CN103956742B - The defining method of power system operation mode under a kind of complicated energy environment - Google Patents

Abstract

The invention provides a method for determining the operation mode of a power system in a complex energy environment, and belongs to the field of power system safety and stability analysis. The method includes: generating a preliminary operation mode of the power system and determining the control range of the bus voltage; performing a single component safety and stability calculation and evaluating it; performing a safety and stability calculation under severe fault impacts to determine the final power system operation mode. The present invention aims at the problem of determining the way of wind-solar energy bundling and sending out energy bases, and through analyzing the characteristics of wind-fire new energy sending power systems, proposes a method for comparing and analyzing start-up methods using various power sources in different proportions. The failure analysis in the combined mode ensures that the system meets the N-1 requirements after a system failure, and minimizes the amount of security control measures for the system after a serious failure occurs, and creates favorable conditions for system recovery after a failure.

Description

A Method for Determining Operation Mode of Power System in Complex Energy Environment

technical field

The invention belongs to the technical field of power system safety and stability analysis, and in particular relates to a method for determining the operation mode of a power system in a complex energy environment.

Background technique

Northwest China is rich in wind energy and solar energy resources, the local load level is low, the system scale is small, and the wind power consumption capacity is very limited. Large-scale wind power (wind power, photovoltaic and thermal power, referred to as wind power) must be transported to other countries Regional consumption. The annual utilization hours of wind and solar power are low, and the economic efficiency of long-distance transmission alone is very poor; at the same time, the frequent fluctuation of wind and power power on the transmission line is extremely unfavorable to the safe and stable operation of the system. Adopting the bundling and delivery strategy of wind power, photovoltaic and thermal power can not only effectively reduce the fluctuation of line power, but also help the safety and stability of the system, and significantly reduce the power supply cost of the receiving end power system.

However, with the completion and operation of more and more large-capacity solar-thermal energy bundled energy bases, while bringing huge economic benefits, their dynamic behavior has become more and more complex, and the safety and stability characteristics of the power system have also undergone great changes.

Affected by economic, energy and environmental changes, countries have developed and utilized more new energy in recent years. However, due to the different natural conditions and power system environment, the utilization of new energy at home and abroad is also different. In foreign countries, new energy sources are mostly developed in a decentralized manner and connected nearby. The power system is closely connected and the technology is mature, and it develops in harmony with other power sources. In China, affected by the distribution of natural resources, new energy power generation presents high concentration, long-distance power transmission, and insufficient peak regulation capacity. And the characteristics of weak networking.

At present, the geographical distance between new energy and load centers in Germany, Denmark and other countries is relatively short, and most of them are scattered and connected nearby and consumed locally, so the development cost is also low. While developing new energy power generation, European and American countries are also vigorously developing units with strong regulation capabilities such as fuel oil and gas to meet the needs of large-scale grid-connected wind power. At the same time, its power system is closely connected and its power exchange capability is strong, which provides a solid foundation for the cross-regional and transnational consumption of new energy power generation. Newly installed wind turbines in foreign countries have the ability to adjust active/reactive power and low-voltage ride-through capability, and the new grid-connected guidelines for photovoltaic power generation also put forward similar requirements.

China's wind power, photovoltaic power generation and other new energy sources are mostly distributed in Northwest, Inner Mongolia, and Northeast China, far away from the load center, and electric energy must be transmitted over long distances in large capacity, so the development cost is relatively high; my country's power supply is dominated by thermal power, which currently accounts for about 76% of the installed capacity, the system has limited capacity for peak regulation and frequency regulation, and the difference between peaks and valleys is large; and the territory is wide, the span of the power system in each region is large, the connection between regional power systems is weak, and the power exchange capability is not strong. In addition, wind power and photovoltaic power generation started relatively late compared with foreign countries, and the technology is relatively immature. Wind turbines and photovoltaic power plants have poor active/reactive power adjustment capabilities, and many do not have low-voltage ride-through capabilities.

Therefore, it is necessary to deeply study the method of determining the system operation mode under the complex energy environment of wind and fire, so as to ensure the stable operation of the system at the minimum cost.

Contents of the invention

In order to overcome the above-mentioned deficiencies in the prior art, the present invention provides a method for determining the operation mode of the power system in a complex energy environment. Aiming at the problem of determining the mode of wind-and-fire bundling and sending energy bases, the method of wind-and-fire new energy sending power system Characteristic analysis, a method of comparative analysis of start-up methods using different ratios of various power sources is proposed. Through fault analysis under various start-up combinations, it is possible to ensure that the system meets the requirements of N-1 after a system failure, and makes the system fail after a serious failure. The amount of security control measures is minimal, and it creates favorable conditions for system recovery after failure.

In order to realize the above-mentioned purpose of the invention, the present invention takes the following technical solutions:

The present invention provides a method for determining the operation mode of a power system in a complex energy environment. The complex energy environment is an environment with wind power, photovoltaic power and thermal power. The method includes the following steps:

Step 1: Generate the preliminary operation mode of the power system and determine the control range of the bus voltage;

Step 2: Carry out a single component safety and stability calculation and evaluate it;

Step 3: Carry out safety and stability calculations under the impact of severe faults, and determine the final power system operation mode.

Described step 1 comprises the following steps:

Step 1-1: According to the annual load curve, load forecast and power system load capacity, determine the annual maximum value of power supply demand for heavy load or the annual minimum value of power supply demand for small load;

Step 1-2: According to the respective installed capacity and geographical distribution of wind power, photovoltaic and thermal power units in the power system, combined with the seasonal characteristics determined by the method, various power generation combinations are generated;

Step 1-3: Calculate the power transmission capacity limit of each section of the power system according to the generated various power generation combinations;

Steps 1-4: Compare the difference in transmission capacity limit of each section of the power system under different power generation combinations, optimize a reasonable power generation combination, and generate a preliminary operation mode of the power system;

Steps 1-5: According to the generated preliminary operation mode of the power system, determine the bus voltage control range.

In the step 1-2, the power generation set includes wind power generation, photovoltaic power generation or thermal power generation.

In the above steps 1-3, the process of calculating the transmission capacity limit of each section of the power system is as follows: first determine the composition of the section, gradually increase the power-up capacity of the sending end, and reduce the power-up capacity of the receiving end; then check N-1 faults until the system becomes unstable ; Finally calculate the transmission capacity limit of the section.

In the steps 1-4, according to the principle of the influence of the power generation set on the transmission capacity, the power generation combination is optimized according to the following criteria;

1) The power transmission capacity limit of each section meets the transmission and reception capacity requirements of each section determined by the load capacity in step A and the geographical distribution in step B;

2) Reduce the interaction between the transmission capacity limits of each section, and avoid the significant decline in the transmission capacity limits of other related sections when the power transmission scale of some sections is large.

In the steps 1-5, for the generated preliminary operation mode of the power system, the safety and stability constraints of the power system are introduced to determine the control range of the bus voltage, so as to achieve the goal of ensuring the safety and stability of the power system and the range of voltage fluctuations after the pre-control failure;

The power system safety and stability constraints refer to the operation mode of the power system meeting the requirements of the "Guidelines for Stability of Electric Power Systems"; the bus voltage control range refers to the bus voltage meeting the requirements of the "Technical Guidelines for Power System Voltage and Reactive Power".

Described step 2 comprises the following steps:

Step 2-1: According to the generated preliminary operation mode of the power system, perform safety and stability calculations for a single component, and evaluate whether it satisfies the power system safety and stability constraints; if yes, proceed to step 2-2; if not, return to step 1 -4;

Step 2-2: Determine whether the voltage level of the power system after a single component failure affects the stable operation of wind power, photovoltaics or even related DC systems, thereby causing cascading failures; if there is an impact, return to steps 1-5; if there is no impact, perform steps 3.

In the step 2-1, the evaluation of whether a single component meets the power system security and stability constraint standard is: the power system operation mode meets the requirements of the "Power System Stability Guidelines", that is, after a single component failure disturbance occurs in the power system under normal operation mode , Protection, switch and reclosing are correct actions, no stability control measures are taken, the stable operation of the power system and the normal power supply of the power system are maintained, other components do not exceed the specified accident overload capacity, and continuous tripping does not occur.

In the step 2-2, evaluate whether there is an overvoltage or low voltage after a single component failure according to the evaluation standard, and judge whether the voltage level of the power system after a single component failure affects the stable operation of wind power or even photovoltaics, thereby causing cascading failures; evaluation standard It is: if the recovery voltage of the busbar rises to 1.1p.u. after a single component failure, it is considered to affect the stable operation of wind power and photovoltaic power generation; if the busbar voltage recovery level is lower than 0.87p.u. after the failure, it is considered to affect the stable operation of the DC system.

In the step 3, the safety and stability calculation of serious faults is carried out according to the preliminary operation mode of the power system, and the scale of the safety and stability control measures of the power system is evaluated, mainly the measures of machine cutting and load shedding; if the cost of the safety and stability control measures is too large , then return to steps 1-4; if the amount of safety and stability control measures is acceptable, it is determined as the final set of power system operation modes.

The serious faults include three-phase permanent short-circuit jump double-circuit faults and DC blocking faults of the main grid frame voltage level of the power system paralleled to the pole; according to the "Technical Guidelines for Power System Safety and Stability Control" When the safety and stability of the power system is damaged, take measures to cut the machine at the sending end or shed the load at the receiving end to prevent the power system from collapsing. If the amount of safety and stability control measures exceeds the amount of power transfer or loss after a serious fault, it is considered that the cost of safety and stability control measures is too high , otherwise, it is considered that the amount of security and stability control measures is acceptable.

Compared with prior art, the beneficial effect of the present invention is:

The method for determining the operation mode of a power system in a complex energy environment provided by the present invention aims at the problem of arranging energy bases for bundling and sending out wind and power, and through the analysis of the characteristics of wind and power new energy sending grids, various start-up combinations can be used. The failure analysis in this mode minimizes the amount of security control measures for the system after a serious failure and creates favorable conditions for system recovery after a failure, under the condition of ensuring that the system meets the requirements of N-1 after a failure.

Description of drawings

Fig. 1 is a flow chart of a method for determining the operation mode of a power system in a complex energy environment provided by the present invention;

Fig. 2 is a schematic diagram of the grid structure in the calculation of the embodiment of the present invention;

Fig. 3 is the 750kV busbar voltage curve of Dongjiao-Turpan N-2 part under the original mode in the calculation of the embodiment of the invention;

Fig. 4 is the voltage curve of the 750kV busbar in Dongjiao-Turpan N-2 in the calculation of the embodiment of the invention after considering the arrangement method of the system operation mode under the complex energy environment of wind and fire.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the present invention provides a method for determining the operation mode of a power system in a complex energy environment, where the complex energy environment is an environment with wind power, photovoltaic power and thermal power, including the following steps:

Step 1: Generate the preliminary operation mode of the power system and determine the control range of the bus voltage;

Step 1-1: According to the annual load curve, load forecast and power system load capacity, determine the annual maximum value of power supply demand for heavy load or the annual minimum value of power supply demand for small load;

Step 1-2: According to the respective installed capacity and geographical distribution of wind power, photovoltaic and thermal power units in the power system, combined with the seasonal characteristics determined by the method, various power generation combinations are generated;

Generation collection includes wind power generation, photovoltaic power generation or thermal power generation;

1) Wind power generation method: the actual output of wind power reaches more than 45% of the installed capacity of wind power, and other insufficient power is borne by thermal power and photovoltaic power generation;

2) Photovoltaic power generation method: The actual output of photovoltaic power reaches more than 80% of the installed capacity of photovoltaic power generation, and other insufficient power is borne by thermal power and wind power;

3) Large-scale generation of thermal power: the actual output of thermal power reaches more than 90% of the installed capacity of thermal power; other insufficient power is borne by wind power and photovoltaics.

Step 1-3: Calculate the power transmission capacity limit of each section of the power system according to the generated various power generation combinations;

The process of calculating the transmission capacity limit of each section of the power system is as follows: first determine the composition of the section, gradually increase the power-on capacity of the sending end, and reduce the power-on capacity of the receiving end; then check the N-1 fault until the system becomes unstable; finally calculate the power transmission capacity limit of the section .

Steps 1-4: Compare the difference in transmission capacity limit of each section of the power system under different power generation combinations, optimize a reasonable power generation combination, and generate a preliminary operation mode of the power system;

In the steps 1-4, according to the principle of the influence of the power generation set on the transmission capacity, the power generation combination is optimized according to the following criteria;

1) The power transmission capacity limit of each section meets the transmission and reception capacity requirements of each section determined by the load capacity in step A and the geographical distribution in step B;

2) Reduce the interaction between the transmission capacity limits of each section, and avoid the significant decline in the transmission capacity limits of other related sections when the power transmission scale of some sections is large.

Steps 1-5: According to the generated preliminary operation mode of the power system, determine the bus voltage control range.

According to the preliminary operation mode of the generated power system, the safety and stability constraints of the power system are introduced to determine the control range of the bus voltage, so as to achieve the goal of ensuring the safety and stability of the power system and pre-controlling the voltage fluctuation range after a fault;

The power system safety and stability constraints refer to the operation mode of the power system meeting the requirements of the "Guidelines for Stability of Electric Power Systems"; the bus voltage control range refers to the bus voltage meeting the requirements of the "Technical Guidelines for Power System Voltage and Reactive Power".

Step 2: Carry out a single component safety and stability calculation and evaluate it;

Step 2-1: According to the generated preliminary operation mode of the power system, perform safety and stability calculations for a single component, and evaluate whether it satisfies the power system safety and stability constraints; if yes, proceed to step 2-2; if not, return to step 1 -4;

The standard for evaluating whether a single component meets the security and stability constraints of the power system is: the operation mode of the power system meets the requirements of the "Guidelines for Stability of Power Systems", that is, after a single component fault disturbance occurs in the power system under normal operation mode, the protection, switching and reclosing are correct. Action, do not take stability control measures, maintain stable operation of the power system and normal power supply of the power system, other components do not exceed the specified accident overload capacity, and continuous tripping does not occur.

Step 2-2: Determine whether the voltage level of the power system after a single component failure affects the stable operation of wind power, photovoltaics or even related DC systems, thereby causing cascading failures; if there is an impact, return to steps 1-5; if there is no impact, perform steps 3.

According to the evaluation standard, evaluate whether there is an overvoltage or low voltage after a single component failure, and judge whether the voltage level of the power system after a single component failure affects the stable operation of wind power or even photovoltaics, thereby causing cascading failures; the evaluation standard is: if a single component fails, the busbar When the recovery voltage rises to 1.1p.u., it is considered to affect the stable operation of wind power and photovoltaic power generation; if the bus voltage recovery level is lower than 0.87p.u. after the fault, it is considered to affect the stable operation of the DC system.

Step 3: Carry out safety and stability calculations under the impact of severe faults, and determine the final power system operation mode.

Carry out safety and stability calculations for serious faults based on the preliminary operation mode of the power system, and evaluate the scale of power system safety and stability control measures, mainly for machine cutting and load shedding measures; if the cost of safety and stability control measures is too high, return to step 1- 4. If the amount of safety and stability control measures is acceptable, it is determined as the final set of power system operation modes.

The serious faults include three-phase permanent short-circuit jump double-circuit faults and DC blocking faults of the main grid frame voltage level of the power system paralleled to the pole; according to the "Technical Guidelines for Power System Safety and Stability Control" When the safety and stability of the power system is damaged, take measures to cut the machine at the sending end or shed the load at the receiving end to prevent the power system from collapsing. If the amount of safety and stability control measures exceeds the amount of power transfer or loss after a serious fault, it is considered that the cost of safety and stability control measures is too high , otherwise, it is considered that the amount of security and stability control measures is acceptable.

Taking the coordinated optimization of wind power and thermal power cut-off strategies after the power system failure shown in Figure 2 as an example, there are the following embodiments:

A. Build the Northwest power system research level annual data as the research basis, and the power flow schematic diagram is shown in Figure 1.

B. Digital simulation shows that the operating power of the Dongjiao-Turpan line is 2910MW. After the N-2 fault occurs on the Dongjiao-Turpan line, the Xinjiang main network will be disconnected from the first and second outgoing channels. The specific simulation results are shown in Figure 2 Show. From the simulation results, it can be seen that the frequency of the two parts of the power system is within a stable range after decoupling; however, due to the direct reduction of the power flow at each section of the first and second channels due to the disconnection, the 750kV bus voltage of the channel has mostly exceeded 1p.u. (800kV). At the same time, the voltages of the 500kV converter bus of Harbin-Zhengjiang DC and the 330kV converter bus of Qinghai-Tibet DC exceeded the maximum extreme voltage limit of 550kV and 363kV required by the design manual respectively, affecting the reliable operation of the two DCs.

C. According to the situation after the fault, adjust the basic mode, adjust the controllable high resistance on the Shazhou-Yuka line to 156Mvar, leaving a controllable margin of 234Mvar; adjust the controllable high resistance on the Dunhuang bus to 150Mvar, leaving The controllable margin is 150Mvar; the substations in Dunhuang, Qaidam, Jiuquan, Riyueshan, Hami, Hami, and Turpan have all been adjusted. Refer to Table 1 for the adjustment comparison table of the methods. After the method is adjusted, the situation after the Dongjiao-Turpan N-2 fault is analyzed again. After the Dongjiao-Turpan N-2 fault occurs, the 234Mvar controllable high-resistance reserved on the Shazhou-Yuka line is put into operation, and the Dunhuang bus The reserved 150Mvar was put into operation, and all the reactances in Dunhuang, Qaidam and Jiuquan substations were put into operation. See Figure 3 for the results.

Table 1

D. Digital simulation shows that after the N-2 fault occurred on the Eastern Suburb-Turpan line, the 800kV bus and 500kV bus, diesel The voltage of Damu 800kV busbar and 330kV busbar has dropped below 1.0p.u., which can meet the system operation requirements.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the scope of the claims of the present invention.

Claims (11)

1. A method for determining the operation mode of an electric power system under a complex energy environment, wherein the complex energy environment is an environment in which wind power, photovoltaic power and thermal power have both, and is characterized in that: the method comprises the following steps: Step 1: Generate the preliminary operation mode of the power system and determine the control range of the bus voltage; Step 2: Carry out the safety and stability calculation of a single component, and evaluate the single component; Step 3: Carry out safety and stability calculations under the impact of severe faults, and determine the final power system operation mode. 2. The method for determining the operation mode of a power system in a complex energy environment according to claim 1, wherein said step 1 comprises the following steps: Step 1-1: According to the annual load curve, load forecast and power system load capacity, determine the annual maximum value of power supply demand for heavy load or the annual minimum value of power supply demand for small load; Step 1-2: According to the respective installed capacity and geographical distribution of wind power, photovoltaic and thermal power units in the power system, combined with the seasonal characteristics determined by the method, various power generation combinations are generated; Step 1-3: Calculate the transmission capacity limit of each section of the power system according to the generated various power generation combinations; Step 1-4: Compare the differences in transmission capacity limit of each section of the power system under different power generation combinations, optimize a reasonable power generation combination, and generate a preliminary operation mode of the power system; Step 1-5: According to the generated preliminary operation mode of the power system, determine the bus voltage control range. 3. The method for determining the operation mode of a power system in a complex energy environment according to claim 2, characterized in that: in the step 1-2, the power generation set includes wind power generation, photovoltaic power generation or thermal power generation . 4. The method for determining the operation mode of a power system in a complex energy environment according to claim 2, characterized in that: in the step 1-3, the process of calculating the transmission capacity limit of each section of the power system is: first determine the composition of the section, Gradually increase the power-on capacity of the sending end and reduce the power-on capacity of the receiving end; then check N-1 faults until the system becomes unstable; finally calculate the transmission capacity limit of the section. 5. The method for determining the operation mode of a power system in a complex energy environment according to claim 2, characterized in that: in said step 1-4, according to the principle of the influence of generation aggregation on power transmission capacity, the generation combination is optimized according to the following criteria ; 1) The power transmission capacity limit of each section meets the transmission and reception capacity requirements of each section determined by the load capacity in step 1-1 and the geographical distribution in step 1-2; 2) Reduce the interaction between the transmission capacity limits of each section, and avoid the significant decline in the transmission capacity limits of other related sections when the power transmission scale of some sections is large. 6. The method for determining the operation mode of the power system in a complex energy environment according to claim 2, characterized in that: in the step 1-5, for the generated preliminary operation mode of the power system, the safety and stability constraints of the power system are introduced to determine Bus voltage control range, to achieve the goal of ensuring the safety and stability of the power system and pre-controlling the range of voltage fluctuations after faults; The power system safety and stability constraints refer to the operation mode of the power system meeting the requirements of the "Guidelines for Stability of Electric Power Systems"; the bus voltage control range refers to the bus voltage meeting the requirements of the "Technical Guidelines for Power System Voltage and Reactive Power". 7. The method for determining the operation mode of a power system in a complex energy environment according to claim 2, wherein said step 2 comprises the following steps: Step 2-1: According to the generated preliminary operation mode of the power system, carry out the safety and stability calculation of a single component, and evaluate whether it satisfies the safety and stability constraints of the power system; if it is satisfied, proceed to step 2-2; if not, return to step 1 -4; Step 2-2: Determine whether the voltage level of the power system after a single component failure affects the stable operation of wind power, photovoltaics or even related DC systems, thereby causing cascading failures; if there is an impact, return to step 1-5; if there is no impact, execute step 3. 8. The method for determining the operation mode of the power system in a complex energy environment according to claim 7, characterized in that: in the step 2-1, evaluating whether a single component meets the security and stability constraint standard of the power system is: the operation mode of the power system Meet the requirements of the "Guidelines for Stability of Power Systems", that is, after a single component fault disturbance occurs in the power system under normal operation, the protection, switching and reclosing will act correctly, and no stability control measures will be taken to maintain the stable operation of the power system and the stability of the power system Normal power supply, other components do not exceed the specified accident overload capacity, and continuous tripping does not occur. 9. The method for determining the operation mode of a power system in a complex energy environment according to claim 7, characterized in that: in the step 2-2, whether there is an overvoltage or low voltage after a single component failure is evaluated according to the evaluation standard, Judging whether the voltage level of the power system after a single component failure affects the stable operation of wind power or even photovoltaic power generation, thereby causing cascading failures; the evaluation standard is: if the bus recovery voltage rises to 1.1p.u. after a single component failure, it is considered to affect the stable operation of wind power and photovoltaic power generation ; If the recovery level of the bus voltage after the fault is lower than 0.87p.u., it is considered to affect the stable operation of the DC system. 10. The method for determining the operation mode of a power system in a complex energy environment according to claim 2, characterized in that: in said step 3, the safety and stability of serious faults are calculated according to the preliminary operation mode of the power system, and the safety and stability of the power system is evaluated The scale of control measures is mainly the amount of machine cutting and load shedding measures; if the cost of safety and stability control measures is too large, return to step 1-4; if the amount of safety and stability control measures is acceptable, it is determined as the final power system operation way collection. 11. The method for determining the operation mode of a power system in a complex energy environment according to claim 10, characterized in that: the serious fault includes a three-phase permanent short circuit jumping double circuit of the main grid frame of the power system with the same pole and parallel erection line Faults and DC blocking faults; according to the "Technical Guidelines for Power System Safety and Stability Control" standard, if a serious fault occurs in the power system and the safety and stability of the power system is damaged, measures to cut the machine at the sending end or load at the receiving end are taken to prevent the power system from collapsing. If the amount of safety and stability control measures exceeds the amount of power transfer or loss after a severe fault, the cost of safety and stability control measures is considered to be too high; otherwise, the amount of safety and stability control measures is considered acceptable.