Ji Zhenshuang: Under the Market Mechanism, Where Does Photovoltaic Power Generation Technology Go?

market mechanism, Ji Zhenshuang

, deputy director of Beijing Jianheng Certification Center, should explore

the technical characteristics of photovoltaic power generation and the direction of industrial technology development. The door of photovoltaic power generation from "planned system" to "market mechanism" has been officially opened, and the industry is undergoing a big test of transformation and development, so we need to find a way to break through as soon as possible. This paper starts with the analysis of the advantages and disadvantages of photovoltaic power generation, and explores the development direction of photovoltaic power generation technology and its technical form and characteristics from the perspective of better meeting the needs of the market.

1. Analysis of Advantages and Disadvantages of Photovoltaic Power Generation and Exploration of

Development Strategy Figure 1 is based on the author's experience. "Strengths — Weaknesses — Opportunities — Threats" (SWOT) analysis diagram of photovoltaic power generation is given.

Figure 1. In addition, resource conditions determine that some disadvantages of photovoltaic power generation can not be completely bridged. From the perspective of market competition, the overall strategy for the future development of the industry should be "clean + low price".

2. Brief analysis of

the technical characteristics of photovoltaic power plants and the development direction of industrial technology in the medium and long term, focusing on the future market demand, based on the deep integration of photovoltaic and energy storage and other power and energy regulation means, supported by digital and intelligent means, the power plant will be regarded as an "integrated product", and the photovoltaic power plant will be regarded as an "integrated product". Considering the future photovoltaic or photovoltaic storage power generation with product thinking, it should have the following technical characteristics. In terms of

system output, source-load integration, timing matching, precision and efficiency;

in terms of system safety, risk-oriented, probability control, active adaptation;

in terms of credibility management, it is connected from top to bottom, compatible and orderly, intelligent and minimalist.

Focusing on the terminal demand and the technical characteristics of power plants, the industry needs to break the inertial thinking, coordinate upstream and downstream, rely on technological progress, and constantly enhance the competitiveness of the industry.

1. Through the integration of photovoltaic and storage, it is an effective means to solve the current outstanding problems by suppressing fluctuations, improving the output form of photovoltaic and alleviating the mismatch of power generation and consumption sequence. In the long run, strong coupling of solar energy, photovoltaic power generation and other energy production facilities, cascade conversion and recycling of various energy carriers, and autonomous energy balance in different time domains are important options to expand industrial development space and improve power supply security.

Fig. 2 is an example of the fluctuation of solar energy resources, which can indirectly reflect the fluctuation of photovoltaic power generation output. Intermittence and fluctuation are the biggest disadvantages of photovoltaic power generation. Coupling with energy storage can:

1) smooth photovoltaic output, that is, alleviate the fluctuation and control of photovoltaic power generation;

2) adjust the timing distribution of electric energy, that is, alleviate the timing mismatch between photovoltaic power generation and power load.

Figure 2. However, in general, the regulation capability of energy storage is limited. The wide range of diurnal fluctuations and seasonal fluctuations shown in the figure cannot be regulated by energy storage, and it is necessary to find another way.

In recent years, the industry has taken photovoltaic hydrogen production and hydrogen extension chemical chain as the main direction to solve the problems of consumption, energy conversion and recycling, as shown in Figure 3. In the long run, strong coupling between photovoltaic and other energy facilities, cascade conversion and recycling of multi-type energy carriers, and autonomous energy balance within a certain range and in a longer time domain should be an important development direction.

Figure

3.2. The balance between generation cost, electricity price and capacity and output timing distribution will become the dominant factor in system design, that is, the system design needs to be switched from "output traction" to "value dominance".

Future power plant design requires technical and financial considerations. After multiple factors are superimposed, the requirements for power plant design capacity will be qualitatively different, and the "scissors + paste" design will become the past. Figure 4 is an example of the value points that need to be considered in the design process of future power plants.

Figure 4.

Like conventional power sources, it is inevitable that photovoltaic power generation has grid support capability. Generally speaking, the research on photovoltaic power plants is still in its infancy, and there is still a lot of work to be done. Taking primary frequency modulation and inertia support as an example, corresponding to the current standard requirements (see Figure 5), taking "light" and "storage" as a whole, the following technical problems need to be solved.

1) For a specific power station, how to accurately verify the rated power of the power station, that is, "PN" in Figure 5, and use it as the reference for regulation and control of the network side and the station side?

2) How to realize the "quasi-steady state" control of PV transient output, i.e. "PO" in Figure 5, which involves the accurate prediction and control of PV output?

3) How to reasonably configure the installation capacity of active and reactive power regulation equipment to meet the limit requirements of power grid support, i.e. "△ P" in Figure 5?

4) How to improve the dynamic response capability of the power station to meet the time limit requirements of each section "t" in Figure 5? Ccement. Com/news/2604/richtext/IMG/j4yl0fh2vfi1776304442771.png ">

Figure 5. Among them, by improving efficiency and reducing cost, becoming the cheapest power type or becoming the clear strategic goal of photovoltaic power generation; Through scenario-based design and relying on modern technology, it is a necessary lesson for photovoltaic power generation to comprehensively improve the controllability and basic support capability of all aspects of power plant performance.

Fig. 6 is a graph of photovoltaic cell efficiency extracted from NERL. It can be seen from the figure that the crystalline silicon-perovskite tandem battery or

"Wide range of applications, flexible and diverse" is one of the advantages of photovoltaic power generation. Comparing with the block diagram of application scenarios given in Figure 7, at present, all kinds of scenarios have been applied to varying degrees, and the diversified development pattern of photovoltaic power generation has been formed. However, there are two outstanding problems:

1) the research on the characteristics and application requirements of different application scenarios is not systematic and in-depth enough, and the degree of scenario integration is not high;

2) The ability of cross-border research and two-way integration is not strong, and the compound application is "seemingly at odds with each other". Guided by the terminal requirements of different scenarios, scenario-based in-depth design is carried out around the "wide range" scenario conditions, including solar energy resources and other natural environments, power market environment, infrastructure and other conditions, including the re allocation of scenario-based functional baselines of power plant equipment and the adaptation of performance requirements. It will gradually replace the construction mode of "design and integration based on existing shelf assembly".

Figure 6.Photovoltaic cell efficiency chart (example)

Figure 7. At present, in some areas with serious light curtailment, there is a tendency of "letting it go and breaking the pot", which is worth noting. Under market conditions, enterprises need to change their management ideas, refine and deepen the underlying management of power plants, rather than vice versa.

1) In terms of power generation performance and reliability, the industry has been plagued by the problems of "inaccurate measurement, unclear judgment and inaccurate control". How to meet the dual needs of power dispatching and market transactions by "photovoltaic power generation, power forecasting and control accuracy" has become a top priority. Generally speaking, the optical power prediction of most power stations is still in the state of "where to hit, where to know later", which can not meet the needs of the future market. In order to change this state, the initial and periodic calibration of performance level under subdivision conditions is carried out around the core content and logic shown in Figure 8, and it is used as the input of model parameter setting or correction. Or become an important option for performance management.

Figure 8. In general, the safety of the power station, especially the electrical fire, still has the problems of insufficient mechanism research, unclear focus and direction of provention and control, and "seeking medical advice indiscriminately"; the current standard "copying here and there, lack of root and targeted provention and control requirements" is more prominent. Tracing back to the causes of fire accidents in the past, most of them are due to the fact that the point fault is not effectively identified and controlled, which induces other safety faults, and all kinds of faults occur alternately and interweave, as shown in Figure 9. Based on the above analysis, combined with the construction and operation characteristics of photovoltaic power generation projects and the existing technical conditions, it is advisable to highlight the technical development and management of the link of "monitoring and protection of electrical safety faults".

Figure 9.