含分布式电源和电动汽车的配电网可靠性评估
作者:
作者单位:

三峡大学 电气与新能源学院

中图分类号:

TM732

基金项目:

国家自然科学基金资助项目(52107107)。


Reliability evaluation of distribution network with distributed generation and electric vehicle
Author:
Affiliation:

College of Electrical Engineering $ New Energy,China Three Gorges University

Fund Project:

Supported by the National Natural Science Foundation of China (52107107).

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    摘要:

    目的:针对目前大规模分布式电源(DG)和电动汽车(EV)接入配电网后,对配电网的可靠性造成一定影响的问题,提出了一种含有DG和EV的新型配电网可靠性评估方法。方法:首先,考虑到风光出力在时空上的互补特性,基于Copula理论引入Spearman秩相关系数、Kendall秩相关系数及欧氏距离等指标,选择拟合性最优的Frank-Copula函数,并建立了风光联合出力概率模型,作为可靠性计算中分布式电源的输出功率模型。其次,分析了电动汽车用户行为特征,提出了基于动态分时电价的EV有序充放电控制策略。最后,采用改进的IEEE-RBTS Bus6测试系统的主馈线F4,分别从分布式电源的类型、电动汽车数量、有序充放电方式三个方面对系统的可靠性进行计算分析。结果:1)从接入不同类型DG后系统的可靠性计算结果可以看出:接入单独的光伏发电机(PVG)/风力发电机(WTG),系统的平均断电频率(SAIFI)由2.7914 次降至2.7586 次,平均断电持续时间(SAIDI)由15.0939 h降至14.6790 h;采用文中所建立的风光互补发电系统时供电可用率(ASAI)由99.82%升至99.84%,电量不足期望(EENS)由79.1722MW降至75.0307MW。2)从接入不同数量的EV并采用无序充电方式后系统的可靠性计算结果可以看出:当接入200 辆EV后,SAIFI、SAIDI由原来的2.7745 次、14.0786 h分别增加到2.9317次、14.9640 h,变化比较明显;随着EV接入的数量增加到1000辆,可靠性指标SAIFI、SAIDI明显增大,ASAI由99.84%降到99.83%。3)从EV采用不同有序充放电方式后系统的可靠性计算结果可以看出:与无序充放电方式相比,采用分时电价和动态电价的充放电方式后系统的SAIDI由14.9640h分别降至14.7296h、14.1118h,EENS也由77.4233 MW分别降至76.3983 MW、75.7556 MW。结论:1)与无DG接入的情况性相比,接入DG后可以有效地提高配电网的可靠性。2)系统中接入单独的WTG比PVG的可靠性要高,而接入风光互补发电系统比单独的WTG/PVG的可靠性更高。3)接入无序充电的电动汽车不仅会增加系统的负荷峰值,还大大降低了配电网的可靠性,随着数量的增加,可靠性恶化程度加剧。4)与无序充电的方式相比,采用分时电价和动态电价的有序充放电方式不仅能够有效地平抑负荷峰值,还可以降低EV接入配电网后对系统可靠性的影响,其中采用文中的动态分时电价的充放电方式对配电网可靠性影响最小。

    Abstract:

    Objective: Aiming at the problem that large-scale distributed generation (DG) and electric vehicle (EV) has a certain impact on the reliability of the distribution network after they are connected to the distribution network, a new reliability evaluation method of a distribution network based on DG and EV is proposed. Methods: Firstly, considering the complementary characteristics of wind and solar output in time and space, based on Copula theory, Spearman rank correlation coefficient、Kendall rank correlation coefficient, and Euclidean distance are introduced, the Frank-Copula function with the best fitting is selected, and the wind-solar joint power output probability model is established as the output power model of DG in reliability calculation. Secondly, the behavior characteristics of EV users are analyzed, and an EV orderly charge-discharge control strategy based on dynamic time of use (TOU) price is proposed. Finally, using the main feeder F4 of the improved IEEE-RBTS Bus6 test system, the reliability of the system is calculated and analyzed from three aspects: the type of DG, the number of EVs, and the orderly charging and discharging mode. Results:1) The results show that when connecting with a separate photovoltaic generator (PVG)/wind turbine generator (WTG), the system average interruption frequency index (SAIFI) decreases from 2.7914 times to 2.7586 times. The system average interruption duration index (SAIDI) decreases from 15.0939 h to 14.6790 h. However, when using the wind-solar complementary power generation system established, the average service availability index (ASAI) increases from 99.82% to 99.84%, and expected energy not supplied (EENS) decreases from 79.1722MW to 75.0307MW. 2) The results show that the system, after connecting 200 EVs, SAIFI and SAIDI increased from 2.7745 times and 14.0786 hours to 2.9317 times and 14.9640 hours, respectively; As the number of EVs increased to 1000, the reliability indexes SAIFI and SAIDI significantly increased, and the ASAI decreased from 99.84% to 99.83%. 3) The results show that compared with the disordered charging mode, the SAIDI of the system decreases from 14.9640 to 14.7296h and 14.1118h, and the EENS also decreases from 77.4233 MW to 76.3983 MW and 75.7556 MW. Conclusion: 1) Compared with the situation without DG access, DG can effectively improve the reliability of the distribution network.2) The system's reliability connected with a single WTG is higher than PVG. However, the system's reliability connected with a wind-solar complementary power generation system is higher than that of a single WTG / PVG. 3) EVs connected with disorderly charging will increase the system's peak load and significantly reduce the reliability of the distribution network. With the increase in the number, the deterioration of reliability will intensify. 4) Compared with the disordered charging mode, the orderly charging and discharging mode using TOU price and dynamic TOU price can effectively suppress the peak load and reduce the impact on the system reliability after the EV is connected to the distribution network. Among them, the charging and discharging mode using dynamic TOU price has the most negligible impact on the reliability of the distribution network.

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  • 收稿日期:2022-04-08
  • 最后修改日期:2022-05-08
  • 录用日期:2022-05-11
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