We thought, the development of energy storage technology, the use of the scene and the value of mining should be divided into three levels, the first level for a single revenue model, refers to the system by only considering the existing mechanism of investment income, regardless of the mechanical system is not covered by the other indirect benefits, this method is simple, but with the energy storage value deviation is bigger, such as time-sharing electricity price management mode of the scene, Power plant frequency modulation; The second level is the system value model, which considers all the benefits of energy storage in the power system and the system value of energy storage, but does not consider the social benefits of energy storage, such as emission reduction, improve the utilization rate of infrastructure, etc. This method can better reflect the actual value of energy storage, such as the demand-side response of energy storage. The third hierarchy model for comprehensive benefit, refers to the regional energy system as the research object, by comparing the system in the presence of energy storage in both cases the operation cost of production and social benefit to calculate the yield of energy storage, the method can more fully reflect the actual value of the energy storage, energy storage is the inevitable trend of economic research, At present, there is no economic benefit model corresponding to the comprehensive benefit mode of energy storage. The development at this level will be combined with the comprehensive energy utilization of society, such as the interconnection mode of transportation, electricity and gas network, and carbon trading model under the future energy Internet mode.
First, traditional power generation
(1) Auxiliary dynamic operation
Dynamic operation refers to that in order to keep the balance between load and power generation in real-time, the output of the thermal power unit needs to be adjusted according to the requirements of dispatching, instead of working at the rated output state constantly. Specifically, it includes four operating states: start, climb, not full, and shut down. Auxiliary application of dynamic operation refers to the common energy storage device and thermal power units in accordance with the requirements of the scheduling to adjust the output size, reduce power output range as much as possible, as far as possible let thermal power unit work under the close to the running state of the economy, in general, thermal power unit is designed ManFa running state of the economy, the unit has the highest thermal efficiency.
Due to the rapid response speed of energy storage technology, the auxiliary dynamic operation of energy storage technology can improve the efficiency of thermal power units and reduce carbon emissions. Dynamic operation will cause some components of the unit to creep, resulting in the damage of these equipment, improve the possibility of failure, that is, reduce the reliability of the unit. At the same time, it increases the possibility of equipment replacement and the cost of maintenance, and ultimately reduces the service life of the whole unit. The application of energy storage technology can avoid the damage of dynamic operation to unit life, reduce the cost of equipment maintenance and equipment replacement, and then delay or reduce the demand for new generator set on the generating side.
Renewable energy
(1) Peak cutting and valley filling
Intermittent renewable energy to charge the storage device during low load or power rationing; When the load is high or unlimited, the energy storage device charges the power grid. This application enables energy storage and renewable energy to be adjustable and dispatchable when functioning as a complete system, reducing the capacity of power system backup units and making intermittent, renewable energy grid-friendly and dispatchable.
(2) Follow up the plan and contribute
In recent years, large-scale wind power has been integrated into the operation of the power grid. As the output of wind power is characterized by randomness and volatility, the power balance of the power grid is affected. Therefore, it is necessary to predict the power of wind farms to ensure the power balance and operation safety of the power grid.
3. Auxiliary services
(1) frequency modulation
The frequency of the power systems is one of the main indexes of power quality. In actual operation, the frequency can not always keep in the state of the reference frequency, when the power of the original motor and load power change, will inevitably cause the change of the power system frequency. The deviation of frequency is not conducive to the safe and efficient operation of electricity and power generation equipment, and in some cases, it will even damage the equipment. Therefore, after the system frequency deviation exceeds the allowable range (the deviation range in China is 0.2Hz), frequency adjustment must be carried out.
(2) Peak regulation
In the actual operation of the power system, there are peaks and valleys of electricity load. It is necessary to equip certain generator sets to generate electricity when the peak load is needed to meet the power demand and achieve the balance between power production and power consumption in the power system. Due to the different operation modes of power systems in different countries, the classification of power auxiliary services is also different. At present, peak auxiliary services are not included in foreign auxiliary service markets such as the United States, while in China's auxiliary service market, peak auxiliary services are divided into basic peak load adjustment and paid peak load adjustment.
(3) Reserve capacity
Reserve capacity refers to the active power reserve reserved for ensuring power quality and safe and stable operation of the system in case of accidents in addition to meeting the expected load demand of the power system. Spare capacity can be called at any time, and the output load is adjustable. Generally speaking, the reserve capacity in the power system should be equal to 15% ~ 20% of the normal power supply capacity of the system, but the minimum value should be equal to the maximum unit capacity of the system.
Distributed energy and microgrid
(1) Time-of-use electricity price management
At present, power grid companies adopt tOU price based on retail price. Users can arrange electricity consumption plan according to their actual situation, and transfer the electricity demand in the period of higher electricity price to the period of lower electricity price, so as to achieve the purpose of reducing the overall electricity price level, namely tOU electricity price management. Tou price management is similar to peak shift, but tOU price management is realized based on tOU price system. Energy storage is an ideal way to help power users to manage tOU in the electricity market with tOU implemented. Charging the energy storage system when the electricity price is low and discharging the system when the electricity price is high can not only reduce the overall electricity cost through low storage and high discharge, but also do not change the habits of users, even when the electricity price is the highest, they can still use the electricity according to their own needs. The benefits of tOU price management are mainly obtained through price difference and adjustment of power consumption plan.
(2) Capacity cost management
In the electricity market, there are two forms of electricity price, one is electricity price, the other is capacity electricity price. The electricity price refers to the electricity price charged according to the actual transaction electricity. The capacity price is different from the electricity price, which mainly depends on the maximum value of the user's power, and has nothing to do with the length of time under the power and the total amount of the user's power. The use of energy storage technology can supplement the capacity of users during peak hours, thus reducing the amount of electricity to the power company.
(3) Improve the reliability of power supply
Energy storage is used to improve the power supply reliability of the micro grid. It means that when a power failure occurs, energy storage can supply the reserved energy to the end user to avoid the power interruption during the fault repair process and ensure the power supply reliability. The economic value of reliability is generally difficult to calculate. On the one hand, the economic benefit corresponding to improving reliability is related to the loss of power failure, and different loads are affected differently in a certain power failure event. On the other hand, it is difficult to quantify the value of providing power supply assurance services in critical loads involving public safety, disaster relief and special wartime situations. Therefore, this part of revenue mainly depends on the value of power service to users, and the compensation of power failure loss is also a part of this part of revenue.
(4) Improving power quality
Energy storage technology is used to improve power quality, which means that the energy storage at the load end can maintain power quality under the condition of short-term failure, and reduce the influence of voltage fluctuation, frequency fluctuation, power factor, harmonics, and load disturbance of second to minute level on power quality. Similar to the improvement of power supply reliability, the benefits of improving power quality through energy storage are mainly related to the number of power quality unqualified events and the loss degree caused to users by low-quality power service. Meanwhile, the capacity of the equipped energy storage system and other indicators can also affect the benefits of this part.
The income model of energy storage is established by analyzing the main function and income model of energy storage in energy system. In the field of traditional power generation, energy storage mainly plays a role of assisting dynamic operation, replacing or delaying new units. In the field of renewable energy, energy storage mainly plays the role of peak load cutting and valley filling and tracking plan output. In the field of auxiliary services, energy storage mainly plays the role of frequency modulation, peak regulation and reserve capacity. In the field of distributed energy and micro-grid, energy storage mainly plays the role of tOU price management, capacity cost management and power supply reliability improvement.
