| A reasonable capacity calculation method is the basic of compensation system to calculate compensation capacity, estimate engineering cost, optimize capacity, etc. And using a hybrid compensation system is an effective measure to reduce the cost for solving power quality problems. So to find a more suitable capacity calculation method and topology structure design method for hybrid compensation system is of great significance to solve power quality problems economically and promote the development of fundamental theory for hybrid compensation system.From choosing the compensation goal, several common compensation goals in single-phase and three-phase system are expounded respectively in this thesis. Power theories corresponding to different compensation goals are summarized. And distribution relation among power supply side, compensation system and load side are analyzed under different power theories. Advantages and disadvantages of different compensation goals are studied from three aspects, which are the compensative effect, the feasibility of each compensation goal and the electric quantities after compensation at the source side. The necessity of the impact on compensation effect, considering of voltage and current non-ideal component, is proved when estimating the compensation capacity of compensation equipments, which proves that the ideal compensation goal is the most scientific compensation goal to realize the optimal power distribution relationship.To avoid the restriction of compensation system topology connection form for hybrid compensation system capacity calculation method, the energy exchange relation among the compensation system, the active current power grid and the compensated load system is analyzed. The connection relation between compensation system and other parts of power system is defined as compensation interface, which is divided into three categories according to different natures of compensating signal. The traditional compensation capacity estimation method is summarized and its defects are proved in several aspects, such as the compensation capacity of each part is unable to determined, the influence of neutral line current is not taken into account, the influence of non-ideal voltage component was ignored, and so on. Based on the IEEE Std 1459-2010, total compensation capacity calculation method and compensation capacity calculation method of each part for single-phase and three-phase hybrid compensation system are proposed for different compensation interface, which can be directly determined by voltage and current of access point. Thus the corresponding compensation capacity calculation process is also given. By analyzing the change trend of total compensation capacity under the influence of fundamental power factor, harmonic distortion rate and asymmetric degree, the rationality of the new compensation capacity estimation method is proved. And the power components related to different voltage and current characteristics are given in the new method by decomposing the voltage and current, which makes it possible to set up the compensation system capacity of each part respectively for different power quality problems.Based on the fundamental theorems of circuit, topology connection rules and the compensation target, a new method to design a passive compensation network of three phase load asymmetry system is proposed which can be obtained only from the power supply voltage and load current. This method is independent to specific structures and parameters of load network. Different calculation formulas of compensation network parameters with different special constrains are obtained. It provides a new idea for optimal design of compensation network, unifies design method for three-phase four-wire and three-phase three-wire load asymmetry system passive compensation networks. Simulations show that the compensation used for three phase load asymmetry system designed with this new method is effective. According to the traditional compensation capacity Calculation method and the new one respectively, the compensation capacity of the simulation examples are estimated and the rationality of the new estimation method is confirmed in the thesis again. |
PDF Full Text Request