Improvements in power safety require a response plan from the 14th Five-Year Plan

Under the current international situation, concerns about security issues are increasing, and constraints related to power system operation and network security must be formulated into explicit response plans in the "14th Five-Year Plan".

Text | Zhang Shuwei

The 13th Five-Year Plan for Energy Development, issued in 2017, proposed the overall goal of building a clean, low-carbon, safe and efficient modern energy system, with safety being one of the eight core concerns. Energy supply security and stability is an important topic, which traditionally refers more to oil (and natural gas), often including the three dimensions of "availability, transportability and affordability".

Interestingly, this security perspective is often the perspective of consumers, but for energy exporters such as Russia and Saudi Arabia, their concern about demand stability is also understood by them as an "energy security" issue.

In recent years, with the weakening of the international order based on international collective governance and rules, and with oil, coal and gas prices all stable and at a relatively low level in history, the issue of energy supply security has returned to people's attention. In October this year, the National Energy Commission held a meeting, emphasizing China's resource endowment, which is mainly coal, to diversify energy supply and improve energy security.

The security of electricity covers multiple time dimensions because the system needs real-time balance. In the "13th Five-Year Plan" electricity planning, security concerns in all aspects of the power system are widely involved, especially the safe and stable operation of large power grids and distribution networks, as well as network and information security issues. Regardless of the policy documents or declarations, any changes to the planning and operation of the power system often emphasize "on the premise of ensuring the safety and stability of the power system." It can be seen that this issue has priority in the sequence of goals that decision makers pay attention to.

In this column, we discuss the topic of power supply security. Since security issues involve many aspects, we divide them into short-term operational reliability, long-term system adequacy, renewable energy characteristics and related system flexibility. On this basis, we discuss several arrangements with Chinese characteristics, including the rigid "big flying line transmission", the balance responsibility interface between dispatch and power plants, and the potential security issues and implications of renewable energy's reliance on precious metals.

We believe that under the current international situation, concerns about security issues are increasing, and constraints related to power system operation and network security must be explicitly addressed in planning. my country's traditional dispatching "battlefield commander" paradigm has brought about excessive safety and security issues in system balance, resulting in unclear responsibility interfaces between system operators and power generators, making it impossible to achieve the goal of long-term system evolution (such as a continuously evolving power auxiliary service system). Essential changes in operation and dispatching are of great significance and long-term value that need to be focused on in my country's power system reform and the "14th Five-Year Plan" work.

General energy security concerns are not about the power sector

In October 2019, the National Energy Commission held a meeting. Premier Li Keqiang pointed out that we should develop energy supply in a diversified way and improve the level of energy security based on my country's basic national conditions and development stage. Based on my country's coal-based energy resource endowment, we should scientifically plan the layout of coal development, accelerate the construction of large channels for coal and power transmission, and promote safe and green coal mining and clean and efficient coal-fired power generation.

This statement was interpreted by many domestic and foreign researchers as a signal that my country has reaffirmed the dominant position of coal and may slow down the development of renewable energy.

I think this is undoubtedly an over-estimate. China's energy security problem is more about the high dependence on oil and natural gas, while the power sector is more about the substitution of coal power and renewable energy. Coal is already safe enough, and renewable energy is localized. Neither of them involves energy security issues of external dependence.

In the past, the power industry relied on partially dispatchable coal-fired power, hydropower and nuclear power to meet the growing power demand with increasing peak-to-valley differences. Now, the addition of uncontrollable random and intermittent renewable energy has objectively created a demand for fully dispatchable and extremely flexible natural gas single-cycle units. Undoubtedly, this will increase the utilization of natural gas resources.

As a natural gas unit to make up for the lack of wind and sunshine, it can meet the limited number of hours a year, which will not increase the consumption of natural gas significantly. The natural gas in my country is not a binary issue of "yes or no", but a wide range of hundreds of billions.

For example, for a 20MW natural gas single-cycle power plant with 300 operating hours per year, which can fully meet the demand in the evening (2-3 hours) in summer (90 days), its annual natural gas consumption is only 1.2 million cubic meters, which is equivalent to the daily processing capacity of an LNG processing station. Even if my country adds 1,000 more such peak-shaving flexible power sources, its average cost is much lower than that of large coal-fired power plants with heavy assets and inflexibility. From the current total of 5 million kilowatts to 25 million kilowatts, the additional natural gas consumption is only 1 billion cubic meters, which is the gas consumption of Beijing residents for 10 days, accounting for less than 5% of the current total natural gas utilization.

What kind of energy supply security problem will this cause, given the current external dependence of about 40%? Because 100% natural gas share is terrible (the world's natural gas is not enough for us), so the current 5% status is normal? This is a typical logical error of binaryization of continuous problems. This 5% increase is just a small marginal change.

Electricity supply security is not of infinite value

Electricity safety is important, but it is undoubtedly an extreme to extend this value. In reality, the questions that need to be discussed are: What level of safety is appropriate? Based on the current status quo, is the cost of achieving safety too high? Is there additional room for improvement without sacrificing safety performance, such as economic efficiency?

Safety is more of a constraint than a goal. Constraints are fundamentally different from goals. Goals are “the more extreme the better”, while constraints only need to meet a certain level. Safety performance exceeding this level will inevitably mean a disproportionate sacrifice of other goals (such as money). Of course, how to define whether it is proportional requires a unified unit of measurement, such as economic cost.

There is an indicator in the power system called the value of loss due to power outages (VOLL), which represents the economic loss of consumers caused by power outages. It is obviously greater than zero, but it is not an infinite number. The power outage losses of industrial users are often greater than those of residents, because it represents the cessation of industrial activities and the loss of production; the power outage losses of residents tend to expand rapidly over time (for example, if the power outage lasts more than 6 hours, the food in the refrigerator will start to spoil), but the long-term losses are decreasing, and people get used to it after a long outage, such as the rural areas in China that were still without electricity during the power shortage period in the past.

Different methods give a wide range of values ​​for how big this loss is. Different markets also make specific settings based on their own market conditions (such as whether there are other income channels). For example, in the French market, which has a capacity market, the price is 3 euros per kWh, which means that the administrative setting of electricity prices is not allowed to exceed 3 euros per kWh. The Texas market in the United States uses the Remaining Reserve Price Curve (ORDC) to bid for backup resources under tight supply and demand balance, and its VOLL is capped at $9 per kWh. This also means that if the price exceeds this, the system operator will no longer provide a bidding price.

Reliability, flexibility and long-term adequacy of the power system

From the supply side, power security can be defined as the ability of the power system to withstand disturbances (such as events or accidents that produce abnormal system conditions) or unexpected events (such as failure or shutdown of system components) with minimal acceptable service interruption. Undoubtedly, this is a definition covering all time scales and spatial ranges.

Discretely speaking, the safety concerns of the power system often include short-term operation and long-term system adequacy. The former can be called a kind of reliability, which often refers to the safety of operation and the stability in the face of various disturbances; while the latter is often related to the system not being able to have a "hard power shortage" under normal circumstances - lack of sufficient installed capacity.

Between traditional short-term reliability and long-term adequacy, the flexibility of system operation has become another hot topic. Due to the greater volatility of renewable energy, the frequent up and down adjustments and ramping of the system, as well as the maintenance of system robustness under high proportions of renewable energy, have become more important.