Power grid evolution trend analysis method
Technical Field
The invention belongs to the technical field of power systems, and particularly relates to a power grid evolution trend analysis method.
Background
With the increasingly large and complex power grid structures of power systems, the safety and stability analysis of the power grid has certain difficulties, and dispatchers urgently need an auxiliary tool which can analyze the steady-state characteristics of the system, analyze the dynamic characteristics of the system, judge the state of the current system and give recent operation guidance. Due to the rapid development of computer performance, network and communication technology, it becomes possible to construct large-scale computer groups in the field of power engineering to perform high-speed operation and obtain measurement data of a wide area, so that the system is an important basis for scheduling decisions of dispatchers for application and popularization of online stable monitoring and early warning systems in power systems. In recent years, major power failure accidents are continuous, the safe operation of a power system is threatened, and the social hazard and the economic loss caused by the continuous major power failure accidents are difficult to estimate. In order to better guarantee the reliable operation of the power system, it is necessary to perform safety evaluation on the system. Therefore, the power system can stably and reliably operate, and is of great importance, and the working stability and safety of the power grid are improved. Firstly, by utilizing the trend of the online power grid, the stability characteristics and safety indexes of the short-term future state are evaluated online, and the change conclusion of the online operation trend of the power grid is given.
The online stability analysis system of the power system is an analysis system which is based on the current running state of the power system, comprehensively analyzes and evaluates the safety and stability of the system and provides early warning and guidance for potential threats to dispatching personnel. The online stability monitoring can perform various static and dynamic stability monitoring on the current time section, remind operating personnel of various possible safety threats, provide operation guidance based on the current operation state, and the online transmission limit analysis is an important aspect. As is well known, the harmonic content of the power grid is improved year by year, and no evolution analysis method system exists before, so that problems in the production process cannot be intuitively analyzed, and a solution suggestion cannot be given to power grid workers in time. Aiming at the situation, a power grid evolution trend analysis system technology is developed, so that the comprehensive management and prediction capability of the power system problem is greatly accelerated.
At present, technologies and patents are rarely specially designed for checking the operation trend of a power grid, and a general checking method is not combined with the operation rule and characteristics of the actual power grid, so that the practicability of the checking method is not high.
Disclosure of Invention
Based on the technical problems, the invention provides a power grid evolution trend analysis method, which is characterized in that the stability characteristics and safety indexes of a short-term future state are evaluated on line by utilizing an on-line power grid trend, and a power grid on-line operation trend change conclusion is given according to the load at the obtained equivalent network node and the current operation condition of the power grid.
The technical scheme of the invention is as follows:
a power grid evolution trend analysis method comprises the following steps:
step 1: data inspection, including: checking the rationality of the online data of the power grid, and using the online data with good data quality; checking the reasonability of the planning data and the prediction data, removing unreasonable data and giving an alarm;
step 2: calculating trend load flow, namely performing block calculation on the trend load flow of a large-scale power grid based on the current operation mode, scheduling operation adjustment, real-time scheduling plan, new energy ultra-short period forecast and ultra-short period load prediction data of the power grid, simplifying an equivalent model for each block, wherein in the process, nodes on a boundary are kept unchanged, finally calculating the equivalent network of each region and the load value of the boundary, predicting the load value of the nodes through the calculated data, combining each small block on the node to form a combined large network and obtain the equivalent model, injecting the node load into the combined equivalent network model, calculating by adopting a Newton method, and estimating the power grid load flow at a future moment;
ΔP=-HΔθ-NΔV/V;
ΔQ=-MΔθ-LΔV/V;
wherein, Δ P is boundary load after equivalence, Δ Q is power supply differential after equivalence, is node voltage phase angle after equivalence, Δ V, V is amplitude differential after equivalence, H is active-to-voltage phase angle differential, N is product of active-to-voltage amplitude differential and voltage amplitude, M is reactive-to-voltage phase angle differential, and L is product of reactive-to-voltage amplitude differential and voltage amplitude, it can be known from the above calculation that, in power flow calculation of a power system, analysis is performed according to the value of the obtained data to form budget and prediction of power flow of a power grid;
and step 3: safety and stability trend analysis, comprising: based on the power grid power flow predicted by the trend power flow and the current stability analysis conclusion of the power grid, whether the power flow exceeds the limit or not is judged; pL is the proportion of the transmission power to the rated power of the line, whether the load flow calculation is converged is judged, and if not, the reason is searched; if the calculation is not converged after multiple times of verification, the system has potential safety hazards, obtains a new load flow calculation result, evaluates the change trend of the safety and stability condition of the power grid at the future moment, obtains an initial load flow calculation result, and evaluates the change trend of the safety and stability condition of the power grid at the future moment;
and 4, step 4: trend-aided decision making, including: the potential safety hazard existing in the power system in a period of time in the future is subjected to assistant decision calculation, wherein the sensitivity of the power flow is calculated to be used as a normal state monitoring quantity,
Δφ=ΔPΣ/Δα;
PΣis the total transmission capacity of the line; alpha is the line power angle; the position of a system where power flow transfer occurs is captured, if the power flow transfer sensitivity of a certain power transmission corridor is too high, the line changes, potential safety hazards exist on a power grid, and power grid faults are prevented through monitoring of the power flow sensitivity;
and 5: task parallel computing, comprising: the method adopts a mode of unified parallel computing of all computing tasks of a plurality of pre-estimated power grid operation modes with pre-allocation as a main mode and dynamic allocation as an auxiliary mode, integrates all the steps, and reduces data interaction and computing result waiting time;
step 6: computing process monitoring, comprising: monitoring the operation states and the calculation progress of all functions in real time in the whole process, and assisting system maintenance personnel to quickly carry out fault diagnosis and system maintenance; and finally, displaying the calculation setting, the fault set and the visual display content result of the maintenance trend analysis system, and displaying the evolution trend of the power grid.
The invention has the advantages and effects that:
the invention provides a power grid evolution trend analysis system technology, and provides a method for evaluating the stability characteristics and safety indexes of a short-term future state on line by using an on-line power grid trend according to the static safety trend analysis, the transient safety trend analysis, the small interference stability trend analysis, the short-circuit current trend analysis and the voltage stability trend analysis of the traditional on-line stability analysis of a power grid, and provides a power grid on-line operation trend change conclusion by combining the current operation condition of the power grid. The method can evaluate an index system of the future stable state of the power grid, and also provides a method for evaluating the safety of the power grid after fault set in an operating state and an ultra-short-term prediction state on line for production scheduling personnel. The power grid evolution trend analysis system technology is the key for reliable development of power supply enterprises, and has great significance for project investment, production, operation and management and the like of power enterprises.
By means of the method for evaluating the safety of the power grid in the running state, the index system of the future stable state of the power grid is accurately mastered, equipment faults are reduced by taking effective measures, the realization of the energy-saving and efficiency-increasing target is further promoted, the power plant is promoted to carry out energy-saving and consumption-reducing work, the economic benefit of an enterprise is improved, and the economic safety running of the power plant is promoted. The monitoring and management on the electric energy quality of the public power grid are increased, the automatic management level of the electric power system is comprehensively improved, and the guarantee is provided for the safe operation of the power grid. By means of establishment of information platforms such as information technology and network technology, the effects of power quality verification and electric quantity information acquisition and comprehensive management of power generation enterprises are greatly improved, and the level of enterprise power utilization management is improved.
Drawings
FIG. 1 is an integrated schematic diagram of a power grid evolution trend analysis system;
fig. 2 is a power flow threshold crossing model.
Detailed Description
The invention is further explained below with reference to the figures and the examples.
The invention relates to a power grid evolution trend analysis method, which firstly provides a static safety trend analysis, a transient safety trend analysis, a small interference stability trend analysis, a short circuit current trend analysis and a voltage stability trend analysis method which are different from the traditional online stability analysis; secondly, summarizing the leading factors influencing the change of the power grid stability situation, classifying and concluding an index system capable of evaluating the future stability condition of the power grid; finally, aiming at the future trend 'quick evaluation' of the power grid, the dynamic power flow calculation method is adopted to meet the calculation convergence of the continuous power flow when the power is unbalanced, and the robustness improvement of the estimated step length is carried out on the existing continuous power flow method; and (4) evaluating the safety after the fault set in the power grid operation state and the ultra-short term (after 5 mins) prediction state on line by using the online power grid operation data and the ultra-short term prediction data.
The invention relates to a power grid evolution trend analysis method, which comprises the following steps:
step 1: and (6) data checking. Which comprises the following steps: checking the rationality of the online data of the power grid, and using the online data with good data quality; the study thus carried out led to the conclusion that it is more convincing. Checking the reasonability of the planning data and the prediction data, removing unreasonable data and giving an alarm;
step 2: and calculating the trend load flow. Based on data such as the current operation mode, scheduling operation adjustment, real-time scheduling plan, new energy ultra-short-term forecast and ultra-short-term load forecast of the power grid, the trend load flow of the large power grid is calculated in blocks, an equivalent model is simplified for each block, in the process, nodes of the boundary are kept unchanged, finally, the equivalent network and the load value of the boundary of each region are calculated, and the load value of the nodes can be predicted through the calculated data. And combining each small block to form a combined large network and obtain an equivalent model, injecting the node load into the combined equivalent network model, and calculating by adopting a Newton method. Predicting the power grid flow at a future moment;
ΔP=-HΔθ-NΔV/V;
ΔQ=-MΔθ-LΔV/V;
wherein, Δ P is boundary load after equivalence, Δ Q is power differential after equivalence, is node voltage phase angle after equivalence, Δ V, V is amplitude differential after equivalence, H is active-to-voltage phase angle differential, N is product of active-to-voltage amplitude differential and voltage amplitude, M is reactive-to-voltage phase angle differential, and L is product of reactive-to-voltage amplitude differential and voltage amplitude. From the above calculations, it can be seen that in the power flow calculation of the power system, budgeting and predictions for the grid power flow are formed by analyzing the values of the obtained data.
And step 3: and (5) analyzing the safety and stability trend. Which comprises the following steps: based on the power grid power flow predicted by the trend power flow and the current stability analysis conclusion of the power grid, whether the power flow exceeds the limit or not is judged; as shown in fig. 2, pL is the ratio of the transmission power to the rated power of the line. Judging whether the load flow calculation is converged, and if not, searching the reason; if the calculation is not converged after multiple times of verification, the system has great potential safety hazard, but the non-convergence does not represent that the power grid is about to crash. Obtaining a new load flow calculation result, evaluating the change trend of the safety and stability condition of the power grid at the future moment to obtain an initial load flow calculation result, and evaluating the change trend of the safety and stability condition of the power grid at the future moment.
And 4, step 4: the trend assists in the decision-making. Which comprises the following steps: and carrying out auxiliary decision calculation on potential safety hazards existing in the power system in a future period of time, wherein the sensitivity of the power flow is calculated and used as a normal state monitoring quantity.
Δφ=ΔPΣ/Δα;
PΣIs the total transmission capacity of the line; alpha is the line power angle; the position of the system where the power flow transfer occurs is captured. If the power flow transfer sensitivity of a certain power transmission corridor is too high, the power transmission corridor means that the line is greatly changed. Safety of the gridHidden danger, and the occurrence of power grid faults can be prevented through monitoring of tidal current sensitivity;
and 5: and (4) performing task parallel computing. Which comprises the following steps: the method adopts a mode of unified parallel computing of all computing tasks of a plurality of pre-estimated power grid operation modes with pre-allocation as a main mode and dynamic allocation as an auxiliary mode, integrates all the steps, and reduces data interaction and computing result waiting time;
step 6: the computing process is monitored. Which comprises the following steps: monitoring the operation states and the calculation progress of all functions in real time in the whole process, and assisting system maintenance personnel to quickly carry out fault diagnosis and system maintenance; and finally, displaying intuitive results such as calculation setting, fault set and display content of the maintenance trend analysis system, and displaying the evolution trend of the power grid.