The AC/DC hybrid distribution network is one of the trends in distribution network development, which poses great challenges to the traditional distribution transformer. In this paper, a new topology suitable for AC/D...The AC/DC hybrid distribution network is one of the trends in distribution network development, which poses great challenges to the traditional distribution transformer. In this paper, a new topology suitable for AC/DC hybrid distribution network is put forward according to the demands of power grid, with advantages of accepting DG and DC loads, while clearing DC fault by blocking the clamping double sub-module(CDSM) of input stage. Then, this paper shows the typical structure of AC/DC distribution network that is hand in hand. Based on the new topology, this paper designs the control and modulation strategies of each stage, where the outer loop controller of input stage is emphasized for its twocontrol mode. At last, the rationality of new topology and the validity of control strategies are verified by the steady and dynamic state simulation. At the same time, the simulation results highlight the role of PET in energy regulation.展开更多
The DC grid technology of multi-power supply and multi-drop-point power reception is an effective solution for large-scale renewable energy integration into the power grid.Line-commutated converter-Voltage source conv...The DC grid technology of multi-power supply and multi-drop-point power reception is an effective solution for large-scale renewable energy integration into the power grid.Line-commutated converter-Voltage source converter(LCC-VSC)power grids are one of the more important developmental directions of the future power grid that have occured in recent years.But the multi-terminal high voltage direct current system has the problems of inconsistent boundary characteristics,inconsistent control,and fault response characteristics,which puts higher requirements on the protection scheme.Thus,a completely new protection principle is proposed in this paper.Firstly,the fault characteristics of distributed capacitance current are analyzed.The reactive power calculated by the distribution parameters of different frequencies is different.Subsequently,the fault characteristics of DC reactive power are analyzed,and a DC reactive power extraction algorithm is proposed.The polarity of the multi-band DC reactive power is used to construct the protection scheme.Finally,the LCC-VSC power grid model verifies the correctness and superiority of the proposed protection scheme.The proposed scheme uses DC reactive power instead of fault current to solve the long delay problem caused by distributed capacitance.Compared with the prior art,the proposed solution is not affected by distributed capacitance and has a stronger anti-interference ability(600Ω+10 dB+1 ms).展开更多
随着电力系统中多类型直流线路占比的逐步提升,调度系统与异构平台间的潮流数据交换需求明显增大,亟需研究新形态下交直流混联系统的潮流计算数据生成问题。该文从拓扑转换、网络拓扑分析、设备建模以及数据生成策略4个主要步骤,实现含...随着电力系统中多类型直流线路占比的逐步提升,调度系统与异构平台间的潮流数据交换需求明显增大,亟需研究新形态下交直流混联系统的潮流计算数据生成问题。该文从拓扑转换、网络拓扑分析、设备建模以及数据生成策略4个主要步骤,实现含交直流系统的基于可扩展标记语言的通用信息模型(common information model/extensible markup language,CIM/XML)数据到潮流计算输入数据的转换。首先,该文从设备间开关拓扑的角度,进行深度优先算法(depth first search,DFS)搜索和设备拓扑拼接,实现开关/节点模型到母线/支路模型的转换;其次,在筛选出活拓扑岛、剔除不带电设备后,着重分析了CIM/XML中换流器建模对交直流节点选取的影响,进而提出了直流节点选取规则和具备普适性的直流数据生成策略。最后,以某地调度500kV及以上交直流网络导出的CIM/XML数据为算例,潮流计算结果与数据采集与监视控制系统(supervisory control and data acquisition,SCADA)量测数据比对验证所提策略的有效性。展开更多
能量路由器的核心元件为双有源桥(dual active bridge,DAB)直流变压器,针对其短路故障时电流上升速率快,峰值大,导致DAB内部电力电子器件闭锁的问题,该文提出一种具有限流型结构的直流变压器,限流装置结构为从DAB高压侧H桥连接单相整流...能量路由器的核心元件为双有源桥(dual active bridge,DAB)直流变压器,针对其短路故障时电流上升速率快,峰值大,导致DAB内部电力电子器件闭锁的问题,该文提出一种具有限流型结构的直流变压器,限流装置结构为从DAB高压侧H桥连接单相整流桥,再与输出端口的限流电感相连。当直流系统发生短路故障时,限流型直流变压器采用混合控制算法进行整流,为限流电感提供钳位电压,限制故障电流的峰值,并与断路器配合实现无弧开断,该方法避免DAB中电力电子器件发生闭锁,快速实现故障限流和隔离。在仿真系统中搭建了基于10kV/750V直流变压器的限流型直流变压器的模型,仿真结果表明限流型直流变压器与断路器配合实现故障限流和隔离的有效性和可行性。展开更多
The line side winding is under the fundamental frequency AC voltage, while the valve side winding contains not only fundamental AC voltage component, but also the DC voltage component, fundamental AC voltage component...The line side winding is under the fundamental frequency AC voltage, while the valve side winding contains not only fundamental AC voltage component, but also the DC voltage component, fundamental AC voltage component, and higher harmonic voltage components when the converter transformer is at its normal operating condition, and the electric field of converter transformer is a non-sinusoidal steady one. To analyze the non-sinusoidal steady electric field containing the DC component, fundamental AC and higher harmonic components, the voltage spectrum of the valve winding in a ±500 kV converter transformer is firstly analyzed, and the non-sinusoidal periodic steady electric field is obtained by the fast discrete Fourier transform. Different resistivity of the oil and oil-immersed paper is adopted to simulate the aging of oil paper insulation at operation, and get the non-sinusoidal steady electric field.展开更多
基金supported by National Key Research and Development Program of China (2016YFB0900500,2017YFB0903100)the State Grid Science and Technology Project (SGRI-DL-F1-51-011)
文摘The AC/DC hybrid distribution network is one of the trends in distribution network development, which poses great challenges to the traditional distribution transformer. In this paper, a new topology suitable for AC/DC hybrid distribution network is put forward according to the demands of power grid, with advantages of accepting DG and DC loads, while clearing DC fault by blocking the clamping double sub-module(CDSM) of input stage. Then, this paper shows the typical structure of AC/DC distribution network that is hand in hand. Based on the new topology, this paper designs the control and modulation strategies of each stage, where the outer loop controller of input stage is emphasized for its twocontrol mode. At last, the rationality of new topology and the validity of control strategies are verified by the steady and dynamic state simulation. At the same time, the simulation results highlight the role of PET in energy regulation.
基金supported by the National Natural Science Foundation of China-State Grid Joint Fund for Smart Grid(No.U2066210).
文摘The DC grid technology of multi-power supply and multi-drop-point power reception is an effective solution for large-scale renewable energy integration into the power grid.Line-commutated converter-Voltage source converter(LCC-VSC)power grids are one of the more important developmental directions of the future power grid that have occured in recent years.But the multi-terminal high voltage direct current system has the problems of inconsistent boundary characteristics,inconsistent control,and fault response characteristics,which puts higher requirements on the protection scheme.Thus,a completely new protection principle is proposed in this paper.Firstly,the fault characteristics of distributed capacitance current are analyzed.The reactive power calculated by the distribution parameters of different frequencies is different.Subsequently,the fault characteristics of DC reactive power are analyzed,and a DC reactive power extraction algorithm is proposed.The polarity of the multi-band DC reactive power is used to construct the protection scheme.Finally,the LCC-VSC power grid model verifies the correctness and superiority of the proposed protection scheme.The proposed scheme uses DC reactive power instead of fault current to solve the long delay problem caused by distributed capacitance.Compared with the prior art,the proposed solution is not affected by distributed capacitance and has a stronger anti-interference ability(600Ω+10 dB+1 ms).
文摘随着电力系统中多类型直流线路占比的逐步提升,调度系统与异构平台间的潮流数据交换需求明显增大,亟需研究新形态下交直流混联系统的潮流计算数据生成问题。该文从拓扑转换、网络拓扑分析、设备建模以及数据生成策略4个主要步骤,实现含交直流系统的基于可扩展标记语言的通用信息模型(common information model/extensible markup language,CIM/XML)数据到潮流计算输入数据的转换。首先,该文从设备间开关拓扑的角度,进行深度优先算法(depth first search,DFS)搜索和设备拓扑拼接,实现开关/节点模型到母线/支路模型的转换;其次,在筛选出活拓扑岛、剔除不带电设备后,着重分析了CIM/XML中换流器建模对交直流节点选取的影响,进而提出了直流节点选取规则和具备普适性的直流数据生成策略。最后,以某地调度500kV及以上交直流网络导出的CIM/XML数据为算例,潮流计算结果与数据采集与监视控制系统(supervisory control and data acquisition,SCADA)量测数据比对验证所提策略的有效性。
文摘能量路由器的核心元件为双有源桥(dual active bridge,DAB)直流变压器,针对其短路故障时电流上升速率快,峰值大,导致DAB内部电力电子器件闭锁的问题,该文提出一种具有限流型结构的直流变压器,限流装置结构为从DAB高压侧H桥连接单相整流桥,再与输出端口的限流电感相连。当直流系统发生短路故障时,限流型直流变压器采用混合控制算法进行整流,为限流电感提供钳位电压,限制故障电流的峰值,并与断路器配合实现无弧开断,该方法避免DAB中电力电子器件发生闭锁,快速实现故障限流和隔离。在仿真系统中搭建了基于10kV/750V直流变压器的限流型直流变压器的模型,仿真结果表明限流型直流变压器与断路器配合实现故障限流和隔离的有效性和可行性。
文摘The line side winding is under the fundamental frequency AC voltage, while the valve side winding contains not only fundamental AC voltage component, but also the DC voltage component, fundamental AC voltage component, and higher harmonic voltage components when the converter transformer is at its normal operating condition, and the electric field of converter transformer is a non-sinusoidal steady one. To analyze the non-sinusoidal steady electric field containing the DC component, fundamental AC and higher harmonic components, the voltage spectrum of the valve winding in a ±500 kV converter transformer is firstly analyzed, and the non-sinusoidal periodic steady electric field is obtained by the fast discrete Fourier transform. Different resistivity of the oil and oil-immersed paper is adopted to simulate the aging of oil paper insulation at operation, and get the non-sinusoidal steady electric field.
