Multi-level transient stability online prediction and optimization control system and method for provincial, prefecture and county stations

Abstract

The present invention discloses a multi-level transient stability online prediction and optimization control system and method for provincial, prefectural and county stations, which includes a provincial dispatching monitoring master station connected to a prefectural dispatching monitoring sub-station; the prefectural dispatching monitoring sub-station is connected to a control master station; the control master station is respectively connected to control sub-stations; the control sub-stations include a wind power control sub-stations, b photovoltaic control sub-stations, c small hydropower control sub-stations, d large hydropower control sub-stations, e thermal power control sub-stations, f prefectural dispatching sub-stations and g county dispatching sub-stations; the prefectural dispatching monitoring sub-station is connected to the county dispatching monitoring sub-station; it solves the technical problems in the prior art that in the regional power grid, the management authorities and the jurisdiction scopes of each level of dispatching departments are different, and the power grid operation scopes they need to understand and pay attention to are also different, and the complexity, security and reliability of the transmission information of the stability control system have not been fully emphasized.

Description

Technical Field

[0001] The present invention belongs to the technical field of power system stability control, and particularly relates to a multi-level transient stability online prediction and optimization control system and method for provincial, regional and county substations. Background Art

[0002] Regarding the impact of large-scale small hydropower, wind power or photovoltaic power generation connected to the grid on the safety and stability of the power grid and the research and development of supporting stability control systems, the existing online pre-decision technologies mainly carry out relevant research work for large interconnected power systems. However, there is still little research on the online safety and stability control technology for combined power generation systems containing various intermittent energy sources such as wind, light, large-scale small hydropower, and coalbed methane. The randomness and volatility of intermittent energy sources such as wind power and photovoltaic power generation on the safe and stable operation of the system are not fully considered. Moreover, intermittent energy sources such as wind and light are different from conventional synchronous power generation technologies, and their unit types, unit controls, grid connection modes, etc. will bring a series of impacts on the formulation of safety and stability control strategies.

[0003] The safety and stability control system of the power system is one of the main measures to ensure the safe and stable operation of the power grid. The traditional safety and stability control system adopts the technical route of "offline calculation and online matching". Its disadvantages are that the offline calculation workload is large, it is almost impossible to accurately match the operating conditions of the actual system with the pre-set conditions, and the strategy table must be recalculated and verified after the grid structure changes. Moreover, when major changes occur in the power system, repetitive and cumbersome calculations and adjustments of the strategy table are required, and the operation and maintenance tasks are extremely heavy. At the same time, in the regional power grid, the management authorities and jurisdiction scopes of each level of dispatching departments are different, and the grid operation scopes they need to understand and pay attention to are also different. The complexity, security of the transmission network of the stability control system and the reliability of the transmitted information have not been fully emphasized. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a multi-level transient stability online prediction and optimization control system and method for provincial, regional and county substations, so as to solve the problems in the prior art that in the regional power grid, the management authorities and jurisdiction scopes of each level of dispatching departments are different, and the grid operation scopes they need to understand and pay attention to are also different. The complexity, security of the transmission network of the stability control system and the reliability of the transmitted information have not been fully emphasized; the offline calculation workload of the safety and stability control is large, it is almost impossible to accurately match the operating conditions of the actual system with the pre-set conditions, and the strategy table must be recalculated and verified after the grid structure changes. Moreover, when major changes occur in the power system, repetitive and cumbersome calculations and adjustments of the strategy table are required, and the operation and maintenance tasks are extremely heavy and other technical problems.

[0005] Technical Solution of the Present Invention

[0006] A multi-level transient stability online prediction and optimization control system for provincial, prefectural, and county-level stations, which includes a provincial dispatching monitoring master station, and the provincial dispatching monitoring master station is connected to the prefectural dispatching monitoring sub-station; the prefectural dispatching monitoring sub-station is connected to the control master station; the control master station is respectively connected to the control sub-stations; the control sub-stations include a wind power control sub-stations, b photovoltaic control sub-stations, c small hydropower control sub-stations, d large hydropower control sub-stations, e thermal power control sub-stations, f prefectural dispatching substation control sub-stations, and g county dispatching substation control sub-stations; the prefectural dispatching monitoring sub-station is connected to the county dispatching monitoring sub-station.

[0007] Each of the a wind power control sub-stations, b photovoltaic control sub-stations, c small hydropower control sub-stations, d large hydropower control sub-stations, and e thermal power control sub-stations includes a stability control sub-station terminal, an in-station line protection and measurement and control device, an in-station regional power grid out-of-step splitting device, an in-station unit measurement and control device, an in-station bus measurement and control device, an in-station DC feeder panel, an in-station common measurement and control panel, and a digital distribution interface device; the stability control sub-station terminal is connected in series with the current loop of the in-station line protection and measurement and control device; the stability control sub-station terminal is connected in parallel with the voltage loop of the in-station line protection and measurement and control device; the stability control sub-station terminal is connected to the trip loop of the in-station line protection and measurement and control device or the in-station regional power grid out-of-step splitting device; the stability control sub-station terminal is connected to the in-station unit measurement and control device; the stability control sub-station terminal is connected in parallel with the voltage loop of the in-station bus measurement and control device; the stability control sub-station terminal is connected to the in-station DC feeder panel; the stability control sub-station terminal is connected to the in-station common measurement and control panel; the stability control sub-station terminal is connected to the communication interface device through an optical fiber, and the communication interface device is connected to the digital distribution interface device through a coaxial cable.

[0008] Each of the f prefectural dispatching substation control sub-stations and g county dispatching substation control sub-stations includes: a stability control sub-station terminal, an in-station line protection and measurement and control device, an in-station bus measurement and control device, an in-station DC feeder panel, an in-station common measurement and control panel, and a digital distribution interface device; the stability control sub-station terminal is connected in series with the current loop of the in-station line protection and measurement and control device; the stability control sub-station terminal is connected in parallel with the voltage loop of the in-station line protection and measurement and control device; the stability control sub-station terminal is connected to the trip loop of the in-station line protection and measurement and control device, used to issue generator tripping or load shedding commands and obtain the operating switch quantity information of the line; the stability control sub-station terminal is connected in parallel with the voltage loop of the in-station bus measurement and control device; the stability control sub-station terminal is connected to the in-station DC feeder panel; the stability control sub-station terminal is connected to the in-station common measurement and control panel; the stability control sub-station terminal is connected to the communication interface device through an optical fiber, and the communication interface device is connected to the digital distribution interface device through a coaxial cable.

[0009] The control master station includes a stability control master station device, an in-station common measurement and control panel, an in-station DC feeder panel, a digital distribution interface device, a stability control communication interface device, and a dedicated line router; the stability control master station device is connected to the in-station common measurement and control panel; the stability control master station device is connected to the in-station DC feeder panel; the stability control master station device is connected to the communication interface device through a tail fiber, and the communication interface device is connected to the digital distribution interface device through a coaxial cable; the stability control master station device is connected to the stability control communication interface device through an optical fiber, and the stability control communication interface device is connected to the dedicated line router in the regional power grid optical transmission equipment panel through a network cable.

[0010] The control method of a multi-level transient stability online prediction and optimization control system for provincial, regional, and county stations includes:

[0011] Step 1: N control sub-stations upload the collected power grid operation information to the control master station;

[0012] Step 2: Set the voltage instability criterion threshold Vξ of the power grid, the integration threshold Aμ for real-time collection of wide-area voltage values, the lowest threshold V of the unstable voltage trajectory swing voltage L and the integration termination threshold A of the unstable voltage set ;

[0013] Step 3: By obtaining in real time the power grid operation information collected in Step 1 and extracting the wide-area voltage information of the power grid, and comparing it with the voltage instability criterion threshold Vξ of the power grid, if the real-time collected wide-area voltage value V(t) of the power grid is less than or equal to the voltage instability criterion threshold Vξ of the power grid, it is judged that the power grid is in a stable state; if the real-time collected wide-area voltage value V(t) of the power grid is greater than the voltage instability criterion threshold Vξ of the power grid, go to Step 4;

[0014] Step 4: Calculate the integral value A of the real-time collected wide-area voltage value V(t), and compare it with the integration threshold Aμ of the real-time collected wide-area voltage value. If the integral value A of the real-time collected wide-area voltage value V(t) is greater than or equal to the integration threshold Aμ of the real-time collected wide-area voltage value, return to Step 1; if the integral value A of the real-time collected wide-area voltage value V(t) is less than the integration threshold Aμ of the real-time collected wide-area voltage value, go to Step 5;

[0015] Step 5: Judge whether the voltage is in the allowable fluctuation stage. When the criterion conditions are met, return to Step 1; when the criterion conditions are not met, it is considered to be in the allowable fluctuation stage and go to Step 6;

[0016] Step 6: Obtain the real-time collected wide-area voltage value V2(t) of the power grid and compare it with the non-standard voltage reference value V u ; when the real-time collected wide-area voltage value V2(t) of the power grid is greater than or equal to the non-standard voltage reference value V u If, within a continuous βT time, V2(t) is greater than V u, it is determined that the system is transiently stable. Within a continuous βT time, V2(t) is not completely greater than or equal to V u , it is determined that there is a local low voltage situation in the system; when the wide - area voltage value V2(t) collected in real - time by the power grid is less than the non - standard voltage reference value V u , then go to step 7;

[0017] Step 7: Calculate the voltage integral value A p , and let A P be compared with the lowest threshold value V of the swing voltage of the unstable voltage trajectory. When A L is less than the lowest threshold value V of the swing voltage of the unstable voltage trajectory P L , then take the value A q = A p , and enter step 8;

[0018] Step 8: Compare A q with the termination threshold value A of the unstable voltage integral set . When A q is less than the termination threshold value A of the unstable voltage integral set , then return to step 6 for recalculation; when A q is greater than or equal to the termination threshold value A of the unstable voltage integral set , then it is determined that the system is transiently unstable, and enter step 9;

[0019] Step 9: When the master control station determines that the system is unstable, send the control sub - station corresponding to V2(t) to the stable control device to act, for generator tripping or load shedding.

[0020] The power grid operation information described in step 1 includes the three - phase current values, three - phase voltage values and frequency information of the lines, the operation switch quantity information of the lines, the operation conditions of the units and the information of the units that can be tripped, the operation information of the units, and the three - phase voltage values and frequency information of all voltage - level busbars in the substation.

[0021] The formula for calculating the integral value A of the wide - area voltage value V(t) collected in real - time is:

[0022]

[0023] In formula (1), A is the integral value of the wide - area voltage value V(t) collected in real - time, t0 is the initial value of the integral time of the wide - area voltage value V(t) collected in real - time; t end is the termination value of the integral time of the wide - area voltage value V(t) collected in real - time; V u is the non - standard voltage reference value, that is, the starting voltage of the integral.

[0024] The formula for judging whether the voltage is in the allowable fluctuation stage is:

[0025] ​

[0026] Where: ΔV(t) = V(t) - V(t - T), T is the sampling time, and V(t - T) is the voltage value at the previous sampling moment; when |ΔV(t)| - |ΔV(t - T)| does not meet the criterion condition of formula (2), it is considered the allowable fluctuation stage.

[0027] Voltage integral value A p and the voltage integral value A q The calculation formula is:

[0028]

[0029]

[0030] Advantages of the present invention:

[0031] The present invention sets up a control master station, collects the information of the wind power control sub-station, photovoltaic control sub-station, small hydropower control sub-station, large hydropower control sub-station, thermal power control sub-station, sub-transmission sub-station control sub-station of the local power grid, and sub-transmission sub-station control sub-station of the county power grid to the master station, and makes a centralized online judgment by the master station. When the master station system judges that the system is unstable, it issues the action of the stability control device corresponding to V2(t) to cut off generators or shed loads; it has the advantages of being real-time, fast, and accurate; it solves the technical problems in the prior art that the offline calculation workload of the safety and stability control is large, it is almost impossible to accurately match the operating conditions of the actual system with the pre-set conditions, it is necessary to recalculate and check the strategy table after the grid structure changes, and when major changes occur in the power system, it is necessary to perform repeated and cumbersome calculations and adjustments of the strategy table, and the operation and maintenance tasks are extremely heavy.

[0032] The present invention constructs a transient stability online prediction and optimization emergency control system based on wide-area response including a control master station, a wind power control sub-station, a photovoltaic control sub-station, a small hydropower control sub-station, a large hydropower control sub-station, a thermal power control sub-station, a sub-transmission sub-station control sub-station of the local power grid, and a sub-transmission sub-station control sub-station of the county power grid. It does not need to formulate a control strategy set according to offline calculation, upload the electrical quantities and switch quantities and other information of the control sub-station to the control master station for online calculation, and make an online judgment with the voltage instability criterion threshold Vξ of the power grid, the integral threshold Aμ of the real-time collected wide-area voltage value, the lowest threshold V of the swing voltage of the unstable voltage trajectory L and the termination threshold A of the unstable voltage integral set and other indicators. At the same time, a provincial dispatching monitoring master station, a local dispatching monitoring sub-station, and a county dispatching monitoring sub-station are respectively set up to effectively monitor the stable operation of the power grid within the scope of management and jurisdiction of each dispatching agency according to the management authority and jurisdiction scope of each dispatching agency.

[0033] The present invention connects the provincial dispatching monitoring master station with the local dispatching monitoring sub-station; connects the local dispatching monitoring sub-station with the control master station; connects the local dispatching monitoring sub-station with the county dispatching monitoring sub-station; enabling the provincial dispatching monitoring master station, the local dispatching monitoring sub-station and the county dispatching monitoring sub-station to implement the information of the control master station, conduct information interaction with the control sub-station, enabling the monitoring sub-station to real-time control the information of the control master station, and monitor the control master station and the following control sub-stations; solving the technical problems in the prior art that in the regional power grid, the management authorities and the jurisdiction scopes of each level of dispatching departments are different, the power grid operation scopes that need to be understood and concerned are also different, and the complexity, security and reliability of the transmission information of the stability control system have not been fully emphasized. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic structural diagram of the present invention;

[0035] Figure 2 It is a schematic structural diagram of the photovoltaic, wind power, small hydropower, large hydropower, and thermal power control sub-stations;

[0036] Figure 3 It is a schematic structural diagram of the local dispatching sub-station and the county dispatching sub-station control sub-stations;

[0037] Figure 4 It is a schematic flow diagram of the control method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0038] A multi-level transient stability online prediction and optimization control system and method for provincial, local and county stations, which includes a provincial dispatching monitoring master station, a local dispatching monitoring sub-station, a county dispatching monitoring sub-station, a control master station and N control sub-stations.

[0039] Among them, the N control sub-stations include a wind power control sub-stations, b photovoltaic control sub-stations, a small hydropower control sub-station, d large hydropower control sub-stations, e thermal power control sub-stations, f local dispatching sub-station control sub-stations and g county dispatching sub-station control sub-stations.

[0040] Among them, a + b + c + d + e + f + g = N.

[0041] Among them, a wind power control sub-stations, b photovoltaic control sub-stations, c small hydropower control sub-stations, d large hydropower control sub-stations, e thermal power control sub-stations, each control sub-station includes a stability control sub-station terminal in the control sub-station, as well as an in-station line protection and measurement and control device, an in-station regional power grid out-of-step splitting device, an in-station unit measurement and control device, an in-station bus measurement and control device, an in-station DC feeder panel, an in-station common measurement and control panel, a digital distribution interface device, etc.;

[0042] The stability control sub-station terminal is connected in series with the current loop of the in-station line protection and measurement and control device for collecting the three-phase current value of the line;

[0043] The voltage circuit of the stability control substation terminal is connected in parallel with the in-station line protection and measurement and control device, and is used to collect the three-phase voltage values and frequency information of the line;

[0044] The trip circuit of the stability control substation terminal is connected to the in-station line protection and measurement and control device or the in-station regional power grid out-of-step splitting device, and is used to issue generator tripping commands and obtain the operating switch quantity information of the line;

[0045] The stability control substation terminal is connected to the in-station unit measurement and control device, and is used to collect the unit operating conditions and the information of the generators that can be tripped, and the unit operating information; the unit operating information includes voltage, current, power, power angle, and frequency.

[0046] The voltage circuit of the stability control substation terminal is connected in parallel with the in-station bus measurement and control device, and is used to collect the three-phase voltage values and frequency information of all voltage levels of the in-station buses;

[0047] The stability control substation terminal is connected to the in-station DC feeder panel, and is used to obtain the device power supply of the stability control substation terminal;

[0048] The stability control substation terminal is connected to the in-station common measurement and control panel, and is used to transmit the locking of the in-station PMU device, the abnormality of the in-station PMU device, the locking of the stability control substation terminal, the alarm of the stability control substation terminal, the locking of the stability control substation terminal, the action of the stability control substation terminal, and the channel alarm of the stability control substation terminal.

[0049] The stability control substation terminal is connected to the communication interface device through an optical fiber pigtail, and the communication interface device is connected to the digital distribution interface device through a coaxial cable, and is used to interactively transmit information with the control master station of the wide-area response-based transient stability online prediction and optimized emergency control system.

[0050] Among them, there are f sub-control stations of the local power dispatching substations and g sub-control stations of the county power dispatching substations. Each control sub-station includes the stability control substation terminal in the control sub-station, as well as the in-station line protection and measurement and control device, the in-station bus measurement and control device, the in-station DC feeder panel, the in-station common measurement and control panel, the digital distribution interface device, etc.;

[0051] The current circuit of the stability control substation terminal is connected in series with the in-station line protection and measurement and control device, and is used to collect the three-phase current values of the line;

[0052] The voltage circuit of the stability control substation terminal is connected in parallel with the in-station line protection and measurement and control device, and is used to collect the three-phase voltage values and frequency information of the line;

[0053] The trip circuit of the stability control substation terminal is connected to the in-station line protection and measurement and control device, and is used to issue generator tripping or load shedding commands and obtain the operating switch quantity information of the line;

[0054] The voltage circuit of the stability control substation terminal is connected in parallel with the in-station bus measurement and control device, and is used to collect the three-phase voltage values and frequency information of all voltage levels of the in-station buses;

[0055] The stability control substation terminal is connected to the in-station DC feeder panel for obtaining the device power supply of the stability control substation terminal.

[0056] The stability control substation terminal is connected to the in-station common measurement and control panel for transmitting the locking of the in-station PMU device, the abnormality of the in-station PMU device, the locking of the stability control substation terminal, the alarm of the stability control substation terminal, the locking of the stability control substation terminal, the action of the stability control substation terminal, and the channel alarm of the stability control substation terminal.

[0057] The stability control substation terminal is connected to the communication interface device through an optical fiber pigtail. The communication interface device is connected to the digital distribution interface device through a coaxial cable for interactive transmission of information with the control master station of the wide-area response-based transient stability online prediction and optimization emergency control system.

[0058] (Among them, the control master station includes a stability control master station device, an in-station common measurement and control panel, an in-station DC feeder panel, a digital distribution interface device, a stability control communication interface device, and a telecontrol dedicated line router.

[0059] The stability control master station device consists of two levels, including a data interaction layer and a decision-making layer, to realize the generation and issuance of transient discrimination and generator tripping commands; the core of the data interaction layer realizes the reception of collected information and the issuance of generator tripping commands, and the functional modules of the data interaction layer include a data acquisition module and a control command issuance module; the core of the decision-making layer realizes the discrimination of transient instability and gives the generator tripping strategy, and the functional modules of the decision-making layer include a transient instability discrimination module.

[0060] The stability control master station device includes one relational database server and one real-time database server to realize data processing; the relational database server also serves as a computing / application server to realize the computing and application services of the system; one acquisition server is also provided to realize data acquisition.

[0061] The stability control master station device is connected to the in-station common measurement and control panel for transmitting the alarm of the stability control master station device, the locking of the stability control master station device, the action of the stability control master station device, and the channel alarm of the stability control master station device.

[0062] The stability control master station device is connected to the in-station DC feeder panel for obtaining the device power supply of the stability control master station device.

[0063] The stability control master station device is connected to the communication interface device through an optical fiber pigtail. The communication interface device is connected to the digital distribution interface device through a coaxial cable for interactive transmission of information with the control substation of the wide-area response-based transient stability online prediction and optimization emergency control system.

[0064] According to the different management authorities and jurisdiction scopes of each dispatching department in the power grid, the power grid operation scopes that need to be understood and concerned about are also different.

[0065] The stability control master station device of the control master station is connected to the stability control communication interface device through optical fiber. The stability control communication interface device is connected to the remote control dedicated line router in the regional power grid optical transmission equipment screen through network cable, and is uploaded to the local dispatching monitoring sub-station through the dispatching data network. The local dispatching monitoring sub-station uploads all information to the provincial dispatching monitoring master station, and transmits the information under the jurisdiction of the county dispatching to the county dispatching monitoring sub-station through the dispatching data network according to the dispatching management authority.

[0066] The control method of the multi-level transient stability online prediction and optimization control system for provincial, local and county stations includes:

[0067] Step 1: N control sub-stations upload the collected power grid operation information to the control master station;

[0068] Step 2: Set the voltage instability criterion threshold Vξ of the power grid, the integral threshold Aμ for real-time acquisition of wide-area voltage values, the lowest threshold V of the unstable voltage trajectory swing voltage L and the integral termination threshold A of the unstable voltage set ;

[0069] Step 3: By obtaining the power grid operation information collected in Step 1 in real time, extracting the wide-area voltage information of the power grid, and comparing it with the voltage instability criterion threshold Vξ of the power grid. If the real-time acquired wide-area voltage value V(t) of the power grid is less than or equal to the voltage instability criterion threshold Vξ of the power grid, it is judged that the power grid is in a stable state; if the real-time acquired wide-area voltage value V(t) of the power grid is greater than the voltage instability criterion threshold Vξ of the power grid, go to Step 4;

[0070] Step 4: Calculate the integral value A of the real-time acquired wide-area voltage value V(t), and compare it with the integral threshold Aμ of the real-time acquired wide-area voltage value. If the integral value A of the real-time acquired wide-area voltage value V(t) is greater than or equal to the integral threshold Aμ of the real-time acquired wide-area voltage value, return to Step 1; if the integral value A of the real-time acquired wide-area voltage value V(t) is less than the integral threshold Aμ of the real-time acquired wide-area voltage value, go to Step 5;

[0071] Step 5: Judge whether the voltage is in the allowable fluctuation stage. When the criterion conditions are met, return to Step 1; when the criterion conditions are not met, it is considered to be in the allowable fluctuation stage and go to Step 6;

[0072] Step 6: Obtain the real-time acquired wide-area voltage value V2(t) of the power grid, and compare it with the non-standard voltage reference value V u ; When the real-time acquired wide-area voltage value V2(t) of the power grid is greater than or equal to the non-standard voltage reference value V u , if within the continuous βT time, V2(t) is greater than V u , it is judged that the system is transiently stable. Within the continuous βT time, V2(t) is not completely greater than or equal to V u, it is determined that there is a situation of relatively low local voltage in the system; when the real-time wide-area voltage value V2(t) of the power grid is less than the non-standard voltage reference value V u , then go to step 7;

[0073] Step 7: Calculate the voltage integral value A p , and take A P and compare it with the lowest threshold value V of the swing voltage of the unstable voltage trajectory L . When A P is less than the lowest threshold value V of the swing voltage of the unstable voltage trajectory L , then take the value A q =A p , and enter step 8;

[0074] Step 8: Compare A q with the termination threshold value A of the unstable voltage integral set . When A q is less than the termination threshold value A of the unstable voltage integral set , then return to step 6 for recalculation; when A q is greater than or equal to the termination threshold value A of the unstable voltage integral set , it is determined that the system is transiently unstable and enter step 9;

[0075] Step 9: When the master station judges that the system is unstable, send the stable control device action corresponding to V2(t) to the control substation for generator tripping or load shedding.

[0076] The power grid operation information described in step 1 includes the three-phase current values, three-phase voltage values and frequency information of the line, the operation switch quantity information of the line, the operation conditions of the units and the information of the units that can be tripped, the operation information of the units, and the three-phase voltage values and frequency information of all busbars of all voltage levels in the substation.

[0077] The formula for calculating the integral value A of the real-time wide-area voltage value V(t) is:

[0078]

[0079] In formula (1), A is the integral value of the real-time wide-area voltage value V(t), t0 is the initial value of the integral time of the real-time wide-area voltage value V(t); t end is the termination value of the integral time of the real-time wide-area voltage value V(t); V u is the non-standard voltage reference value, that is, the starting voltage of the integral.

[0080] The formula for judging whether the voltage is in the allowable fluctuation stage is:

[0081]

[0082] Where: ΔV(t) = V(t) - V(t - T), T is the sampling time, and V(t - T) is the voltage value at the previous sampling moment; when |ΔV(t)| - |ΔV(t - T)| does not meet the criterion condition of formula (2), it is considered to be the allowable fluctuation stage.

[0083] Voltage integral value A p and the voltage integral value A q The calculation formula is:

[0084]

[0085]

Claims

1. A control method for a multi-level transient stability online prediction and optimization control system of provincial, prefecture and county stations. The system includes a provincial dispatching monitoring master station, and is characterized in that: The provincial dispatching monitoring master station is connected to the local dispatching monitoring sub-station; the local dispatching monitoring sub-station is connected to the control master station; the control master station is respectively connected to the control sub-stations; The said control sub-stations include a wind power control sub-stations, b photovoltaic control sub-stations, c small hydropower control sub-stations, d large hydropower control sub-stations, e thermal power control sub-stations, f local dispatching substation control sub-stations and g county dispatching substation control sub-stations; The local dispatching monitoring sub-station is connected to the county dispatching monitoring sub-station; The control method includes: Step 1, N control sub-stations upload the collected power grid operation information to the control master station; Step 2: Set the voltage instability criterion threshold Vξ of the power grid, the integration threshold Aμ for real-time acquisition of wide-area voltage values, the lowest threshold V of the swing voltage of the unstable voltage trajectory L and the integration termination threshold A of the unstable voltage set ; Step 3, by obtaining in real time the power grid operation information collected in Step 1, and extracting the wide-area voltage information of the power grid, comparing it with the voltage instability criterion threshold Vξ of the power grid. If the real-time collected wide-area voltage value V(t) of the power grid is less than or equal to the voltage instability criterion threshold Vξ of the power grid, it is judged that the power grid is in a stable state; if the real-time collected wide-area voltage value V(t) of the power grid is greater than the voltage instability criterion threshold Vξ of the power grid, then enter Step 4; Step 5, calculate the integral value A of the real-time collected wide-area voltage value V(t), compare it with the integral threshold Aμ of the real-time collected wide-area voltage value. If the integral value A of the real-time collected wide-area voltage value V(t) is greater than or equal to the integral threshold Aμ of the real-time collected wide-area voltage value, return to Step 1; if the integral value A of the real-time collected wide-area voltage value V(t) is less than the integral threshold Aμ of the real-time collected wide-area voltage value, then enter Step 5; Step 6, judge whether the voltage is in the allowable fluctuation stage. When the criterion conditions are met, return to Step 1; when the criterion conditions are not met, it is considered to be in the allowable fluctuation stage and transfer to Step 6; Step 6: Obtain the real-time acquired wide-area voltage value V2(t) of the power grid and compare it with the non-standard voltage reference value V u ; When the real-time acquired wide-area voltage value V2(t) of the power grid is greater than or equal to the non-standard voltage reference value V u , if within a continuous βT time period, V2(t) is greater than V u , then it is determined that the system is transiently stable. If within a continuous βT time period, V2(t) is not completely greater than or equal to V u , then it is determined that there is a local low voltage situation in the system; When the real-time acquired wide-area voltage value V2(t) of the power grid is less than the non-standard voltage reference value V u , then proceed to Step 7; Step 7: Calculate the voltage integral value A p , A P The lowest threshold of the swing voltage V L In contrast, when A P Less than the minimum threshold of the unstable voltage trajectory swing voltage V L , then the value A q =A p , and go to step 8; Step 8: Take A q and compare it with the integral termination threshold value of the voltage instability A set . When A q is less than the integral termination threshold value of the voltage instability A set , return to Step 6 for recalculation; when A q is greater than or equal to the integral termination threshold value of the voltage instability A set , it is determined that the system experiences transient instability and proceed to Step 9; Step 9, when the control master station judges that the system is unstable, send the control sub-station corresponding to V2(t) to actuate the stability control device for generator tripping or load shedding.

2. The control method of a multi-level transient stability online prediction and optimization control system for provincial, prefectural and county stations according to claim 1, characterized in that: Each of the a wind power control sub-stations, b photovoltaic control sub-stations, c small hydropower control sub-stations, d large hydropower control sub-stations and e thermal power control sub-stations includes a stability control sub-station terminal, an in-station line protection and measurement and control device, an in-station regional power grid out-of-step splitting device, an in-station unit measurement and control device, an in-station bus measurement and control device, an in-station DC feeder panel, an in-station common measurement and control panel and a digital distribution interface device; the stability control sub-station terminal is connected in series with the current loop of the in-station line protection and measurement and control device; the stability control sub-station terminal is connected in parallel with the voltage loop of the in-station line protection and measurement and control device; the stability control sub-station terminal is connected to the trip loop of the in-station line protection and measurement and control device or the in-station regional power grid out-of-step splitting device; the stability control sub-station terminal is connected to the in-station unit measurement and control device; the stability control sub-station terminal is connected in parallel with the voltage loop of the in-station bus measurement and control device; the stability control sub-station terminal is connected to the in-station DC feeder panel; the stability control sub-station terminal is connected to the in-station common measurement and control panel; the stability control sub-station terminal is connected to the communication interface device through an optical fiber, and the communication interface device is connected to the digital distribution interface device through a coaxial cable.

3. The control method of a multi-level transient stability online prediction and optimization control system for provincial, prefectural and county stations according to claim 1, characterized in that: Each of the f sub-stations of the regional dispatching substation and the g sub-stations of the county dispatching substation includes: a stability control sub-station terminal, an in-station line protection and measurement control device, an in-station bus measurement control device, an in-station DC feeder panel, an in-station common measurement control panel, and a digital distribution interface device; the stability control sub-station terminal is connected in series with the current loop of the in-station line protection and measurement control device; the stability control sub-station terminal is connected in parallel with the voltage loop of the in-station line protection and measurement control device; the stability control sub-station terminal is connected to the trip circuit of the in-station line protection and measurement control device for issuing generator tripping or load shedding commands and obtaining the operating switch quantity information of the line; the stability control sub-station terminal is connected in parallel with the voltage loop of the in-station bus measurement control device; the stability control sub-station terminal is connected to the in-station DC feeder panel; the stability control sub-station terminal is connected to the in-station common measurement control panel; the stability control sub-station terminal is connected to the communication interface device through an optical fiber, and the communication interface device is connected to the digital distribution interface device through a coaxial cable.

4. The control method of a multi-level transient stability online prediction and optimization control system for provincial, prefectural and county stations according to claim 1, characterized in that: The control master station includes a stability control master station device, an in-station common measurement control panel, an in-station DC feeder panel, a digital distribution interface device, a stability control communication interface device, and a dedicated line router; the stability control master station device is connected to the in-station common measurement control panel; the stability control master station device is connected to the in-station DC feeder panel; the stability control master station device is connected to the communication interface device through an optical fiber, and the communication interface device is connected to the digital distribution interface device through a coaxial cable; the stability control master station device is connected to the stability control communication interface device through an optical fiber, and the stability control communication interface device is connected to the dedicated line router in the regional power grid optical transmission equipment panel through a network cable.

5. The control method of a multi-level transient stability online prediction and optimization control system for provincial, prefectural and county stations according to claim 1, characterized in that: The grid operation information described in step 1 includes the three-phase current value, three-phase voltage value, and frequency information of the line, the operating switch quantity information of the line, the operating conditions of the units and the information of the units that can be tripped, the operating information of the units, and the three-phase voltage value and frequency information of all voltage levels of the buses in the station.

6. The control method of a multi-level transient stability online prediction and optimization control system for provincial, prefectural and county stations according to claim 1, characterized in that: The formula for calculating the integral value A of the real-time collected wide-area voltage value V(t) is: In formula (1), A is the integral value of the real-time collected wide-area voltage value V(t), and t0 is the initial value of the integral time of the real-time collected wide-area voltage value V(t); t end is the integral time termination value for real-time acquisition of wide-area voltage value V(t); V u is a non-standard voltage reference value, i.e., the starting voltage of integration.

7. The control method of a multi-level transient stability online prediction and optimization control system for provincial, prefectural and county stations according to claim 1, characterized in that: The formula for judging whether the voltage is in the allowable fluctuation stage is: Where: ΔV(t) = V(t) - V(t - T), T is the sampling time, and V(t - T) is the voltage value at the previous sampling moment; when |ΔV(t)| - |ΔV(t - T)| does not meet the criterion condition of formula (2), it is considered to be in the allowable fluctuation stage.

8. The control method of a multi-level transient stability online prediction and optimization control system for provincial, prefectural and county stations according to claim 1, characterized in that: Voltage integral value A p and voltage integral value A q The calculation formula is as follows:

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