VVR real-time dynamic voltage controller

1 Overview
Introduction to voltage sag
With the rapid development of the modern power industry and the major changes in the power load structure in the system, the dependence of factory and office automation on electronic equipment has grown rapidly. For power users, voltage sags are becoming a major problem. The entire process of electrical energy generation to use spans a wide geographic area. Among them, the entire transmission system generally encounters accidents such as lightning, heavy rain, strong wind, construction, and personnel misoperation, causing voltage sags caused by short-circuit failures, and some are enough to affect To the normal operation of sensitive equipment.

At present, most of the voltage problems in the power grid are voltage sags/swells. Voltage sags/swells are common voltage problems. Abnormal increase in the effective value of the voltage will directly damage the equipment. The mains voltage sag, which can cause electrical equipment failures or shutdowns, has occurred more than 10 times more often than complete main grid outages. According to the authoritative data of EPRI (American Electric Power Research Institute), more than 92% of power quality events are voltage sags and swells, and other power quality events account for less than 8%. Voltage sag has been determined by many international research institutions as the most common event in the power system. Therefore, it is particularly important to protect sensitive equipment from voltage sags (swells). Voltage Sag (Voltage Sag) is also called voltage sag, voltage sag, voltage sag, and electric shock. It refers to the phenomenon that the effective value of the voltage drops suddenly and then suddenly returns to normal.

According to the authoritative data of EPRI (American Electric Power Research Institute), more than 92% of power quality events are voltage sags and swells, and other power quality events account for less than 8%.

The International Institute of Electrical and Electronics Engineers (IEEE) defines it as falling to 90% to 10% of the rated value, and its typical duration is 0.1~1s.

Causes of voltage sag
There are many reasons for voltage sags. When short-circuit faults, lightning strikes, large motors start and other events occur in the power transmission and distribution system, voltage sags may all be caused. Therefore, the voltage sag cannot be avoided.

● Weather

Because most of the transmission lines are exposed to nature and are affected by lightning, rainstorms, and strong winds, they can easily break down the insulating medium between the lines, causing discharges between lines or lines to ground, resulting in voltage sags.

● accident

Traffic accidents, building construction causing damage to transmission lines, human error, and-some small animals entering the power distribution room can also cause discharge between lines or lines to ground, resulting in voltage sags.

●Other failures

Large motor starting, short-circuit failure, line switching, and power distribution device failure can also cause voltage sags.

Technical indicators of voltage sag
●Suspended amplitude

Defined as the ratio of the effective value of the voltage during the sag to the effective value of the rated voltage;

●Suspended duration

Defined as the time between the occurrence and the end of the sag;

●Sag frequency

It is defined as the number of voltage sags occurring per unit time (usually one year at the time of evaluation).

The hazards of voltage sag
Voltage sags can cause malfunctions of sensitive controllers (causing tripping), causing failures of the computer system, stalling or malfunctioning of automation devices, stalling of the frequency converter, etc.; causing contactor tripping or low-voltage protection to start, causing the motor , Elevators, etc. stop; cause the high temperature light source (iodine tungsten lamp) to go out, and cause the loss of lighting in public places.

Voltage sags will cause huge economic losses to many industries. Such as the damage and waste of silicon wafers of semiconductor products, the scrapping of automobile engine products, the scrapping of display products, the interruption or disorder of the production line and so on.

Voltage sags not only cause economic losses, but may also cause casualties and major safety production accidents. For example, computer-controlled brain surgery, cardiovascular surgery, and ophthalmic surgery in hospitals can cause serious consequences when the equipment fails to work due to voltage drops; in the petrochemical industry, due to voltage sags, the control system malfunctions. Cause a short-term risk of pressure flow out of control, etc.

2 VVR product introduction
Introduction to VVR
VVR adopts power electronic technology. When the system voltage suddenly drops, VVR can realize the rapid adjustment of the voltage, at the same time eliminate the voltage E phase imbalance, and has the adjustment voltage deviation to ensure that the output voltage is seamlessly connected to the rated value and protect the load. run.

How VVR works
When the grid voltage is within the normal range, VVR is in the standby state, the control thyristor is in the on state, the inverter is not working, and the super capacitor is in a fully charged state. The output voltage is the grid voltage.
 

When a voltage sag occurs in the grid voltage, the thyristor is immediately controlled to be off, and the grid voltage is completely isolated from the load. After the inverter is discharged, it passes through an injection transformer to output a preset voltage to the load. The voltage support of VVR completely avoids the harm to the load due to voltage sag.

When the grid voltage returns to the normal value, it stops working, and at the same time controls the thyristor to turn on, the output voltage returns to the grid voltage, and the super capacitor starts to charge, preparing for the next voltage sag.

VVR product model description
To choose an application, you need to know the following information:

●Grid voltage and frequency

●Load capacity kV A and kW

●Required protection time

●Inlet and outlet method and wire system

●Installation space

Remarks: ①Protection time: three digits, the unit is (s). Scientific notation, such as 363 represents 3.6x103s, which is 1 hour; 040 represents 0.4s.

　　②Rated protection capacity: 30~5000kVA, see the following technical parameter table for details.

　　Example: WVR 04-300HFN-040C (VVR product 400VAC 300KVA is connected before the incoming line, the protection time is 0.4s, the energy storage element is a super capacitor)

Advantages of VVR
●High reliability, specially designed for industrial loads

Multi-level protection, simple circuit, high reliability, and maintenance-free.

●High system efficiency and fast response speed

The efficiency is as high as 99.2%; the protection switching time is not more than 2ms; single-phase, two-phase, and three-phase drops to 0% can be managed.

●Superior rectifier performance, no harmonic injection

Adopt the fourth-generation insulated gate bipolar transistor (IGBT) power device and multiple protection technology to ensure the absolute reliability of the equipment, advanced IGBT green rectification technology, no harmonic injection pollution, and improve power utilization.

●Full digital control technology based on DSP, high reliability

Using the most advanced 32-bit DSP (digital signal processor), VVR can achieve extremely high performance and reliability by advanced flexible logic algorithms.

●Advanced parallel expansion function, modular design

Parallel expansion function increases the capacity of the VVR system as a redundant backup for each other, which further improves the reliability of the power supply.

●Multi-function panel with graphic TFT true color display

VVR's multifunctional panel is equipped with an 8 o'clock graphic TFT display. Through the graphical display and the friendly interface menu operating system, users can easily browse the input, output, load and operating parameters.

●Completely maintenance-free, low operating cost

The energy storage device has high reliability, no wearing parts, minimal self-consumption, and a design life of 20 years.

●No need for cooling equipment

The self-consumption is only 0.8%, and no forced cooling system is required.

●Compact structure design, small footprint

The compact structure design greatly reduces the requirements for installation space and floor load-bearing, allowing users to save space and investment, and the floor space is 1/2 to 1/3 of the traditional UPS.

overall benefit
●Through the protection of voltage sag and swell, it can prevent serious failure and shutdown loss, avoid raw material waste and damage to production equipment.

●Avoid the use of low-quality electricity for equipment, reduce plant maintenance costs, and protect product quality.

●Avoid accidents caused by disorder of data and control system caused by voltage sag.

●Compared with the traditional online UPS system, the self-consumption of VVR equipment is only one tenth of that, which greatly saves users' electricity bills. Save for users

● Considerable maintenance and battery replacement costs, while avoiding the disposal of waste batteries, to avoid environmental pollution. Extremely efficient

●High, the equipment itself does not generate heat, and does not require heat dissipation and cooling systems such as air conditioners, which saves the hardware investment and usage fee of the air conditioner.

●No harmonics are injected into the grid, no additional filtering equipment investment required by traditional UPS.

208V series VVR technical parameters

400V系列VVR技术参数

600V series VVR technical parameters

6KV系列VVR技术参数

10KV series VVR technical parameters

3 size, layout and gap
The following illustrations show the dimensions, cabinet layout and clearance requirements of the cabinet. (Take a common cabinet as an example.)

The following clearance requirements apply to all cabinets:

-Leave a gap of 200mm (minimum) above the cabinet.

4 product comparison
Compared with similar voltage sag protection products