1, the wind power plummeted and the grid frequency fell below the safety red line.
Behind the rare electricity consumption of residents in Northeast China is the result of multiple factors. The direct reason is that the power grid operation faces the risk of accidents.
According to the news released by Liaoning Daily on the evening of September 26th, the Liaoning Provincial Department of Industry and Information Technology held the provincial electric power work security conference that day. The meeting pointed out that from September 23 to 25, due to the sudden decrease of wind power and other reasons, the power supply gap further expanded to a serious level. Liaoning Province started three rounds of Grade II orderly power consumption measures (load gap 10-20%), and the biggest mistake was to avoid peaks when implementing orderly power consumption measures in individual periods.
According to the Regulation on Power Grid Dispatching Management, the dispatching department of Northeast Power Grid directly issued instructions to implement "Power Grid Accident Blackout" according to relevant plans. A pre-notice issued by Northeast Electric Power Dispatching Center of State Grid on September 23rd shows that the frequency modulation means of the whole network have been exhausted, and there is no room for downward adjustment for Lu Gu DC-Ludong and Gaoling DC-North China lines, and the system frequency is lower than 49.8 Hz. According to the relevant documents, in order to ensure the safe operation of the power grid, emergency power cut-off is adopted.
According to this notice, Liaoning, Jilin and Heilongjiang provinces are expected to have power outages from 16: 30 to 2130 on the afternoon of 23rd, with limited capacity of 440,000 kilowatts, 360,000 kilowatts and 200,000 kilowatts respectively, totaling 6.5438+0.000 kilowatts.
The reporter confirmed the authenticity of the notice from relevant people. The normal operating frequency of China power grid is 50 Hz, which allows a certain range of fluctuation. 49.8 Hz is the first important safety threshold. When the power grid frequency is lower than 49.8 Hz, the switch must be turned on to limit the power, otherwise it will face the risk of a wider range of disconnection and collapse accidents.
The latest lesson is the blackout in Britain on the afternoon of August 9, 2009. At that time, a large number of offshore wind power and distributed photovoltaics in the British power grid failed, resulting in the system frequency dropping to 48.9 Hz, triggering the operation of low-frequency load shedding devices in the system, cutting off a large number of loads, and causing power outages for 1 10,000 power users, including London.
In case of power failure, the power grid dispatching department will directly cut off the 10 kV voltage line according to the preset switching sequence table. 10 kV lines are usually connected to industrial and commercial loads as well as residential loads. So residents will suddenly lose power without notice.
Liaoning Provincial Department of Industry and Information Technology pointed out at the meeting on September 26th that power cut-off is different from orderly power use, and it is the ultimate means to ensure the safety of power grid, and the scope of film use is extended to residents and enterprises that do not implement orderly power use measures.
2. Due to the reduction of coal-fired power, the power supply in Northeast China is tight.
The power outage caused by power grid operation risk is the direct cause of residents' unexpected power outage, but if the normal operation process is followed, the power shortage accident should not be so serious. For example, in Guangdong, which is also short of electricity, the continuous peak load has exceeded 20 million kilowatts recently, and there has been no temporary power cut by residents. Power cuts in Northeast China will eventually affect residents, and there are further reasons.
The most fundamental reason is that the coal-fired power output as a ballast stone for voltage supply is insufficient. On September 26th, Jilin Province held a video dispatching meeting of the province's coal supply to protect the winter industry. Wu Jingping, executive vice governor of Jilin Province, pointed out that power supply in most provinces is tight due to the national coal shortage, high coal price and upside-down price of coal and electricity. According to Caijing, during the recent power shortage, Liaoning's thermal power output was only about half of its installed capacity.
In addition to the difficulty of coal-fired power output, a number of unexpected factors that cannot be ignored have worsened the supply and demand of power in Northeast China. First of all, the orderly use of electricity has not been well implemented.
For example, according to the meeting information of Liaoning Provincial Department of Industry and Information Technology, before the power cut, the power supply pressure in Liaoning Province began to increase from September 10, which could not meet all the power demand, and the orderly power consumption measures were initiated. From September 10 to September 22, 9 rounds of orderly power consumption were started, with a maximum peak avoidance of 2,436,700 kilowatts. From 23rd to 25th, the maximum peak avoidance is 4169200kW.
According to the Measures for the Administration of Orderly Electricity Consumption issued by the National Development and Reform Commission and the Measures for the Administration of Orderly Electricity Consumption issued by the State Grid, in principle, the orderly electricity consumption plan arranges power limiting measures in the order of shifting the peak first, avoiding the peak later, limiting electricity again and finally pulling the road. Priority should be given to ensuring electricity consumption for emergency command, dangerous production, important social activities, infrastructure, residents, agriculture and key engineering enterprises, focusing on restricting illegal projects, eliminating and restricting enterprises, and high energy consumption and high emissions and landscape lighting.
When there is a power shortage, power supply enterprises at all levels put forward suggestions to the competent department of power operation of the government at the same level to start the orderly power consumption plan, and cooperate with the competent department of the government to issue a start announcement. During the implementation of the plan, the provincial power grid company issued the next day's power limit index according to the supply and demand situation and the electricity consumption index of the competent government department. When it is found that the user's power restriction measures are not in place, report to the local government's power department and urge the government to coordinate users to implement the orderly power consumption plan.
Some people in the local power grid company said that orderly power consumption had been implemented for ten days before the switch was turned on, but later the user did not implement it well, that is, the power grid company did not cut off the power as required, and there was no way to do this.
Some insiders also said that there was no large-scale orderly electricity consumption in Northeast China for a long time after the 1990s, and local governments and orderly electricity consumption enterprises did not pay much attention to it, and there was also resistance. At first, they will implement it, and then they will come back after slowly using electricity. In addition, under the background that there is no shortage of electricity in Northeast China for many years, the situation of power cut is rare, while the industrial load in Northeast China is not high and the power grid company is inexperienced, which leads to the lax operation of power cut.
The increase in the proportion of new energy also increases the risks faced by the power system. The Liaoning Provincial Department of Industry and Information Technology mentioned that before the power cut, wind power suddenly dropped. According to the reporter, the total installed capacity of wind power in the three northeastern provinces has reached about 35 million kilowatts. However, after the cold air on September 2 1 day, the wind power output decreased obviously. During the recent power outage, the wind power output was much lower than 10% of the installed capacity.
This kind of problem has happened before. Dong Yu, secretary of the Party Committee of the State Grid Dispatching and Control Center, introduced at the International Summit of Power Market on September 27th that at the peak of this summer, the total output of wind power with an installed capacity of 35 million kilowatts in Northeast China was only 34,000 kilowatts, which was an instantaneous small probability event, but the contradiction was very prominent.
3. The urgency of burning coal
The shortage of coal supply, high coal price and upside-down price of coal-fired power are the fundamental reasons for the current shortage of coal-fired power output as the ballast stone of power system, and also directly lead to the shortage of power supply in many provinces, and there is a tendency to expand, so the urgency of burning coal is imminent.
At present, it is in the off-season of traditional coal use, but the coal price and coal storage days stand at the highest and lowest points in the same period of history respectively. At present, the actual market price of thermal coal is above per ton 1.600 yuan, which is about three times that of the beginning of 2020, far exceeding the index price; The available days of coal storage in national key power plants are reduced to 10.3 days, which is far below the red line requirement of 20 days in off-season.
Northeast China may be one of the regions with the most serious coal shortage in China, and it has been pushed to the forefront because of expanding the scope of power restriction to residential electricity consumption. A senior analyst of a coal organization told the reporter that since 20 16, driven by the coal de-capacity policy, the three northeastern provinces have withdrawn more coal production capacity, and they face greater demand for replenishment in winter, mainly relying on the transfer of Mengdong coal mine.
According to the reporter's statistics, the total output of raw coal in Heilongjiang, Liaoning and Jilin will be 93 million tons in 2020, which is about 1.65 and 438+0.3 billion tons in 2065, 438+06, and the proportion of the three northeastern provinces in the national total coal output will also drop from 3% to 2.4%.
The three northeastern provinces have all responded to power cuts.
On September 26, Liaoning held a provincial conference on power security, requiring local power operation authorities to avoid power cuts involving safety production, people's livelihood and important users; On the same day, the video dispatching meeting of Jilin Province's thermal coal supply to keep warm and protect winter stressed that it is necessary to fully protect the basic people's livelihood electricity demand and avoid power cuts as much as possible.
On the 27th, the Development and Reform Commission of Heilongjiang Province said through the official media that it would give priority to the prevention and control of epidemic situation, residents' life, key public facilities, public interests and national security, and the electricity demand of important customers.