Introduction:

based on DSP control technology and Instantaneous power control theory, Wanlida thyristor switched capacitor banks (TSC/TSF) with high-speed switching capability are designed to support the supply voltage of distribution systems and to correct the power factor and eliminate the harmonic current of connected loads.

Thyristor zero-crossing switching switches are resistant to mechanical wear, operate without noise, and are capable of practically transient-free switching, so it is more safety than contactor switched capacitor banks.

Functions:

• Improve power factor
• Stabilize busbar voltage and suppress subsynchronous resonance
• Eliminate harmonic current
• Decrease grid loss
• Optimize reactive power
• Increase transformer loading capacity

Principles:

Thyristor switched capacitor banks is the compensating device based on switching operation of capacitor banks by thyristor. TSC mainly consists of control system, thyristor, capacitors and reactors. Capacitor banks are divided into multiple units to realize step control. TSC is able to implement step regulating in reactive power, accuracy of regulating depends on numbers of multiple unit.

Thyristor switched capacitor banks (TSC/TSF) apply delta wiring. To optimize effect of reactive power compensating and harmonic filtering, TSC capacity and branch configuration must be designed according to reactive power variation and harmonic components from nonlinear load. 

Technical features:

Structure

Thyristor-switched capacitor banks (TSC/TSF) consists of controller, capacitor, reactor, thyristor and others.

Controller

• Process digital control signal and real-time control calculation based on the DSP. The dynamic response time is less than 10ms.
• Applying multi-control methods to realize the three-phase, separate phase, reactive power, voltage, harmonic control and voltage, reactive power and harmonic control in unified.
• The standard communications ports are convenient to connect with substations automation system to meet the quick data transmission, quick control (I/O) and remote communications requirements.
• Pass the EMC test with strong anti-interference ability: ESD Immunity, Surge immunity, Power frequency magnetic field immunity, Radio-frequency electromagnetic field immunity, Damped oscillation impulse immunity etc
• Perfect reactive power and harmonic measuring functions: AC sampling technology four quadrant analysis, harmonic distortion rate, harmonic histograms.
• Powerful data inquire and store functions: faults record, inquire, and all kinds of electrical parameters and charts checking.
• Multiple protection functions: over voltage, under voltage, over current, under current, switching input value etc.
• Multi-Task operation system core can control maximum 16 steps of capacitor banks and 16-way switching values detection.

Capacitor 

• Apply self-healing low-voltage shunt capacitor, built-in protection device and built-in discharge resistance.
• Bear 1.35 times of over current continually.
• Voltage withstand among poles: AC 2.15Un, DC 4.3Un. 10 seconds.
• The single capacitor tolerance is no more than ±2.5% and the whole set of capacitor banks tolerance is no more than ±1.5%
• Three phase tolerance of capacitor: Maximum/Minimum is no more than 1.01
• Build-in pressure protection mechanism, when the inside fault pressure increased, the capacitor exits automatically.
• Conform to IEC831-1 and GB12747-91 self-healing low voltage shunt capacitor standard.

Reactor 

• Apply dry-type iron-core reactor with low-loss import Cold rolled orientation silicon steel sheet
• The coil adopted H-class or C-class enamelled rectangular wire perfect appearance and heat elimination performance.
• After assembly of reactor coil and iron-core, it passed pre-heat→vacuum dipping coating→ heat curing, so the structure is solid and resistant to high temperature and noise.
• The iron-core fasteners adopted Non-magnetic materials to ensure high quality factor and low temperature rise, and then realize better filtering effect.
• The outer parts adopted anticorrosion treatment, and the leading-out terminals adopted Cold-pressed copper tube terminals.

• Bear the 1.35 times of over current continually and bear 20 times over current for 2 seconds.

• The inductance tolerance: single phase tolerance is no more than ±1%, each phase difference to average value is no more than±1% too.

• Conform to JB5346-1998 series reactor national standard.

 Thyristor switches       

• Modularized design: Integrated by zero-crossing triggering thyristor module, RC absorbed circuit, fuse, radiator, fan, thermo switch.
• import zero-crossing triggering thyristor module.
• Transient free and no noise during switching
• Input signals are coupled with control signals by optical isolation
• System measures thyristor temperature in real-time
• Phase loss/ fault phase protection 
• Fast response time
• Maintenance free and long service life

Other components

Isolation switch, lightning arrestor, current transformer are from the excellent manufactures at home and abroad to ensure TSC/TSF quality.