针对小负荷下基于避雷器能耗特性的最后断路器保护可能发生误动作的问题,分析了交流负荷的切除会导致高端换流变进线电压升高的机理,指出基于避雷器能耗特性的最后断路器保护无法正确区分交流线路处于小负荷运行状态抑或隔离状态是造成...针对小负荷下基于避雷器能耗特性的最后断路器保护可能发生误动作的问题,分析了交流负荷的切除会导致高端换流变进线电压升高的机理,指出基于避雷器能耗特性的最后断路器保护无法正确区分交流线路处于小负荷运行状态抑或隔离状态是造成保护误动作的重要原因。提出引入交流场开关量、各条出线首端电压作为判断交流线路状态的信号,使其能够正确区分交流线路处于何种状态,并针对不同状态发出正确的动作信号。结合云广±800 k V特高压直流输电工程的实际运行参数建立了仿真模型,仿真分析了原始判据与改进判据在不同场景下的动作情况,验证了改进判据的有效性。展开更多
By using the coupled duster method and the numerical density matrix renormalization group method, we investigate the properties of the quantum plateau state in an alternating Heisenberg spin chain. In the absence of a...By using the coupled duster method and the numerical density matrix renormalization group method, we investigate the properties of the quantum plateau state in an alternating Heisenberg spin chain. In the absence of a magnetic field, the results obtained from the coupled cluster method and density matrix renormalization group method both show that the ground state of the aiternating chain is a gapped dimerized state when the parameter a exceeds a critical point ac. The value of the critical points can be determined precisely by a detailed investigation of the behavior of the spin gap. The system therefore possesses an m = 0 plateau state in the presence of a magnetic field When a 〉 ac. In addition to the m = 0 plateau state, the results of density matrix renormaiization group indicate that there is an m = 1/4 plateau state that occurs between two critical fields in the alternating chain if a 〉 1. The mechanism for the m = 1/4 plateau state and the critical behavior of the magnetization as one approaches this plateau state are also discussed.展开更多
文摘针对小负荷下基于避雷器能耗特性的最后断路器保护可能发生误动作的问题,分析了交流负荷的切除会导致高端换流变进线电压升高的机理,指出基于避雷器能耗特性的最后断路器保护无法正确区分交流线路处于小负荷运行状态抑或隔离状态是造成保护误动作的重要原因。提出引入交流场开关量、各条出线首端电压作为判断交流线路状态的信号,使其能够正确区分交流线路处于何种状态,并针对不同状态发出正确的动作信号。结合云广±800 k V特高压直流输电工程的实际运行参数建立了仿真模型,仿真分析了原始判据与改进判据在不同场景下的动作情况,验证了改进判据的有效性。
基金Supported by the National Natural Science Foundation of China under Grant Nos.10804053 and 61203147the Natural Science Foundation of Jiangsu Province under Grant No.BK20131428+2 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions under Grant No.13KJD140003the Scientific Research Foundation of Nanjing University of Posts and Telecommunications under Grant No.NY211008Qing Lan Project of Jiangsu Province
文摘By using the coupled duster method and the numerical density matrix renormalization group method, we investigate the properties of the quantum plateau state in an alternating Heisenberg spin chain. In the absence of a magnetic field, the results obtained from the coupled cluster method and density matrix renormalization group method both show that the ground state of the aiternating chain is a gapped dimerized state when the parameter a exceeds a critical point ac. The value of the critical points can be determined precisely by a detailed investigation of the behavior of the spin gap. The system therefore possesses an m = 0 plateau state in the presence of a magnetic field When a 〉 ac. In addition to the m = 0 plateau state, the results of density matrix renormaiization group indicate that there is an m = 1/4 plateau state that occurs between two critical fields in the alternating chain if a 〉 1. The mechanism for the m = 1/4 plateau state and the critical behavior of the magnetization as one approaches this plateau state are also discussed.
