A power capacitor is an electrical device used to improve the power factor of the electrical power system that operates in an inductive load. Many industries use induction motors that induce a low power factor in the adjacent distribution line, which leads to massive Kvar loss. It has a negative impact on the usage of energy. Improvement in power is an important factor for conserving energy. Power capacitors that are connected to a transmission line improve the overall power factor of end-user industries. Though it has limited usage, capacitors are sometimes used to store energy.

Power transformers are essential electrical equipment used to increase or decrease voltage in the power transmission process. They are segmented into 100 MVA-500 MVA and 501 MVA-1200 MVA capacities.

Transformer monitoring solutions are used to monitor and diagnose the health of a transformer. A monitoring solution helps end-users detect and identify failures in transformers in due time, reducing the repairing costs. A transformer monitoring solution is an integration of sensors, data management and analysis, and software application. It collects data from the sensors, and turns them into meaningful information for required action. The Utilities, Industrial, and Commercial sectors are the major end-users of these solutions.

A transformerless UPS is a piece of electrical equipment that provides power when the main power supply fails. It does not contain power line frequency magnetics such as a transformer or inductor. It is an evolving technology under the family of UPS and has several advantages over transformer-based UPS systems without sacrificing the required reliability. Some of its advantages are lower size and weight, carbon footprint, and capital expenditures. In addition, with a transformerless UPS, the power equipment requires less cooling as it does not contain a transformer, thereby leading to lower heat generation compared to transformer-based UPS systems.

针对模块化多电平换流器型高压直流输电系统(modularmultilevel converter based high-voltage directcurrent，MMC-HVDC)，为了确保停运过程中子模块电容能够可靠且快速地放电，提出一套完整的停运控制策略。根据作用机理的不同，停运过程被划分为能量反馈阶段，可控能量耗散阶段和不可控能量耗散阶段。在能量反馈阶段中，通过提高调制比 m，三次谐波注入，调节换流变压器变比及冗余子模块的投入，降低子模块电容电压，最大程度地将电容中的储存能量反馈至电网。在可控能量耗散阶段，子模块电容通过直流线路或者启动电阻进行放电，避免了放电电阻的使用。在不可控能量耗散阶段，子模块电容仅通过子模块电阻进行放电。最后，基于时域仿真软件 PSCAD/EMTDC 下搭建的 400 MW/±200 kV 数字仿真模型，验证所提出方法的有效性。

风轮大转动惯量导致最优转矩最大功率点追踪(maximumpower point tracking，MPPT)控制方法暂态时间过长，效率降低。通过研究风力发电系统(wind turbine generatorsystem，WTGS)工作机理，对问题及原因作具体分析，并设计基于梯度估计的最优转矩补偿器，对电磁转矩给定值进行补偿，以减小大转动惯量对风轮转速变化的影响。通过建立兆瓦级双馈 WTGS 小信号模型及系统闭环传递函数，分析系统闭环极点、阶跃响应曲线及频率特性。小信号模型分析及仿真结果表明，改进后的方法具有良好的系统稳定性及动态特性，暂态过程时间小，兼有经典最优转矩法稳定性和叶尖速比法快速性等部分优点，风能转化率较高。

逆变器死区、功率管导通压降及开关过渡过程等非线性因素易导致直接转矩控制(directtorque control，DTC)多相永磁同步电机定子电流严重畸变。该文针对六相对称偏置60 定子绕组永磁同步电机提出一种 DTC 策略。首先，基于零序电流等于零思想进行电压矢量重构，并由此提出理想DTC；其次，基于死区补偿原理对实际电压矢量作用时间进行离散补偿；最后，利用 PI 调节器对电压矢量作用时间进行连续补偿，实现零序电流等于零目的。实验结果表明该文提出的驱动控制系统具有快速的转矩动态响应特性；同时零序电流基本等于零，定子电流总谐波含量较低。

调制策略是影响无变压器非隔离型光伏逆变器系统漏电流大小的重要因素之一。针对非隔离型三电平光伏逆变器，首先分析系统寄生电容电压和开关状态之间的关系，然后研究载波正向层叠和反向层叠调制对系统共模电压的影响，通过逻辑状态关系提出一种新型载波调制方案，并对三种载波调制方案进行仿真研究，最后在 TMS320F28335DSP + XC3S400 FPGA 数字控制实验平台上对上述方案进行实验研究，结果验证了提出方法的可行性和有效性。