The new element of "new energy + energy storage" is considered a key technology between storage and

Energy storage as a new element of the new power system has been widely concerned.

As the country has sounded the clarion call for a "two-carbon" goal, building a new power system has become the primary goal. A high proportion of new energy sources will lead to fundamental changes in the power grid. The problems such as electronic power, low moment of inertia and weak controllability of wind-solar complementary power generation challenge the safe and reliable operation of power grid. Energy storage has been recognized by industry experts as the key to supporting the construction of new power systems. The National Development and Reform Commission and the National Energy Administration have successively issued the Guiding Opinions on Accelerating the Development of New Energy Storage and the Implementation Plan for the Development of New Energy Storage in the Tenth Five-Year Plan Period. Local governments responded positively and introduced corresponding policies. Industry experts actively carry out research on energy storage technology, and energy storage industry presents a hot development trend.

The application of energy storage faces many practical problems. Although energy storage has made some progress in technology research and development, project construction, business model exploration and other aspects, there are still many practical problems in the actual construction process.

First of all, objectively speaking, existing energy storage faces the problem of high construction costs. Consider service life, service times, maintenance cycles, and environmental requirements. In particular, the capacity attenuation of electrochemical energy storage involves battery replacement in the later stage, and the investment cost is huge. The existing investment subject can be divided into power generation enterprise investment, power grid investment, user investment and other commercial subject investment. Overall, the typical construction cost of storage is in the tens of billions of dollars, and the cost of storage has remained high. The related marketization mechanism, investment return mechanism and cost diversion mechanism are not perfect, which makes energy storage investors hesitate.

Second, energy storage while it is possible in the system frequency modulation, voltage regulator, peak shift, big users of peak valley price arbitrage, black start delaying transmission equipment upgrades, system, and new energy bound to improve output characteristics, act as emergency power supply and auxiliary service, and many other aspects play a huge role, but its essence is adjusted by the energy storage capacity and power of the energy storage. According to the ratio of energy storage power to capacity, energy storage can be divided into power type, energy type and capacity type. Capacitive energy storage generally needs to meet the requirements of long-term continuous charge and discharge, while dynamic energy storage batteries need to realize rapid charge and discharge in seconds, and energy storage is in between. Each type of energy storage has its own application needs. It is unrealistic to talk about the role of energy storage without the specific type, capacity and power of energy storage. Moreover, in practice, the application scenarios of various energy storage technologies are not clearly defined, which will lead to a large deviation between planning and operation and actual benefits.

In addition, the main role of energy storage after construction and how to participate in power grid dispatching are not clear, and the enthusiasm of new energy enterprises to actively invest in energy storage is generally not high. There is no clear mechanism for the supervision and maintenance of energy storage after its completion, nor has it been effectively implemented to the responsible subject, and the relevant standard system has yet to be formed. Therefore, the commercialization and scale of energy storage is still in the exploratory stage, and it requires the joint promotion of technologies and systems to make energy storage play a role in supporting the construction of new power systems.

Research on energy storage configuration method and key technologies of grid-connected regulation for new energy power stations

At present, Yunnan Power Grid Company has carried out research on the planning, scheduling and control technology of "new energy + storage".

(1) Energy storage optimization allocation technology that takes into account the active support ability and technical economy of new energy stations.

Due to the random, intermittent and volatility of wind power and photovoltaic power generation will cause power frequency voltage and a series of problems, "new energy and energy storage" coordinate is used to relieve related problems, put forward the new energy station storage optimization configuration method, comprehensive consider ease of new energy output fluctuation, improve the power supply ability, and promote new energy given and support the stable operation of power grid.

The main consideration to tame new energy output volatility, promote new energy given, meet the demand of power grid peak shaving economically, support voltage frequency adjustment, improve the technical economy and other requirements, on the basis of according to power grid conditions, resources, energy storage characteristic economy and technology, studied the peaking and frequency modulation, voltage regulator, more time, and stood under the coordination between functional positioning of energy storage configuration boundary, The target scenario of energy storage configuration is proposed. Considering the differentiated operation characteristics and stable operation requirements of the system under different proportions of new energy generation in the future, the functional positioning and technical economy of the energy storage of new energy stations were analyzed from the aspects of frequency after disturbance, voltage recovery, power fluctuation suppression, peak shifting and valley filling, power prediction deviation compensation, etc. The guiding principles of energy storage configuration under various typical scenarios are formed, and the technical economy is evaluated, which is expected to provide guidance for the energy storage configuration of new energy stations.

(2) Optimal scheduling model and method strategy of new energy + storage

Considering the collaborative regulation ability of energy storage and new energy, the scheduling algorithm is designed around the uncertainty of new energy generation, power balance of the grid, security of the grid, peak regulation, frequency modulation, voltage regulation, etc. Combined with the characteristics of rapid regulation of energy storage, regulation space, power generation output and load prediction, and new energy output characteristics, the characteristics of new energy and all kinds of energy storage can be fully considered. According to the actual situation of new energy stations, the mathematical model of "new energy plus storage" dispatching object applicable to power grid analysis can be arbitrarily combined to build "new energy" which can flexibly match the operation demand of power grid.

According to the typical scenario of different proportion of new energy power generation, energy storage under large disturbance events determine the function of the frequency and voltage support ability orientation and system requirements, consideration and conventional units and new energy power generation of FM regulating ability of coordination, set up technical and economic energy storage capacity of the optimal allocation model of the photovoltaic, wind power and energy storage combined system involved in system frequency response of ancillary services. By adjusting the relationship between frequency subsidy, energy storage capacity allocation and comprehensive income of new energy stations, the centralized and local dispatching mode of "new energy + energy storage" is constructed, which can not only adapt to different fluctuation levels of new energy output, but also meet the support of frequency, voltage and safety, and realize the multi-level energy storage scheduling mode with orderly and hierarchical management. Based on the change of power grid operation mode, maintenance arrangement and new energy forecast results, the scheduling strategy to meet the power supply demand in the next three days is realized.

(3) "New energy + energy storage" integrates active support control technology to improve system stability

Based on the inertial support, frequency control and voltage control requirements of new energy power stations, the "new energy + energy storage" integrated active support control technology has been developed to improve the system stability in view of the large number of control objects, complex dynamic characteristics and difficulties in source and storage coordination of new energy power stations with energy storage.

To construct a multivariate aggregation index system of new energy power station considering inertia, frequency modulation sag characteristics, voltage regulation sag characteristics and other factors; Aiming at the problems of inaccurate parameters and inaccurate output prediction of new energy power stations, the construction method of active and reactive power control model of new energy power stations driven by operation data under incomplete parameters is proposed. Aiming at the complex dynamic operation characteristics of new energy power stations, an online evaluation method of inertia, frequency and voltage integrated regulation characteristics of new energy power stations driven by data models is studied. The transient process mechanism of fan rotor kinetic energy release and photovoltaic DC bus capacitor discharge is analyzed, and an integrated active support control technology of source and storage is proposed to improve the frequency stability of the system. Aiming at the contradiction between the overall frequency support characteristics of new energy power station and the optimal power distribution in the station, the frequency optimization control method of new energy power station based on the hybrid drive of data model is studied, and an adaptive and efficient frequency feedback correction control method of wind power generation is proposed, and the integrated control strategy of source and storage is proposed.

"The 14th Five-Year Plan" is a critical period of "peak carbon dioxide emission", and energy storage will play a key supporting role in the construction of new power system. Yunnan Power Grid Company will continue to promote the further research and discussion of energy storage related technologies, to ensure the safe and stable operation of the new power system play an important supporting role.

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