Static capacitor banks SCB

STATIC CAPACITOR BANKS (SCB)

The issues of rational use of fuel and energy resources in our time are relevant both in our country and abroad. Rational use of energy is a priority in the energy policy of developed and developing countries. To achieve maximum efficiency it is necessary to consider the whole chain of energy production and consumption.

Electrical power transmission over long distances along electricity transmission lines is inevitably accompanied by voltage losses of active and reactive energy. A transmitted electrical power with a low power factor increases the loading of transmission and distribution equipment. Operation reliability of power network elements is reduced.

PURPOSE AND SCOPE

SCB are applied to increase power factor in electrical grids. They allow reactive power producing exactly in load centers but not at long-distance electrical stations, what reduces voltage and power losses in power supply system. They are applied in a close proximity to large load centers on the high voltage side. Individual and group reactive power compensation (RPC) is carried out by various devices at the voltage class 0,4-6-10 kV, at a high voltage with the help of SCB, as a rule, a centralized RPC.

TASKS SOLVABLE BY SCB INSTALLATION:

Electrical energy losses reduction
Voltage level stabilization (voltage losses reduction)
Electrical energy quality increase
Reduction of reactive energy consumption from powerful grids
Increase of carrying capacity of electrical grid without power increase of power equipment
Increase of electrical power supply system stability
SCB DESIGN

For today most demanded SCB are of open performance type for operation at open distribution units without additional constructions. UKCP SCB are fully satisfied the requirements of GOST 15543.1-89 concerning technical requirements of stability to climatic factors impacts for areas UHL1.

Static Capacitor Banks are completed with single-phase PFC capacitors of KEPF type. Fuses are installed in series with each capacitive element inside a capacitor; they secure a localization of inside damages not allowing capacitor failure.

Capacitors are placed in metal frames made of rolled metal and have a reliable anticorrosive hot-dip galvanized protective coating, resistant to atmosphere impacts. The internal and external insulation of capacitors is made taking into account the potential of supporting frames.

Electric connections of capacitors are carried out by flexible stranded (multiple core) wires and rigid busbars. Connection of flexible conductors with capacitor terminals is carried out by means of a specially designed groove clamp, which has a special coating to avoid oxidation as a result of creating a galvanic pair with the material of terminals and conductors. To ensure minimum transient resistance, the contact joints are treated with a special conductive grease.

For signaling of possible malfunctions static capacitor banks are connected among themselves according to the scheme “double star” or “H-type”. If there is a breakdown of capacitor element in emergency and pre-accident conditions, the internal fuse of this element burns out, resulting in a capacitance change of one of the bank shoulders.

Then in the conductor connecting the neutral points of stars (for the scheme “double star”) or connecting the midpoints of two parallel branches of each phase, the unbalance current flows, which is controlled by a special unbalance relay, separated from the power circuit by unbalance current transformer.

The unbalance relay, in its turn, signals the occurrence of a non-standard state in static capacitor bank operation or sends a signal to turn off the high-voltage switch of supply line.

The lowest value of natural unbalance current is achieved by forming the plans for placement and selection of capacitors individually for each bank.

SCB completion depends on customer’s requirements. The SCB composition includes metal frames to install capacitors covered by hot or cold galvanizing, polymer or porcelain support insulators and busbar insulators, busbar of electrical connections, current instrument transformers, protection devices of the bank from unbalance current, current-limiting reactors and a set of fasteners.

SCBs, depending on the type, are supplied in assembled or disassembled view. A final assembly is performed directly at the operating facility under the supervision of UKCP engineering supervisor. Long-term experience of SCB production allows to provide a maximum simplicity of installation and to reduce time and costs for mounting.

SCB assembling at operating object

Damping reactors are installed in series with SCB to limit the in-rush starting currents at the moment of switching and to reduce disturbances in the supply network.

Static Capacitor Banks with current-limiting reactors of Coil Innovation production, Austria

Designation structure of SCB:

For instance: SCB-110-52 UHL1 –static capacitor bank, rated voltage 110 kV, rated power – 52 MVAr, climatic performance and location category as per GOST 15150-69 – UHL1.

Distinguishing features of UKCP SCB:

• SCB attestation in OJSC “FGC “UES”;
• relatively low cost and quick payback;
• rich experience in manufacturing of capacitors and power capacitor equipment;
• quick installation and easy operation;
• SCB design as per customer’s requirements;
• a possibility to use SCB in a composition of filter compensating devices, static thyristor compensators.

IMPLEMENTED PROJECTS