考虑子模块均压约束的混合型模块化多电平换流器功率极限分析

The hybrid modular multilevel converter has the capabilities of operating at a reduced voltage and riding through DC faults without blocking. The sub-module voltage balancing constraint is the main operational constraint that limits the steady-state power operating range during reduced voltage operation. Based on the characteristics of the converter bridge arm current and bridge arm voltage that satisfy the sub-module voltage balancing constraint, the power limit operating range of the hybrid modular multilevel converter during reduced voltage operation is analyzed. A calculation method for quickly determining the feasible power operating region of the hybrid modular multilevel converter is proposed. The accuracy and effectiveness of the calculation method are jointly verified by comparing the results of analytical scanning calculations and electromagnetic transient simulations. The influence of the proportion of full-bridge sub-modules on the power operating limit range is analyzed. A design method for the minimum proportion of full-bridge sub-modules is proposed from the perspective of power operating capabilities.

混合型模块化多电平换流器具备降压运行和不闭锁穿越直流故障的能力,子模块均压约束是其降压运行时对稳态功率运行范围起主要限制的运行约束。从满足子模块均压约束的换流器桥臂电流和桥臂电压的特性出发,分析了混合型模块化多电平换流器在降压运行时的功率极限运行范围。提出了快速确定混合型模块化多电平换流器可行功率运行域的计算方法。通过对比解析扫描计算的结果和电磁暂态仿真共同验证了计算方法的准确性和有效性。分析了全桥子模块比例对功率运行极限范围的影响。从功率运行能力的角度提出了全桥子模块最小比例的设计方法。