Discussion on issues related to the development of

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Discussion on issues related to the development of new energy such as solar energy

(I) comparison between centralized development and decentralized development

the viewpoint of advocating centralized development of new energy believes that northern China has a vast land and rich wind and light energy resources, but the power load is small and the power is weak. It cannot be developed according to the European model of "decentralized and local consumption", and can only adopt the transmission mode of "large-scale high concentration long-distance high voltage transmission"

if the resources of a certain place can be developed unconditionally, the above view is beyond reproach. However, the development of resources must be restricted by many conditions such as technology and economy. In a certain stage of development, not all "rich resources" can be developed and utilized. The most basic method is to make a comprehensive comparison of technology and economy, and consider the above new energy characteristics and scientific principles, so as to find the best mode and method that is technically feasible and economically reasonable. China has gained some experience and lessons in the development practice, which should be summarized in time

at present, the key problem of wind power development is power consumption. Most of the wind power centralized development areas in the north have encountered serious problems of wind curtailment and power curtailment. The proportion of wind curtailment and power curtailment in winter in some areas in the Northeast has been nearly 50%, and the factor of major wind farms in the Northwest has been off accident for times, and the current power curtailment is as high as%. In some areas with the best wind energy resources, the annual utilization hours of equipment are less than 1400

at present, there is an upsurge of concentrated large-scale construction of solar power generation in the vast and sparsely populated areas in the west, and its power consumption also encounters the problem of long-distance transmission. Some of them need to be transported kilometers to the provincial load center, but the province is unable to digest it all, and they have to be transported to the East. The annual utilization hours of photovoltaic power generation are only about 1700. To develop electric energy that is "thinner" than wind power in desert areas, it is also necessary to build a series of high-voltage, ultra-high voltage and even ultra-high voltage power transmission and transformation devices to increase the voltage layer by layer, so as to transmit expensive photovoltaic power to thousands of kilometers or even thousands of kilometers away

centralized development and construction of giant wind farms and photovoltaic power stations in areas far away from power load centers has the advantage of high efficiency in project construction and management. If it is proved to be economically reasonable, it is certainly an efficient development model. It should be said that the development mode involves many technical and economic comparison problems, which is actually the understanding of a, from theory to practice; The differences and comparison between the above "energy block" and "energy film" development and utilization methods:

(1) for long-distance transmission of wind power optoelectronics, it is necessary to increase the voltage layer by layer, and build a complete set of power transmission and transformation facilities with various voltage levels from 10 kV to 750 KV

taking the investment estimate of a 3million kW wind farm project as an example, the investment in the wind power body is 22.5 billion yuan, and the investment in the supporting power transmission and transformation project is as high as 6.67 billion yuan. Moreover, the 6.67 billion yuan investment has not included the new power transmission and transformation investment required by the step-down of the receiving end power from 750 kV to 10 kV. In contrast, wind power projects with low-voltage decentralized access system have much less investment in new power transmission and transformation

(2) the annual equivalent utilization hours of wind power generation equipment are about 2000, with less photoelectric, which reduces the efficiency of the transmission system

in addition to the transmission of expensive wind power optoelectronics, long-distance line losses and layer by layer variable losses have a great impact on the economy of transmission, and the cost further reduces the economic competitiveness. The new energy power consumed locally does not have these costs

(3) injecting randomly fluctuating energy flow into the electricity with the highest voltage level is a bit like randomly supplying intermittent "blood flow" in the "aortic system", which has a great negative impact on the safe and stable operation of the whole system, especially the receiving end power and power quality. This problem does not exist in foreign countries, and has not been encountered and experienced in China in the past

(4) Mengxi power has an installed wind power capacity of 7.77 million KW, of which 82% of the capacity is connected to the system at the voltage level of 220 kV, and the rest is connected at 110 kV

here is a brief introduction to the three small skills of ordinary maintenance of electronic universal experimental machines. The concentration of wind power in Western Mongolia has exceeded that in the United States, so there is a certain phenomenon of wind abandonment, and power generation enterprises also complain from time to time. However, on October 15, 2011, there was a record that the total daily electricity consumption accounted for 24% of stroke electricity, reaching the world advanced level. Mengxi power is a local enterprise and a pure thermal power system. In addition, the proportion of "hard load" of coal-fired Cogeneration in winter is very large. Except for the built "point-to-point" coal-fired power transmission channel to the East, there is no means of wind power transmission

it is meaningful that Mengxi region can make such achievements in developing wind power under many difficult conditions. A little analysis shows that, on the one hand, local governments have "direct advantages" in the management of local enterprises, and the management objectives are consistent with the development objectives of wind power, that is, electricity is what is needed, and the energy-saving principle of "giving priority to wind power and giving way to coal power" is thus realized

compared with Mengxi, many other regions are still implementing a wide range of administrative instructions on various generator units, such as "average distribution index of planned and unplanned power generation", "price difference between planned and unplanned power generation". These planning methods of "generator equalization" seem fair, and their role is precisely to protect fossil energy and waste new energy

on the other hand, Mengxi power mainly consumes wind power at the voltage level of 220 kV, which has a far less adverse impact on the dynamic characteristics of the power than configuring wind power at the highest voltage level of 500 kV. It is also a success factor that cannot be ignored. Nevertheless, the 220 kV voltage is still high for the operation of wind power. The period when the electricity proportion in Mengxi region exceeds 20% is limited, with an average of less than 10%. The increase in the number of abandoned wind and the difficulties brought to power operation cannot be ignored. In general, the development of wind power has tended to the limit

(5) it is worth mentioning that in 2010, an enterprise conducted an experiment near a large wind farm in Damao Banner, Mengxi. Four 1.5 MW wind turbines are built outside the wall of a 35 kV distribution substation, which are directly connected to the power end. After a period of operation, the results are exciting. Since there is no need to build on-site power transmission and transformation projects for these four turbines, the cost is 1300 yuan/kW lower than that of adjacent wind farms, saving 16% of construction investment

the daily output of the fan is equivalent to the average load of the substation, and the power generation is directly consumed without boosting and returning, directly replacing the coal power supply. In particular, due to the low access voltage level, it has no impact on the main parameters of Mengxi power system operation, and there has never been "abandoned wind", and the converted annual utilization hours of power generation is about 2500. However, in the wind field not far from it, which is connected to the high-voltage system with a voltage of 220 kV, wind power is sometimes abandoned and limited, and the utilization hours of power generation are significantly lower than those of the test unit

(II) on the large-scale centralized and long-distance transmission and consumption of wind power and optoelectronics

at present, the proposed solution is mainly "wind and fire binding", and a large number of pumped storage power stations are built. One thing is certain: if enough measures are taken, all problems can be solved. It just depends on whether these measures are economically reasonable and feasible

it is not economical to use UHV and UHV transmission lines to transmit wind power alone, because there are only more than 2000 hours of electricity. "Wind and fire binding and remote transmission" aims to improve the load rate of power transmission and transformation facilities, so as to improve the transmission economy and power operation safety. However, this practice is unprecedented after all, and a series of technical and economic issues need to be considered

first, the load rate of wind power is low, the power is large and the power is small, and the output process curve is in a steep zigzag shape. In order to improve the load rate and stability of power transmission, if coal-fired thermal power stations are considered as a means of regulating power and supplementing power, and "bundled transmission" with wind power, thermal power units need to play the role of "filling in the blank", follow the change of wind power output in reverse, and cooperate with the operation of deep range variable output, otherwise a large number of wind will be abandoned. Then supercritical parameters, ultra supercritical parameters coal-fired power generation units, it is inevitable to often run out of the best operating conditions, increasing coal consumption

in addition, whether the operation safety can meet the requirements of long-term, frequent, deep amplitude and random variable output operation mode

second, in a certain transmission capacity space, due to the "fill in" operation mode, the thermal power unit will not only increase the coal consumption of power supply, but also reduce the power generation by more than 2000 hours in the year, and the annual utilization hours of its own equipment will drop to about 3000, which is economically acceptable; Third, if we build tens of millions of kilowatts of thermal power stations thousands of kilometers away from the central and Eastern load centers according to the proportion of "two fires and one wind", we should not only thoroughly demonstrate the macro layout of power planning, but also consider the long-term operation of such a large-scale thermal power station group in the desert Gobi Region. There is still a lot of work to be done to the feasibility of consuming local water resources and the acceptability of the impact on the ecological environment

as for pumped storage power stations, after years of practice, the understanding of all parties has become increasingly clear

first of all, according to the previous analysis, according to the world's scientific and technological level, the electric energy in the AC power system cannot be stored commercially. That is to say, it is not economical to store electric energy on a large scale. This understanding should be the basis for discussing the storage power station; Second, the storage power station is the most flexible and expensive regulating device in the power system

once it is available, the regulation ability and safety and stability level of the whole system will be improved to a higher level; Third, the storage power station has many functions, such as peak shaving, valley filling, system emergency standby and black start. If its development goal and operation mode are fixed as "peak shaving", it is not comprehensive. It should also be pointed out that the time scale of the transformation of pumped storage power station energy storage and power generation operation mode is an order of magnitude larger than the time scale of wind power change, and it is difficult to "bundle" it with wind power

The development goal of the energy storage power station is to serve the whole system, and its construction decision should be based on the demonstration results of the whole power system for the marginal benefit of this investment. If only one or a certain type of power station is considered, the development goal of the storage power station is to "convert secondary energy into tertiary energy". The kW input of this "integrated power generation facility" is increased by 6000 yuan, and the net electricity output is reduced by 25%. It is difficult to be economically feasible

(III) how to treat "fast" and "slow"

if the development speed of new energy is too slow, it cannot meet the requirements of the urgent situation of adjusting the energy structure in China. After a period of practice, it has been proved that the mode of highly centralized development of wind power and Optoelectronics has brought leapfrog and rapid development to the equipment industry and equipment manufacturing field, and can create a "fast" miracle. However, equipment is only a "tool", and what we ultimately want is new energy and electricity

at present, power enterprises have encountered great difficulties in the safe and stable operation of the system and the consumption of wind power. There have been many wind abandonment and several system stability accidents, so that the impact of large-scale centralized wind power on the safety of power operation has been highly concerned. A large number of power restrictions have reduced the economy of wind power projects, a large number of wind power equipment production capacity backlog, and output ups and downs. In the current situation of many problems, even if we want to continue the original development mode, we also need to carefully summarize experience and solve the contradictions and problems that have occurred as soon as possible. These are the reasons why the current development speed of wind power has slowed down compared with previous years. In other words, if something goes wrong, it won't get up soon

if we build fans one by one, the development speed must be too slow. however

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