Voltage Stability Of Power Grid Research Articles

Impacts of UHVDC from Hami to Zhengzhou on Voltage Stability of Henan Power Grid

Based on the planning data of Henan power grid in 2014, the impacts of 800kV UHVDC from Hami to Zhengzhou on static voltage stability of Henan power grid are analyzed in details. Firstly, this paper introduces the principle of voltage stability analysis, the stability margin index has been established. Secondly, the analysis of static voltage stability for Henan power grid before and after the UHVDC from Hami to Zhengzhou putting into operation is carried out, the weak buses and regions in Henan power grid are pointed out. Finally, the operation patterns of Henan power grid after the UHVDC putting into operation are classified and optimized. Simulation results show that the improper operation pattern may significantly deteriorate the static voltage stability of power grid. The operation patterns of HVDC power multi-channel transferring from Henan to Central China grid combined with partly internal consumption are favorable to improve the static voltage stability of the whole system. The analysis results provide theoretical basis for the future operation of Henan grid.

Research on a Hierarchical Dynamic Automatic Voltage Control System Based on the Discrete Event-Driven Method

In this paper, concepts and methods of hybrid control systems are adopted to establish a hierarchical dynamic automatic voltage control (HD-AVC) system, realizing the dynamic voltage stability of power grids. An HD-AVC system model consisting of three layers is built based on the hybrid control method and discrete event-driven mechanism. In the Top Layer, discrete events are designed to drive the corresponding control block so as to avoid solving complex multiple objective functions, the power system’s characteristic matrix is formed and the minimum amplitude eigenvalue (MAE) is calculated through linearized differential-algebraic equations. MAE is applied to judge the system’s voltage stability and security and construct discrete events. The Middle Layer is responsible for management and operation, which is also driven by discrete events. Control values of the control buses are calculated based on the characteristics of power systems and the sensitivity method. Then control values generate control strategies through the interface block. In the Bottom Layer, various control devices receive and implement the control commands from the Middle Layer. In this way, a closed-loop power system voltage control is achieved. Computer simulations verify the validity and accuracy of the HD-AVC system, and verify that the proposed HD-AVC system is more effective than normal voltage control methods.

规模化光伏接入对地区电网电压稳定性的影响

光伏发电的大规模接入对传统电网的控制运行带来了重大影响，包括其对接入地区电网的电压稳定性。本文将针对大规模光伏发电对接入地区电网电压稳定性的影响进行深入研究。文章首先对光伏电场的运行与出力特性进行了深入分析，进而构建了不同的光伏发电场景，并对比分析了不同场景下光伏发电对接入电网电压稳定性的影响。以上述影响分析为基础，文章进一步研究了光伏电场的并网逆变器及场侧无功补偿装置对提升地区电网电压稳定性的贡献。最终在不增加额外无功调节装置的情况下，实现了大规模光伏接入地区电网电压稳定性的提升，对含大规模光伏接入的地区电网具有重要的借鉴、参考意义。 Large-scale photovoltaic hair to control access to the traditional power grid operation has brought a signifi-cant impact, including photovoltaic generation on voltage stability. This article will focus on large-scale photovoltaic power generation access for regional power grid voltage stability in-depth study to explore large-scale photovoltaic access to the regional power grid voltage stability related effects existing This article first makes a deep analysis on solar farm operation and output characteristics, and constructs different scenes, under which makes a comparative analysis on the PV grid voltage stability. Based on the above analysis of impact, this article further studies the photovoltaic grid- connected inverter electric field and the field side reactive power compensation device to enhance the region’s contribu- tion to the stability of the grid voltage. Finally, in no additional reactive power regulation unit case, the realization of large-scale photovoltaic regional power grid voltage stability raised, which has an important reference value for large-scale photovoltaic grid connected areas.

Algorithm of Continuous Power Flow Considering Auto-Disconnection of Large-Scale Wind Farms

Voltage stability of power grid would be affected greatly by the connection of large-scale wind farms. Conventional continuous power flow method can not accurately simulate the system’s operation when wind farms are connected to power gird. A new continuous power flow method is proposed, considering auto-disconnection of large-scale wind farms. The step-size control segment is improved in this algorithm in order to simulate the operation characteristics of wind farm and determine the precise time when a certain wind farm is cut off.