AC/DC parallel systems shows that critical points satisfying transient angle stability can be got by changing active powers, voltage magnitudes of generator nodes and active powers, reactive powers of load nodes. The practical dynamic security regions （PDSR） can be surrounded by the vertical hyper-planes that are the upper and lower limits of the above variables, and one or several critical hyper-planes that describe the critical points, given the fault, DC power and convertor＇s control mode The critical hyper-planes corresponding to different DC powers are approximately parallel for the same fault, unstable mode, and convertor＇s control mode. Further, the geometrical distance between them is linear to the change of DC power. So DC power can be considered as a active power variable of the critical hyper-plane function. Also it has been found that the active powers of nodes in critical group and voltage magnitudes of critical generators obviously affect transient angle stability of AC/DC systems, however, reactive powers of load nodes slightly do it.