Operation Risk Assessment And Control In Regional Power Grid

Modern power system operation has the characteristics of uncertainty and complexity.Hence, the application of security analysis tool to evaluate power system risk and the adoptionof preventive control are of significant importance. Risk-based security assessment methodcan take into account both probability and consequences of an undesirable factor, giving aneffective evaluation of system security level. In this paper, we apply risk theory to systemsecurity analysis and preventive control in regional power grid.First of all, a risk indices system suitable for regional power grid is defined. We dividerisk indices into three aspects, using bus voltage violation risk, branch overload risk and lossof load risk to reflect different perspectives of total system risk.Secondly, the operation risk assessment process is presented in details. In connection withthe practical situation of regional power grid, we apply four types of component outagemodels. They are the independent outage model, the common cause outage model, thecomponent group outage model and the power station related outage model. Then,contingency enumeration method based on a dominant fault set is employed to determine thesystem fault state. After considering two probability influence factors, we can solve the faultprobability. To value the risk consequences, loss of load analysis, overload analysis andvoltage analysis are necessary. This analysis process include various research methods, suchas the islanding detection based on Jacobin matrix singularity, the action analysis of busbarautomatic transfer switch(BATS) and the load flow calculation method. Finally, we combineprobability with consequence to attain the system risk.Meanwhile, an integrated risk preventive control method is described. We proposed a riskbased generation re-dispatching method and a risk based optimal load reduction method,adding minimizing the risk level as one of the control objectives. The WSCC9-bus system isused to demonstrate the efficiency of the proposed control methods. Also, we introduced aphased reconfiguration method to recover power supply and reduce the impact of failures.Finally, we develop a SCADA based risk assessment and decision support system,applying to an actual regional power grid. The results shows that the proposed risk assessmentand control method can explore the weak link of power grid, effectively identify system risk,and offer decision supports to prevent interruption of service.