This paper applies the singular integral operators, singular quadrature operators and discretization matrices associated with singular integral equations with Cauchy kernels, which are established in [1], to give a un...This paper applies the singular integral operators, singular quadrature operators and discretization matrices associated with singular integral equations with Cauchy kernels, which are established in [1], to give a unified framework for various collocation methods of numerical solutions of singular integral equations with Cauchy kernels. Under the framework, the coincidence of the direct quadrature method and the indirect quadrature method is very simple and obvious.展开更多
This paper proposes a hybrid decoupled power flow method for balanced power distribution systems with distributed generation sources. The method formulates the power flow equations in active power and reactive power d...This paper proposes a hybrid decoupled power flow method for balanced power distribution systems with distributed generation sources. The method formulates the power flow equations in active power and reactive power decoupled form with polar coordinates. Second-order terms are included in the active power mismatch iteration, and constant Jacobian and Hessian matrices are used. A hybrid direct and indirect solution technique is used to achieve efficiency and robustness of the algorithm. Active power correction is solved by means of a sparse lower triangular and upper triangular （LU） decomposition algorithm with partial pivoting, and the reactive power correction is solved by means of restarted generalized minimal residual algorithm with an incomplete LU pre-conditioner. Typical distribution generation models and distribution load models are included. The impact of zero-impedance branches is explicitly modeled through reconfiguring of the adjacent branches with impedances. Numerical examples on a sample distribution system with widespread photovoltaic installations are given to demonstrate the effectiveness of the proposed method.展开更多
锂离子电池在电动汽车行业中的应用引起了广泛的关注。然而,由于锂离子电池在运行过程中会逐渐老化,这可能导致意外发生,因此需要对锂离子电池进行监管和维护。荷电状态(state of charge,SOC)对锂离子电池的监测和维护起着至关重要的作...锂离子电池在电动汽车行业中的应用引起了广泛的关注。然而,由于锂离子电池在运行过程中会逐渐老化,这可能导致意外发生,因此需要对锂离子电池进行监管和维护。荷电状态(state of charge,SOC)对锂离子电池的监测和维护起着至关重要的作用。准确的SOC估计可以确保锂离子电池正常充放电并延长其使用寿命。对锂离子电池SOC估计方法进行了总结和分类,介绍了各种方法的原理,总结了其优缺点,并对未来锂离子电池SOC估计方法做出展望。展开更多
模块化多电平换流器(Modular Multilevel Converters,MMC)具有维护方便,易扩容等优点,在柔性直流输电(High Voltage Direct Current,HVDC)、电网谐波治理等领域得到广泛应用。但其子模块中的分散电容,在实际使用中会产生谐波环流,影响...模块化多电平换流器(Modular Multilevel Converters,MMC)具有维护方便,易扩容等优点,在柔性直流输电(High Voltage Direct Current,HVDC)、电网谐波治理等领域得到广泛应用。但其子模块中的分散电容,在实际使用中会产生谐波环流,影响了模块电容电压波动,降低换流器的安全裕度和经济性。文章首先介绍了MMC组成结构;然后通过建立桥臂瞬时功率方程,分析环流产生机理,并得出桥臂环流中存在二次谐波分量的结论,通过控制直流侧电压与桥臂等效输出电压之间的差值,调节环流中的谐波分量,进而将现阶段国内、外环流抑制方法分为间接环流抑制方法与直接环流抑制方法,并对环流的利用也做了相关阐述。最后对环流抑制存在的问题进行总结与展望。展开更多
基金NNSF of China, SF of SEC of China and SF of Wuhan University.
文摘This paper applies the singular integral operators, singular quadrature operators and discretization matrices associated with singular integral equations with Cauchy kernels, which are established in [1], to give a unified framework for various collocation methods of numerical solutions of singular integral equations with Cauchy kernels. Under the framework, the coincidence of the direct quadrature method and the indirect quadrature method is very simple and obvious.
文摘This paper proposes a hybrid decoupled power flow method for balanced power distribution systems with distributed generation sources. The method formulates the power flow equations in active power and reactive power decoupled form with polar coordinates. Second-order terms are included in the active power mismatch iteration, and constant Jacobian and Hessian matrices are used. A hybrid direct and indirect solution technique is used to achieve efficiency and robustness of the algorithm. Active power correction is solved by means of a sparse lower triangular and upper triangular （LU） decomposition algorithm with partial pivoting, and the reactive power correction is solved by means of restarted generalized minimal residual algorithm with an incomplete LU pre-conditioner. Typical distribution generation models and distribution load models are included. The impact of zero-impedance branches is explicitly modeled through reconfiguring of the adjacent branches with impedances. Numerical examples on a sample distribution system with widespread photovoltaic installations are given to demonstrate the effectiveness of the proposed method.
文摘锂离子电池在电动汽车行业中的应用引起了广泛的关注。然而,由于锂离子电池在运行过程中会逐渐老化,这可能导致意外发生,因此需要对锂离子电池进行监管和维护。荷电状态(state of charge,SOC)对锂离子电池的监测和维护起着至关重要的作用。准确的SOC估计可以确保锂离子电池正常充放电并延长其使用寿命。对锂离子电池SOC估计方法进行了总结和分类,介绍了各种方法的原理,总结了其优缺点,并对未来锂离子电池SOC估计方法做出展望。
文摘模块化多电平换流器(Modular Multilevel Converters,MMC)具有维护方便,易扩容等优点,在柔性直流输电(High Voltage Direct Current,HVDC)、电网谐波治理等领域得到广泛应用。但其子模块中的分散电容,在实际使用中会产生谐波环流,影响了模块电容电压波动,降低换流器的安全裕度和经济性。文章首先介绍了MMC组成结构;然后通过建立桥臂瞬时功率方程,分析环流产生机理,并得出桥臂环流中存在二次谐波分量的结论,通过控制直流侧电压与桥臂等效输出电压之间的差值,调节环流中的谐波分量,进而将现阶段国内、外环流抑制方法分为间接环流抑制方法与直接环流抑制方法,并对环流的利用也做了相关阐述。最后对环流抑制存在的问题进行总结与展望。
