A Two-Layer Volt-Var Control Method in Rural Distribution Networks Considering Utilization of Photovoltaic Power

Yang Hu,Weizhou Wang,Wenying Liu

doi:10.1109/access.2020.3003426

Abstract

With the large-scale integration of poverty alleviation photovoltaic(PV) into China's rural power grids, the randomness has caused large fluctuations in the voltage with relatively weak compensation of reactive power, and the problem of voltage violation has become particularly prominent. With this concern, a two-layer volt-var control method using the reactive power regulation of the PV inverter is proposed. Firstly, the framework of “distributed control among partitions and local control in partitions” is established. In the first distributed control, based on the collected operation information of PV and load on a minute scale, to minimize the overall network loss, the volt-var droop control rate is optimized in a distributed manner, which uses decomposition-coordination method and the auxiliary problems principle. In the second local control, set the key parameters of the droop control curve adaptively, and adjust the reactive power output in real-time to suppress the voltage violation and fluctuation based on the optimized volt-var droop curve in the timescale of seconds. Finally, simulation results of a practical power grid with poverty alleviation PV show that the method can effectively suppress the voltage overrun, reduce the voltage fluctuation and minimize the network loss.

Highlights

With the implementation of the ‘‘Thirteenth Five-Year Plan for Energy Development ’’and the ‘‘Photovoltaic Poverty Alleviation’’ policies, the number of PVs in China’s low-voltage distribution network has grown rapidly, especially in western China, due to abundant solar energy resources and high altitude terrain [1]
How to effectively reduce the adverse effects brought by the PV, ensure the economic and safe operation of the network, and make a voltage control method with a high proportion of PV are of great significance
Agalgaonkar used on-load tap changer (OLTC) and line voltage regulators (LVR) to adjust the node voltage, but the regulation ability of this method was usually limited by the position of the tap and the poor economy [4], [5]

Summary

INTRODUCTION

With the implementation of the ‘‘Thirteenth Five-Year Plan for Energy Development ’’and the ‘‘Photovoltaic Poverty Alleviation’’ policies, the number of PVs in China’s low-voltage distribution network has grown rapidly, especially in western China, due to abundant solar energy resources and high altitude terrain [1]. Y. Hu et al.: Two-Layer Volt-Var Control Method in Rural Distribution Networks Considering Utilization of PV Power stable control of node voltage, they have received widespread attention [7]. The rural power grid model that includes large-scale distributed PVs is complex and difficult to solve, and the centralized controller will accept massive amounts of information, which will cause serious communication delays [14] and affect the reliability of global optimization. The lack of interaction information under local control makes it difficult to coordinate reactive power and cannot achieve global optimization. 3. A local control model in partitions is established, which can make fuller use of the reactive capacity of each PV inverter, and is more effective in responding to node voltage fluctuations.

CHARACTERISTICS OF POVERTY ALLEVIATION PV

VOLTAGE CONTROL METHOD AMONG PARTITIONS

VOLTAGE CONTROL METHOD IN PARTITIONS

CASE ANALYSIS

CONCLUSIONS AND FUTURE WORK