Design of an electric part of regional substation of PS of 110/35/10 kV

Development of simplified schematic diagram of ps

2.1. Selection and description of high voltage (HV) electrical connection diagram

For the HV switchgear of the designed district substation, having ten connections (eight lines, two transformers with a capacity of S nom T = 40 MV∙A), taking into account the absence of data on the parallelism of the lines or the presence of a reserve from other IR, and in accordance with recommendations [1], standard scheme No. 11013 "Two working and one bypass bus systems" is adopted.

In normal mode, both operating systems of K1C and K2C buses are energized, and the bypass system of KBC buses is disconnected. All connection switches and QKC bus switch are ON and QBC bypass switch is OFF. All QSB connections to the KBC bypass bus system are also disconnected.

The first K1C bus system includes transformer T 1 and lines W1C, W3C, W5C, W7C, the second bus system includes T 2 and lines W2C, W4C, W6C, W8C. The bypass bus system covers all connections and is required to bring any connection switch to repair without disconnecting this connection. During repair of the main switch it is replaced by bypass switch QBC.

The reliability of the circuit is quite high even in the absence of power supply to consumers by lines in pairs. If short circuit occurs on the first system of K1C buses, T 1 will be disconnected and W1C, W3C, W5C, W7C lines will be de-energized only during their transfer to the serviceable second system of K2C buses by actuation of bus disconnectors. If the damage on the bus system requires prolonged repairs, it is possible to connect T 1 via the bypass KBC bus system and the bypass QBC switch to the second K2C bus system and put it into operation. In case of short circuit on the line, for example, W1C, the Q1C switch is turned off. In case of failure in its disconnection, the short circuit from the line changes over to the first system of K1C buses and all connections fixed for this section are disconnected for the time required for Q1C repair. The main drawback of the circuit is the short circuit on the QKC bus connection switch is equivalent to the short circuit on both bus systems, that is, it leads to the disconnection of all switchgear connections.

The circuit is not very difficult to maintain (disconnectors are used only for the removal of electrical equipment for repair) and is economical - 12 switches are required for 10 connections. The inconvenience of operation of the circuit is due to the need for a relatively large number of operations by disconnectors when putting the switches out for repair.

2.2. Selection and description of MV-side electrical connection diagram (MV)

For the control stick 35 kV, having 8 connections (two transformers, six lines) according to recommendations [1], standard diagram No. 359 "one bus system partitioned by a switch" is adopted.

In normal operation, the transformer and line switches are on and the QK section switch is off. Three lines and one input from the transformer are connected to each section. The circuit has a fairly high reliability only for power supply to consumers of categories I and II, since in this case redundancy is provided over the network.

When any of the transformers is damaged, its input switch is turned off, but consumers connected to the de-energized section will be able to receive power from another section through the section switch. In this case, power supply interruption is limited by time for ALT actuation. However, in case of short circuit, all connections of this section are disconnected on the bus system section until the repair work is complete. In this case backup power shall be provided from busbars of other IR for consumers of categories I and II. This is also necessary if the switch of any of the lines is taken out for repair. The design of the switchgear is 35 kV inexpensive - for eight connections nine switches are required, visual and easy to maintain.

2.3. Selection and description of 10.5 kV LV electrical connection diagram

For 10 kV switchgear with 14 outgoing cable lines, diagram No. 102 "Two single, sectioned bus system switches" is adopted. It is accepted according to item 3.10 [6] separate operation of autotransformers to reduce the level of short-circuit currents. ATS device is provided on QK1 and QK2 section switches.

10 KV switchgear is performed using switchgear cells with switches on rolled-out trolleys, which allows to abandon disconnectors. Their functions are performed by plug-in contacts of the rolling-out trolley of the KRU cell. The use of KRU cells increases the reliability of the circuit, improves operating conditions, and reduces costs during the construction of the switchgear.

For each section of the first bus system, the same number of cable lines (4 KW) and one input from the autotransformer are connected, similarly on the second bus system - 3 KW for each section. In normal mode switches of all connections are ON, section switches are OFF and equipped with circuit for automatic switching on of ATS reserve. The circuit provides quite reliable power supply to consumers of I and II categories only if there is redundancy.

At short-circuit breaker on the section is switched off and the section is de-energized for all repair works. Short circuit on the line is disconnected by one switch, but if there is a failure to disconnect the switch, the short circuit changes from the line to the section, which is also de-energized for all the time necessary to put the line and the non-disconnected switch out for repair. In such cases, for consumers of categories I and II, backup power shall be provided from busbars of another MS.

The circuit is simple and easy to maintain, comparatively economical for sixteen connections, twelve switches will be required.

2.4. Selection and description of wiring diagram on HV side of PS 330/110/10

For a 330 kV switchgear having six connections (two autotransformers, four lines), in accordance with recommendations [1], standard diagram No. 33016 "Transformer - buses with half-timed connection of lines" is adopted. In normal operation, all switches are switched on, thus each connection is connected to the circuit through two switches. In closed ring mode, the circuit has high reliability. Setting of the circuit breaker for repair is simple and is not accompanied by disconnection of connections. But at the same time, the ring opens and the reliability of the circuit is somewhat reduced.

Disconnectors are used only for equipment repair, they do not perform operational switching. This simplifies the maintenance of the switchgear and improves the safety of switching. The circuit is economical - there is one switch per connection; has a development perspective. The main disadvantage of the circuit is the complex current distribution in the ring, which changes significantly when the mode of operation of the circuit changes.

Selection of operating current

Operating current is used to supply control circuits of switching devices, relay protection, automation and signaling, emergency lighting, etc. In accordance with the recommendations of paras. 6.4, 6.5 [6], DC operating current in the form of two lead-acid storage batteries (PSA) 220 V will be used as the operating current.

The AR batteries are operated in constant recharging mode, that is, the AR is connected in parallel with the recharging unit, which provides power to the connected load with rectified current and at the same time recharges the battery with a small current, making up for the loss of capacity as a result of self-discharge. In the event of an accident on the AC side of the C.R. or stopping the recharging unit, the battery takes over the entire load of the DC network. After the accident is eliminated, the batteries are again switched to work in constant recharging mode.

Selection of power supply circuit

Transformers n. are connected to 10 kV buses via switches of KRUN cells. On the 0.4 kV side, a single bus system partitioned by an automatic air circuit breaker is used. Transformers n. work separately with ATS on sectional communication.

Switchgear Design Selection and Description

In this course project, it is planned to use typical RP structures developed mainly by the Energetproekt design institute. The main task is to select a typical switchgear design according to the electrical connection diagram, the rated voltage level, the type of electrical equipment selected and the type of current-carrying parts.

All electrical equipment, current-carrying parts, insulators, fasteners, fences and supporting structures of the switchgear shall be installed in such a way that forces, heating, electric arc or other related phenomena caused by normal operating conditions of the electrical installation could not harm the maintenance personnel, and under emergency conditions could not damage the surrounding objects and cause K3 or ground fault. In addition, it is necessary that when removing voltage from any circuit, the current-carrying parts, devices and structures related to it can be safely inspected, changed and repaired without disrupting the normal operation of the connected circuits and the possibility of convenient transportation of equipment is provided .

Among the typical RU-6 (10) kV designs, RU made of prefabricated modular elements and from prefabricated prefabricated cells (KRU) were most widely used.

In our case, a step-down MS with group twin reactors is usually carried out with a two-row installation of PRUN cells with four sections, one corridor. Group reactors are installed in extensions to the switchgear. Typical KRU cell consists of four main compartments: linear (cable), relay (low-voltage), switch compartment (high-voltage) and busbar compartment:

in the relay compartment there is low-voltage equipment: RZiA devices, switches, choppers; on the door of the relay compartment, as a rule, there are light signal valves, electric power metering and measurement devices, cell control elements;

power switch is located in high-voltage compartment; often the compartment is made with a rolling out element, on which the switch is installed;

in the compartment of prefabricated tires there are power tires, of which the RP section consists;

linear compartment serves for placement of current measuring transformers, voltage transformers, OPN.

Open switchgears have the following advantages over closed ones: less construction work, since it is necessary only to prepare the site, build roads, build foundations and install supports, and therefore the construction time and cost of the switchgears are reduced; easier expansion and reconstruction; all sets are available for observation. The layout of the switchgear is significantly influenced by the design features of the devices installed in them and the methods of sheathing. Currently, all structural elements of the switchgear are usually made of prefabricated reinforced concrete elements. In some cases, metal structures can be used at high loads on columns and crossarms (330 kV and higher in the MCR).

Single-port 35 kV OPC with one partitioned system of prefabricated tires is designed to install VMD35 or VMP35 switches with a cell pitch of 4.6 m. Rigid prefabricated tires are located on support insulators mounted on consoles of the main bearing structure. Under the busbars there are bus and line disconnectors with their grounding knives, and even lower - switches with drives, relay protection cabinets and automation.

In the 110 kV OPC, two operating bus systems are adjacent to each other, the bypass bus system is assigned to linear portals. Leads to transformers are crossed by two operating systems of buses. Switches are installed in one row; in front of them there is a road for the passage of repair mechanisms, etc. The connection between the switches and current transformers above the passage is made by a rigid bus. Single-pole double-column disconnectors are installed in all circuits. Under the internal working system of buses asymmetric keel arrangement of disconnectors is adopted. Linear portals made of reinforced concrete structures have braces.

In the 330 kV OPC made according to the one-and-a-half diagram with air switches VNB330, suspended disconnectors RPG330 are used. Installation of switches is three-row, cell spacing is 24 m, height of bus portals is 18 m, and line 25 m. Current transformers TFUM330U1 are installed on foundations providing the normalized distance to the lower edge of porcelain, and if there is a passage of repair mechanisms between the switch and the current transformer, the normalized vertical dimension from the mechanisms to the bus bar.

RNDZ1 (2) HL1 disconnectors are used mainly only to open the circuit without load, although it is allowed to turn off minor charging currents of the busbars and connections, idling currents of transformers (subject to a number of limiting conditions), as well as load currents passing through parallel circuits (operations when switching the connection from one bus system to another). Disconnectors are installed in phase, each phase of the disconnector has its own drive of the PDN1 type.

Flexible busbar is performed by AC steel aluminum wires in one or two wires in phase in accordance with voltage class. Depending on the span, the wires are either suspended between the portals (prefabricated buses, cell jumpers), or attached directly to the apparatuses and support insulators (jumpers between apparatuses with a span of up to 10-15 m). Branches and connections of wires to devices are carried out by pressed clamps. Rigid busbars (if necessary) are made by rectangular and profile busbars or pipes. Tyres are attached to support insulators by bus holders. Compensation for thermal elongation of tyres is carried out using bus compensators.

Insulation of the busbar is carried out by tension and suspended garlands of PS70D glass insulators, as well as by support insulators. According to standard designs of RMS, for RMS 35 kV garland is recruited from four insulators, for RMS 110 kV out of nine, for RMS 330 kV out of twenty-three insulators. Support insulators are used to attach a rigid bus bar, small spans of flexible bus bar.

Two main types of voltage transformers are used: electromagnetic and capacitive. Oil cascade voltage transformers of NKF are installed similar to current transformers. Capacitive voltage transformers consist of a capacitive voltage divider, as which communication capacitors are used, and a voltage extraction device. Voltage extraction devices are installed on the foundations of communication capacitors. Voltage extraction from communication capacitors is carried out by a device installed on a separate foundation.

High-frequency communication equipment consists of capacitors, barriers and connection filters. Capacitors connected directly to the VL are installed on the insulating support and are grounded through a connection filter fixed on the foundation pillar. Barriers, which are made in the form of multi-turn coils connected in series with the VL, are installed on a communication capacitor or on a separate support insulator or suspended on output portals of the switchgear.

Protection against direct lightning strikes of the switchgear is made by rod lightning rods installed on the switchgear structures. The grounding connectors of the separate lightning leads installed on the searchlight masts shall be connected to the grounding device of the substation. Protection against atmospheric and switching overvoltage is provided by surge limiters of NPL.

Compressor station with operating pressure of 2.6 - 4.0 MPa is required to supply air circuit breakers and their actuators with compressed air. The unit consists of four or five compressor units, one of which is standby. The operation of the plant is usually carried out in a fully automated manner.

Control cables shall be laid on the territory of the substation in suspended trays laid at a height of 2 m from the level of layout (frames and block posts are used as supporting structures), and in ground trays made of precast reinforced concrete. Suspended trays are box-like structure opened from below. The lower opening is covered by removable bars, on which cables are laid. Trays are attached to supporting metal structures and are joined to each other by means of inserts, which enter both connected trays. Cable shafts are used to transfer cables from ground trays to suspended ones.

For general lighting of the territory of the substation, lighting installations of the OU2 type are used, each of which houses four lamps at a height of about 7 m. The design of the lighting installation provides maintenance of the lamps from the ground and allows for beyond

Switchgear design

To date, there are wide possibilities for a variety of arrangement of individual elements of RP electrical equipment in relation to each other, even for the same electrical connection scheme. The RP arrangement consists in optimal arrangement of the devices, according to their purpose and the requirements of the existing rules (minimum distances from current-carrying parts to various elements), their electrical connection to each other in accordance with the accepted circuit.

All electrical equipment, current-carrying parts, insulators, fasteners, fences and supporting structures of the switchgear shall be installed in such a way that forces, heating, electric arc or other related phenomena caused by normal operating conditions of the electrical installation could not harm the maintenance personnel, and under emergency conditions could not damage the surrounding objects and cause K3 or ground fault. In addition, it is necessary that when voltage is removed from any circuit, the current-carrying parts, devices and structures related to it can be subjected to

safe inspection, change and repair without disruption of normal operation of connected circuits and the possibility of convenient transportation of equipment was provided.

Open switchgears have the following advantages over closed ones: less construction work, since it is necessary only to prepare the site, build roads, build foundations and install supports, and therefore the construction time and cost of the switchgears are reduced; easier expansion and reconstruction; all sets are available for observation. The layout of the switchgear is significantly influenced by the design features of the devices installed in them and the methods of sheathing. Air VNV33040U1 switches are installed longitudinally on the bases which height provides observance of standard distance to the lower edge of porcelain.

Current transformers TFUM330AU1 are installed on foundations providing the normalized distance to the lower edge of porcelain, and if there is a passage of repair mechanisms between the switch and the current transformer, the normalized vertical dimension from the mechanisms to the bus bar.

RNDZ1 (2) 330 HL1 disconnectors are used mainly only to open the circuit without load, although it is allowed to turn off minor charging currents of the busbars and connections, idling currents of transformers (subject to a number of limiting conditions), as well as load currents passing through parallel circuits (operations when switching the connection from one bus system to another). Disconnectors are installed in phase, each phase of the disconnector has its own drive of the PDN1 type.

Flexible busbar is performed by AC steel aluminum wires in one or two wires in phase in accordance with voltage class. Depending on the span, the wires are either suspended between the portals (prefabricated buses, cell jumpers), or attached directly to the apparatuses and support insulators (jumpers between apparatuses with a span of up to 10-15 m). Branches and connections of wires to devices are carried out by pressed clamps. Rigid busbars (if necessary) are made by rectangular and profile busbars or pipes. Tyres are attached to support insulators by bus holders. Compensation for thermal elongation of tyres is carried out using bus compensators.

Insulation of the busbar is carried out by tension and suspended garlands of PS70D glass insulators, as well as by support insulators. According to standard designs of RMS, for ORU35 kV the garland is assembled from four insulators, for ORU110 kV out of nine, for ORU330 kV out of twenty-three insulators. Support insulators are used to attach a rigid bus bar, small spans of flexible bus bar.

Two main types of voltage transformers are used: electromagnetic and capacitive. NKF electromagnetic transformers are installed similar to current transformers. Capacitive voltage transformers consist of a capacitive voltage divider, as which communication capacitors are used, and a voltage extraction device. Voltage extraction devices are installed on the foundations of communication capacitors. Voltage extraction from communication capacitors is carried out by a device installed on a separate foundation.

High-frequency communication equipment consists of capacitors, barriers and connection filters. Capacitors connected directly to the VL are installed on the insulating support and are grounded through a connection filter fixed on the foundation pillar. Barriers, which are made in the form of multi-turn coils connected in series with the VL, are installed on a communication capacitor or on a separate support insulator or suspended on output portals of the switchgear.

Protection against direct lightning strikes of the switchgear is made by rod lightning rods installed on the switchgear structures. The grounding connectors of the separate lightning leads installed on the searchlight masts shall be connected to the grounding device of the substation. Protection against atmospheric and switching overvoltage is provided by OPN overvoltage limiters

Compressor station with operating pressure of 2.6 - 4.0 MPa is required to supply air circuit breakers and their actuators with compressed air. The unit consists of four or five compressor units, one of which is standby. The operation of the plant is usually carried out in a fully automated manner. Control cables shall be laid on the territory of the substation in suspended trays laid at a height of 2 m from the level of layout (frames and block posts are used as supporting structures), and in ground trays made of precast reinforced concrete. Suspended trays are box-like structure opened from below. The lower opening is covered by removable bars, on which cables are laid. Trays are attached to supporting metal structures and are joined to each other by means of inserts, which enter both connected trays. Cable shafts are used to transfer cables from ground trays to suspended ones.

For general lighting of the territory of the substation, lighting installations of the OU2 type are used, each of which houses four lamps at a height of about 7 m. The design of the lighting installation allows servicing of lamps from the ground.