摘要
非隔离型单相三桥臂统一电能质量控制器(UPQC)可以实现交流电压调节和并网点无功治理等功能,但传统控制方法直流侧母线电压高、二倍频波动大,既给设备带来巨大的电容成本,又影响设备的安全可靠运行。为了解决这些问题,该文详细分析了不同工况下直流侧电压的约束范围,推导了直流电压波动随并网点和负载功率因数、串联电压补偿相位、参考直流电压等复杂因素的关联性,并提出一种直流电压灵活降低与主动波动抑制控制方法。相比于传统控制,应用所提方法母线电压可降低至相电压峰值附近,二倍频电压波动可降低约80%。最后,实验验证了所提三桥臂UPQC直流电压控制技术的正确性。
The single-phase transformerless three-leg UPQC can achieve AC voltage regulation and reactive power compensation at the grid connection point.However,traditional control methods always result in high DC-link voltage and significant voltage fluctuations,which incur substantial capacitor costs and affect the equipment’s safety and reliability.Although an additional auxiliary device can be installed on the DC bus to suppress voltage fluctuations actively,it adds additional costs.This paper proposes a control method to achieve flexible reduction and active ripple suppression for DC-link voltage.From the modulation perspective,the constraint range of DC-link voltage is analyzed.A mathematical model is derived for DC-link voltage fluctuations with complex factors,such as grid power factor,load power factor,series compensation voltage phase,and reference DC-link voltage.With the objective of the lowest bus voltage and the lowest voltage fluctuation,the optimal solution of the compensation voltage phase and reactive power compensation coefficient are calculated,and the corresponding DC bus voltage reference is obtained.Finally,all parameters are sent to the voltage-current closed-loop controller of UPQC.The proposed method can effectively reduce the DC side voltage value and suppress the DC voltage fluctuation magnitude.The experimental results show that the proposed method does not affect the function of UPQC.Regardless of whether the grid voltage per-unit value is 0.8(pu)or 1.2(pu),the proposed method can stabilize the load side voltage at 1.0(pu).In the instant of voltage jumps,no obvious fluctuation exists in the load voltage.The equipment can ensure stable operation,and the DC-link voltage meets the regular changes of the proposed control strategy.In addition,compared with the traditional same-phase load voltage compensation method,the proposed method significantly affects the DC bus voltage suppression.The DC-link voltage fluctuation amplitude is 50%and 35%of the traditional method when the grid-side power factor is required to be 1.0 and no less than 0.9,respectively.The DC-link voltage fluctuation amplitude is 20%of the traditional method when the grid-side power factor is limited.The following conclusions can be drawn.(1)The setting of the DC side bus voltage should consider factors such as the grid voltage,compensation voltage,compensated load voltage,and DC side voltage fluctuation.The proposed DC side voltage flexible adjustment method reduces the bus voltage to near the phase voltage peak,decreasing the DC side voltage size and the cost of DC bus capacitance.(2)The DC bus voltage fluctuation is affected by the load capacity,load power and grid power factors,and load voltage phase-shift angle after compensation.The proposed method reduces DC bus voltage fluctuation by adjusting the phase shift angle of load voltage after compensation and reactive power compensation coefficient,which significantly reduces the DC-link’s voltage fluctuation and ensures the equipment’s safe and stable operation.
作者
孟维奇
何晋伟
韩俊飞
蒋玮
王成山
Meng Weiqi;He Jinwei;Han Junfei;Jiang Wei;Wang Chengshan(School of Electrical and Information Engineering,Tianjin University,Tianjin 300072,China)
出处
《电工技术学报》
EI
CSCD
北大核心
2024年第20期6517-6525,共9页
Transactions of China Electrotechnical Society
基金
国家电网公司总部科技资助项目(5400-202316195A-1-1-ZN)。
关键词
单相三桥臂统一电能质量控制器
直流电压波动
直流电压控制
主动波动抑制
Single-phase three-leg unified power quality controller(UPQC)
DC voltage fluctuations
DC-link voltage control
active voltage fluctuation suppression
