A dynamic active protection method for a rural electric-gas coupling system

Abstract

The application is suitable for power distribution network system technical field, and provides a dynamic active protection method for rural electric-gas coupling system, which comprises the following steps: establishing an electric-gas coupling model, and constructing a gas network dynamic model based on the model and a natural gas pipeline network topology; when an abnormal gas supply event is monitored, predicting the time sequence change of the affected gas type power source inlet pressure through the gas network dynamic model and generating a pressure prediction sequence, and calculating the supportable operation duration; taking the supportable operation duration and the gas type power source regulation capacity as constraints, generating an active power reduction curve and a dynamic exit time limit that can be executed before low pressure protection triggering, and rolling correction; within the dynamic exit time limit, a multi-resource connection compensation model is established, the adjustable resources on the power distribution network side are coordinated to connect and compensate the power gap, the output plans of each compensation resource are outputted, and the control actions are executed. The response speed and the active protection capability of the rural electric-gas coupling system to the risk of the power grid side caused by the abnormality of the gas network side are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of power distribution network system technology, and in particular to a dynamic active protection method for rural electric-gas coupling systems. Background Technology

[0002] With the widespread integration of distributed photovoltaic power, energy storage, gas-fired combined heat and power (CHP) equipment, and adjustable loads, rural energy systems are gradually exhibiting a multi-source energy supply and electricity-gas coordinated operation. Among these, gas-fired CHP equipment and gas turbines, among other gas-fired power sources, not only support local power generation but also rely on the natural gas network for stable fuel. Their available output is influenced by both grid-side operational constraints and the gas supply status of the gas grid. Current operational control methods for rural smart energy systems typically rely primarily on electrical measurement data from the distribution network. When abnormal conditions such as node voltage exceeding limits, system power deficits, or equipment protection activation are detected, the system's operating status is corrected by adjusting the output of distributed power sources, utilizing energy storage systems for charging and discharging, increasing the power supply from the upstream grid, or reducing some loads to restore power balance and voltage stability.

[0003] Pressure changes and pipeline gas release in natural gas networks occur over time. When a gas supply anomaly occurs on the gas network side, the inlet pressure of gas-fired power sources typically does not drop instantaneously to the low-pressure protection threshold, but rather decreases gradually as pipeline gas is consumed. Current methods treat gas-fired power sources as ordinary adjustable power sources, lacking the means to sense the gas network pressure status and pipeline supply support capacity. This makes it difficult to identify the risk of impending restriction or shutdown of gas-fired power sources during the inlet pressure drop. Compensation can only be implemented after the gas-fired power source has been shut down due to the inlet pressure falling below the protection threshold, and after power deficits or voltage exceedances have occurred on the distribution network side. This leads to insufficient ramp-up time for compensation resources, voltage exceedances, or load loss, among other secondary problems. Therefore, existing technologies suffer from a lag in responding to grid-side risks caused by gas network anomalies. Summary of the Invention

[0004] This invention provides a dynamic active protection method for rural electric-gas coupled systems, which addresses the problem of delayed response to risks on the power grid side caused by anomalies on the gas grid side.

[0005] This invention provides a dynamic active protection method for rural electro-pneumatic coupling systems, comprising: Using the acquired operational data from the distribution network and natural gas network, an electro-gas coupling model is established to reflect the relationship between the electrical output and gas consumption of gas-fired power sources. Based on the electro-gas coupling model and the natural gas pipeline network topology, a gas network dynamic model is constructed to describe the dynamic change process of node pressure under abnormal gas supply. When an abnormal gas supply event is detected, the time-series changes in the inlet pressure of the affected gas-type power source are predicted using the gas network dynamic model, and a pressure prediction sequence is generated. Based on the pressure prediction sequence, calculate the operating time that a gas-fired power source can sustain when the inlet pressure drops to the protection threshold under the current output. Constrained by the supported operating time and the adjustment capability of gas-fired power sources, an active power reduction curve and dynamic exit time limit that can be executed before the low-pressure protection is triggered are generated, and rolling corrections are made based on the latest predicted state during execution. Within the dynamic exit time limit, a multi-resource continuity compensation model is established with the power gap determined by the active power reduction curve as the compensation target. The multi-resource continuity compensation model is used to coordinate the adjustable resources on the distribution network side for power continuity. Based on the solution results of the multi-resource succession compensation model, the output plan of each compensation resource is output, and the corresponding control actions are executed.

[0006] Furthermore, the establishment of the electro-gas coupling model reflecting the relationship between the electrical output and gas consumption of gas-fired power sources includes: Determine the set of gas-fired power sources participating in dynamic active protection, and identify the grid connection node and gas supply node of each gas-fired power source in the distribution network and the gas supply node in the natural gas network. Collect the electrical output value and operating status indication of the gas-type power source at the current control moment, and obtain the gas consumption coefficient per unit electrical output of the gas-type power source, the gas consumption coefficient per unit electrical output of the gas-type power source, and the basic gas consumption required to maintain operation. Using the collected electrical output value as a variable, the gas consumption coefficient as a proportional factor, and the basic gas consumption as a bias, a linear relationship between gas consumption and electrical output and operating status is established.

[0007] Furthermore, the construction of the gas network dynamic model for describing the dynamic change process of node pressure under abnormal gas supply includes: Based on the operating status of pipelines in the natural gas network, determine the set of operational pipelines that can participate in gas transmission after a gas supply anomaly. For each pipe in the set of operable pipes, the pipe is discretized along its length and divided into several pipe segments. A recursive relationship between pressure and mass flow rate is established between adjacent discrete points. The gas supply node connected to the gas-type power source is taken as the boundary node. The external mass flow boundary of the boundary node is determined by the gas consumption of the corresponding gas-type power source in the electro-gas coupling model, thus forming a gas network dynamic model.

[0008] Furthermore, upon detecting an abnormal gas supply event, the process of predicting the temporal changes in the inlet pressure of the affected gas-fired power source using the gas network dynamic model, and generating a pressure prediction sequence, includes: The gas supply nodes associated with the detected gas supply anomalies are identified as the prediction targets. The inlet pressure value of the gas supply node collected at the current moment is used as the initial state and input into the gas network dynamic model. Based on the faulty pipe section, valve status, gas source status, and the natural gas network topology connectivity after the fault, the gas supply nodes affected by the gas supply anomalies are determined. Within the set prediction time domain, the gas network dynamic model is driven to perform iterative calculations at time intervals with a control step size, and outputs the predicted inlet pressure values ​​of the gas supply nodes at each discrete time. The predicted inlet pressure values ​​at each discrete moment are arranged in chronological order to obtain the pressure prediction sequence.

[0009] Furthermore, the step of calculating the sustainable operating time of a gas-fired power source under the current output when the inlet pressure drops to the protection threshold, based on the pressure prediction sequence, includes: From the pressure prediction sequence, starting from the current time, extract the inlet pressure prediction values ​​corresponding to each discrete time point in chronological order. Each extracted inlet pressure prediction value is compared with a preset low-pressure protection threshold to determine the discrete moment when the first inlet pressure prediction value is less than or equal to the low-pressure protection threshold. Calculate the time difference between the discrete moment and the current moment to obtain the available operating time; if the inlet pressure prediction value of all discrete moments in the pressure prediction sequence is higher than the low pressure protection threshold, then the available operating time is taken as the preset maximum remaining support time.

[0010] Furthermore, the generation of an active output reduction curve and dynamic exit time limit, constrained by the supported operating time and the adjustment capability of the gas-fired power supply, before triggering low-voltage protection, includes: Obtain the current output value, minimum stable output value, and maximum allowable output reduction rate of the gas-fired power source, and calculate the shortest physical exit time required for the gas-fired power source to reduce from the current output to the minimum stable output. Compare the supported runtime with the shortest physical exit time, and take the smaller of the two as the initial dynamic exit time limit; Within the initial dynamic exit time limit, with the minimum stable output as the output reduction endpoint and the maximum allowable output reduction rate as the constraint, an active output reduction curve for gas-fired power sources is generated.

[0011] Furthermore, the step of performing rolling corrections based on the latest predicted state during execution includes: Within the dynamic exit time limit, an intermediate evaluation time is selected. When the intermediate evaluation time is reached, the remaining supportable operating time is recalculated based on the latest gas power output and gas supply node pressure status. Based on the comparison between the recalculated remaining supportable runtime and the remaining time of the current dynamic exit time limit, the dynamic exit time limit and the active power reduction curve are updated until the preset correction stop condition is met, thus obtaining the final dynamic exit time limit and active power reduction curve.

[0012] Furthermore, the multi-resource succession compensation model takes minimizing the overall operating cost as its objective function, and its expression is: in: For the overall operational costs, This represents the total number of control moments within the dynamic exit time limit. To control time numbering, For the upper-level power grid in the first Support power at each control moment For distributed adjustable power sources in the first The output at each control moment For renewable energy in the first The output at each control moment For energy storage systems in the first Discharge power at each control moment For the first Load reduction amount at each control moment to These are the unit cost coefficients for power purchase from the upper-level grid, dispatch of distributed adjustable power sources, dispatch of renewable energy sources, energy storage discharge, and load shedding, respectively. The control step size is measured in hours; where the load reduction cost factor is... It is greater than all other cost coefficients.

[0013] Furthermore, the multi-resource succession compensation model includes power balance constraints, resource capacity and ramping constraints, and energy storage operation constraints.

[0014] Furthermore, the step of outputting the output plan of each compensation resource based on the solution results of the multi-resource succession compensation model and executing the corresponding control actions includes: From the solution results of the multi-resource succession compensation model, the optimized values ​​of the upstream grid support power, distributed adjustable power output, renewable energy output, and energy storage charging and discharging power at each control moment are extracted. The extracted optimized values ​​are arranged in order of control time to generate the output plan of each compensation resource within the dynamic exit time limit; According to the power output plan, control commands are sent to the control terminals corresponding to each compensation resource to execute power continuity compensation actions.

[0015] As can be seen from the above technical solutions, the present invention has the following advantages: This invention establishes an electro-gas coupling model using operational data from the distribution network and natural gas network, and constructs a gas network dynamic model based on this model and the natural gas pipeline network topology. When an abnormal gas supply event is detected, the gas network dynamic model predicts the temporal changes in the inlet pressure of the affected gas-based power source and generates a pressure prediction sequence, thereby calculating the available operating time. With the available operating time and the regulating capacity of the gas-based power source as constraints, an active power reduction curve and dynamic exit time limit that can be executed before the low-pressure protection is triggered are generated and continuously corrected. Within the dynamic exit time limit, a multi-resource continuity compensation model is established to coordinate adjustable resources on the distribution network side to continuously compensate for the power gap, and finally outputs the power output plan of each compensation resource and executes the control action. Unlike existing methods that only address power deficits or voltage exceedances on the grid side after they occur, this invention utilizes the physical time delay of natural gas grid pressure propagation to proactively identify and execute power reduction and multi-resource coordinated compensation before gas grid-side supply anomalies occur and before the inlet pressure of gas-fired power sources falls below the protection threshold. This suppresses the risk of gas grid-side faults propagating to the grid side during the evolution process, avoiding the power surge caused by passive tripping of gas-fired power sources. Simultaneously, a multi-resource continuity compensation model coordinates orderly power continuity among the upstream grid, distributed power sources, renewable energy, and energy storage systems, ensuring line power flow and node voltage safety during the compensation process. Therefore, this effectively improves the response speed and proactive protection capabilities of rural power-gas coupling systems against grid-side risks caused by gas grid-side anomalies. Attached Figure Description

[0016] Figure 1 This is a flowchart of a dynamic active protection method for rural electro-pneumatic coupling systems according to the present invention; Figure 2 This is a flowchart illustrating the electro-gas coupling model for gas-fired power sources in this invention. Figure 3 This is a flowchart of the process for constructing the dynamic model of the gas network in this invention; Figure 4 This is a flowchart illustrating the generation of the pressure prediction sequence in this invention; Figure 5 This is a flowchart for calculating the supported runtime in this invention; Figure 6 This is a flowchart for generating the active power reduction curve and dynamic exit time limit in this invention; Figure 7 The result diagram shows the dynamic active protection power scheduling. Figure 8A graph showing the changes in pressure and pressure margin in the natural gas network; Figure 9 This is a diagram showing the voltage verification results for the power distribution network. Detailed Implementation

[0017] The terms "first," "second," "third," "fourth," etc. (if present) in the specification and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "corresponding to," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0018] The implementation method in this embodiment can be implemented in a system, on a server, or on a terminal; no specific limitation is made. The method of this invention will be described below from the perspective of system implementation. Please refer to... Figure 1 The method provided in this embodiment of the invention includes the following steps: S1. Using the acquired operating data from the distribution network side and the natural gas network side, establish an electro-gas coupling model that reflects the relationship between the power output and gas consumption of gas-fired power sources. The rural electricity-gas coupling system is divided into three categories: the distribution network side, the natural gas grid side, and the electricity-gas interface equipment. The distribution network side includes upstream grid access nodes, load nodes, distributed adjustable power generation nodes, energy storage nodes, renewable energy nodes, and gas-fired power grid-connected nodes. The natural gas grid side includes gas source nodes, pipeline nodes, ordinary gas load nodes, and gas-fired power supply nodes. The electricity-gas interface equipment includes gas-fired combined heat and power (CHP) equipment, gas turbines, and other equipment that relies on natural gas for energy supply and provides electrical power to the distribution network. Based on the above classification, this embodiment first establishes an electricity-gas coupling model for gas-fired power sources to describe the quantitative relationship between their electrical output and gas consumption. Please refer to [link to relevant documentation]. Figure 2 Specifically, it includes the following: S11. Determine the set of gas-fired power sources participating in dynamic active protection, and identify the grid connection node and gas supply node of each gas-fired power source in the distribution network and the gas supply node in the natural gas network, respectively. Let the set of gas-fired power sources be: For any gas-powered power source The node that connects to the distribution network is denoted as The node connected to the natural gas network is denoted as By using the above identifiers, the node correspondence between gas-fired power sources and the distribution network and natural gas network is established, providing a topological basis for subsequent electro-gas coupling analysis and gas supply anomaly location.

[0019] S12. Collect the electrical output value and operating status indication of the gas-type power supply at the current control moment, and obtain the gas consumption coefficient per unit electrical output of the gas-type power supply, the basic gas consumption required to maintain ignition, and the basic gas consumption required to maintain no-load. Let the first The electrical output of the gas-fired power source at each control moment is The equipment operating status variables are ,when When, it indicates that the equipment is in operation; when When the time is specified, it indicates that the equipment has stopped operating. The gas consumption coefficient per unit of electrical output. The gas consumption-output characteristic curve under rated operating conditions is obtained; the basic gas consumption required to maintain ignition and the basic gas consumption required to maintain no-load are unified as parameters. This parameter can be determined through no-load testing of the equipment or by the technical parameters provided by the manufacturer.

[0020] S13. Using the collected electrical output value as a variable, the gas consumption coefficient as a proportional factor, and the basic gas consumption as an bias, establish a linear relationship between gas consumption and electrical output and operating status.

[0021] Specifically, gas-fired power supplies At any moment gas consumption With electrical output and running status The linear relationship between them is expressed as: Among them: when When the device exits operation, the following occurs: .

[0022] To avoid inconsistencies between equipment operating status and output level, an output boundary constraint is added to the above linear relationship: in: and Gas-fired power sources The minimum stable output and maximum permissible output are specified. This constraint ensures that the output remains within the safe operating range when the equipment is in operation; when the equipment is out of operation, the output is forced to zero.

[0023] The aforementioned electro-gas coupling model links the power output on the distribution network side with the fuel consumption on the natural gas network side through state variables and linear parameters, providing external mass flow boundary conditions for each gas supply node for the subsequent construction of the gas network dynamic model.

[0024] S2. Based on the electro-gas coupling model and the natural gas pipeline network topology, a gas network dynamic model is constructed to describe the dynamic change process of node pressure under abnormal gas supply. Based on the established electro-gas coupling model, this embodiment further constructs a gas network dynamic model to describe the dynamic evolution of pressure at each node of the natural gas network after a gas supply anomaly occurs. This provides a model basis for subsequent prediction of the time-series changes in the inlet pressure of gas-fired power sources. Please refer to [link / reference needed]. Figure 3 Specifically, it includes the following: S21. Based on the operating status of pipelines in the natural gas network, determine the set of operable pipelines that can participate in gas transmission after a gas supply anomaly; When a pipeline fault, valve malfunction, partial pipeline isolation, or gas supply restriction occurs on the natural gas side, the natural gas network topology is first updated based on the post-fault pipeline operating status. Let the natural gas pipeline set be... , corresponding to any one of the pipes Its operating status is based on It means that, among them This indicates that the pipeline can transport gas. This indicates that the pipeline is not involved in gas transmission due to a fault or isolation. The set of operational pipelines after a fault is as follows: This set filters out all pipelines that still have the ability to transmit gas after a gas supply anomaly, excluding pipelines that are faulty or isolated, thus providing a correct topological basis for subsequent dynamic calculations of the gas network.

[0025] S22. For each pipe in the set of operable pipes, discretize it along the length of the pipe, divide it into several pipe segments, and establish a recursive relationship between pressure and mass flow rate between adjacent discrete points. For any working pipeline The pipe is discretized along its length into several segments to describe the spatial distribution of pressure and flow rate inside the pipe. Let... Indicates pipeline No. The pressure discrete point at the th ... The pressure at that moment, Indicates pipeline No. The pipe section in the first The mass flow rate at any given time. Gas network pressure and mass flow rate can be updated according to a pressure-flow dynamic recursive model: in: For time step, For pipelines The actual distance from the walk is long. Indicates the equivalent capacity coefficient of the pipeline. This represents the equivalent inertia coefficient of the pipeline. This represents the equivalent friction coefficient of the pipe section. and Unit conversion factor.

[0026] The above recursive relationship describes the change of pressure in the pipeline with the difference between inflow and outflow mass flow rate, as well as the change of mass flow rate with pressure gradient and friction loss. It is the core calculation framework of the gas network dynamic model.

[0027] S23. The gas supply node connected to the gas-type power source is taken as the boundary node. The external mass flow boundary of the boundary node is determined by the gas consumption of the corresponding gas-type power source in the electro-gas coupling model, thus forming a gas network dynamic model.

[0028] After establishing the internal recursive relationships within the pipeline, it is necessary to determine the external mass flow boundary conditions for each node in the gas network. For gas-fired power sources... The gas supply nodes that are connected Its external mass flow boundary is determined by the gas consumption of this gas-type power source in the electro-gas coupling model. Confirmed, expressed as: This formula indicates that gas-fired power sources, acting as the gas load of the gas network, are measured by gas consumption. The rate at which natural gas is drawn from the gas supply node is represented in the model as a negative mass flow injection.

[0029] For ordinary gas load nodes Its external mass flow boundary is: in: For ordinary gas load nodes At any moment The gas intake. If a node simultaneously experiences gas source injection, ordinary gas load, and gas consumption for gas-fired power generation, then the external mass flow rate of that node can be uniformly expressed as: in: For nodes The amount of gas injected. Represents all access nodes The sum of gas consumption for gas-fired power sources. This formula is used to uniformly describe the external flow boundary of a node under the combined effects of gas source, ordinary gas load, and gas-fired power source.

[0030] The aforementioned gas network dynamic model takes the set of operable pipelines as its object, the pressure-flow recursive relationship within the pipelines as its core, and the external mass flow rate of each gas supply node as its boundary condition. It can describe the dynamic change process of the pressure of each node in the natural gas network with time and space after a gas supply anomaly, providing model support for the next step of predicting the time-series changes of the inlet pressure of affected gas-fired power sources.

[0031] S3. When an abnormal gas supply event is detected, the time-series changes in the inlet pressure of the affected gas-type power source are predicted through the gas network dynamic model, and a pressure prediction sequence is generated. Based on the completed dynamic model of the gas network, once an abnormal gas supply event is detected, this embodiment of the invention initiates time-series prediction of the inlet pressure of the affected gas-fired power source to obtain its pressure change trend over a future period. This provides a data foundation for subsequent calculations of the supported operating time and the formulation of proactive power output reduction strategies. Please refer to... Figure 4 Including the following: S31. Identify the gas supply nodes associated with the detected abnormal gas supply events as the prediction targets, and input the inlet pressure value of the gas supply node collected at the current moment as the initial state into the gas network dynamic model. When a gas supply anomaly is detected by real-time acquisition of the inlet pressure values ​​and their rate of change at each gas supply node in the natural gas network, the gas supply nodes associated with the anomaly are identified as the prediction targets. To describe the safety status of this gas supply node under gas supply anomaly conditions, its gas supply safety margin is first defined. Let the gas supply node be... In the Gas supply safety margin at each control moment for: in: Gas-fired power supply Gas supply nodes connected At any moment Inlet pressure; This is the minimum inlet pressure required for continuous operation of gas-fired power sources. If This indicates that the gas-powered power source is still within a safe gas supply range; if This indicates that the device is at risk of triggering low-voltage protection or being forced to shut down.

[0032] Meanwhile, to characterize the short-term support capability of the terminal pipeline for gas-based power sources after a fault, the terminal gas supply support capacity is defined as: in: Even after the fault, it is still connected to gas-powered power sources. A collection of interconnected pipes that can provide short-term gas supply support; For pipelines The cross-sectional area; This refers to the length of the pipe. For pipelines At any moment Average pressure; This indicates taking the non-negative part; Indicates pipeline The equivalent conversion factor is used to convert pipeline volume and pressure margin into equivalent gas supply support capacity. This indicator measures the ability of gas-fired power sources to maintain operation by relying on gas stored in terminal pipelines after gas supply is limited or gas supply channels are blocked.

[0033] Based on the above safety status characterization, at the current control time Measured values ​​of gas supply node inlet pressure collected As the initial state, the already constructed dynamic model of the gas network is input as the starting point for iterative prediction.

[0034] S32. Within the set prediction time domain, the dynamic model of the driving gas network is iteratively calculated at time intervals with the control step size as the interval, and the predicted inlet pressure of the gas supply node at each discrete time is output. Prediction Time Domain The settings take into account the following factors: terminal gas supply support volume The data reflects the pipeline's gas storage capacity and the minimum physical shutdown time required for gas-fired power sources to reduce their current output to a minimum stable output, as well as the maximum time delay for gas network pressure waves to propagate to the gas supply nodes of gas-fired power sources. Specifically, the prediction time domain... The prediction time should be no less than the gas consumption time corresponding to the ratio of the terminal gas supply support to the gas-fired power supply outlet flow rate, while reserving a certain time margin to ensure that the prediction sequence can fully cover the entire process of the pressure dropping from the current value to the low-pressure protection threshold. If the terminal gas supply support is large, the prediction time domain can be appropriately extended; if the gas source is severely limited, the prediction time domain can be appropriately shortened to reduce the computational burden.

[0035] S33. Arrange the predicted inlet pressure values ​​at each discrete time point in chronological order to obtain the pressure prediction sequence.

[0036] Once the prediction time domain is determined, it is divided into sections with a control step size as the time interval. At discrete moments, the dynamic model of the driving gas network starts from the current moment. Starting from the initial state, iterative calculations are performed time-by-time, and the results are arranged sequentially according to time chronology to output the gas supply nodes at each discrete time point. Inlet pressure prediction This pressure prediction sequence characterizes the temporal variation trend of the inlet pressure of the affected gas-fired power supply node after a gas supply anomaly event, from the current moment to the predicted values ​​at discrete moments within the future prediction time domain. This sequence allows for a direct observation of the gradual decrease in inlet pressure as gas in the pipeline is consumed, providing complete data input for the next step of calculating the supported operating time.

[0037] S4. Based on the pressure prediction sequence, calculate the operating time that a gas-fired power source can sustain when the inlet pressure drops to the protection threshold under the current output. Based on the pressure prediction sequence generated in S3, this embodiment further calculates the sustainable operating time of a gas-fired power source at the current output level, corresponding to the inlet pressure dropping from the current value to the low-pressure protection threshold. This provides a time constraint basis for subsequently formulating an active output reduction strategy. Please refer to... Figure 5 Specifically, it includes the following: S41. From the pressure prediction sequence, starting from the current time, extract the inlet pressure prediction values ​​corresponding to each discrete time point in chronological order; S42. Compare each extracted inlet pressure prediction value with the preset low-pressure protection threshold to determine the discrete moment when the first inlet pressure prediction value is less than or equal to the low-pressure protection threshold; S43. Calculate the time difference between the discrete moment and the current moment to obtain the available operating time; if the inlet pressure prediction value of all discrete moments in the pressure prediction sequence is higher than the low pressure protection threshold, then the available operating time is taken as the preset maximum remaining support time.

[0038] Specifically, the preset low-voltage protection threshold Gas-fired power supply The minimum inlet pressure allowed for continuous operation is a threshold determined by the technical parameters or on-site operating procedures provided by the gas-fired power equipment manufacturer. This threshold indicates that when the inlet pressure falls below this value, the equipment will trigger a low-pressure protection mechanism, posing a risk of forced shutdown. The predicted inlet pressure values ​​extracted at each discrete moment are then compared sequentially with this threshold. The comparison process starts from the most recent moment. Initially, the process proceeds sequentially along the direction of increasing time. When a certain discrete time moment first appears... satisfy At that time, the moment The first discrete moment of pressure exceeding the limit is identified, and the comparison process is terminated. For the identified first discrete moment of pressure exceeding the limit... Calculate its relationship with the current time. The time difference between them yields gas-fired power sources. The operating time that can be sustained when the inlet pressure drops to the protection threshold under the current output is: in: To control the step size. If within the prediction time domain. Always higher Then it is believed The timeframe exceeding the current forecast period is taken as the preset maximum remaining support duration. This duration represents the available time from the current moment, under given gas-fired power source output trajectory and gas-side load conditions, before the gas-fired power source inlet pressure reaches the protection threshold.

[0039] S5. Based on the constraints of the operating time and the regulation capability of gas-fired power sources, generate an active output reduction curve and dynamic exit time limit that can be executed before the low-pressure protection is triggered, and make rolling corrections based on the latest predicted status during execution; Based on the calculated supported operating time, this embodiment of the invention combines it with the inherent physical regulation capabilities of gas-fired power sources to generate an active output reduction curve and a dynamic exit time limit. During execution, it performs rolling corrections based on the latest predicted state to ensure that the gas-fired power source completes controlled retreat before low-voltage protection is triggered. Please refer to... Figure 6 Including the following: S51. Obtain the current output value, minimum stable output value, and maximum allowable output reduction rate of the gas-fired power source, and calculate the shortest physical exit time required for the gas-fired power source to reduce from the current output to the minimum stable output. Gas-fired power supply The initial output before the gas supply anomaly was: This value represents the measured electrical output of the gas-fired power source at the moment the gas supply anomaly was detected. Minimum stable output value. Gas-fired power supply The minimum output level required to maintain stable combustion and continuous operation is determined by the technical parameters or operating procedures provided by the equipment manufacturer. When the output falls below this value, the equipment will not be able to operate stably. Maximum permissible rate of output reduction. Gas-fired power supply The maximum allowable reduction in output per unit time is determined by the thermodynamic characteristics of the equipment, mechanical stress limits, and the adjustment capability of the control system.

[0040] Based on the above parameters, the gas-fired power source is determined from its current initial output. Reduced to minimum stable output The minimum required physical exit time is calculated as follows: The shortest physical exit time characterizes the shortest time required to reduce the output of a gas-fired power source from its current output level to the minimum stable output level under the condition that the power source continuously reduces its output at the maximum rate. It is the lower limit of the physical constraint imposed by the gas-fired power source's own regulation capability on the exit process.

[0041] S52. Compare the available operating time with the minimum physical exit time; when the available operating time is not less than the minimum physical exit time, determine the dynamic exit time limit within the range that does not exceed the available operating time and meets the power reduction rate constraint of gas-fired power sources; when the available operating time is less than the minimum physical exit time, determine that the smooth exit time is insufficient, generate an emergency power reduction curve according to the maximum allowable power reduction rate, and simultaneously initiate emergency compensation or load reduction measures on the power side. set up To maintain initial output before gas supply anomalies occur in gas-powered power sources. Under unchanged conditions, the initial sustainable runtime is calculated according to S4. To avoid issues related to discrete control step size... The problem of the exit timeout being numerically unachievable is addressed by using the initial dynamic exit timeout in the 0th round of active protection calculations as follows: The above-mentioned larger operation means: if the gas side can support the operating length. If the time is greater than the sum of the physical exit time and a control step, then... This serves as an initial dynamic shutdown time limit, allowing sufficient time for gas-fired power sources to smoothly reduce output; if the gas-side pressure drops rapidly... Less than Then As an initial dynamic exit time limit, it ensures that the exit time limit at least meets the minimum time requirement of the physical output force, while adding a margin of control step size to avoid unrealizable problems caused by discrete control.

[0042] S53. Within the initial dynamic exit time limit, with the minimum stable output as the output reduction endpoint and the maximum allowable output reduction rate as the constraint, generate an active output reduction curve for gas-fired power sources.

[0043] Specifically, within the determined initial dynamic exit time limit Internally, the current output of gas-fired power sources is... Starting with the minimum stable output As the endpoint, the change in output at any adjacent control time does not exceed Under constraints, generate a path from Monotonically decreasing to The output trajectory. This trajectory is the active output reduction curve of the gas-fired power source. Its slope does not exceed the maximum allowable output reduction rate, and the endpoint corresponds to the current time plus... .

[0044] After the initial dynamic exit time limit and active power reduction curve are generated, this embodiment performs rolling corrections based on the latest predicted state during execution. The specific process is as follows: 1. Select an intermediate assessment time within the dynamic exit time limit. When the intermediate assessment time is reached, recalculate the remaining operating time based on the latest gas power output and gas supply node pressure status. 2. Based on the comparison between the recalculated remaining supportable runtime and the current dynamic exit time limit, update the dynamic exit time limit and active power reduction curve until the preset correction stop condition is met, and obtain the final dynamic exit time limit and active power reduction curve.

[0045] Specifically, let the first The exit time limit calculated in round 1 is Select an intermediate evaluation time: in: To dynamically evaluate the proportional coefficient, it must meet the following requirements. .

[0046] exist At that moment, based on the current cycle's reduced output trajectory of gas-fired power sources, the gas grid pressure is re-predicted, and the remaining sustainable operating time after that moment is calculated. The exit timeout will be updated subsequently. in, This is the maximum allowable control time limit. To ensure the exit time limit meets the physical output reduction capacity of gas-fired power sources, further constraints are imposed: The above update rules state that if the gas side still has strong support capacity at the intermediate assessment time, the output reduction process of gas-fired power sources can be appropriately extended to reduce the compensation pressure on the distribution network side; if the gas-side pressure drops rapidly, the original exit time limit will be maintained or constrained by the maximum control time limit, and will not be extended further. When the exit time limit update magnitude is less than one control step, the load reduction meets the allowable threshold, or the terminal gas supply support is close to the lower limit, the exit time limit update will stop, and the final dynamic exit time limit will be obtained. .

[0047] Through the above rolling correction process, the active power reduction strategy of gas-fired power sources can adapt to the uncertainty in the abnormal evolution of gas supply. When the gas-side support conditions allow, the power reduction process can be appropriately extended to reduce the pressure on the distribution network side. When the gas-side deteriorates, the exit time limit can be maintained or shortened to ensure safety.

[0048] S6. Within the dynamic exit time limit, a multi-resource continuity compensation model is established with the power gap determined by the active power reduction curve as the compensation target. The multi-resource continuity compensation model is used to coordinate the adjustable resources on the distribution network side for power continuity. After determining the dynamic withdrawal time limit of gas-fired power sources, this embodiment constructs a dynamic active protection optimization model for the distribution network side. This model is used to coordinate resources such as the upstream power grid, distributed adjustable power sources, renewable energy and energy storage, to continuously compensate for the power gap caused by the reduced output of gas-fired power sources, and to ensure that the power flow of distribution network lines and node voltages meet the operating requirements.

[0049] set up To provide power support for the upper-level power grid, To provide power for distributed adjustable power sources Contribute to renewable energy and These are the energy storage discharge power and the charging power, respectively. This is the load reduction amount. For system load, Power is supplied to affected gas-fired power sources. The power balance of the distribution network then satisfies: The multi-resource succession compensation model takes minimizing the overall operating cost as its objective function, and its expression is: in: For the overall operational costs, This represents the total number of control moments within the dynamic exit time limit. to These are the unit cost coefficients for power purchase from the upper-level grid, dispatch of distributed adjustable power sources, dispatch of renewable energy sources, energy storage discharge, and load shedding, respectively. The control step size is measured in hours; where the load reduction cost factor is... It is greater than all other cost coefficients.

[0050] After determining the dynamic exit time limit, set active output reduction constraints for the affected gas-fired power sources.

[0051] Output upper and lower limits constraints and ramp rate constraints: in: This is the upper limit of the lift-off rate. This refers to the upper limit of the output rate. These represent the maximum allowable increase and decrease in output per unit time, determined by the equipment manufacturer's technical parameters.

[0052] During the dynamic active protection phase, for gas-fired power sources affected by abnormal gas supply, the following settings are implemented: This allows the system to maintain its current output or reduce its output, preventing any further increase in output. When the control time reaches the dynamic exit limit, the gas-fired power supply will cease operation. The upstream power grid, distributed adjustable power sources, and renewable energy meet capacity and ramping constraints: in: These correspond to the upper-level power grid, distributed adjustable power sources, and renewable energy, respectively. and Resources The lower and upper limits of output; For resources The upper limit of the ramp rate represents the maximum allowable change in resource output per unit time, which is determined by the resource's adjustment characteristics and the response speed of the control system.

[0053] The charging and discharging power of the energy storage system at each control moment must meet the rated power limit: In the formula: This represents the maximum discharge power of the energy storage system. The maximum charging power of the energy storage system is determined by the rated power of the energy storage converter.

[0054] The remaining power of the energy storage system is updated according to the following recursive relationship: In the formula: For the first The state of charge of the energy storage system at each control moment is the ratio of the remaining energy stored to the rated capacity, which is dimensionless. This refers to the rated capacity of the energy storage system. For energy storage charging efficiency, The energy storage discharge efficiency is a positive number less than 1, determined by the type and operating characteristics of the energy storage battery.

[0055] The state of charge of the energy storage system must always be maintained within the allowable range: In the formula: This represents the minimum permissible state of charge for an energy storage system. This represents the highest permissible state of charge. These two parameters are determined by the technical specifications provided by the energy storage battery manufacturer or the protection settings of the battery management system.

[0056] For radial rural distribution networks, the downstream net load method is used to describe line power flow. For any distribution line... ,set up For the line Given the set of downstream nodes, the active power flow of the line is as follows: in: For nodes The load power, For nodes Power injected from distributed power sources, renewable energy sources, or gas-fired power sources. For nodes Net energy injection power of energy storage, For the line The proportion of downstream load to total system load. Line power flow satisfies: in: This represents the upper limit of the allowable power flow for the line.

[0057] After obtaining the active protection scheduling results, the node voltages are linearized and verified. For the line... If node For nodes If the upstream node is: in: and These are the line resistance and reactance, respectively. For reactive power flow of the line, For linearization conversion factors. Node voltages satisfy: In the formula: and These are the lower and upper limits of the allowable node voltage, determined based on the distribution network voltage quality standards and the insulation withstand capability of the equipment. S7. Based on the solution results of the multi-resource succession compensation model, output the output plan of each compensation resource and execute the corresponding control actions.

[0058] After solving the multi-resource succession compensation model in S6 to obtain the optimal output value of each adjustable resource at each control moment, this embodiment transforms the optimization results into executable control commands to complete the actual compensation for the power gap caused by the reduced output of gas-fired power sources. Specifically, this includes the following: 1. Extract the optimized values ​​of the upstream grid support power, distributed adjustable power output, renewable energy output, and energy storage charging and discharging power at each control moment from the solution results of the multi-resource succession compensation model; 2. Arrange the extracted optimized values ​​in order of control time to generate the output plan of each compensation resource within the dynamic exit time limit; 3. Send control commands to the control terminals corresponding to each compensation resource according to the output plan, and execute power continuity compensation actions.

[0059] Specifically, mathematical programming methods are used to solve the model, obtaining the optimal values ​​for the upstream grid support power, distributed adjustable power source output, renewable energy output, energy storage charging and discharging power, and load reduction at each control time. The optimized values ​​of these variables are arranged in order of control time to form the output plan for each compensation resource within the dynamic exit time limit. The generated output plan is then sent sequentially to the control terminals corresponding to each compensation resource according to the control time. Power purchase instructions are sent to the power controller at the upstream grid interface; output setpoint instructions are sent to the controller of the distributed adjustable power source; output instructions are sent to the renewable energy inverter or power controller; charging and discharging power instructions are sent to the energy management system or converter controller of the energy storage system; and if there is a load reduction requirement, a load reduction instruction is sent to the corresponding load switch or load management terminal. Each control terminal executes the corresponding power adjustment action according to the received instruction values, ensuring that the actual output of each adjustable resource tracks the output plan. While gas-fired power sources gradually reduce their output according to the active output reduction curve, each compensation resource simultaneously increases its output or adjusts its charging and discharging state, achieving seamless compensation for the power gap. The entire process, from gas-side risk identification, proactive yield strategy formulation, multi-resource compensation scheme optimization to final execution and control, is completed, enabling gas-fired power sources to complete controlled output reduction and withdrawal before triggering low-voltage protection, while ensuring power balance and voltage safety on the distribution network side.

[0060] To verify the effectiveness of the proposed dynamic active protection method for rural power-gas coupled systems, a joint simulation system was constructed, comprising a 33-node rural power distribution network and a 6-node natural gas network. On the power distribution network side, an upstream grid interface, distributed generation (DG), battery energy storage system (BESS), photovoltaic / wind power resources (PV / WT), and gas-fired combined heat and power (CHP) equipment were included. On the natural gas side, dual gas source nodes, load nodes, CHP supply nodes, and end-load nodes were included. By simulating a natural gas branch fault, the pressure at the CHP supply node continuously decreased to simulate the transmission process from non-electrical side faults to the power side, and to verify the invention's ability to intervene early, actively regulate, and provide cross-system collaborative protection during the evolution of gas-side risks.

[0061] Please see Figure 7 After the natural gas failure occurred, CHP did not passively shut down after the gas supply pressure reached the low-pressure protection threshold, but instead shut down at the moment the protection was activated. Then, output is gradually reduced according to the dynamic exit time limit, and... The system smoothly transitioned ahead of schedule. Simultaneously, the power output from DG, BESS, PV / WT, and the main grid increased synchronously, continuously compensating for the reduced output of CHP. The sub-figure below shows that the reduction in CHP output and the increase in power-side compensation remained generally in line, with the system power deficit consistently close to zero.

[0062] Please see Figure 8 Following a natural gas outage, the pressure at gas network nodes exhibited a gradual transmission trend from the upstream stable zone to the affected downstream zone. While the pressure on the upstream gas source side remained generally stable, the pressure in the downstream gas supply area where CHP was located decreased over time, indicating that the impact of the gas-side outage was mainly concentrated near the gas supply nodes of gas-fired power sources.

[0063] Under the risk trajectory of maintaining initial output, the pressure at the CHP gas supply node continuously decreased and gradually approached the low-pressure protection threshold, indicating that without active control, gas-fired power sources were at risk of being forced to shut down. After adopting the dynamic active protection method of this invention, the CHP output decreased earlier, its gas consumption decreased accordingly, the downward trend of the gas supply node pressure was suppressed, and it remained above the protection threshold. The pressure margin results further show that without active protection, the pressure margin at the CHP node continuously decreased and eventually crossed the protection boundary; however, with the method of this invention, the pressure margin remained positive, indicating that the low-pressure protection was not triggered during the active retreat process of the gas-fired power source.

[0064] The above results demonstrate that the present invention can utilize the time window formed by the pressure propagation lag in the natural gas network and the buffer formed by gas storage in the pipeline to actively intervene before the risk on the gas side is transmitted to the power side, so that the gas-fired power source changes from passive low-pressure shutdown to controlled power reduction shutdown, thereby reducing the possibility of natural gas side faults being transmitted to the power distribution network for power deficits and voltage risks.

[0065] Please see Figure 9 During the execution of dynamic active protection, as the output of the CHP gradually decreased, the distribution network side was compensated by DG, BESS, PV / WT, and main grid power purchase. Although the system power flow distribution changed, the voltage of each key node remained stable overall, with the minimum voltage consistently above the set lower voltage limit, and no voltage exceedance occurred. Typical node voltage distribution results showed that the voltage profiles before the fault, at the protection start time, and at the protection end time were all within the allowable operating range. After the protection ended, the voltage of some end nodes decreased, but remained above the safety boundary, indicating that grid-side compensation scheduling did not trigger new distribution network voltage risks.

[0066] The above results demonstrate that, while reducing the output of gas-fired power sources and suppressing the risk of low voltage on the gas grid side, the present invention can coordinate multiple resources on the distribution network side to complete compensation and maintain the voltage safety of the distribution network. These results verify that the proposed dynamic active protection method can not only prevent CHP low-voltage outages but also ensure the safe operation of the grid side during the active protection process.

[0067] It is understood that those skilled in the art can combine various implementation methods in the above embodiments under the guidance of the above examples to obtain technical solutions with multiple implementation methods.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dynamic active protection method for rural electro-pneumatic coupling systems, characterized in that, include: Using the acquired operational data from the distribution network and natural gas network, an electro-gas coupling model is established to reflect the relationship between the electrical output and gas consumption of gas-fired power sources. Based on the electro-gas coupling model and the natural gas pipeline network topology, a gas network dynamic model is constructed to describe the dynamic change process of node pressure under abnormal gas supply. When an abnormal gas supply event is detected, the time-series changes in the inlet pressure of the affected gas-type power source are predicted using the gas network dynamic model, and a pressure prediction sequence is generated. Based on the pressure prediction sequence, calculate the operating time that a gas-fired power source can sustain when the inlet pressure drops to the protection threshold under the current output. Constrained by the supported operating time and the adjustment capability of gas-fired power sources, an active power reduction curve and dynamic exit time limit that can be executed before the low-pressure protection is triggered are generated, and rolling corrections are made based on the latest predicted state during execution. Within the dynamic exit time limit, a multi-resource continuity compensation model is established with the power gap determined by the active power reduction curve as the compensation target. The multi-resource continuity compensation model is used to coordinate the adjustable resources on the distribution network side for power continuity. Based on the solution results of the multi-resource succession compensation model, the output plan of each compensation resource is output, and the corresponding control actions are executed.

2. The dynamic active protection method for rural electro-pneumatic coupling systems according to claim 1, characterized in that, The establishment of the electro-gas coupling model reflecting the relationship between the electrical output and gas consumption of gas-fired power sources includes: Determine the set of gas-fired power sources participating in dynamic active protection, and identify the grid connection node and gas supply node of each gas-fired power source in the distribution network and the gas supply node in the natural gas network. Collect the electrical output value and operating status indication of the gas-type power source at the current control moment, and obtain the gas consumption coefficient per unit electrical output of the gas-type power source, the basic gas consumption required to maintain ignition, and the basic gas consumption required to maintain no-load. Using the collected electrical output value as a variable, the gas consumption coefficient as a proportional factor, and the basic gas consumption as a bias, a linear relationship between gas consumption and electrical output and operating status is established.

3. The dynamic active protection method for rural electro-pneumatic coupling systems according to claim 2, characterized in that, The construction of the gas network dynamic model for describing the dynamic changes in node pressure under abnormal gas supply conditions includes: Based on the operating status of pipelines in the natural gas network, determine the set of operational pipelines that can participate in gas transmission after a gas supply anomaly. For each pipe in the set of operable pipes, the pipe is discretized along its length and divided into several pipe segments. A recursive relationship between pressure and mass flow rate is established between adjacent discrete points. The gas supply node connected to the gas-type power source is taken as the boundary node. The external mass flow boundary of the boundary node is determined by the gas consumption of the corresponding gas-type power source in the electro-gas coupling model, thus forming a gas network dynamic model.

4. The dynamic active protection method for rural electro-pneumatic coupling systems according to claim 3, characterized in that, Upon detecting a gas supply anomaly, the gas network dynamic model is used to predict the temporal changes in the inlet pressure of the affected gas-fired power source, generating a pressure prediction sequence, including: The gas supply nodes associated with the detected abnormal gas supply events are identified as the prediction targets. The inlet pressure value of the gas supply node collected at the current moment is used as the initial state and input into the gas network dynamic model. Within the set prediction time domain, the gas network dynamic model is driven to perform iterative calculations at time intervals with a control step size, and outputs the predicted inlet pressure values ​​of the gas supply nodes at each discrete time. The predicted inlet pressure values ​​at each discrete moment are arranged in chronological order to obtain the pressure prediction sequence.

5. The dynamic active protection method for rural electro-pneumatic coupling systems according to claim 4, characterized in that, The step of calculating the sustainable operating time of a gas-fired power source under the current output when the inlet pressure drops to the protection threshold, based on the pressure prediction sequence, includes: From the pressure prediction sequence, starting from the current time, extract the inlet pressure prediction values ​​corresponding to each discrete time point in chronological order. Each extracted inlet pressure prediction value is compared with a preset low-pressure protection threshold to determine the discrete moment when the first inlet pressure prediction value is less than or equal to the low-pressure protection threshold. Calculate the time difference between the discrete moment and the current moment to obtain the available operating time; if the inlet pressure prediction value of all discrete moments in the pressure prediction sequence is higher than the low pressure protection threshold, then the available operating time is taken as the preset maximum remaining support time.

6. The dynamic active protection method for rural electro-pneumatic coupling systems according to claim 1, characterized in that, The process, constrained by the supported operating time and the adjustment capability of gas-fired power sources, generates an active output reduction curve and dynamic exit time limit that can be executed before triggering low-voltage protection, including: Obtain the current output value, minimum stable output value, and maximum allowable output reduction rate of the gas-fired power source, and calculate the shortest physical exit time required for the gas-fired power source to reduce from the current output to the minimum stable output. Compare the supported runtime with the shortest physical exit time, and take the smaller of the two as the initial dynamic exit time limit; Within the initial dynamic exit time limit, with the minimum stable output as the output reduction endpoint and the maximum allowable output reduction rate as the constraint, an active output reduction curve for gas-fired power sources is generated.

7. The dynamic active protection method for rural electro-pneumatic coupling systems according to claim 6, characterized in that, The step of rolling adjustments based on the latest predicted state during execution includes: Within the dynamic exit time limit, an intermediate evaluation time is selected. When the intermediate evaluation time is reached, the remaining supportable operating time is recalculated based on the latest gas power output and gas supply node pressure status. Based on the comparison between the recalculated remaining available runtime and the remaining time of the current dynamic exit time limit, the dynamic exit time limit and the active power reduction curve are updated until the preset correction stop condition is met, thus obtaining the final dynamic exit time limit and active power reduction curve.

8. The dynamic active protection method for rural electro-pneumatic coupling systems according to claim 1, characterized in that, The multi-resource continuity compensation model takes minimizing the overall operating cost as its objective function, and its expression is: in: For the overall operational costs, This represents the total number of control moments within the dynamic exit time limit. To control time numbering, For the upper-level power grid in the first Support power at each control moment For distributed adjustable power sources in the first The output at each control moment For renewable energy in the first The output at each control moment For energy storage systems in the first Discharge power at each control moment For the first Load reduction amount at each control moment to These are the unit cost coefficients for power purchase from the upper-level grid, dispatch of distributed adjustable power sources, dispatch of renewable energy sources, energy storage discharge, and load shedding, respectively. The control step size is measured in hours; where the load reduction cost factor is... It is greater than all other cost coefficients.

9. The dynamic active protection method for rural electro-pneumatic coupling systems according to claim 8, characterized in that, The multi-resource succession compensation model includes power balance constraints, resource capacity and ramping constraints, and energy storage operation constraints.

10. The dynamic active protection method for rural electro-pneumatic coupling systems according to claim 9, characterized in that, The step involves outputting the output plan for each compensation resource based on the solution results of the multi-resource succession compensation model, and executing corresponding control actions, including: From the solution results of the multi-resource succession compensation model, the optimized values ​​of the upstream grid support power, distributed adjustable power output, renewable energy output, and energy storage charging and discharging power at each control moment are extracted. The extracted optimized values ​​are arranged in order of control time to generate the output plan of each compensation resource within the dynamic exit time limit; According to the power output plan, control commands are sent to the control terminals corresponding to each compensation resource to execute power continuity compensation actions.

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