Reliability of Power Transmission and Transformation 2019

In 2019, the power transmission and transformation facilities incorporated into the reliability statistics included transformers, reactors, circuit breakers, overhead lines, cable lines and other 13 types facilities of 220kV and above.

In 2019, the forced outage rates of overhead lines, transformers and circuit breakers were 0.064 times per hundred km·year, 0.235 times per hundred units·year and 0.172 times per hundred units·year respectively, an increase of 0.002 times , 0.047 times and 0.051 times respectively over the previous year.

Operational Reliability of DC Transmission Systems

In 2019, 36 DC transmission systems were incorporated into reliability statistics, including 33 in operation for the whole year.  The total energy availability was 86.165%, a decrease of 5.893 percentage points year on year. The total energy utilization rate was 46.44%, an increase of 2.33 percentage points year on year.

In 2019, the total energy availability of the point-to-point EHVDC systems incorporated into reliability statistics was 93.589%, which decreased by 2.732 percentage points over the previous year. The total energy availability of the point-to-point UHVDC systems incorporated into reliability statistics was 82.083%, which decreased by 7.685 percentage points over the previous year. The total energy availability of the back-to-back DC transmission systems incorporated into reliability statistics was 95.662%, which decreased by 0.554 percentage points over the previous year.

Reliability of Power Supply System

In 2019, there were 10.0996 million 10 kV consumers in China, of which the proportion of urban and rural consumers was 1:2.78. The total consumer capacity was 3725GVA, and the proportion of urban and rural consumers is about 1:1.10. The insulation rate (insulation rate=length of insulated lines/total line length) and cable rate (cable rate=length of cable lines/ total line length) of overhead lines in urban areas were 60.72% and 56.23% respectively, while those in rural areas were 23.65% and 8.34% respectively.

In 2019, the average outage time of consumers nationwide was 13.72 hours per household, a year-on-year decrease of 2.03 hours per household, with 4.50 hours per household in urban areas and 17.03 hours per household in rural areas. The difference between urban and rural areas is 12.53 hours per household. The average outage frequency of consumers nationwide is 2.99 times per household, a year-on-year decrease of 0.29 times per household, with 1.08 times per household in urban areas and 3.67 times per household in rural areas. The difference between urban and rural areas is 2.59 times per household.

Among the six major regions of North China, Northeast China, East China, Central China, Northwest China and South China in 2019, the average reliability of power supply service for consumers in East China region was the highest, and the average outage time was 7.11 hours per household. The average reliability of power supply service for consumers in Northwest China was the lowest, with an average outage times of 26.71 hours per household.

In 2019, the reliability of power supply in 50 major cities across the country continued to maintain a high level, with an average reliability rate of 99.931%. The average outage time of consumers was 6.04 hours per household, and the average outage  frequency of consumers was 1.49 times per household. In Shanghai, Shenzhen and Xiamen, the average outage time was less than one hour per household.

In 2019, "Scheduled Outage" was still the main reason for the outage of medium voltage customers, accounting for 59.84% of the total outage time of consumers, with the average outage time of 8.21 hours per consumer. Among them, the engineering and maintenance interruption accounted for 51.69% and 46.31% of the total scheduled outage, respectively. The "failure interruption" accounted for 40.16% of the total outage, and the average outage time of customers was 5.51 hours per consumer.