基于光伏逆变器调相运行的网源协调控制技术

论文总字数：28117字

摘 要

随着光伏产业的迅速发展，我国光伏年发电量已经超过了1000亿千瓦时。然而，由于光伏发电的出力随环境变化的不确定性，在电网中大规模渗透之后，会对电网的稳定性运行造成较大的影响，其中，电压问题就是制约并网光伏发电的一个核心问题。

为了解决光伏逆变器大规模接入后的并网点电压调压问题，本文在完善光伏元件模型以及MPPT控制的基础上，针对光伏电站中的多无功源提出了适用于并网光伏电站的网源协调技术。

本文对光伏逆变器的调相运行提出了基于恒定直流侧电压和无功的双闭环控制模型，能够让光伏单元稳定直流侧电压的同时，通过逆变器产生能够跟踪给定值的无功功率注入进电网中；提出了一种基于电压的无功功率控制策略，通过检测并网点的电压大小在逆变器侧生成相应的无功功率参考值；同时，在光伏发电站具有多无功源的情况下，完善了无功功率在多无功源以及多个逆变器之间的分配策略，使得光伏电站效率更高。

最后，在Simulink软件中建立仿真模型，对控制系统进行仿真分析，验证提出方案的可行性。仿真结果表明，采用直流侧电压和无功功率解耦的双闭环控制在控制光伏发电直流侧电压恒定的同时，有效地让光伏发电单元产生能够跟踪给定值得无功功率。在采用了基于电压的无功功率调整策略之后，能够使得光伏电站向电网提供所需的无功功率以使得并网点在额定电压水平运行。通过使用站内无功功率优化策略，能够使得线路中的有功功率损耗最小，使光伏电站实现经济运行。

关键词：光伏发电，逆变器调相运行，双闭环控制，网源协调技术，损耗最优化

Abstract

With the rapid development of the photovoltaic industry, China's annual photovoltaic power generation has exceeded 100 billion kWh. However, due to the uncertainty of the output of photovoltaic power generation when outside environmental conditions change, after its infiltration in the power grid, it will lead to a profound impact on the stability operation of the power grid. Among them, the voltage situation is a core problem that restricts grid-connected photovoltaic power generation

In order to solve the voltage regulation problem of grid-connected point after large-scale PV inverter access, this paper proposes a suitable photovoltaic grid power station for multiple reactive power sources in photovoltaic power plants based on network- source coordination technology based on the improvement of photovoltaic component model and MPPT control.

In this paper, a dual closed-loop control model based on constant DC side voltage and reactive power is proposed for the phase-modulation operation of photovoltaic inverter. It allows photovoltaic units to stabilize the DC-side voltage and generate reactive power that can track the given value through the inverter. A voltage-based reactive power control strategy is proposed to give a corresponding reactive power reference value to each inverter by detecting the voltage level of the grid-connected point. At the same time, because there are multiple reactive power sources in the photovoltaic power station, the distribution strategy of reactive power between multiple reactive sources and multiple inverters is improved accordingly, and the goal of economic operation of the power grid is achieved.

Finally, the simulation model is built in Simulink software, in which the control system is simulated and analyzed to verify the feasibility of the proposed scheme. The simulation results show that the proposed double closed-loop control with DC voltage and reactive power decoupling can effectively control the photovoltaic power generation unit to track the given reactive power and at the same time, control the DC voltage of the photovoltaic power generation. After the voltage-based reactive power adjustment strategy is employed, the photovoltaic power plant can be enabled to provide the required reactive power to the grid to operate the grid point at the rated voltage level. By using the reactive power optimization strategy in the station, the active power loss in the line can be minimized, and the photovoltaic power station can achieve economic operation.

KEY WORDS: photovoltaic power generation, inverter phase modulation operation, double closed loop control, network source coordination technology, loss optimization

目 录

摘要 I

Abstract II

目 录 IV

第一章 绪论 1

1.1 研究背景与意义 1

1.2 光伏并网发电的现状 2

1.2.1 国外光伏发电的现状 2

1.2.2 国内光伏发电的现状 2

1.2.3 光伏逆变器调相运行 3

1.3 本文主要工作 3

第二章 光伏阵列的MPPT控制 5

2.1 引言 5

2.2 理想光伏阵列数学模型的建立 5

2.3 不同条件下光伏阵列的输出特性 6

2.3.1 电流-电压特性曲线 6

2.3.2 最大功率点 7

2.3.3 光伏阵列输出受辐照强度的影响 7

2.3.4 光伏阵列输出受温度的影响 8

2.4 DC-DC变换拓扑 8

2.5 MPPT控制与仿真 9

2.5.1 MPPT基本原理 9

2.5.2 MPPT仿真 12

2.6 本章小结 16

第三章 光伏逆变器调相运行控制 18

3.1 引言 18

3.2 光伏发电并网基本拓扑结构 18

3.3 光伏逆变器无功功率控制方法 19

3.3.1 电压外环控制 19

3.3.2 电流内环控制 21

3.4 本章小结 22

第四章 基于光伏逆变器调相运行的电压调整策略 23

4.1 引言 23

4.2 并网光伏电站结构分析 23

4.3 光伏电站的电压分布 24

4.3.1 并网点电压 24

4.3.2 光伏单元输出端口电压 25

4.4 基于电压的无功调整策略 25

4.5 无功功率分配算法 29

4.6 本章小结 30

第五章 包含调相运行逆变器的网源协调技术仿真 31

5.1 引言 31

5.2 光伏并网系统模型建立 31

5.2.1 光伏单元直流侧模型 31

5.2.2 光伏单元交流侧模型 32

5.2.3 光伏单元交流侧控制电路 32

5.2.4 大型光伏发电站并网模型图 33

5.3 双闭环控制仿真分析 34

5.3.1 直流侧电压控制 34

5.3.2 额定工作情况下的并网点情况 35

5.3.3 过负荷运行时无功功率参考值的生成 36

5.3.4 大型光伏电站站内无功优化 37

5.4 本章小结 40

第六章 总结与展望 41

6.1 总结 41

6.2 展望 41

参考文献 43

致谢 46

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