Recently, the National Development and Reform Commission issued the Notice on Further Improving the TOU Electricity price Mechanism (FA&REFORM Price (2021) No. 1093), which put forward the overall requirements for optimizing the tOU electricity price mechanism and strengthening the implementation of tOU policies. Meanwhile, it also emphasized that specific mechanisms and measures should be formulated according to local conditions.
The adjustment and improvement of tOU price mechanism in various regions is a work of "affecting everything". On the one hand, tOU price will play an important role in guiding users to adjust production and living load, encouraging flexible resources on the user side to participate in system balance, and improving the absorption capacity of new energy in the power system, which is a key policy for constructing a new power system. On the other hand, the tOU price, as a specific implementation of the sale price, will directly affect the electricity cost of the end users, and it is easy to cause the public opinion that is not conducive to the promotion of the implementation without proper consideration. In particular, the design of the time-sharing policy for residents should be scientific and rigorous. Therefore, no matter from the long-term effect or immediate effect, tOU price mechanism should be designed carefully according to local conditions.
Peak and valley periods:
Multi - factor decision, multi - round adjustment
With the large-scale development of new energy on the power generation side and the accelerated change of power consumption structure on the power consumption side, the two-way fluctuation of power production and consumption has broken the previous mode of "stable power output" to meet the "fixed power load". In this context, the determination of peak and valley periods is no longer the result of simply observing historical load curves, but consistent with the "core" that market price accurately reflects unit power supply cost. Marginal power supply cost is taken as the core decision variable, that is, the peak period corresponds to high power supply cost, and the trough period corresponds to low power supply cost.
Power is a product with real-time balance between supply and demand and cannot be stored on a large scale. The greater the instantaneous demand for electricity, the higher the demand for power output and power network capacity, and the higher the corresponding power supply cost. Therefore, the load curve is the basis for dividing peak and valley periods. However, the observation load curve should be expanded in the time dimension as far as possible: for provinces with obvious seasonal characteristics of production and domestic electricity consumption, it can be considered to set different peak and valley periods in summer and winter to fully reflect the influence of air conditioning load. If the load curve is significantly different on weekdays and weekends, the peak and valley period on weekends can be designed in more detail, or the peak and valley period on weekends can be excluded.
After a large number of new energy is connected to the power system, the marginal power supply cost changes greatly with the change of power output structure at different times, so the proportion of new energy generation gradually becomes an important factor affecting the peak and valley period. In order to adapt to this change, typical countries and regions such as California in the United States generally refer to the net load curve after subtracting "scenery" output to divide peak and valley periods, so as to effectively cope with the influence of "duck curve". With the rapid development of new energy, the peak and valley characteristics of net load curve will be more obvious and change faster, which requires timely adjustment of peak and valley period.
In addition, the changes of users' behavior and flexible adjustment of resource development also affect the marginal cost of power supply. On the one hand, the large-scale application of new energy storage devices and stations in power generation and consumption will improve users' power response ability, smooth out the influence of "scenery" output fluctuation, and play a role in adjusting the shape of total load and net load curves. On the other hand, the proportion of coal and gas power as peak-modulating power source, the change of external power proportion and other factors related to the development and change of regional power supply capacity and system regulation capacity will also affect the marginal power supply cost.
It can be seen that when dividing peak and valley periods in different regions, not only local load curve and net load curve should be referred to, but also seasonal and holiday load, power supply and regulation capacity should be considered comprehensively, and appropriate tools such as true/false positive rate, fuzzy membership degree and load characteristic clustering should be selected. In addition, at the beginning of policy implementation, time division should be adjusted and improved through several rounds of practice; In the process of implementation, it is necessary to regularly evaluate the implementation effect and continue to optimize. In addition, the division of peak and valley time should adhere to the principle of reasonable production arrangement for users, and control the number of time periods and ensure the duration of time periods as far as possible.
Peak-valley spread:
Effective incentives, income balance
There are two main ways for users to respond to peak-valley electricity price: one is to save electricity consumption by reducing electricity consumption during peak hours (in the short term, only increasing electricity consumption during peak hours is rare); Another is to adjust the use of electricity, reduce peak time consumption while increasing valley time consumption. In view of these two response behaviors, it is necessary to comprehensively consider the influence of price elasticity and flexibility of electricity demand of different types of users, so as to maximize the incentive effect of time-sharing policy.
Price elasticity of electricity demand is the sensitivity of users' behavior to electricity price, which reflects whether users "want" to save electricity or adjust electricity consumption. Economically, whether users respond to time-sharing policy depends on the relative size of benefits and costs. However, the decision-making of electricity consumption behavior is not always an "economic man" behavior, especially when the cost of electricity consumption accounts for the total production or living cost is very low, although the adjustment of electricity consumption mode can benefit, it still may not reach the "psychological" threshold of users. In general, production power consumption is more sensitive to electricity price than domestic power consumption and energy consuming enterprises are more sensitive to electricity price than other enterprises. Therefore, when designing peak-valley price difference, it is necessary to give full consideration to local users' electricity consumption type structure, and analyze the impact of price difference change on electricity consumption change based on average demand price elasticity or demand price elasticity of major consumers.
Flexibility of electricity consumption refers to the dependence of users' electricity consumption behavior on time period, reflecting whether users can "save" electricity consumption or adjust electricity consumption. Some users' electricity consumption time is relatively fixed, such as 24-hour non-stop production enterprises, electricity consumption flexibility is very low, can not change the electricity consumption time according to peak valley period. When designing peak-valley price difference, users' flexibility of power consumption should be taken into account, so that the price difference level is enough to stimulate the load with adjustment ability to transfer from peak period to valley period, and at the same time, users who lack flexibility can avoid a sharp rise in power consumption cost.
The whole balance of time-sharing income is a principle based on the design of peak-valley price difference. For different users, due to differences in demand price elasticity and flexibility of electricity consumption, the electricity cost after peak-valley pricing will be higher or lower than the original level. But on the whole, the income formed by the policy should be basically stable with that before the mechanism adjustment. On the one hand, it will not produce obvious excess income, thus increasing the burden of electricity cost. On the other hand, it will not form an obvious deficit, but will share the time-sharing electricity cost to all users through the electricity transmission and distribution price, forming an unfair burden.
The adjustment methods of peak-valley price difference include peak-valley adjustment and peak-valley homology. Peak (valley) adjustment is to determine the peak (valley) electricity price on the basis of flat period, and then determine the valley (peak) electricity price according to the electricity quantity relationship. It is suitable for the regions with simple load structure, less peak-valley price constraint and clear price guidance target. Peak-valley coadjustment is to determine peak-valley prices by floating up and down in a certain proportion on the basis of flat phase electricity prices, which is helpful to meet the requirements of peak-valley ratio and floating level, but it is relatively difficult to meet the requirements of income balance. In addition, the price elasticity of user demand can be considered to dynamically reflect the effect of electricity bank adjustment in peak-valley price difference. Or adjust peak-valley price difference in time in combination with income settlement afterwards to maintain long-term income balance.
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