Analisis ug Solusyon sa 35 kV Low-Voltage Side Incoming Switchgear Fire sa PV Base

Sa 12:45 sa Agosto 4, 2022, ang isang dispatching center adunay report gikan sa usa ka 100 MW photovoltaic power generation base. Gi-report nga ang incoming line switchgear sa 35 kV low-voltage side sa main transformer sa collection station nagsulto ug ang protection action trip. Pagkahuman sa pagtanggap sa notification, ang mga personal mibisita sa site ug gitumanan ang on-site accident investigation sama sa operation technicians. Sa pamala-ayon sa on-site inspection, natukod nga ang contact box sa switchgear, ang handcart, ug ang copper busbar para sa incoming line sa phase U sa hard busbar sa switchgear gi-burn out.

1 Paghunahuna sa Rason sa Accident

Sa pag-analisa sa on-site fault phenomena, kasama ang voltage ug current waveforms sa fault recording, ang pangunang rason sa fault mao ang dili maayo nga contact sa V-phase contact sa circuit breaker. Tungod kay ang V-phase contact wala maayo nga nakontak, ang temperatura sa karon bahin abnormal nga nagtaas ug nagsulto sa panahon sa operasyon, resulta og short-circuit arc tali sa U ug V phases. Bisan na, ang moving contact sa handcart circuit breaker, ang static contact sa contact box, ang contact box, ug ang down-lead sa U phase gi-burn. Sa parehas nga panahon, ang current transformer gibati sa arc ug electric shock sa iba't ibang lebel. Sa pamala-ayon sa on-site inspection ug analisis, ang root causes sa dili maayo nga contact sa V phase gikan sa duha ka aspeto:

• Dili maayo nga operasyon sa handcart circuit breaker: Sa panahon sa pag-operate sa handcart circuit breaker, ang gitawag nga V phase wala maayo nga nahimong (ang handcart wala maayo nga nabuto ug naseat), ug ang contacts wala maayo nga nakontak.

• Dili maayo nga presyon sa contact spring: Ang presyon sa V-phase contact spring gamay ra, sumala sa contact resistance sa contacts. Kung ang contact resistance sa V-phase current loop contact labi ka dako, ang gap sa contact prone sa discharge ug heat, ug ang heat generation nagtaas abruto sa continuous flow sa current. Kung ang conventional heat dissipation sa switchgear wala maayo nga makapahimulos sa heat, ang lokal nga temperatura magtaas abnormal.

Ang pag-form sa heating fault sa high-voltage switchgear dili usa ka short-term sudden occurrence, apan usa ka gradual accumulation process. Tungod kay ang dili maayo nga working environment ug ang iyang kaugalingon nga abnormalities, ang temperatura sa contact surface sa high-voltage switchgear unang nagtaas. Superimposed sa continuous action sa current heating effect, ang temperatura sa contact gradual nga nagtaas. Kung ang temperature rise trend molabay ug ang contact temperature gi-abuso sa rated heat resistance standards sa internal current transformer ug insulating bushing, it will damage the equipment, cause a single-phase or two-phase short circuit, amplify the fault damage, and spread to the surrounding auxiliary facilities. In this case, if the protection device did not operate correctly, the spread of the fire and the continuous rise of the temperature would most likely cause an explosion.

2 Exposed Problems
(1) Loopholes in Personnel Operation and Maintenance Management

Ang mga personal sa photovoltaic power generation base wala maayo kaayo ang ilang kaalam sa equipment, dili maayo nga familiar sa functions sa automation system, dili maayo nga conduct in-depth research ug judgment sa background messages, ug ang patrol inspection dili maayo nga gibuhat. Wala sila mosulti hangtod ang smoke alarm sa high-voltage room mobati. Nagsulti kini nga ang mga personal wala maayo nga systematic training, insufficient professional knowledge reserves, lack safety vigilance, ug failed to effectively perform their equipment operation and maintenance supervision responsibilities.

(2) Lack of Equipment Operation and Maintenance Mechanism

Ang high-voltage switchgear wala implement regular maintenance ug patrol inspection, ug ang hidden dangers gradually accumulated during long-term operation. On one hand, the high-voltage switchgear has high requirements for mechanical stability and closing reliability. If the circuit breaker handcart is not in place, when running with a large current, the handcart and the cabinet are prone to displacement, the contact resistance of the contacts will increase sharply, causing an arc and even an explosion; on the other hand, the long-term operation will aggravate the mechanical wear of the moving and static contacts, highlighting the hidden danger of poor contact. In addition, there are also risks in the equipment installation link. The level of the handcart track of the handcart circuit breaker and the standardization of the installation operation will damage the integrity of the switchgear and lay the groundwork for accidents.

3 Solutions
(1) Improve the Operation and Maintenance Management System

During the construction phase of photovoltaic and new energy power stations, it is necessary to establish a complete patrol inspection system, conduct simulation drills, and strengthen the systematic training of employees. Improve the knowledge and skill levels of personnel, make them familiar with the equipment principles and automation systems, accurately identify abnormalities in background messages, and carry out patrol inspections in a standardized manner.

(2) Standardize the Maintenance and Operation Process

The operation and maintenance unit of the photovoltaic power station should improve the maintenance system, and strictly require the staff to learn and implement the operation procedures. Clarify the standards of the operation process, ensure that key links such as the seating of the handcart circuit breaker and the contact of the contacts are operated in a standardized manner, and ensure the stable operation of the switchgear from the operation and maintenance process.

(3) Deepen the Management of Preventive Tests

Before the high-voltage switchgear is put into operation, preventive tests must be strictly carried out. During the test, the fault cannot be judged only based on the result of a single test. It is necessary to combine the historical data for vertical comparison and comprehensive analysis, accurately identify the potential defects of the equipment, and eliminate hidden dangers in advance to ensure the reliable operation of the equipment.