﻿ 配电网合环操作中的循环电流计算方法与降低措施研究 Research on Calculation Method and Reduction Measures of Circulating Current in Closing Loop Operation in Distribution Network

Transmission and Distribution Engineering and Technology
Vol.07 No.02(2018), Article ID:25714,12 pages
10.12677/TDET.2018.72007

Research on Calculation Method and Reduction Measures of Circulating Current in Closing Loop Operation in Distribution Network

Peixian Liu1, Yang Yang1, Gongshuai Zhang1, Jingyu He2, Zhijian Hu2

1Yuxi Power Supply Bureau, Yunnan Power Grid Company, Yuxi Yunnan

2School of Electrical Engineering, Wuhan University, Wuhan Hubei

Received: Jun. 3rd, 2018; accepted: Jun. 22nd, 2018; published: Jun. 29th, 2018

ABSTRACT

In order to reduce the risk of distribution network operation, this paper calculates the power flow of distribution network based on the equivalent circuit diagram of distribution network, studies the calculation method of circulating current caused by loop closing operation of distribution network is studied, and puts forward a load control strategy to reduce circulating current, then uses the MATLAB/Simulink simulation software to build a simulation model of the operation of the distribution network, and the proposed control strategy to reduce the circulating current is simulated. The results verify the effectiveness of the proposed method.

Keywords:Distribution Network, Closing Loop Operation, Circulating Current Calculation, Control Strategy

1云南电网公司玉溪供电局，云南 玉溪

2武汉大学电气工程学院，湖北 武汉

1. 引言

2. 循环电流实时计算方法研究

$\Delta {U}_{a}={U}_{a1}-{U}_{a0}$ (1)

$\Delta {U}_{b}={U}_{b1}-{U}_{b0}$ (2)

$Z=\frac{\Delta {U}_{a}-\Delta {U}_{b}}{I}$ (3)

${I}_{循环}=\frac{{U}_{a0}-{U}_{b0}}{Z}$ (4)

Figure 1. Equivalent circuit diagram of combined loop current calculation

Figure 2. Simulation circuit diagram of circulating current calculation

3. 合环操作影响判据

4. 提高合环转供电成功率的应对措施

4.1. 负荷控制

Table 1. Current phasor measurement values

Table 2. Voltage phasor measurement values

Table 3. Calculated values of circulating currents

${U}_{AH2}={U}_{AL2}+\Delta {U}_{T2}={U}_{AL2}+{Z}_{T1}\frac{{S}_{AL2}}{U{}_{AL2}}$ (5)

${U}_{BH2}={U}_{BL2}+\Delta {U}_{T2}={U}_{BL2}+{Z}_{T2}\frac{{S}_{BL2}}{U{}_{BL2}}$ (6)

$\Delta {U}_{H2}=\frac{{S}_{AL2}{Z}_{T1}-{S}_{BL2}{Z}_{T2}}{U{}_{L2}}$ (7)

$S={S}_{AL2}+{S}_{BL2}$ (8)

$\Delta S={S}_{AL2}-{S}_{A}-{S}_{C}$ (9)

$\Delta S={S}_{BL2}-{S}_{B}-{S}_{D}$ (10)

${I}_{\text{c}}=\frac{\Delta S}{{U}_{L2}}$ (11)

${I}_{c}=\frac{\left({S}_{A}+{S}_{C}\right){Z}_{T1}-\left({S}_{B}+{S}_{D}\right){Z}_{T2}-\Delta {U}_{H2}{U}_{L2}}{\left({Z}_{T1}+{Z}_{T2}\right){U}_{L2}}$ (12)

Figure 3. System closed-loop flow analysis diagram

4.2. 负变压器分接头调整

U1和U2为合环操作前合环开关两侧电压，对U1所属线路上的110 kV/10.5 kV变压器进行分接头调整，即U1可在其相量延长线上变化，U2保持不变。在对U1进行电压幅值调整时，影响合环电流大小的因素是电压相量差ΔU，因此应该以U2在U1相量上的投影U1t为准进行调整，此时合环点两侧电压差拥有最小值ΔUmin，分接头调整公式如下所示。

$k=\frac{{U}_{2}\mathrm{cos}\left({\theta }_{1}-{\theta }_{2}\right)-{U}_{1}}{{U}_{1}}$ (13)

5. 仿真与分析

5.1. 负荷控制仿真

5.1.1. 负荷1有功功率控制

5.1.2. 其他负荷功率控制

Figure 4. Voltage phasor diagram for transformer tap adjustment

Figure 5. Load control simulation simplified diagram

5.1.3. 仿真步长为1 MW下的功率控制

Table 5. Load 1 circulating current in active power control process

Figure 6. Load control simulation circuit diagram

Figure 7. Load 1 active power control

(a) (b) (c)

Figure 8. Other load power control; (a) Load 1 reactive power control; (b) Load 2 active power control; (c) Load 2 reactive power control

(a) (b)

Figure 9. Load 1 power control (a) Load 1 active power control; (b) Load 1 reactive power control

5.2. 变压器分接头调整仿真

6. 结论

1) 本文所提基于叠加原理的电流注入法测量系统等效阻抗，进而计算合环操作引起的循环电流具有实时性和直观性的优点。

2) 通过采用提高合环点两侧负荷对称性的负荷控制策略，特别是以减负荷达到提高对称性的方式，能有效降低合环操作引起的循环电流大小，进而降低合环操作的风险，提高作业过程中系统运行的安全

Table 6. Transformer tap changer parameters

Table 7. Loop current in the tapping process

Figure 10. Load 1 active power control

3) 通过合理调整变压器分接头，控制合环开关两侧电压幅值差，能有效减小合环电流，提高合环成功率。

4) 本文对合环操作中降低循环电流的研究中提出了合理的负荷控制策略，实际工程中可以通过投切电容器或电抗器等措施实现，今后应对这些具体的负荷控制措施的实施过程及其对系统安全稳定的影响做深入研究。另外在变压器分接头调整的研究中可知合环点两侧电压相角差也是影响循环电流的重要因素之一，目前国内没有较好的解决办法，因此今后应该重点研究降低合环点两侧电压相角差的有效措施。

Research on Calculation Method and Reduction Measures of Circulating Current in Closing Loop Operation in Distribution Network[J]. 输配电工程与技术, 2018, 07(02): 50-61. https://doi.org/10.12677/TDET.2018.72007

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