Tao Niu

Autonomous Voltage Security Regions to Prevent Cascading Trip Faults in Wind Turbine Generators

Cascading trip faults in large-scale wind power centralized integration areas bring new challenges to the secure operation of power systems. In order to deal with the complexity of voltage security regions and the computation difficulty, this paper proposes an autonomous voltage security region (AVSR) for each wind farm and the point of common coupling (PCC) substation, whose voltage can be controlled in a decoupled way. The computation of the AVSR can be completed using a stepwise search method exchanging voltage and power information between the control center and the wind farms. At each wind farm, an AVSR is determined to guarantee the normal operation of each wind turbine generator (WTG), while in the control center, each region is designed in order to guarantee secure operation both under normal conditions and after an N-1 contingency. A real system in Northern China was used to carry out case studies to verify the effectiveness of the AVSRs proposed, and good performance was demonstrated using the Monte Carlo method.

Crucial power flow interface discrimination based on distributed improved-SVM classification in a big data set

The operational states of power system become much more complicated and variable, since the size of power system grows larger. To secure power system operation, crucial power flow interfaces should be monitored. Therefore, a power system safe operation knowledge base should be established to help system operators to make decisions. The base works like an automatic operator (AO), which can quickly discriminate the crucial power flow interfaces according to power system real-time operation conditions. In this paper, first a description of the classification problem is given. Next, models of conventional support vector machines (SVM) and increment SVM are briefly described. Then the distributed computing framework of the power system safe operation knowledge is designed and the knowledge base can be established and updated based on improved-SVM. Finally, the application of the knowledge base in Guangdong Province Power System in China shows its advantages in accuracy and classification speed.

Voltage security analysis with high PVs penetration considering the interaction of transmission and distribution grids: Case studies

With the increasing of the capacity of PVs all over the world, the impact of power gird operation due to the output fluctuations of PVs has become increasingly significant. As a kind of PV, distributed PVs are closer to user side, which are difficult to observation and control at the transmission network side, and can bring unknown challenges to the operation of power grid. So the impact of distributed PVs on the voltage security of the transmission and distribution associated systems should be taken seriously. In this paper, a transmission and distribution associated system contains distributed PVs was built based on DIgSILENT/powerfactory. Then the article analysis the impact of distributed PVs to the voltage security of transmission and distribution two levels power grid containing high penetration distributed PVs in two aspects, the output fluctuations of distributed PVs and the faults in the transmission network lines using simulation. At last, the article makes a conclusion of the impact of grid connect distributed PVs to the power grid.