SINVERT. Technical requirements for medium-voltage transformers for use with SINVERT central inverters. Application manual 04/2012

Transcription

1 Technical requirements for medium-voltage transformers for use with SINVERT central inverters Application manual 04/2012 SINVERT Answers for the environment.

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3 Technical requirements for medium- Technical requirements for medium-voltage 1 transformers voltage transformers for use with SINVERT central inverters SINVERT Technical requirements for mediumvoltage transformers for use with SINVERT central inverters Application manual 04/2012 A5E

4 Legal information Legal information Warning notice system This manual contains notices you have to observe in order to ensure your personal safety, as well as to prevent damage to property. The notices referring to your personal safety are highlighted in the manual by a safety alert symbol, notices referring only to property damage have no safety alert symbol. These notices shown below are graded according to the degree of danger. DANGER indicates that death or severe personal injury will result if proper precautions are not taken. WARNING indicates that death or severe personal injury may result if proper precautions are not taken. CAUTION with a safety alert symbol, indicates that minor personal injury can result if proper precautions are not taken. CAUTION without a safety alert symbol, indicates that property damage can result if proper precautions are not taken. NOTICE indicates that an unintended result or situation can occur if the relevant information is not taken into account. If more than one degree of danger is present, the warning notice representing the highest degree of danger will be used. A notice warning of injury to persons with a safety alert symbol may also include a warning relating to property damage. Qualified Personnel The product/system described in this documentation may be operated only by personnel qualified for the specific task in accordance with the relevant documentation, in particular its warning notices and safety instructions. Qualified personnel are those who, based on their training and experience, are capable of identifying risks and avoiding potential hazards when working with these products/systems. Proper use of Siemens products Note the following: WARNING Siemens products may only be used for the applications described in the catalog and in the relevant technical documentation. If products and components from other manufacturers are used, these must be recommended or approved by Siemens. Proper transport, storage, installation, assembly, commissioning, operation and maintenance are required to ensure that the products operate safely and without any problems. The permissible ambient conditions must be complied with. The information in the relevant documentation must be observed. Trademarks All names identified by are registered trademarks of Siemens AG. The remaining trademarks in this publication may be trademarks whose use by third parties for their own purposes could violate the rights of the owner. Disclaimer of Liability We have reviewed the contents of this publication to ensure consistency with the hardware and software described. Since variance cannot be precluded entirely, we cannot guarantee full consistency. However, the information in this publication is reviewed regularly and any necessary corrections are included in subsequent editions. Siemens AG Industry Sector Postfach NÜRNBERG GERMANY A5E P 04/2012 Technical data subject to change Copyright Siemens AG All rights reserved

5 Table of contents 1 Technical requirements for medium-voltage transformers Rated voltages and low-voltage infeed Rated voltages Low-voltage and high-voltage winding Interconnection of the components Voltage peaks and filtering Transformer design Design of surge arresters (AC-side) Short-circuit voltages Types of construction Special requirements for oil-immersed transformers...10 Technical requirements for medium-voltage transformers for use with SINVERT central inverters Application manual, 04/2012, A5E

6 Table of contents Technical requirements for medium-voltage transformers for use with SINVERT central inverters 6 Application manual, 04/2012, A5E

7 Technical requirements for medium-voltage 1 transformers 1.1 Rated voltages and low-voltage infeed Rated voltages The rated voltage is dimensioned to the respective low voltage dependent on the inverter type: Inverter SINVERT TL 500/1000/1500/2000 SINVERT PVS 500/1000/1500/2000 SINVERT PVS 585/1170/1755/2340 SINVERT PVS 600/1200/1800/2400 SINVERT PVS 630/1260/1890/2520 Rated voltage 328 V 288 V 340 V 370 V 370 V Low-voltage and high-voltage winding Figure 1-1 Configuration example of a medium-voltage transformer 1200 kva (370 V / 370 V / 21 kv) Technical requirements for medium-voltage transformers for use with SINVERT central inverters Application manual, 04/2012, A5E

8 Technical requirements for medium-voltage transformers 1.1 Rated voltages and low-voltage infeed A separate isolated low-voltage and high-voltage winding is required for each inverter subunit. If several low-voltage windings are available (four-winding transformer design), the transformer must be suitable for use with asymmetrical load of the low-voltage and highvoltage windings. The high voltage is selected between 8 kv and 66 kv dependent on country-specific, grid-operator-specific, and project-specific requirements. Note The country-specific grid frequency, standards and regulations, as well as the stipulations of the local grid operator must be complied with Interconnection of the components Figure 1-2 Basic principle of interconnecting components in the inverter station in a configuration with SINVERT PVS 2000 or SINVERT PVS 2400 inverters Technical requirements for medium-voltage transformers for use with SINVERT central inverters 8 Application manual, 04/2012, A5E

9 Technical requirements for medium-voltage transformers 1.2 Voltage peaks and filtering 1.2 Voltage peaks and filtering Transformer design The technical design of the transformer must be suitable for operation with pulsed inverters. The voltage peaks can reach ±1500 V to ground (pulses). The rms value of the voltages to ground must not exceed 800 V. The low-voltage winding must be designed for gradients du/dt up to max. 500 V/ µs to ground. For dry-type transformers, a shield winding (du/dt filter) between the low-voltage winding and the high-voltage winding can be dispensed with by means of appropriately implemented design measures. Overvoltage protection in accordance with VDE 0101, Section (spark gaps to VDE ) is required for all transformers Design of surge arresters (AC-side) The surge arresters must be suitable for pulsed operation. The surge arrester must be effectively designed for voltages of ±1500 V and 800 V AC. One surge arrester must be installed per phase. It must be ensured that no grounding or artificial neutral point is caused by this installation. 1.3 Short-circuit voltages The short-circuit voltage Uk must be selected at 6%. In doing so, 5.4% to 6.6% must be maintained. With four-winding transformers, the short-circuit voltage between the low-voltage windings must be 10%. If the high-voltage winding is not connected, the measurement is carried out by shortcircuiting one low-voltage winding, and voltage infeed at the second up to the rated current. For thermal dimensioning, the respective site conditions and isolation classes must be taken into account. Technical requirements for medium-voltage transformers for use with SINVERT central inverters Application manual, 04/2012, A5E

10 Technical requirements for medium-voltage transformers 1.4 Types of construction 1.4 Types of construction The permissible types of construction are Dy5Dy5 and Dy11Dy11. The neutral point must not be brought out on the low-voltage side. At least 5 voltage levels must be brought out on the high-voltage side: -5.0%, -2.5%, rated voltage, +2.5% and +5% Note In the case of thin-film modules, a range of up to -15% may be required, depending on the manufacturer. Since it is an infeed transformer, the rated voltage must be 5% higher than the rated grid voltage (rated grid voltage 20 kv, rated transformer voltage 21 kv). When using the transformer in conjunction with the Siemens 8DJH switchgear, the rated voltage of the transformer must not exceed 24 kv. 1.5 Special requirements for oil-immersed transformers If oil-immersed transformers are used, oil sumps must be provided and acceptance-tested by an appointed person depending on the location of use (water regulations). In water reserves, special permits must be obtained for transporting and using oil sumps. With oil-immersed transformers, a suitable du/dt filter shield winding must be provided between the low-voltage and high-voltage winding. This must be grounded on the tank. Technical requirements for medium-voltage transformers for use with SINVERT central inverters 10 Application manual, 04/2012, A5E

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