CITS (complete indoor transformer substation) up to 1000 kVA – a new decisions for all industries
Penjagina Yu.A., Principal engineer of the Informational Center of OJSC «Energoprom», Ozyorsk
The domestic equipment which makes a technical basis of electric power industry, is morally obsolete, do not meet the modern requirements and concedes to the best world products. Therefore it is necessary now not only to maintain the serviceability, but also to update essentially the basic production assets on the basis of new techniques and technologies of power production and distribution.
The worn-out, overage equipment, the share of which has already exceeded 15% of all capacities in power supply systems, and absence of an opportunity of its restoration leads to technological refusals, failures and, as consequence, power supply reliability weakness.
Dynamics of the equipment ageing demands taking the thoroughgoing measures to stop this process. It is necessary to work out the directions of development of the equipment used in electric grid, and the principles of grid construction. The main issue is updating the distributive grids, creation of grids which meets the new technical requirements and the modern level of power distribution. And this problem should be solved in conditions of rigid lack of financial assets.
Complete indoor transformer substations are usually constructed in large shops of the industrial enterprises. The nearest approach of these substations to the centers of electric loadings provides the best technical and economic parameters in regard to consumption of both the power and nonferrous metals.
Having addressed to foreign experience, one may see that the basic idea at new substations construction is the use of compact cells, which enable to modernize substation without change of a building. This is a very important point since the basic cost is connected with the capital construction, and with the additional cable routing near new substation.
Nowadays the OJSC «Transneft» makes rigid demands to the power supply systems of the pump stations (PS). PS’s electrical receivers are the receivers of 1st category and should be fed from two independent sources: own 2 transformer substations, or two sections of buses of the power supplying company.
Used transformers should be equipped with the device of automatic voltage regulation under loading (RUL). The substation should be connected to the higher dispatcher, to the general common telephone system, to the channels of remote control. The commercial power metering is required on the border of the consumer and power supplying company ownership.
Devices of the electric power commercial metering and quality control (EPCMQC) should meet the requirements of the wholesale market operator. The technical electric power metering should meet the requirements of the hourly recording at power supply systems.
Therefore since 2004 the OJSC «Energo-prom» makes complete indoor transformer substations of CITS series of the capacity from 250 up to 1000 kVA, intended for the reception, transformation and distribution of a three-phase alternating current power of 50 Hz frequency for various industrial electrical receivers power supply.
One – and two-transformer CITS will find the application in electric power industry, at the objects of oil and gas extraction, transportation and refining, at the systems of power supply for the industrial enterprises and in municipal economy in the regions with a temperate climate; they are designed for installation inside unheated rooms.
The priorities of our company in items development and manufacturing are the incorporation of the Client’s requirements and expansion of production functionalities.
Therefore by development CITS the following has been stipulated:
1. High-voltage device (HVD) is metal housing of enclosed design, in which depending on the circuit can be established the load-break switch of VNA-6 (10) U2 type with fuses of PKT-6 (10) U3 type or any other switch with the similar characteristics.
2. CITSs are completed with three-phase dual-winding dry or oil-filled transformers. The transformers are connected to input of switching centers of high or low voltage either by rigid not insulated or flexible copper insulated buses.
3. The following devices of the sliding or plug-in design can be used as a low-voltage switching centers (SCLV):
1) Switches of the VA series produced by JSC “Contactor” (city of Ulyanovsk) designed for currents from 100 up to 1600 A;
2) Switches of ВА series of OJSC «DZNVA» (city of Divnogorsk) production, designed for currents from 100 up to 630 A;
3) Switches Compact NS of “Schneider Electric” production designed for currents from 100 up to 630 A, equipped with the electronic blocks of protection;
4) Switches Masterpact NT of “Schneider Electric” production designed for currents from 800 up to 1600А equipped with the electronic blocks of protection;
5) Switches DMX of «Legrand» production designed for currents from 800 up to 1600 A, equipped with the electronic blocks of protection, or the switches of other producers with the similar characteristics.
The use of import accessories allows to reduce overall dimensions of a product (which is important at reconstruction of already working objects or at construction of a new one), as well as to increase the reliability and safety in operation.
4. SCLV 0,4 kV is a welded skeleton which consists of two compartments: a compartment of the power equipment and a bus compartment.
The compartment of the power equipment is collected from the racks completed with the following elements:
a) A case of the low voltage input (ShNV);
b) Cases of outgoing lines (ShNL);
c) A section switch case (ShNS);
d) A case of emergency input of the low voltage (ShNA);
e) Cases of relay protection and automatics (ShRV, ShRS).
Each case of a power compartment is a welded construction which is made of structures and which has a demountable back wall. Each case has functional racks on which all the equipment is fastened.
There are eight standard sizes and designs of the SCLV power compartment racks which are distinguished in overall dimensions, functional purpose of cases, number of outgoing connections, and rated current of switches.
5. At use of the import equipment, the introduction switches are completed with COM-ports for integration into automatic control system with an opportunity of monitoring, control, and registration of events, parameters of a current and voltage under the ModBus protocol.
6. The collecting buses, bus brunches for cable and bus connections, transformers are located in bus compartment of SCLV. Buses are fastened with the help of cleats, which provides the simplicity of trunks distributing and service convenience. Power modular trunks, bus connections and buses themselves bear a shock current of short circuit of 50 kA. To reduce the transient resistance all the contact connections of trunks are welded.
7. For two-transformer CITS the automatic load transfer (ALT) scheme is realized on the basis of electromechanical relays or micro-processor technical equipment with the subsequent restoration of a normal mode.
When the electromechanical relays is used, the ALT starts-up within (0,1 … 10) seconds from the voltage control relay with a range of preset voltage regulation within (0,4 … 0,84) of rated voltage. When the microprocessor blocks are used, the ALT scheme is implemented on the basis of blocks BMRZ-0,4VV, BMPA, BMRZ-0,4AV produced by the Scientific and technological centre “Mechanotronics” (Sankt-Petersburg) and has an opportunity of integration into automatic control system of power supply under the ModBus protocol.
8. When mains are interrupted on the side of two working inputs in CITS, a feed of consumers from the third independent lead-in from the Diesel power plant is stipulated, thus the least important consumers are switched-off.
9. An active and reactive power may be measured and recorded by meters of any manufacturer. The board of automatic recording can be fasten to SCLV sidewalls or to a CITS room wall.
10. The electric and mechanical blocking which provides the attendants safe work are implemented in CITS.
Thus, the produced by OJSC «Energoprom» CITS has the following features:
1. The design of cases provides the simplicity and convenience in operation as well as the safety access for check, adjustments, and maintenance service of blocks and devices.
2. There is an opportunity of use the power switches of any manufacturer.
3. All contact connections of power trunks are welded, that provides the reliable connection and reduction of transient resistance.
4. The control circuit has the outlets for remote control system connection.
5. CITS has an opportunity of bilateral information interchange with the automatic control system or personal computer via standard serial communication channels.
6. There is an opportunity of the power recording both on lead-in and on outgoing connections.
7. The carriage for transportation of switches heavier than 30 kg might be included into the complete set of CITS delivery if ordered.
8. There are might be various variants of CITS both inside rooms and in building block construction with the nearest approach of substation to the center of electric loadings.
Taking into account the entire above one may come to a conclusion that transformer substations of OJSC «Energoprom» production possess a high level of reliability and allow to reduce the operational cost by 85%. For the network enterprise it results in saving of material resources, in reduction of operational staff, in reduction of the power losses of the electric power, in resolution of the set of urgent problems regarding automation and remote control of transformer substations.