基于容量互济的柔性有载调压控制策略

Control Strategy for Flexible On Load Voltage Regulation Based on Capacity Sharing

摘要

随着电力系统中可再生能源与电动汽车等新型负载不断接入，新型配电网中的电能质量问题愈加突出，传统有载调压变压器中加入电力电子变换器可以构成柔性有载调压变压器，可以将变压器原有的离散调压转变为连续调压，然而为了改善电能质量问题，现有柔性有载调压变压器中由于电压等级和功率流动路径限制，电能质量治理能力有限．为了解决以上问题，本文提出了一种基于容量互济的柔性有载调压控制策略，使得变换器输入侧与输出侧可以互相进行辅助补偿，变换器输出侧可以通过控制电压相位辅助输入侧进行无功调节，变换器输入侧可以通过控制输入电感电流提高输出侧的电压补偿能力上限，同时在所提出装置的变换器直流侧接入储能，增强了变换器两侧电路的补偿能力；同时分析了分接开关动作对两种控制策略的影响，之后分析了所提出装置在不同控制策略下的功率流动路径，并提出了基于容量互济的多级分层控制策略以及变换器两侧电路的闭环控制策略；最后，通过仿真和试验结果得出以下结论：柔性有载调压装置可以通过分接开关与变换器配合实现连续调压，在柔性有载调压装置的变换器直流侧接入储能，可以减弱变换器两侧电路之间的功率耦合关系，并通过变换器两侧电路之间的容量互济控制，提升柔性有载调压装置中变换器的补偿能力．

Abstract

With the continuous integration of renewable energy sources and the increasing penetration of emerging loads such as electric vehicles in power systems，power quality issues in modern distribution grids are becoming in- creasingly prominent. Traditional on-load tap-changing(OLTC)transformers，when equipped with power electronic converters，can be upgraded to flexible on-load voltage regulating transformers that convert discrete voltage regula- tion into continuous voltage regulation. However，the power quality improvement capability of existing flexible OLTC transformers remains limited due to constraints imposed by voltage levels and power flow paths. To address these challenges，this study proposes a flexible on-load voltage regulation control strategy based on capacity sharing，enabling the converter’s input and output sides to assist and compensate for each other. The converter’s output side can assist the input side in reactive power adjustment by controlling the voltage phase，while the input side can enhance the upper limit of the voltage compensation capability of the output side by controlling the input inductor current. Simultaneously，an energy storage system is integrated into the converter’s DC side to strengthen the com- pensation capabilities of both sides. The effects of tap-changer operations on the two control strategies are analyzed， and the power-flow paths of the proposed device under different control strategies are examined. Based on these findings，a multi-level hierarchical control strategy incorporating capacity sharing control，along with a dual-sided closed-loop control method，is developed. Simulation and experimental results demonstrate that integrating a tap changer with a power electronic converter enables continuous voltage regulation in flexible OLTC transformers. In- corporating an energy storage system to the DC side reduces power coupling between the two circuits of the converter. Moreover，through capacity sharing control between the converter’s two sides，the compensation capability of the converter in the flexible on-load voltage regulation device is greatly enhanced.

关键词

柔性有载调压变压器 / 容量互济 / 分接开关 / 功率流动路径 / 分层多级控制

Key words

flexible on-load voltage regulating transformer(FOVRT) / capacity sharing / tap changer / power flow path / hierarchical and multi-level control

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基金资助

智能电网重大专项(2030)(2024ZD0800800)

国家电网有限公司总部科技项目(SGTJDK00DWJS2400298)