Application Of±200MVar Statcom In A500kV Transformer Substation

China Southern Power Grid is the first AC/DC parallel operating grid, and it hasestablished a Eight AC/Six DC system for west-east electricity transmission project.Guangdong Power Grid has high load density with complicated grid structure and AC/DCmultiple operation, and its reactive voltage problem and AC/DC interaction problem arealso intertwined. AC breakdown causes busbar voltage reduction and then lead to thedefault of multi-circuit DC simultaneous commutation, which has become the one of thebiggest threats that CSP Power Grid faces today. The solution to improve the stability of DCpower transmission channel is to improve the dynamic reactive support capability ofreceiving AC system.Transformer substation, an essential part of AC system, plays the role of voltageconverting, electricity receiving and distributing. A500KV substation has higher voltagegrade and bigger capacitance with longer transmission line and more complicated structure,which makes it more important in the power system. To steady the voltage of500kvsubstations can affect the safety and power supply quality of the entire power grid. Thereare lots of impact load in the operation, and it can lead to typical power quality problem likevoltage fluctuation and flickering, harmonic wave and Unbalance three phase circuits andso on, which can also causes dynamic power quality problems of voltage drop and interruptpower-supply, and even power failure. How to improve voltage stability and supportingcapability has become a urgency, especially in high load density receive-sideSo far, transformer substations still use static compensation devices like stationarymechanical capacitor and reactor to control the busbar voltage, which can adjust the voltagein time when load or system changes. However, these equipments can not solve the problemthoroughly as they can not swift frequently. Though SVC can rapidly realize dynamiccompensation, it may cause large harmonic wave and loss. As the most advanced reactivecompensation technology, STATCOM can better solve the voltage problem, thus it has abroad prospect in substations. This article summarizes the current development of reactive compensation technologyand compares the advantages and disadvantages of various technologies as its base, andthen analyzes the theory of STATCOM and its current situation and development. In the end,the article finds out the effect and significance of STATCOM to500kV substations throughRTDS test.