第2章电力网及其稳态分析.ppt

河北科技大学电气工程系 第二章 电力网及其稳态分析 Steady state analysis 2.1电力网电力线路的结构Transmission Line Structures 2.2 输电线路的电气参数 Transmission Line Parameters 2.3 电力网参数计算中变压器参数的计算方法 Transformer parameters 2.4 输电线的等值电路 Equivalent circuit of Transmission Line 2.5 电力网电压计算 Voltage calculation 2.6 电力系统的无功平衡和电压调节 Reactive Power Compensation and voltage regulation 2.7 电力系统的有功平衡及频率调节 Active power and frequency regulation 2.8 电力网的功率损耗和电能损耗 Power losses 2.9 电力系统潮流分布计算 Power Flow Analysis 2.10 输电线路导线截面的选择 Cross-section of conductor 2.11 电力系统的中性点接地方式 Grounding of neutral-point 小结 Summary 2.1电力线路的结构Transmission Line Structures In the U.S., the nominal voltage of the high-voltage lines is between 100 kV and 230 kV. The voltage of the extra-high-voltage lines is above 230 kV and below 800 kV. The voltage of an ultra-high-voltage line is above 800 kV. The maximum length of high-voltage lines is around 200 miles. Extra-high-voltage transmission lines generally supply energy up to 400–500 miles without intermediate switching and var support. Transmission lines are terminated at the bus of a substation. The physical arrangement of most extra-high-voltage EHV lines is similar. p 45 Chapter 4 The physical arrangement of most extra-high-voltage EHV lines is similar. Figure 4.2 shows the major components of an EHV, which are p 45 1. Tower pole : The figure shows a lattice, steel tower. 2. Insulator: V strings hold four bundled conductors in each phase. 3. Conductor: Each conductor is stranded, steel reinforced aluminum cable. 4. Foundation and grounding: Steel-reinforced concrete foundation and grounding electrodes placed in the ground. 5. Shield conductors: Two grounded shield conductors protect the phase conductors from lightning. Summary 4.1 4.3 The choice of transmitting and distributing electric power through underground vs. overhead systems requires consideration of economical, technical, and environmental issues. Underground systems have traditionally been favored when distributing electric