Chapter 11
Development and Prospect
Ningbo Wang, and Jiandong Wang
Abstract
China's economic development has been increasingly restricted by energy, resources, and the environment. Accelerating wind power development can implement the Chinese government's commitment to tackling climate changes. In addition, it is also the inherent demand of China's sustainable development of economy. The reverse distribution of wind power resources and power consumption market decides large-scale concentrated development, and long-distance transmission is the main mode of China's wind power development.
Keywords
Cluster control system; Grid-friendly new energy power generation technology; Relevant supporting policies; Wind power and thermal power bundling transmission; Wind power development modes11.1. Large-Scale Wind Power Bases Lead the Future Wind Power Development
11.1.1. Selection and Effect of Different Development Modes
In European and American countries onshore wind power is mainly generated in small-sized wind farms, and wind power development is mainly characterized by: approaching the power load center, being in small scale, having multiple owners, being widely distributed, and accommodated locally. In recent years, European and American countries have begun to develop large-scale offshore wind power and mainly adopt the transmission mode of high voltage and centralized integration, but the construction scale is controlled by the power grid's capability to receive wind power, and a single offshore wind power project is in small scale and has scattered points of common coupling. This kind of integration mode of scattered integration and balancing and transmitting wind power on the spot makes a slight impact on the power grid. In some European and American countries where wind power develops rapidly, the power grid usually has a powerful structure and a strong capability to receive wind power. As a result, wind power integration generally has a slight impact on the power grid. In addition, in the progressive wind power development, European and American countries have established complete management systems, made sound technical standards and management specifications for wind farm planning, construction, and operation, mastered a generally high level of wind power equipment manufacturing technology, accumulated rich wind farm operation and management experience, and established complete wind farm integration management procedures and specifications. Therefore, in European and American countries wind power has a slight impact on the power grid.
China has selected the resource development-oriented wind power development mode, and wind power development is mainly characterized by being far away from the load center, in large scale, with few owners, and being highly concentrated. China's wind farms mainly adopt the mode of high voltage integration and long-distance centralized transmission. Large-scale wind power bases are generally located at the end of power grids. Wind farm accidents have a great impact on the power grid owing to the weak structure of local power grid, increasing installed power capacity of wind farms or installed wind power to be transmitted in a centralized way, and the integrated voltage level and the growing power transmission distance. In addition, the wind farm planning, construction, and operation management system is yet to be improved; the wind farm operation management level is quite low; the wind farm integration standards, procedures, and specifications are incomplete. As a result, China's wind farms have a higher accident frequency. Since wind turbines generally do not have the low voltage ride-through capability, wind farm accidents usually lead to wind turbines in the neighborhood getting disconnected with the grid on a large scale and the expansion of the accidents.
The 10 GW Jiuquan Wind Power Base is not only different from the wind power development mode in European and American countries but also quite different from China's existing wind power development mode. In normal operation mode, wind power's randomness and flexibility has resulted in difficulty in controlling the power grid's reactive power voltage. Since most wind farms in Jiuquan Wind Power Base are integrated into the grid through the 330 kV bus of Dunhuang 750 kV substation, at present wind turbines generally do not have the low voltage ride-through capability. Therefore, the problem of wind farm accidents affecting each other is very prominent. The voltage drop of a few wind farms might lead to wind turbines in other wind farms getting disconnected with the grid on a large scale and the expansion of the accidents. Since the 750 kV double-circuit wind power transmission line is almost 1000 km long, it is the typical long transmission line with weak grid structure. If wind turbines are disconnected from the grid on a large scale, this might lead to great fluctuations of grid voltage and frequency and directly threaten the security and stability of the power system.
In addition, the 10 GW Jiuquan Wind Power Base has created a series of wind power development records including the farthest distance from the load center, the largest concentrated integration scale, and highest transmission voltage level. It has constantly challenged the power system's limit of accepting wind power. Meanwhile, it has explored the mode for large-scale concentrated wind power development and ultra-long-distance wind power transmission.
11.1.2. Wind Power Development Trend in the Future
Both China and the whole world abound in wind power resources. If we can explore a mode for ultra-large-scale concentrated wind power development and ultra-long-distance wind power transmission, then we will greatly increase the total amount of the world's exploitable wind power resources and provide more exploitable renewable energy reserve for future economic development.
The ultra-large-scale concentrated wind power development and ultra-long-distance wind power transmission mode of the 10 GW Jiuquan Wind Power Base has broken through existing wind power development theories both at home and abroad, made innovations in wind power development concept, and provided a brand new development mode for the world wind power development. With the decreasing exploitable wind power resources near the load center, more projects both at home and abroad will learn from the experience of Jiuquan Wind Power Base. Therefore, the 10 GW Jiuquan Wind Power Base will probably lead the future world wind power development trend.
11.2. Study and Improve Relevant Supporting Policies
Accelerating wind power development is the inevitable choice of China's energy strategy. The reverse distribution of China's wind power resources and power consumption market decides the prominent conflict between the wind power transmission and accommodation of large-scale wind power bases, and the market accommodation capability is the key factor in restricting wind power construction scale. Transregional wind power accommodation faces a series of technical, policy, and system problems, and supporting policies are the key factor in solving them.
11.2.1. Improve National New Energy Development Policy System Construction
National policies are the key factor in promoting China's wind power superconventional development. With China's wind power development from small to large in scale and from weak to strong in grid structure, especially with the construction of 10 GW wind power bases, the limitation of existing supporting policies has appeared gradually.
1. Reexamine China's energy price and tax policies: China's economic development has been increasingly restricted by energy resources and the environment. The existing low cost pricing policy for energy resources and the environment is no longer in line with China's national conditions. China has implemented the low energy price policy under government regulation and control. Although in recent years China has made some breakthroughs in oil and coal price reform, there is still an obvious gap between China and the European countries in terms of tax policy regulation and control; China lacks substantive progress in electricity price and natural gas price reform, which restricts the pace of industrial restructuring. We suggest gradually adjusting fossil energy price policy and tax policy, narrowing the gap between small-scale wind power feed-in tariff and conventional thermal power feed-in tariff by increasing conventional coal power, environmental protection and emissions taxes and electricity price, and establishing energy prices and a tax system that can help alleviate the conflict between energy resources and environmental protection.
2. Improve renewable energy fund policy: The existing wind power regional benchmark price system has effectively promoted the rapid development of wind power. With the growing wind power generation scale, we need to synchronously increase the overall scale and the collection amount of the renewable energy fund. We suggest gradually increasing conventional thermal power benchmark price through the tax lever, narrowing the gap between conventional thermal power price and wind power price, reducing the renewable energy fund payment required for unit wind power generating capacity, and meanwhile complementing the renewable energy fund with the increased energy consumption and pollutant discharge tax.
3. Issue renewable energy quota policy: We suggest issuing a renewable energy trading mechanism and quota management regulations as soon as possible, improving relevant supporting measures and detailed rules for implementation, making a renewable energy quota policy that stipulates that all regions should accommodate wind power based on their energy consumption proportion, motivating economically developed regions to take the initiative to accept wind power through effective policies and regulations, strengthening promotion of green energy and environmental protection awareness, making a reasonable green power development mode and mechanism, and gradually leading all provinces and regions all over the country to take the initiative to accommodate wind power.
4. Create a national energy strategy: The wind power accommodation market is the key to the development of large-scale wind power bases. We suggest considering wind power development and accommodation as an important part of the national energy strategy, making overall arrangements for the national power market to accommodate wind power according to the national requirements for energy security and optimization of energy resource distribution, studying and making national energy market plans including plans for wind power market, making energy planning that is conducive to transregional optimization of large-scale wind power distribution, and instructing the optimization of wind power resource distribution through the unified national energy strategy.
11.2.2. Strengthen and Unify the Planning Function and Promote the Optimization of Wind Power Resource Distribution
Due to the random and intermittent characteristics of wind power, only when large-scale wind power is matched with other power sources can it provide stable power supply. We suggest integrating supporting power source base construction into the national energy strategic planning to realize replacing fossil energy transmission with power transmission and transforming resource advantages of western regions into national economic development advantages; studying and formulating medium- and long-term energy development plans including those for energy production, transmission, and consumption; reasonably identifying energy structure, transmission mode, and consumption market; guiding the reasonable flow and optimal distribution of domestic energy; and giving precedence to developing renewable energy on the basis of ensuring energy security to achieve China's goal of honoring international commitments and sustainable development.
Stick to the power development principle of integrating planning for the construction of power sources and grids, implement the procedures for preparing and approving power development plans, and conscientiously safeguard the seriousness of power development planning; stick to the power market demand-oriented power source planning principle and prepare wind power development planning in the framework of the unified power source planning to avoid the market “bottleneck” of wind power development; stick to the planning principle of coordinated and synchronous development of power sources and power grids, identify the scale of wind power planning based on the overall scale of power grid planning, and reasonably adjust power grid planning according to the transmission demand in wind power development planning to formulate the mechanism of developing wind power and power grids in a coordinated and interacting way and ensure the coordinated and synchronous development of wind power and power grids. Control wind power construction scale and progress in a scientific and reasonable way so that wind power projects and power grid projects can be completed and put into operation synchronously and give precedence to starting the construction of the transmission channels for wind power bases to realize the development pattern of transregional large-scale wind power transmission.
11.2.3. Improve Wind Power Transmission Mechanism to Promote Sustainable Development of Wind Power
Unlike conventional power sources, wind power does not have the peak load regulating, frequency controlling, voltage regulating, and reserve abilities. The peak-valley regulation for wind power by other power sources and grids in the power system leads to the significant growth of the operation cost. We suggest studying and formulating compensation policies that can reasonably compensate for the peak-valley regulation cost of conventional power sources. Improve the peak-valley regulation-focused ancillary service policy system, integrate wind power into the grid's ancillary service assessment and compensation system, set the basic ancillary service standard for wind turbines and have wind power properly assume ancillary service obligations, assume basic ancillary services free of charge, and provide compensable ancillary services. Pay attention to peak-valley regulation ancillary services, identify wind curtailment rules and standards and allow giving up marginal wind power in extreme conditions. Accelerate promoting transprovincial and transregional ancillary services, and explore and establish the cogeneration operation mechanism and ancillary service market.
In addition, make compensation policies conducive to encouraging wind power transmission, improve supporting policies on long-distance power transmission, frequency control and peak-valley regulation, transprovincial accommodation and system stability, and maintain the basic sustainable development capabilities of power grids and other power generation enterprises.
11.2.4. Establish Technical Standards and Management Specifications to Promote Standardized Development of Wind Power
Construction of 10 GW wind power bases at the end of power grids indicates wind power will step onto the stage of history as the main power source. Establish technical standards suitable for the construction scale and system status of large-scale wind power bases to improve the system stability and wind power transmission capability. Learn from the successful conventional power source management experience and formulate comprehensive process management specifications of large-scale wind power bases including power source planning, prephase management, construction, debugging, trial operation, acceptance of construction, operation, and dispatching.
11.2.5. Strengthen Research and Development to Promote the Scientific Development of Wind Power
1. Accelerate Smart Grid Construction. Accelerate grid construction and optimize grid structure to improve the power system's capability to accept and transmit wind power; improve power source structure, optimize power source layout to improve the power system's peak-valley regulation capability. Speed up the construction of the secondary system including control, protection, and automation to improve the power system's stability control capability and level; accelerate the research on and application of smart grid technologies to improve the overall equipment level of the grid and the power system's overall adaptability. Strengthen research on power dispatching and operation management technologies to further improve the power system's operation management control capability and level.
2. Improve the manufacturing level of domestically produced wind turbines. Speed up the construction of a national wind turbine manufacturing standard system, improve the wind turbine integration license system, strictly implement wind turbine integration technical standards and testing procedures, and standardize wind turbine integration management. Enhance support for the research and development of wind power equipment manufacturers in China, and improve the independent innovation and introduction, digestion and absorption abilities of China's wind power industry to improve the international competitiveness of China's wind power equipment manufacturers in an all-around way; strengthen joint research on key wind turbine manufacturing technologies, improve the research, development, and manufacturing level of key supporting products including inverters and the control system to improve the overall manufacturing level of domestically produced wind turbines in an all-around way.
11.3. Important Research Subjects on Future New Energy
11.3.1. Wind Farm and Photovoltaic Plant Cluster Control System
The wind farm and photovoltaic plant cluster control system mainly includes:
1. Construct the resource and operation real-time monitoring network and data platform covering all resource monitoring points and wind turbine equipment, which cannot only provide the hardware basis and communication environment for the cluster control system but also provide reliable real-time monitoring data support for theoretical research.
2. Study the output characteristics, output fluctuation, and probability distribution of wind turbines/photovoltaic modules; temporal and spatial distribution and characteristics of wind farm/photovoltaic plant cluster output and the matching characteristics of cluster control strategies. Build static/dynamic models of wind turbines, photovoltaic modules, wind farms, and photovoltaic plants to provide verifiable basic mathematical models for the static/dynamic and multiobjective coordination and control strategy of wind power and photovoltaic power clusters.
3. Deepen research on the wind power and photovoltaic power joint forecasting, strengthen the ultra-short-term power forecasting system construction, support online closed-loop control, improve day-ahead forecasting accuracy to meet the cluster internal operation optimization demand, and carry out research on the forecasting error statistical characteristic index screening and evaluation system to provide targeted forecasting plans for different dispatching and controlling objectives of the cluster control system.
4. Based on the instructions of the superior dispatching department and cluster wind power and photovoltaic power resources, reasonably arrange the generation scheduling of all wind farms and photovoltaic plants; optimize cluster operation mode and distribute local security and stability control guard line from the perspective of the harmony between wind turbines and grids to provide basic operation conditions for online active power dispatching; and cooperate with the big grid in constructing and improving security guard line.
5. Focus on studying large wind farm and photovoltaic plant cluster online active and reactive voltage, security and stability control strategy to formulate the control system coordinating wind turbines/photovoltaic modules, wind farms/photovoltaic plants, substations, and clusters, and achieve the real-time online control of clusters based on the several typical operation modes designated by the superior dispatching department.
6. Develop the full digital wind farm and photovoltaic plant cluster control system platform and construct the cluster control system demonstration project based on the 10 GW wind power bases and 1 GW photovoltaic bases in Jiuquan, Gansu. The control system has the control capability covering 70 wind farms (13,000 MW) and 30 photovoltaic plants (1000 MW) in Jiuquan.
Study and develop the control platform for the wind farm and photovoltaic plant cluster control system to externally respond to the dispatching instructions of the superior dispatching center and cooperate with the big grid in completing the coordinated dispatching and emergency control of wind power, photovoltaic power, thermal power, and hydropower and internally control all wind farms, photovoltaic plants, and reactive compensation equipment in a coordinated way to achieve the cluster's internal online active control, reactive voltage control, operation optimization and security and stability control, and make large wind power and photovoltaic power bases controllable.
11.3.2. Key Technology Research on Grid-Friendly New Energy Power Generation and Application
Key technologies of grid-friendly new energy power generation mainly include:
1. Concept and technical index system of grid-friendly wind farms.
2. Wind power forecasting technology and wind power generation decision support system based on complex data sources: study high-precision wind farm power forecasting technologies based on complex data sources such as real-time wind measurement data, wind farm operation data, and weather forecasting data and develop wind farm power forecasting system software based on complex data sources. Study information such as dispatching instructions, wind farm operation data, repair and maintenance plans, wind turbine life, and wind power forecasting results, and develop the wind farm power generation decision support system.
3. Wind farm operation security defense technologies: build the transient simulation models of wind turbines, main electrical equipment, and power integration system to formulate the wind farm transient analysis platform; study the operation characteristics and fault evolution mechanism of wind farms in case of abnormal voltage disturbance.
4. Security defense measures for wind farms to deal with abnormal voltage: study wind farm abnormal voltage withstanding and fault ride-through technology based on the fault ride-through capability of wind turbines, fast reactive compensation devices of wind farms, energy storage and reversing devices, and braking resistors. Study layered protection configuration method and multiple security defense construction technologies for wind farms in abnormal cases.
5. Wind farm equipment dynamic state prediction and intelligent maintenance technologies: study the overall architecture of the wind farm equipment dynamic state monitoring platform and its software and hardware information platform technology. Study wind farm equipment health state evaluation methods, construct the life prediction model, and develop dynamic life prediction software. Study wind farm equipment online fault diagnosis and prediction methods, and intelligent maintenance technologies, and develop wind farm equipment intelligent maintenance expert system.
6. Use power usage energy storage devices to improve wind farms' adjustable performance technologies: study the relationship between wind farm adjustable performance and energy storage allocation proportion, control method, and allocation mode; study the inhibitory effect of energy storage on the rapid fluctuation of wind farm output in the stable state; study the support effect of energy storing devices on the stable operation of wind farms in the faulty state. Explore the multiple-objective coordinated energy storage allocation plan and control mode.
7. Comprehensive application of grid-friendly wind farms: realize the above-mentioned functions by taking a certain wind farm in Jiuquan Wind Power Base as the demonstration project.
By combining newly developed technology with existing integration technologies, realize wind farm power accurate prediction and real-time status monitoring (measurable), active control of active/reactive power (controllable), response to the grid's dispatching demand (adjustable), and short-time support for grid disturbance (transient support), and achieve the goal that main wind farm integration technical indexes reach or approach those for conventional power sources.
11.3.3. Coordinated Control and Security Defense System of Wind-Thermal-Bundled Power Transmitted by AC/DC System in the Energy Base
Coordinated control and security defense system of wind-thermal-bundled power transmitted by alternating current/direct current (AC/DC) system in the energy base mainly includes:
1. Research on the wind turbine and thermal power unit coordinated control technologies of “wind power and thermal power” bundling transmission: study the impact of thermal power unit voltage regulating control and furnace control system on the voltage characteristics and frequency characteristics of the grid; study the thermal power unit excitation control and furnace control system optimization plan targeted at randomness and fluctuation of wind power; study the demand of different ratios of wind power to conventional power sources for grid active power/frequency and reactive power/voltage control.
2. Research on coordinated optimization control technologies of wind-thermal-bundled power transmitted by AC/DC system in the energy base: study the impact of output fluctuation of “wind power and thermal power” bundling transmission on grid frequency characteristics, voltage characteristics, and damping characteristics; study the AC and DC transmission system coordinated control technologies suitable for random power fluctuation of “wind power and thermal power” bundling transmission; study the effect of flexible alternative current transmission systems (FACTS) equipment such as controllable high voltage reactor on improving the operational characteristics of the transmission system of “wind power and thermal power” bundling transmission and control technologies.
3. Research on grid security and stability control strategy of wind-thermal-bundled power transmitted by AC/DC system in the energy base: study the forms, consequences, and countermeasures of serious AC and DC system faults that cause grid instability by “wind power and thermal power” bundling transmission; study grid security and stability control measures suitable for the fluctuation and randomness of wind power; study grid security and stability control technologies suitable for wind turbine active and reactive power control capability, low voltage ride through capability and grid protection configuration; study wind turbine and thermal power unit capacity optimization and coordination technologies in security and stability control measures; study the DC system emergency control strategy of improving “wind power and thermal power” bundling transmission system security and stability; study “wind power and thermal power” bundling transmission system security and stability control strategy in harmony with the DC system power regulating capability.
4. Research on the generating unit relay protection and grid security third defense line coordination technologies of “wind power and thermal power” bundling transmission: study the current situation and development trend of the generating unit relay protection of “wind power and thermal power” bundling transmission; study the impact of grid security and stability characteristics and control measures of “wind power and thermal power” bundling transmission; study the impact of DC transmission system dynamic regulating performance on wind turbine and thermal power unit relay protection settings; study wind turbine and thermal power unit relay protection settings optimization technologies suitable for the safe and stable operation of the “wind power and thermal power” bundling transmission system; study the implementation plans for grid security third defense line measures of generating unit relay protection in coordination with “wind power and thermal power” bundling transmission, including low frequency, low voltage load reduction, getting off the power grid, and high frequency of generating unit tripping.
5. Integration and application of coordinated control and security defense system of wind-thermal-bundled power transmitted by AC/DC system: study the main frame structure and functional requirements of coordinated control and security defense system of wind-thermal-bundled power transmitted by AC/DC system; develop “wind power and thermal power” bundling AC and DC transmission coordination control and security defense system–oriented modules including data management, data communication, and panoramic graphic warning, and conduct integrated development of “wind power and thermal power” bundling AC and DC transmission coordination control and security defense system.
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