Research On Voltage Analysis And Optimization Of The Regional Distribution Network With Small Hydropower

Faced with increasing pressure on energy conservation and reduction as well as severe environmental problems, such as haze, small hydropower, as a mature technology and highly-environmental clean energy, has shown a tremendous potential nowadays. In general, these small hydro generators are usually connected to the distribution network with distributed load and large supply radius. In the wet season, small hydroelectric facilities generate the rated power, which may boost the voltage of distribution network. Conversely, in the dry season, the lack of hydropower generation and the long supply line can also result in lower voltage at the end of distribution network. A series of researches related to distribution network with small hydropower, corving the voltage characteristics, voltage regulation, voltage optimization and other aspects of distribution network, has been investigated and demonstrated in this paper. The paper includes the following contents:(1) Analyse the voltage characteristics of distribution network with small hydropower. In this paper, distribution network is simplified as the combination of a substation node and a load with small hydropower station. According to the voltage of head node, the power of end node as well as the line impedance, a mathematical model of line drop is established to explain the phenomenon of higher or lower voltage problems caused by the integration of micro hydropower. Besides, this section also compares the voltage characteristics of the distribution network before and after the integration.(2) Research measures to regulate the voltage of distribution network with small hydropower. In order to solve the problems existing in distribution network with small hydropower, such as beyond upper limit of volatage in wet season or lower limit of volatage in dry season, this paper presents several measures to regulate the voltage, such as adjusting the line voltage regulator, changing the operation mode of the small hydropower plant, shunting reactive compensation equipment, replacing the transmission line, adjusting the voltage of substation, and etc.In addition, this paper also investigates the principles of these voltage regulation methods and analyzes the features for each method as well as their advantages and disadvantages. Finally, a simple structure of distribution network with 6 nodes is constructed to analyze the actual effects of these regulation methods.(3) Establish a voltage optimization model of distribution network with small hydro and give the corresponding solution to this model. A voltage optimization model of distribution network with small hydro, where the voltage is regulated by the combination of the line voltage regulation, changing operation modes and adjusting the voltage of substation, is established to minimize the active power loss in lines, by considering the constrains of node voltage and power flow. By means of the primal-dual interior point method, this paper solves the nonlinear optimization problem, derives the detailed solution to the model and calculates coefficient matrix and parameter matrix of modified equations of the model.(4) Develop a software named "Voltage optimization of the distribution network with small hydropower". In order to apply voltage optimization method to distribution network with small hydropower, we develop a software named "Voltage optimization of the distribution network with small hydropower".The Software is applicable to voltage optimization problem of the distribution network with small hydropower where voltage of notes is regulated through the combination of the line voltage regulation, changing operation modes and adjusting the voltage of substation. According to the results, corresponding suggestions can be given in terms of the problems with higher or lower voltage of the distribution network under different operating scenarios and the software has been verified as an effective method to regulate voltage in distribution network with small hydro. Based on C++ language, the software is developed in the integrated development environment of Qt Creator, and invoked by NARI ON3000 which is an intelligent and automated dispatching system for regional grid.