High-voltage shunt capacitor device is mainly used for power system with power frequency of 6kV, 10kV and 35kV, etc. for reactive compensation, so as to increase power factor, improve voltage quality, reduce line loss, and give full play to the efficiency of power generation and power supply equipment.

The device consists of high-voltage shunt capacitor, series reactor, zinc-oxide arrester, discharge coil, vacuum contactor special for switching capacitor, isolating switch, fuse special for capacitor protection, reactive voltage integrated controller, and corresponding main circuit and control circuit, of which the control section takes effect of measurement, display and switching control on each circuit.

The standard capacity distribution is based on 5 standard configuration switching units: 300kvar, 600kvar, 900kvar, 1200kvar and 1500kvar, while different switching combinations can be selected according to user needs to meet the requirements for compensation capacity and compensation precision.

Model description

Operating principle

The high-voltage reactive automatic compensation device produced by our Company performs reactive comprehensive control according to the control strategy. The capacitor bank is switched by the vacuum contactor special for high-voltage capacitor. When the reactive power value detected by the controller is lower than the set value, the controller gives a control signal according to the step number of the capacitor bank to be switched on, switches on the high-voltage vacuum contactor automatically, and puts the capacitor bank into operation; When the reactive power is higher than the set value, the capacitor bank quits operating when the vacuum contactor receives the switching off control signal sent by the controller. The above operating state is fully automatic. Schematic diagram of the primary principle and protection logic is shown as below:

Technical performance

● The capacitance deviation is 0~+5%, the deviation between series sections is less than 2%, and the phase deviation is less than 2%;

● It is allowed to run for a long time under the steady over-voltage of 1.1Un power frequency. In this operating state, the voltage peak including all harmonic components shall not exceed 1.2√2Un;

● Allow operation under steady state current of 1.3In due to over-voltage and high harmonics, and for capacitors with maximum positive deviation of capacitance, over-current is allowed to reach 1.43In;

● Capacitor protection is divided into internal fuse protection and external fuse protection. The internal fuse protection has higher reliability, and especially can avoid accident of capacitor damage in bulk. The capacitor device uses open triangle voltage, bridge differential unbalance current or neutral point unbalance current as the primary protection. In addition, the system shall also set over-voltage, voltage loss, bus-bar inter-phase short circuit quick-disconnection and over-current protection;

● Switch the capacitor banks circularly, first switch-on for first switch-off, and the switch time delay can be set;

● Generally, select vacuum contactor special for switching capacitor as the switching switch, which is of frequent operation performance, fast tail-flip speed when switching off and switching on, low re-ignition rate when switching off, reliable operation, less maintenance, long service life and other advantages;

● The configured integrated protection uses a special digital circuit protection and measurement control device for capacitor, which can achieve over-voltage, under-voltage, two section over-current protection and two section fixed time lag zero sequence over-current protection, fault removal and lock the group of capacitors, while other capacitor banks operate normally;

● The controller is provided with RS485 communication port and can realize remote communication.

Composition of complete set

Main wiring mode: the main wiring of the capacitor bank adopts single star type or double star type;

Each grouping circuit mainly includes vacuum contactor special for switching capacitor, shunt capacitor, series reactor, discharge device, zinc oxide arrester, and jet-type fuse; the device is composed of inlet line cabinet, grouping compensation cabinet, etc.

Inlet line cabinet

It consists of isolating switch, electromagnetic lock, current transformer and other components. This part is mainly the device that communicates with the circuit breaker in the upper inlet line cabinet of the compensation device and the current transformer and voltage transformer in the system.

Compensation cabinet

It consists of capacitor, vacuum contactor, reactor, discharge coil, zinc-oxide arrester, current transformer or grounding switch, etc.

When the internal components of a single capacitor are broken down to 50%~70%, the fuse will quickly disconnect the faulty capacitor from the power grid to prevent the fault from expanding. The capacitors are all made of whole membrane medium and extremely stable impregnating agent, which is of small size and low loss. Capacitors are arranged in two or three layers and can be arranged in front and back rows.

5.2.3 The primary winding of the discharge coil is connected to both ends of the capacitor, and the discharge characteristic can meet the requirement that the terminal voltage is decreased from √2 times of the rated voltage to 50V below within 5 seconds after outage of the capacitor. The discharge coil can be fully sealed oil immersed type or dry type, or can be replaced by a voltage transformer. Select HY5WR specially used for capacitor as the zinc-oxide arrester.

Select product, which conforms to performance indicators of switching capacitor and specially used for capacitor as the vacuum contactor; the vacuum contactor for capacitor passed the capacitive switching back to back test of capacitor, and it is of impact resistance and suitable for frequent switching.

Select a reactor with a capacitor reactance of (0.1%~1%) per phase when limiting the switching in inrush current; select a reactor with a capacitor reactance of (4.5%~6%) per phase when restraining the fifth and above harmonic; in order to reduce the space occupied by the reactor in the cabinet, select a dry iron core reactor or an air core reactor with a small inductance.

The controller adopts the “nine-domain zone” control principle to automatically identify various operating modes of transformers and capacitors in the substation to prevent switching oscillations.

Device implementation standards

GB311.1-1997	Insulation Coordination of High-voltage Power Transmission and Transformation Equipment
GB3983.2-89	High-voltage Shunt Capacitor
GB/T 11024.1-2001 GB/T 11024. 1-2001	Shunt Capacitors for A. C. Power Systems Having a Rated Voltage Above 1kV
GB50060-2008	Code for Design of High Voltage Electrical Installation
GB50150-91	Electrical Equipment Installation Engineering and Electrical Equipment Handover Test Standards
GB50227-2008	Code for Design of Installation of Shunt Capacitor
GB11032-2000	Metal Oxide Surge Arrester without Gaps for A. C. Systems
GB/T 14549-93	Quality of Electric Energy Supply - Harmonics in Public Supply Network
SDJ25-85	Technical Specification for Design of Shunt Capacitor Installation
DL/T 840-2003	Technical Conditions for Using High-voltage Shunt Capacitor Installation
DL429.9-91	Oil Quality Test Method of Power System - Insulation Oil Dielectric Strength Determination
DL442-91	Technical Specifications of Protective Fuse of Single High-voltage Shunt Capacitor for Order
DL462-92	Technical Specifications of Series Reactor of High-voltage Shunt Capacitor for Order
DL/T604-2009	Specification of High-voltage Shunt Capacitor Installations for Order
DL/T653-1998	Technical Conditions of Discharge Coils of High-voltage Shunt Capacitor for Order
IEC-6076 和IEC-60289 IEC-6076 and IEC-60289	Reactor
IEC-60871-1	Capacitor

High-voltage AC filter device

High-voltage motor reactive in-situ compensation device