A Single-Ended Protection Principle for LCC-VSC-MTDC System with High Resistance Fault Tolerance

Line-commutated converter-voltage source converter(LCC-VSC)power transmission technology does not have the problem of communication failure very usually.It therefore can support the long-distance,long-capacity transmission of electric energy.However,factors such as topology,control strategy,and short-circuit capacities make the traditional protection principles not fully applicable to LCC-VSC hybrid transmission systems.To enhance the reliability of hybrid DC systems,a single-ended principle based on transmission coefficients is proposed and produced.First,the equivalent circuit of the LCC-VSC hybrid DC system is analyzed and the expression of the first traveling wave is deduced accordingly.Then,the concept of multi-frequency transmission coefficients is proposed by analyzing the amplitude-frequency,and the characteristics of each element.Finally,the LCC-VSCDC system model is built to verify the reliability and superiority of the principle itself.Theoretical analysis and experimental verification show that the principle has strong interference resistance.

Appropriate Attitude and Principle for Strengthening Human Rights Protection——Speech at the opening ceremony of the 12th Sino-German Human Rights Symposium, July 13, 2014

Since 1999, there have been 11 Sino-German Human Rights symposiums. Due to the concept of peace and development and the principle of dialogue through consultation, non- confrontation and pragmatism with equality, which have been upheld by organizers, such symposiums have made great achievements. The dialogue mechanism for human rights topics between China and Germany has helped construct a common, accessible and interactive platform for pushing forward human rights legal advancement in both countries, which has brought about a positive influence on the develop- ment of the human rights cause in the two countries. Strengthening legal construction and ensuring hu- man rights are not only the shared aspiration of all the people in the world, but also the irreversible his- torical trend of human civilization. The symposium, with the theme of international law and human rights protection, encourages participants to discuss and share theories and practices in human rights studies, which makes a significant contribu- tion to enriching the modern human rights concept and building a new type of international cooperation. The international community always pays great attention to the relation- ship between human rights and legal governance. China always abides by international human rights con- ventions including the Universal Declaration of Human Rights, which set up fundamental principles for promoting and ensuring human rights, and has endorsed 26 inter- national human rights conventions such as the International Covenant on Economic, Social and Cultural Rights. Meanwhile, China, through legislation, jurisdiction and admin- istration, brings into full play the active role of international human rights conventions in ensuring hu- man rights in the country.