﻿ 电动汽车的多点接入对区域电网的稳定性影响

# 电动汽车的多点接入对区域电网的稳定性影响The Impact of Electric Vehicles on the Stability of Regional Power Grids

Abstract: This paper is based on the PSASP simulation system, using New England 10-machine 39-node network as the simulation network, analyzes the impact of the electric vehicle (EV) access mode on the system operating characteristics, and calculates the load, voltage offset, initial/limit point participation factor and line margin change under three access points, such as the three access points alone, two or two, and three buses in the power grid. The study found that when multiple buses are connected to an electric vehicle at the same time, the peak-to-valley load difference of the power grid can be reduced by 8.3%, the voltage offset rate can increase to 1.2205%, and the voltage initial point participation factor increases, while the limit point participation factor increases. With the reduction, the line stability margin can be reduced by a maximum of 3.33%. The above results show that the reasonable access of the electric vehicle has a deterrent effect on the daily load curve of the power system, and the weak bus of the power grid will change with the load change.

1. 引言

2. 电动汽车入网模式分析

3. 静态电压稳定分析原理

3.1. 潮流方程式的特征结构分析

$\left[\begin{array}{l}\Delta P\\ \Delta Q\end{array}\right]={J}_{S}\left[\begin{array}{l}\Delta \theta \\ \Delta V\end{array}\right]$ (1)

Figure 1. Schematic of electric vehicles accessing to power grid

$\Delta Q=\left(L-J{M}^{-1}N\right)\Delta V={J}_{R}\Delta V$ (2)

${J}_{R}={\eta }^{-1}\Lambda \eta$ (3)

$\xi ={\eta }^{-1}$ ，则

$\Delta V=\underset{i}{\sum }\frac{{\xi }_{i}{\eta }_{i}}{{\lambda }_{i}}\Delta Q$ (4)

$\Delta V=\underset{i}{\sum }\frac{{\xi }_{i}{\eta }_{i}}{{\lambda }_{i}}\Delta Q$ (5)

$\eta \Delta V={\Lambda }^{-1}\eta \Delta Q$ (6)

$\eta \Delta V=\Delta \nu$$\eta \Delta Q=\Delta \rho$ ，则有

$\Delta \nu ={\Lambda }^{-1}\Delta \rho$ (7)

${\lambda }_{i}\Delta {\nu }_{i}=\Delta {\rho }_{i}$ (8)

3.2. 薄弱节点和薄弱区域的确定

$\frac{\partial {V}_{k}}{\partial {Q}_{k}}=\underset{i}{\sum }\frac{{\xi }_{ki}{\eta }_{ik}}{{\lambda }_{i}}$ (9)

${P}_{ki}={\xi }_{ki}{\eta }_{ik}$ (10)

4. 算例仿真

4.1. 算例系统

Figure 2. Network flow of New England system

Table 1. Line parameters of New England system

4.2. 仿真分析

4.2.1. 电动汽车接入对负荷的影响

Figure 3. Probability of a vehicle to be parked

Figure 4. The impact of electric vehicle access on power grid load

$\chi =\frac{\sigma }{\mu }$ (11)

4.2.2. 电动汽车入网对节点电压的影响

$\Delta U\left(%\right)=\frac{U-{U}_{ref}}{{U}_{ref}}×100%$ (12)

Figure 5. Voltage excursion of different access conditions of electric vehicles

4.2.3. 电动汽车入网对母线参与因子的影响

PSASP以模态分析方法来寻找网络中的薄弱节点及区域，在初始运行点与电压稳定极限点处分别进行模态分析，进一步得出各节点对主导电压失稳的参与因子，由参与因子的大小来判断电网的薄弱节点区域。参与因子越大即此节点越薄弱。表3为初始/极限运行点处节点母线参与因子的计算结果 [23] 。

4.2.4. 电动汽车入网对线路裕度的影响

Table 3. Results of bus participating factor for New England system

Table 4. Calculation results of line margin (%)

${K}_{L}=\frac{P-{P}_{0}}{{P}_{0}}$ (13)

5. 结论

1) 多母线接入电动汽车时，其对电网削峰填谷作用最为显著，其峰值降低了2.02%，谷值增加4.2%。

Figure 6. P-V curve of busbar 3 under different access conditions

Figure 7. P-V curves of different buses at three-point access

2) 参与因子的大小与母线承受扰动的能力呈现负相关的趋势，即参与因子越小，母线承受扰动的能力越强；三母共同接入模式下，参与因子的波动最大，这说明多点同时接入电动汽车时，各母线可承受的扰动相比最小。

3) 随着接入母线数量的增加，线路裕度逐步下降。三母线接入时，线路裕度降低可降低3.33%。

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