何为DVR动态电压恢复器？

2025-07-28

动态电压恢复器（DVR）采用全控型电力电子器件IGBT，核心组成包括储能元件（超级电容）、逆变器、充电单元切换开关及旁路开关。其接入系统的方式独具特点：逆变器采用并联设计，切换开关则串联在供电电源与受保护负载之间，形成高效的电压保障链路。当电网出现电压暂降、暂升或短时中断等异常情况时，DVR 会立即切断输入侧电源，同时从自带的储能器件中汲取所需能量。通过三相桥式逆变电路系统，它能快速生成与电网电压幅值、相位完全一致的补偿电压，无缝输送至负载端，确保输出电压瞬间恢复至额定值，实现负载供电零中断，为设备稳定运行提供坚实保障。作为储能式电压补偿设备，其显著优势在于适应性极强 —— 无论单相、两相或三相电压跌落，即便跌落至 0%，都能有效治理，始终为负载提供合格电能，保障用电安全可靠。动态电压恢复器主要有四种工作状态：电网正常时：待机模式此时 DVR 的晶闸管电子开关导通，负载直接由电网供电，既保证高效运行，又实时监测电网状态。电网异常时：补偿模式当发生电压暂降、骤升或短时中断，设备会快速切断晶闸管电子开关，同步启动IGBT 功率模块，使负载与电网隔离，转而由 DVR 独立供电，实现快速响应与隔离输出。电网恢复稳定：恢复模式DVR 先将输出电压波形与电网波形同步，随后接通晶闸管电子开关，让负载重新由电网直接供电；同时，系统会为储能电容柜补充损耗的能量，整个过程柔性退出、无缝切换。故障或检修时：旁路模式若 DVR 出现故障或需要技术检修，会自动切换至旁路回路供电；待维护完成后，设备将自动恢复正常运行，体现快速旁路与自动复位的优势。What is Dynamic Voltage Restorer ？The Dynamic Voltage Restorer (DVR) adopts IGBT, a fully-controlled power electronic device, with core components including energy storage elements (supercapacitors), an inverter, a charging unit changeover switch, and a bypass switch. Its way of connecting to the system is unique: the inverter is designed in parallel, and the changeover switch is connected in series between the power supply and the protected load, forming an efficient voltage protection link.When the power grid has abnormal conditions such as voltage sag, swell, or short-term interruption, the DVR will immediately cut off the input-side power supply and at the same time draw the required energy from its own energy storage device.Through the three-phase bridge inverter circuit system, it can quickly generate a compensation voltage that is completely consistent with the amplitude and phase of the grid voltage, and seamlessly transmit it to the load end, ensuring that the output voltage instantly returns to the rated value, realizing zero interruption of load power supply, and providing a solid guarantee for the stable operation of the equipment.As an energy storage voltage compensation device, its significant advantage lies in its strong adaptability - no matter the voltage drop of single-phase, two-phase or three-phase, even if it drops to 0%, it can be effectively controlled, and it always provides qualified electric energy for the load, ensuring safe and reliable power consumption.The Dynamic Voltage Restorer mainly has four working states:When the power grid is normal: Standby ModeAt this time, the thyristor electronic switch of the DVR is turned on, and the load is directly powered by the power grid, which not only ensures efficient operation but also monitors the grid status in real-time.When the power grid is abnormal: Compensation ModeWhen a voltage sag, swell, or short-term interruption occurs, the device will quickly cut off the thyristor electronic switch, synchronously start the IGBT power module, isolate the load from the power grid, and then switch to independent power supply by the DVR, achieving rapid response and isolated output.When the power grid returns to stability: Recovery ModeThe DVR first synchronizes the output voltage waveform with the grid waveform, then turns on the thyristor electronic switch to allow the load to be directly powered by the grid again; at the same time, the system will supplement the lost energy for the energy storage capacitor cabinet, and the whole process is flexibly exited and seamlessly switched.During failure or maintenance: Bypass ModeIf the DVR fails or needs technical maintenance, it will automatically switch to the bypass circuit for power supply; after the maintenance is completed, the device will automatically resume normal operation, reflecting the advantages of fast bypass and automatic reset.

新能源充电桩功率因素问题

2025-07-22

超级充电站是一种为电动汽车提供电能的装置，使电动汽车能够存储足够的电量以支持其运行。充电桩现场大多建设在郊区，充电桩的充电频率过低会造成变压器轻载运行时间过多。现场同时出现感性无功和容性无功、功率因数过低同时出现的情况。通常有车充电的时候正常，没有车充电时功率因数就很低。充电桩其实就是把交流电转化为直流电进行一个充电的过程，是一个整流回路，整流过程中必然会改变电流的波形而产生谐波。如果单纯的电容补偿，很容易出现控制器的干扰，导致过补现象。功率因数出现负数，充电桩补偿柜的负载变化频繁，会导致电网电压的电流波动，从而影响电网的稳定性和可靠性。充电桩是属于容性设备，模块里面有很多的电容配件，待机时它会产生无功电流、无功功率；如果充电桩的充电量少了，整体的功率因数低于0.85，那就会被加收力调电费。此时需要加装SVG设备，通过实时监测电网的电压，电流等参数，并根据需要在短时间内发生无功电流来补偿电网中的无功功率，使电网中的电压和电流更稳定，避免力调电费罚款。Power factor issue of new energy vehiclesA supercharging station is a facility designed to provide electrical energy to electric vehicles, enabling them to accumulate sufficient power for their operation. Most of these stations are situated in suburban areas. A low charging frequency at these stations often results in transformers operating under light load for extended periods. On-site, both inductive and capacitive reactive power issues, coupled with a low power factor, arise simultaneously.Typically, the power factor remains normal when a vehicle is being charged, but drops significantly when no vehicle is charging. A charging pile essentially involves converting alternating current (AC) to direct current (DC) for the purpose of charging, functioning as a rectification circuit. Inevitably, this conversion process alters the current waveform, resulting in the generation of harmonics.If pure capacitive compensation is employed, it often leads to controller interference, resulting in overcompensation. A negative power factor, coupled with frequent load variations in the compensation cabinet of charging piles, can induce voltage and current fluctuations in the power grid, impacting its stability and reliability. Charging piles are capacitive devices, equipped with numerous capacitor components within their modules. In standby mode, they generate reactive current and reactive power. If the charging capacity of the charging piles decrease, causing the overall power factor to fall below 0.85, additional surcharges for power factor adjustment will be imposed on the electricity bill.At this juncture, it is necessary to install SVG equipment, which monitors the voltage, current, and other parameters of the power grid in real time. Depending on requirements, it can generate reactive current promptly to compensate for reactive power in the grid, thereby stabilizing the voltage and current and preventing penalties for power factor adjustment.

医用隔离变压器是什么原理？

2025-07-11

医用隔离电源系统的主要作用是保护患者、医护人员的安全及提供稳定的电力供应，通过将传统市电系统转化为不接地系统，使得在发生故障时也能持续输出电力，正常在手术室、ICU这样的特殊环境下使用。医用隔离变压器输入电压等于输出电压，安装后可以消除直接电的联系。正常电力系统中，一根电线是相线，一根电线是零线（中性线）。由于中性线是接地线，因此它和大地同电位，当人体接触大地的同时，在初级象限就会使电流通过人体和大地构成回路，造成触电危险。医用隔离变压器初级、次级是通过磁场交换能量的，没有物理上的连接，二次两根线都不会接地。因此，人站在大地上接触二次任意一根线，都和大地没有电位差，不会发生触电事故。