In the construction of inverter and transformer foundation, attention should be paid to the strength of concrete and the maintenance work after concrete pouring. (Click to read related articles on concrete construction of large-scale photovoltaic grid-connected systems.)
The inverter and related electrical equipment are installed in the inverter booster container. The foundation is a plain concrete pier foundation. After the foundation steel is installed, the top should be 10mm higher than the leveled ground. The fixing between the inverter and the basic section steel should be firm and reliable, and the basic section steel should have obvious reliable grounding. The inverters of 100kW and above power stations should be grounded at two points; the metal panel door should be reliably grounded with bare copper flexible wires and metal frames or grounding bars. Before wiring the DC side cables of the inverter, it must be confirmed that there is an obvious disconnection point on the side of the combiner box, and the cable polarity is correct and the insulation is good. Before wiring the AC side cables of the inverter, check the cable insulation and check the phase sequence of the cables. After the cable connection is completed, the reserved holes and cable nozzles of the inverter body should be sealed. Cable ducts are provided for incoming and outgoing cables. The inverter and supporting electrical equipment are integrally integrated containers, which are delivered by car, and the inverter is hoisted to the installation position by a crane. The inverter booster distribution room is fixed on the foundation embedded parts and fixed by welding. Adjust the level of the basic embedded parts. The inverter booster distribution room is fixed on the embedded parts by welding, and the construction is carried out according to the installation instructions of the inverter. The installation wiring must ensure that the DC and AC wires are separated. Due to the highly sensitive electrical equipment built into the inverter, handle the inverter with great care and use a lifting tool to fix the inverter to the correct position on the foundation.
①Main transformer installation. After the transformer is transported to the installation site through the existing road, a truck crane can be used to place the transformer in place. The equipment should be lifted with a soft hemp rope to prevent damage to its shell paint. The installation procedure is: equipment installation→down-conductor installation→grounding system installation→cable laying and wiring→overall debugging. There shall be no kinks, loose strands, broken strands or severe corrosion after the down conductors are installed. The installation of the equipment base bracket should be firm and flat, in accordance with the design or manufacturer’s regulations. The grounding of all equipment should be galvanized flat iron with sufficient cross-sectional area, and the grounding should be good.
②Cable laying Before installing cables, the drawings should be carefully reviewed and checked to confirm whether the specifications and layers of the cables meet the design requirements, whether the direction of the cables is reasonable, and whether the cables are crossed, otherwise the design modification needs to be proposed. Before installing the cables, a detailed cable laying program table should be prepared according to the design data and specific construction conditions, and the order of installation of each cable should be clearly specified in the table. The use specification and installation path of the cable should be strictly in accordance with the design, and the cable should meet the design regulations. After the cables arrive at the site, they should be stored in strict accordance with the specifications to avoid mixing. When laying cables, the length of each coil should be registered, the power cables should be minimized with intermediate joints, and the control cables should have no intermediate joints. Protective measures should be taken for the places where the cables are easily damaged, and the electrical relays should be marked at certain distances. After the relay is laid, it should be neat and beautiful, and the bending arc of the cable entering the panel should be consistent. The cables entering the tray and other places that must be blocked should be blocked, and rodent-proof insecticides and fire-extinguishing facilities should be provided in the cable concentration area. If the inverter is installed in a vibration place, anti-vibration measures should be taken according to the design requirements. The installation of secondary system components shall not only comply with the relevant regulations of GB50171 “Code for Construction and Acceptance of Electrical Installation Engineering Panels, Cabinets and Secondary Circuit Wiring”, but also comply with the special regulations of the manufacturer. The primary system panel should not be welded with the basic steel, such as relay protection panel, automatic device panel, telecontrol communication panel, etc. The installation of other electrical equipment of the photovoltaic power station shall comply with the requirements of the current national construction and acceptance specifications for the installation of electrical installations.