A transfer switch shifts loads or electrical distribution systems between two power sources, making it an essential part of a standby or emergency power system. There are two main types of transfer switches: an automatic transfer switch and static transfer switch. An automatic transfer switch is used to transfer power between a primary (utility source) and secondary power source (a generator or other backup power source). A static transfer switch shifts loads between two power sources with the help of power semiconductors (such as an SCR). The transfer in these switches is rapid as the switching does not involve the motion of any mechanical parts. Both switches have their merits. When the quality-price ratio is considered, automatic transfer switches have a considerable advantage. However, static transfer switches are used when high quality is of much greater concern than price.

A battery is a rechargeable energy storage device that consists of positive and negative electrodes called cathode and anode, respectively.

Pneumatic equipment uses compressed gas (air or any other inert gas) to produce mechanical motion. The equipment is used in volatile environments where hydraulic or electric tools cannotbe used. It is also used in various industries such as Construction, Metallurgy, and Oil and Petrochemical. Pneumatic equipment is safer than electric and hydraulic tools and it is increasingly being adopted by end-users for industrial applications.

Elevators are a type of transport system that facilitate the vertical transit of people and goods within a building's premises. Escalators are moving staircases that are mainly used for transporting people between the different floors of buildings. People depend on elevators and escalators in various places such as airports, office buildings, malls, residential complexes, schools, and railway stations.

针对海上风电场采用柔性直流输电(voltage source converter based high voltage DC,VSC-HVDC)接入陆上电网的技术方案,提出利用直流电容和风电机组转子动能去模拟同步发电机惯量的协同控制策略。通过网侧换流器直流电压滑差控制,在电网扰动下,直流电容能相应地吸收或释放能量。两端VSC交流系统频率通过风场侧换流器(wind farm VSC,WFVSC)的变频控制实现人工耦合,可以省去两端换流站之间的通信。为响应WFVSC的频率变化,风电机组功率控制器将调整功率指令值,使转子转速相应变化。通过一系列协同控制,海上风电场将参与电力系统频率控制。在允许的风电机组转速和直流电压变化范围内,该协同控制策略可提供大范围的惯量,增加系统稳定性。通过对负荷变化、风速变化和交流系统故障等工况的仿真,验证所提控制策略的有效性。

由于换流站数目、控制模式以及指令值的不同，电压源换流器型多端直流(voltage source converter based multiterminal dc，VSC-MTDC)输电系统在实际运行中具有多种运行方式，并且随着电网运行条件的变化，VSC-MTDC 输电系统的运行方式也随之改变。因此，直流运行中心需要根据换流站运行特性、电网条件和系统参数等快速确定 VSC-MTDC 输电系统运行控制模式与系统状态量，这对系统调控和安全运行具有重要意义。基于此，分析主导换流站、辅助换流站、定有功功率控制换流站和风电场换流站的直流电压-电流运行特性，推导各换流站在不同控制模式下的特性方程，给出各换流站不同控制模式下的电气量范围。接着，提出 VSC-MTDC 输电系统稳态工作点的计算方法，完善换流站的控制模式修正方法。最后，以典型的五端直流输电系统为例，Matlab 编程验证了直流运行特性分析方法和稳态工作点计算方法的准确性；计算结果表明，该稳态分析方法能够快速准确地计算出 VSC-MTDC 输电系统的稳态工作点。