1、 Brief introduction

1. There is a 1000KVA generator, a 100kVA generator, an 800kVA transformer and a 300kVA transformer in the system to be compensated in a diesel engine factory, with rated voltage of 400V and power frequency of 400V. The load is 800 KVA medium frequency holding furnace and 750 kW medium frequency smelting furnace.

2. The medium frequency electric furnace is 6-pulse rectifier and inverter, and the harmonic current accounts for about 30% of the fundamental current.

3. In view of the particularity of the medium frequency furnace power supply system, the harmonic current generated by it will have a serious impact on the whole power generation system, and there are serious potential accidents in the whole system. High order harmonics cause abnormal heating of generator and cable, affect armature balance, cause abnormal vibration and increase noise. High order harmonics will seriously affect the service life of the whole system.

4. Reactive power compensation can improve the power factor of load side and reduce the active power loss of the whole system. Reactive power compensation can reduce the actual output of transformer and generator, and effectively improve the utilization rate of transformer.

2、 Design basis

1. Compensation method

According to the analysis of the actual recorded data, the low-voltage dynamic reactive power compensation and filtering device (TSF) is proposed to be used in the compensation device. The device adopts the zero crossing switching mode of thyristor, which can not only quickly compensate the reactive power, but also has a certain filtering function. In order to ensure the safe operation of the equipment and achieve the desired effect, the TSF equipment adopts 7% reactors in series, mainly to suppress the 5th harmonic current, taking into account the governance of the 7th harmonic current. At the same time, it can ensure that other harmonics will not be amplified.

This set of compensation equipment can switch between 800kVA transformer and 1000KVA generator, that is to say, this set of equipment can be used for transformer during the day and generator at night.

2. Compensation capacity

According to the recorded data and our engineering practice experience, the installation capacity of TSF device is 800 kvar.

3. Implementation standard of design and production

GB7251; 81 low voltage switchgear

GB 7261; 1987 Basic test methods for relays and relay protection devices

Code for design of complete set of parallel capacitors (GB 50227; 95)

Code for design of shunt capacitor installations (GB 50227; 1995)

Jb5346; 1998 series reactor

JB 7L 13; 1993 low voltage shunt capacitor installation

Iec439; 1 low voltage switchgear and controlgear

JB 7L 15; 1993 low voltage reactive power local compensation device

GB / T 15576; 1995 general specification for low voltage reactive power static compensator

GB 11032; 1989 AC gapless metal oxide arresters

GB 6162; 1985 electrical interference test of static relay and protection device

GB 4208; 1993 protection class of enclosure

GB / T 2424; 1992 basic environmental test procedures for electrical and electronic products

3、 Technical proposal

1. Equipment selection

Equipment name: low voltage dynamic reactive power compensation and filtering device (TSF)

Equipment model: tsf-800 / 0.4 1 set

2. Overall plan

TSF installed capacity

Equipment model

number

Installation dimension

Switching series

Capacity switching step

800kvar

Tsf-800 / 0.4

1 set

3*c800*1000*2200

five

160kvar

Installation capacity: 160kvar; 320kvar; 480kvar; 640kvar: 800kvar.

4、 One time design

1. Performance parameters

Model: tsf-800 / 0.4

Rated frequency: 50 Hz

Rated voltage: 400V

Cooling mode: forced air cooling

Rated capacity: 800kvar

Cabinet type: GGD

Adjustment mode: CO compensation / sub compensation

Protection grade: IP20

Switching gear: 5

2. Primary system diagram

5、 Product description

1. Service conditions

Installation location: Indoor

Ambient temperature: - 15 ℃～ 40 ℃

Environmental humidity: the maximum relative humidity at 20 ℃ is not more than 90%, and the maximum relative humidity at 40 ℃ is not more than 50%.

Altitude: below 1000m.

Workplace: good ventilation, no fire and explosion hazards, no conductive dust, no gas or steam that corrodes metal or destroys insulation.

Vibration conditions: the vibration frequency severity is 10 ~ 150Hz, and the vibration acceleration is not greater than 5m / S2.

Pollution level: no more than III.

2. Description of cabinet and secondary control

(1) The cabinet body is made of aluminum zinc coated plate and electrostatic spraying;

(2) All operation buttons on the cabinet body shall be covered with doors or covers to prevent accidental collision and misoperation;

(3) Each door with lock device shall be equipped with at least three keys for each lock;

(4) Protection grade: tp20;

(5) Operation indication of capacitor;

(6) Voltage and current data display;

(7) The controller contains various electric parameters display;

(8) It can be controlled manually and automatically (code switching);

(9) The controller is equipped with color touch screen to facilitate user operation;

6、 Introduction to main performance of products

(1) Brief introduction of low voltage dynamic reactive power compensation and filtering device

Low voltage dynamic reactive power compensation and filtering device (TSF) is a thyristor dynamic switching filter controlled by intelligent controller, which integrates harmonic filtering and reactive power compensation. It can filter out the harmonic, compensate the reactive power, improve the power factor and reduce the line loss, so as to improve the load capacity and power supply quality of the power grid; at the same time, it can also monitor the three-phase voltage, current, frequency, active power, reactive power, power factor and other operation data of the power grid in real time, which is suitable for the occasions with large load harmonic content, low power factor and large load fluctuation. At the same time of dynamic filtering, it also achieves the purpose of local dynamic compensation of reactive power. It has perfect over-voltage, under voltage, phase loss, over-current, short circuit, transient over-voltage, sound and light alarm protection measures. There is no problem of reactive power reverse and harmonic amplification.

(2) How it works

In TSF, the controller collects the voltage and current instantaneous values of three-phase circuit in real time, calculates the voltage, current effective value, harmonic, three-phase active power, reactive power and compensation capacity of the line, and then controls the thyristor to switch the single tuned filter capacitor bank dynamically according to the compensation capacity and switching mode of the capacitor bank set by the controller, so as to ensure the voltage zero crossing trigger and no impact in the switching process No inrush current, no over-voltage, no arc, no noise, realize the automatic switching of the filter without contact, and can switch the filter bank continuously and frequently without affecting the life expectancy of the switch and capacitor.

(3) Typical application places

TSF device plays a significant role in fast reactive power compensation and harmonic filtering, which can minimize the harm of harmonic source, improve power quality and make full use of system capacity. Typical application objects are the following harmonic source loads.

① AC / DC drive motor

The DC power supply of AC inverter and DC motor is usually composed of three-phase bridge rectifier circuit. It leads to voltage fluctuation, power factor reduction, odd harmonic current and voltage distortion.

② Welding machine group

When the welding machine is single-phase load, the odd harmonic current is large, the waveform distortion is serious, the three-phase current is extremely unbalanced, and the voltage flicker is serious.

③ Intelligent building

In the power distribution of commercial buildings and high-rise residential buildings, modern power electronic equipment (adjustable speed motor, air conditioning, online UPS, switching power supply, color TV, laser printer, etc.) is a non-linear load. Although the impact of the load is small, the harmonic current generated is very serious, and the third and fifth harmonics have the most obvious impact.

④ The odd harmonic current produced by the intermediate frequency furnace is serious, which is mainly 5th, 7th and 11th. The harmonic power consumption is very large.

Frequency, active power, reactive power, power factor, compensation capacity, harmonic level and protection action signal, real-time display system date and time;

(4) Comprehensive protection function

Over current protection;

Overload protection;

Overheat protection;

Over voltage and under voltage protection;

It has over limit alarm and protection locking function, and the alarm limit can be set by the user;

Query the fault alarm history.

(5) Comply with the international standard of high-level immunity and work reliably in harsh electromagnetic environment;

(6) Communication function: RS485 interface;

(7) Cooling mode: forced air cooling;

(8) Cabinet type: GC K / GGD:

(9) Main components

■ core filter reactor; ■ self healing filter capacitor; ■ high power thyristor module; ■ reactive power dynamic compensation controller; ■ zero crossing trigger system; ■ display touch screen; ■ cabinet; ■ incoming switch; ■ fuse for thyristor protection;

I ■ cooling fan; ■ temperature controller; ■ display instrument; ■ relay protection.

All fixed capacitance compensation devices are equipped with automatic manual selection transfer switch, which can be selected according to the field operation conditions.

7、 Installation dimension

The TSF device adopts three sides (depth x width x height) 800 * 1000 * 2200mm3 cabinet.

The overall installation size of a set of equipment: (depth x width x height) 800x3000x2200mm3.

Yiphee Electric Furnace Co.,Ltd specializes in producing induction furnace.Tel(WhatsApp):+ 86-13450756789, yiphee@yiphee.cn