Study On Transient Stability And Control Measures For Wind-thermal-bundled Transmission DC Block Fault

Renewable energy development is regarded as the main point in future energystrategy in our country. With the increase of renewable energy, wind power accountsfor more and more proportion in the energy field, which is considered to be one of thematurest and most potential power generation approaches. Based on the specificscenario with wind-thermal-bundled system and HVDC transmission mode andfocusing on the transient stability problems in wind-thermal-bundled sending systemcaused by the severe excess power transfer in a fault of DC monopoles block, theinteraction of wind power and thermal power affecting on power system’s transientstability is studied in this paper, as well as the corresponding optimal stability controlmeasurements to ensure the safety of power grid.Firstly, the models that can adequately reflect the basic characteristic ofwind-thermal-bundled power system are built based on the power system analysissoftware BPA. Based on the models, several different boundary conditions aresimulated and compared to study power system’s stability. And then based on EEACand energy imbalance theory, the instability mechanism and the related influencingfactors are researched in the scenario of DC monopoles block in thewind-thermal-bundled and HVDC power system. And the transient stability degree isquantized, and the differences of transient stability among different boundaryconditions are analyzed. The key factors influencing transient stability by interactionof wind power and thermal power is also discussed. Further studies are made basedon typical system analysis in the real power grid. Based on the realwind-thermal-bundled and HVDC power system in northwest power grid, thesystem’s stability is studied in a fault of Hami-Zhengzhou HVDC monopoles block.Moreover, the different influences on system safety are simulated by differentproportions of wind power and thermal power with constant factor control. The dynamic reactive compensation in wind farms is also discussed for the enhancementof transient stability. Finally, based on the power system stability analysis in part3,many measurements are taken to enhance the system stability, such as DC emergentpower modulation, FACTS emergency control including controllable high resistancein AC transmission channel and generator chipping control including thermal units,wind power units and their mixture. The simulation results show the effectiveinfluence of them.The research results in this paper can provide good reference to maintain the safeand stable operation of wind-thermal-bundled and HVDC power system in ourcountry.