Photovoltaic power station fire prevention

- Sep 06, 2018 -

In combination with the electrical equipment characteristics of photovoltaic power plants, photovoltaic power plants should adopt the following fire prevention measures:

1 general layout

The site selection of photovoltaic power stations should be comprehensively considered in accordance with the national medium- and long-term development plan for renewable energy, solar energy resources, access to the power grid, environmental protection, etc. The construction and structure of the power station and the construction outside the power station The fire separation distance between objects, yards and storage tanks shall comply with the provisions of the “Regulations”. The fire lanes in large and medium-sized photovoltaic power stations should be arranged in a ring shape. When it is the end lane, a return or return lane should be set up.

2 Transformers and other fire-fighting measures with oil electrical equipment

1) Because the oil-filled electrical equipment is prone to fire during use, in order to prevent the fire from spreading to the adjacent building (structure), a firewall should be installed adjacent to other building (structure).

2) For electrical equipment with a total oil volume of 100kg or more in the house, electrical equipment with a single oil capacity of 1000kg or more shall be provided with oil storage or oil retaining facilities, and a pebble layer shall be laid in the oil storage facility.

3 cable fire prevention measures

Due to the large area of the PV power plant and the wide distribution of cables, it is impossible to set up a fixed fire extinguishing device for the cable. Fireproof separation and flame-retardant cables should be used as the main measures for dealing with cable fires in the cable channel, and they should be placed in the channel and the box. The cable should be made of flame retardant cable of Class C or above.

4 photovoltaic power plant operation and maintenance safety

1) Operation and maintenance personnel should have the appropriate professional skills. Safety must be prepared before maintenance. Disconnect all switches should be disconnected to ensure complete discharge of capacitors and inductors. If necessary, wear insulated shoes, with low-voltage insulated gloves, use insulated tools, and eliminate possible accidents in the system after work. .

2) Due to the special nature of the components, a voltage is generated when receiving radiation. When the photovoltaic arrays are connected in series, high-voltage direct current is formed. If the loop is inadvertently formed with the human body, it will cause a major safety accident. Generally, the cluster array should be kept in an open state before the PV array is connected to the system. After the system is connected to the system, the connection is made when the combiner box (box) switch is turned off. During the construction process, the shielding component is used to block the PV module. When the shielding is difficult, the construction personnel should be equipped with safety protection products to ensure safety.

3) In order to prevent equipment from overheating, short circuit and other accidents, flammable and explosive materials shall not be accumulated around the main components of the PV power plant.

Fire facilities

1 design fire water supply system

For the planning and design of fire-fighting hydropower stations, the fire-fighting water supply system shall be designed at the same time. The fire-fighting water source shall be reliably guaranteed. The fire-fighting water supply shall be calculated according to the sum of indoor and outdoor fire-fighting water consumption of the maximum fire-fighting water consumption at the time of fire. The following conditions may not be set:

1) The PV array area (including the inverter booster chamber) should not be equipped with a fire water system. The photovoltaic array area is mainly composed of electrical equipment, and the DC side is always charged during the day, which is not suitable for water fire extinguishing.

2) With reference to the “Firepower Code”, the outdoor power distribution unit of the substation (except for the main transformer fire hydrant with water spray) may not have a fire hydrant.

3) According to the provisions of the "Building Regulations", the building in the power station meets the fire resistance rating not less than two grades, the volume does not exceed 3000m3, and the fire risk is Class E, there may be no indoor and outdoor fire watering.

The unit building volume of the ground photovoltaic power station is generally less than 3000m3, the monitoring system has complete functions, fewer on-duty personnel, and scattered buildings. Large-scale ground-based photovoltaic power plants are generally built in the desert areas of northwestern China. They are dry and water-deficient. The domestic water use is mostly transported by car. The cost of using water is so low that it is difficult to set up a water fire-fighting system.

2 automatic fire extinguishing facilities

According to the "Firepower Code", a main transformer with a capacity of 125 MV ̇A and above shall be equipped with a water spray fire extinguishing system, a synthetic foam spray system or other fixed fire extinguishing devices. Other oiled electrical equipment should be used in powder fire extinguishers.

The oil of the oil-immersed transformer has good insulation and thermal conductivity. The flash point of the transformer oil is generally 130 ° C. It is a flammable liquid. When the internal fault of the transformer is arc flashover, the oil is decomposed by heat to generate steam, which is a fire. Automatic fire extinguishing system, in areas with lack of water, cold, wind and sand, and poor operating conditions, oil and nitrogen injection fire extinguishing device and synthetic foam sprinkler system can be used. Gas fire extinguishing system can also be used for transformers in indoor enclosed space. For medium and small substations, the automatic fire extinguishing system is relatively expensive, and fire extinguishers can be used.

3 fire automatic alarm system

The fire hazard source of photovoltaic power station is mainly cable and electrical equipment. Because the power generation of photovoltaic power station is determined by the size of solar radiation, the electrical equipment load and cable current capacity also change with the change of solar radiation quantity, and it is zero in the morning and evening. Value, so the probability of fire in PV power plants is much smaller than that of conventional thermal power plants. With reference to the "Firepower Code", combined with the characteristics of photovoltaic power plants, fire alarm systems can be installed in large photovoltaic power plants or unattended power plants. Smoke control detectors can be used in the main control room, relay equipment room, reactive power compensation room, and power distribution unit. Linear heat detectors can be selected for the main transformer (indoor), cable layer and cable shaft.

4 fire power supply, emergency lighting and fire extinguisher

In order to ensure the safety of fire-fighting power supply and the normal operation of fire-fighting system, fire-fighting water pump, fire alarm and fire emergency lighting shall be powered according to Class II load. Fire-fighting emergency lighting and evacuation signs shall be set in the main control room and power distribution room of the power station. Fire extinguishers shall be installed in accordance with the requirements of GB50140-2005 "Design Specification for Building Fire Extinguisher".

Photovoltaic power generation is an emerging industry that has developed in recent years and is an important way to solve future energy needs. Since there is no specific fire protection design specification for photovoltaic power stations, this paper combines the relevant regulations of the "Regulations" and "Firepower Codes" on the classification, composition, fire risk, general layout, safety measures and fire protection facilities. The aspects were elaborated and provided a reference for designers and fire auditors.

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