UPFC (Unified Power Flow Controller) control method, device and equipment considering N-1 fault of line

Abstract

The invention discloses a UPFC (Unified Power Flow Controller) control method, device and equipment considering a line N-1 fault. The method comprises the following steps: acquiring a real-time electrical quantity on a UPFC installation line; identifying the running state of the UPFC system according to the real-time electrical quantity to obtain the type of the running state; if the operation state category is an overload state, calculating the optimal regulation voltage of the UPFC according to a preset power regulation model through a sensitivity analysis method; if the type of the operation state is a short-circuit fault state, adjusting the equivalent impedance current limiting of a UPFC series transformer, triggering a UPFC parallel converter to carry out reactive power regulation, and outputting a voltage reference value; and based on the control coefficient of the inner loop controller and a linear weighting method, realizing UPFC adaptive regulation and control according to the optimal regulation voltage or the voltage reference value. The technical problems that in the prior art, self-adaptive adjustment capability based on the real-time electrical quantity is lacked, and the relation between UPFC control and system short-circuit current limitation cannot be coordinated can be solved.

Description

Technical Field

[0001] This application relates to the field of power systems, and in particular to a UPFC control method, apparatus and equipment that takes into account line N-1 faults. Background Technology

[0002] With the continuous increase in urban power grid load density and renewable energy penetration, N-1 faults in transmission lines are one of the main risks threatening the safe operation of urban power grids. The Unified Power Flow Controller (UPFC), as a flexible AC transmission device capable of simultaneously regulating active and reactive power of lines, directly impacts the transient stability of the power grid after an N-1 fault.

[0003] Existing UPFC control strategies suffer from the following technical problems: First, when an N-1 fault occurs in the system, a fixed control mode switching logic is typically used, lacking adaptive adjustment capabilities based on real-time electrical quantities, resulting in a mismatch between the control response and the actual safety requirements of the system. Second, when the fault develops into a short circuit, the activation of UPFC will change the distribution of the system's short-circuit current, and existing methods cannot effectively coordinate the relationship between UPFC control and system short-circuit current limiting, and may even exacerbate the stress on electrical equipment. Summary of the Invention

[0004] This application provides a UPFC control method, apparatus, and equipment that considers line N-1 faults, to solve the technical problems of the prior art lacking adaptive adjustment capability based on real-time electrical quantities and being unable to coordinate the cooperation between UPFC control and system short-circuit current limiting.

[0005] In view of this, the first aspect of this application provides a UPFC control method considering line N-1 faults, comprising:

[0006] Real-time electrical quantities on the UPFC installation line are collected, and the status signals of the circuit breaker and disconnector are obtained. The real-time electrical quantities include line active power, line reactive power, current amplitude and bus voltage.

[0007] The operating status of the UPFC system is analyzed and identified based on the real-time electrical quantities to obtain the operating status category, which includes normal status, overload status and short circuit fault status.

[0008] If the operating state category is the overload state, the optimal regulation voltage of the UPFC is calculated based on the preset power regulation model using a sensitivity analysis method.

[0009] If the operating state category is the short-circuit fault state, then the equivalent impedance current limiting of the UPFC series transformer is adjusted, triggering the UPFC parallel converter to perform reactive power regulation and output a voltage reference value.

[0010] Based on the control coefficients of the inner loop controller and the linear weighting method, UPFC adaptive regulation is achieved according to the optimal adjustment voltage or the voltage reference value.

[0011] Preferably, the step of analyzing and identifying the operating status of the system containing the UPFC based on the real-time electrical quantities to obtain the operating status category includes:

[0012] Calculate the line power surge of UPFC based on the real-time electrical quantities;

[0013] If the power surge of the line is greater than the power surge threshold, and the circuit breaker of the associated line is determined to be in the open state based on the status signal, then the operating state category is determined to be N-1 interruption overload.

[0014] Calculate the load rate of the UPFC critical line based on the real-time electrical quantities;

[0015] If the load rate of each of the UPFC critical lines is less than the lower limit of the load rate and no N-1 interruption overload occurs, then the operating state category is determined to be normal.

[0016] If at least one of the UPFC critical paths has a load rate greater than the lower load rate limit, and the total load rate of all the UPFC critical paths is less than the upper load rate limit, then the operating state category is determined to be a normal overload state.

[0017] If the current amplitude is greater than the short-circuit current threshold, or if the load rate of at least one of the UPFC critical lines is greater than the upper limit of the load rate, then the operating state category is determined to be a short-circuit fault state.

[0018] Preferably, if the operating state category is the overload state, then the optimal regulation voltage of the UPFC is calculated according to a preset power regulation model using a sensitivity analysis method, including:

[0019] If the operating state category is the overload state, calculate the power difference of the overloaded line;

[0020] A preset power regulation model is constructed with the goal of minimizing the power difference.

[0021] The optimal regulation voltage of the UPFC is calculated based on the preset power regulation model using a sensitivity analysis method.

[0022] Preferably, the UPFC adaptive regulation based on the control coefficients of the inner-loop controller and the linear weighting method, according to the optimal adjustment voltage or the voltage reference value, includes:

[0023] The control coefficients are obtained by dynamically adjusting the proportional and integral coefficients of the inner-loop controller using the pole placement method.

[0024] Based on the linear weighting method, a smooth transition command is generated according to the optimal adjustment voltage or the voltage reference value to obtain the control voltage reference value;

[0025] UPFC adaptive regulation is achieved based on the control coefficient and the control voltage reference value.

[0026] Preferably, the UPFC adaptive regulation based on the control coefficients of the inner-loop controller and the linear weighting method, according to the optimal adjustment voltage or the voltage reference value, further includes:

[0027] The control voltage reference value is input into the pulse width modulation unit of the UPFC for safe operation verification, and the verification result is obtained.

[0028] Preferably, the UPFC adaptive regulation based on the control coefficients of the inner-loop controller and the linear weighting method, according to the optimal adjustment voltage or the voltage reference value, further includes:

[0029] The UPFC controller sends the current operating mode of the system and the control voltage reference value to the relay protection information system.

[0030] The relay protection information system dynamically adjusts the braking coefficient of the line longitudinal differential protection based on the received information and the preset correlation matrix.

[0031] A second aspect of this application provides a UPFC control device that takes into account line N-1 faults, comprising:

[0032] The information acquisition unit is used to collect real-time electrical quantities on the UPFC installation line, and at the same time acquire the status signals of the circuit breaker and disconnector. The real-time electrical quantities include line active power, line reactive power, current amplitude and bus voltage.

[0033] The status identification unit is used to analyze and identify the operating status of the system where the UPFC is located based on the real-time electrical quantities, and obtain the operating status category, which includes normal status, overload status and short circuit fault status.

[0034] An overload analysis unit is used to calculate the optimal regulation voltage of the UPFC based on a preset power regulation model using a sensitivity analysis method if the operating state category is the overload state.

[0035] The short-circuit analysis unit is used to adjust the equivalent impedance current limiting of the UPFC series transformer, trigger the UPFC parallel converter to perform reactive power regulation, and output a voltage reference value if the operating state category is the short-circuit fault state.

[0036] The UPFC control unit is used to achieve adaptive UPFC control based on the control coefficients of the inner loop controller and the linear weighting method, according to the optimal adjustment voltage or the voltage reference value.

[0037] Preferably, the state recognition unit is specifically used for:

[0038] Calculate the line power surge of UPFC based on the real-time electrical quantities;

[0039] If the power surge of the line is greater than the power surge threshold, and the circuit breaker of the associated line is determined to be in the open state based on the status signal, then the operating state category is determined to be N-1 interruption overload.

[0040] Calculate the load rate of the UPFC critical line based on the real-time electrical quantities;

[0041] If the load rate of each of the UPFC critical lines is less than the lower limit of the load rate and no N-1 interruption overload occurs, then the operating state category is determined to be normal.

[0042] If at least one of the UPFC critical paths has a load rate greater than the lower load rate limit, and the total load rate of all the UPFC critical paths is less than the upper load rate limit, then the operating state category is determined to be a normal overload state.

[0043] If the current amplitude is greater than the short-circuit current threshold, or if the load rate of at least one of the UPFC critical lines is greater than the upper limit of the load rate, then the operating state category is determined to be a short-circuit fault state.

[0044] Preferably, the overload analysis unit is specifically used for:

[0045] If the operating state category is the overload state, calculate the power difference of the overloaded line;

[0046] A preset power regulation model is constructed with the goal of minimizing the power difference.

[0047] The optimal regulation voltage of the UPFC is calculated based on the preset power regulation model using a sensitivity analysis method.

[0048] A third aspect of this application provides a UPFC control device that considers line N-1 faults, the device including a processor and a memory;

[0049] The memory is used to store program code and transmit the program code to the processor;

[0050] The processor is used to execute the UPFC control method considering line N-1 faults as described in the first aspect, according to the instructions in the program code.

[0051] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:

[0052] This application provides a UPFC control method considering line N-1 faults, including: acquiring real-time electrical quantities on the UPFC installation line, and simultaneously acquiring the status signals of circuit breakers and disconnectors. The real-time electrical quantities include line active power, line reactive power, current amplitude, and bus voltage; analyzing and identifying the operating status of the UPFC system based on the real-time electrical quantities to obtain operating status categories, including normal state, overload state, and short-circuit fault state; if the operating status category is overload state, calculating the optimal regulation voltage of the UPFC based on a preset power regulation model using a sensitivity analysis method; if the operating status category is short-circuit fault state, adjusting the equivalent impedance current limiting of the UPFC series transformer, triggering the UPFC parallel converter to perform reactive power regulation, and outputting a voltage reference value; and achieving adaptive regulation of the UPFC based on the control coefficients of the inner loop controller and the linear weighting method, according to the optimal regulation voltage or the voltage reference value.

[0053] The UPFC control method considering N-1 line faults provided in this application analyzes and identifies the operating status of the UPFC system by collecting various real-time electrical quantities. This enables precise perception of the power grid operating conditions and rapid detection of N-1 faults. Then, targeted analysis is performed on different fault states to provide more accurate decision data for UPFC adaptive control, ensuring that each UPFC adjustment adapts to the actual power grid conditions and guarantees the stability of power system control. Simultaneously, targeted regulation can coordinate the relationship between UPFC control and system short-circuit current limiting. Therefore, this application solves the technical problems of existing technologies lacking adaptive adjustment capabilities based on real-time electrical quantities and being unable to coordinate the relationship between UPFC control and system short-circuit current limiting. Attached Figure Description

[0054] Figure 1 A flowchart illustrating a UPFC control method considering line N-1 faults provided in an embodiment of this application;

[0055] Figure 2 A schematic diagram of the structure of a UPFC control device considering line N-1 faults provided in this application embodiment;

[0056] Figure 3 A diagram of the overall UPFC control architecture considering line N-1 faults provided in this application embodiment;

[0057] Figure 4 The timing diagram for UPFC control and protection coordination and system recovery provided in the embodiments of this application is shown. Detailed Implementation

[0058] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0059] For easier understanding, please refer to Figure 1 An embodiment of a UPFC control method considering line N-1 faults provided in this application includes:

[0060] Step 101: Collect real-time electrical quantities on the UPFC installation line, and simultaneously acquire the status signals of the circuit breaker and disconnector. The real-time electrical quantities include line active power, line reactive power, current amplitude, and bus voltage.

[0061] This embodiment uses a hybrid measurement system for multi-source data acquisition. The hybrid measurement system includes a data acquisition device, a monitoring and control system (SCADA), and a phasor measurement unit (PMU). The system can synchronously acquire real-time electrical quantities of the UPFC installed line, and can also receive circuit breaker and disconnector status signals (Boolean values, 1 indicates closed, 0 indicates open) sent by the power grid energy management system (EMS).

[0062] Real-time electrical quantities include line active power. (Unit: MW), Line reactive power (Unit: Mvar), Current Amplitude (Unit: kA) and bus voltage (Unit: kV). To ensure data timescale consistency, this embodiment uses the IEEE 1588 Precision Clock Protocol (PTP) to synchronize the clocks of all measurement units in the system, with a synchronization accuracy better than 1 millisecond.

[0063] Step 102: Analyze and identify the operating status of the UPFC system based on real-time electrical quantities to obtain the operating status category, which includes normal status, overload status and short-circuit fault status.

[0064] Further, step 102 includes:

[0065] Calculate the line power surge of UPFC based on real-time electrical quantities;

[0066] If the power surge of the line is greater than the power surge threshold, and the circuit breaker of the associated line is determined to be in the open state based on the status signal, then the operating status category is determined to be N-1 interruption overload.

[0067] Calculate the load rate of the critical line in UPFC based on real-time electrical quantities;

[0068] If the load rate of each critical UPFC line is less than the lower limit of the load rate and no N-1 interruption overload occurs, the operating status is determined to be normal.

[0069] If at least one UPFC critical path has a load rate greater than the lower load rate limit, and the total load rate of all UPFC critical paths is less than the upper load rate limit, then the operating state category is determined to be a normal overload state.

[0070] If the current amplitude is greater than the short-circuit current threshold, or if the load rate of at least one critical UPFC line is greater than the upper limit of the load rate, the operating status is determined to be a short-circuit fault state.

[0071] In this embodiment, the system where the UPFC is located is first analyzed based on real-time electrical quantities to determine whether an N-1 fault has occurred. After determining that the N-1 fault is interrupted, a detailed status analysis is then performed based on real-time electrical quantities to determine whether the fault is caused by an overload or a short circuit.

[0072] A comprehensive logical judgment based on the line power surge and circuit breaker status can determine whether an N-1 interruption fault has occurred in the system; the line power surge can be calculated as follows:

[0073]

[0074] in, The sampling interval is typically 20-100 milliseconds. An N-1 interruption fault, i.e., an N-1 interruption overload, is determined to have occurred when both of the following conditions are met simultaneously: First, ,in, The first step is to determine the power surge threshold, typically 15%-30% of the line's rated power. Secondly, based on the acquired switch status signals, it is determined that the circuit breaker of the associated line closely related to the UPFC installation line is in the open state, i.e., the switch status signal. The trip signal changes from 1 to 0. At this point, it is determined that an N-1 fault has occurred in the system, and the operating status is determined to be N-1 overload.

[0075] Then, the load rate of the UPFC critical line can be calculated based on the data in the real-time electrical quantities:

[0076]

[0077] in, This indicates the maximum current-carrying capacity of the line, expressed in kA.

[0078] For normal state If the load rate of each UPFC critical path All ,in, This is the lower limit of the load rate, also known as the light load threshold, which is usually set to 0.7; and the detection determines that no N-1 interruption fault has occurred.

[0079] For overload conditions If there is at least one UPFC critical path with a load factor Greater than the lower limit of load rate ,Right now At this point, an overload can be identified. It should be noted that if at least one UPFC critical line has a load factor... Greater than or equal to the lower limit of load rate However, if no N-1 interruption overload occurs, the current operating state is a normal overload state, not an N-1 interruption overload state caused by an N-1 interruption fault, and it is still treated as an overload state; but if an N-1 interruption overload occurs, and the total load rate of all UPFC critical lines is... Less than the upper limit of load rate ,Right now At the same time, there is a load factor of at least one UPFC critical line. Greater than the lower limit of load rate ,Right now This is also known as the overload alarm threshold, typically set to 0.9, at which point it is determined to be an N-1 interruption overload. In other words, the overload conditions in this embodiment include two types: N-1 interruption fault overload and general overload.

[0080] For short circuit fault conditions If the collected current amplitude Exceeding the short-circuit current threshold ,Right now pu, meaning the short-circuit current characteristic value exceeds the threshold. ; or at least one line has a load factor exceeding the load factor limit, i.e. If the system exhibits a short-circuit fault state, then the system is determined to be in a short-circuit fault state.

[0081] Step 103: If the operating state category is overload state, calculate the optimal regulation voltage of UPFC based on the preset power regulation model using the sensitivity analysis method.

[0082] Further, step 103 includes:

[0083] If the operating status category is overload, calculate the power difference of the overloaded lines;

[0084] A preset power regulation model is constructed with the goal of minimizing the power difference.

[0085] The optimal regulation voltage of the UPFC is calculated based on a preset power regulation model using sensitivity analysis.

[0086] Overload conditions The following lines It can calculate the actual active power of the line. With safe power limits The power difference between them:

[0087]

[0088] It refers to the safe power limit considering the thermal stability limit of the line and the transient stability constraint of the system, in MW, which is usually provided by offline calculation or online safety analysis module.

[0089] Under overload conditions, the primary objective is to eliminate overload on critical lines; therefore, this embodiment focuses on adjusting the power difference. With minimization as the objective, a pre-defined power regulation model is constructed:

[0090]

[0091] The above optimization problem is solved using sensitivity analysis:

[0092]

[0093] in,

[0094]

[0095] The power-voltage sensitivity coefficient is obtained through real-time linearized power flow equations. This is the step size factor, used to ensure convergence; This is the optimal adjustment value for UPFC, which is the optimal adjustment voltage for UPFC.

[0096] Step 104: If the operating status is a short-circuit fault, adjust the equivalent impedance current limiting of the UPFC series transformer to trigger the UPFC parallel converter to perform reactive power regulation and output the voltage reference value.

[0097] If it is in a short circuit fault state The UPFC immediately switches to fault ride-through mode, using fast power electronic switches such as thyristors to activate a preset bypass current-limiting reactor. The unit is pu, which stands for equivalent impedance. Working in conjunction with the UPFC series transformer, it limits the short-circuit current below the equipment's withstand level. Simultaneously, the parallel converter exits active power control and switches to reactive power support mode, and its output voltage reference value... Determined by the following formula:

[0098]

[0099] in, The initial reference voltage, The droop coefficient is... This is the rated voltage of the busbar. The strategy involves raising the voltage during voltage dips. This forces the parallel converters to generate capacitive reactive power to support the bus voltage near the fault point. .

[0100] It should be noted that if it is a non-fault state, that is, a normal state In this case, UPFC can be controlled normally using the traditional dual-closed-loop vector control strategy. The outer-loop power controller generates the inner-loop current reference value. Taking active power control as an example, its PI control is as follows:

[0101]

[0102] in, This is the reference value for the d-axis current of the converter, in kA. For planned trend value, and The proportional and integral coefficients of the controller are tuned according to the system short-circuit capacity and control response requirements. The inner-loop current controller then tracks the circuit rapidly. Finally, the output voltage reference value of the UPFC series-side converter is generated through PWM modulation. .

[0103] Step 105: Based on the control coefficients of the inner loop controller and the linear weighting method, UPFC adaptive regulation is achieved according to the optimal adjustment voltage or voltage reference value.

[0104] Further, step 105 includes:

[0105] The control coefficients are obtained by dynamically adjusting the proportional and integral coefficients of the inner-loop controller using the pole placement method.

[0106] Based on the linear weighting method, a smooth transition command is generated according to the optimal regulation voltage or voltage reference value to obtain the control voltage reference value;

[0107] UPFC adaptive regulation is achieved based on control coefficients and control voltage reference values.

[0108] It should be noted that, in order to avoid power oscillations caused by switching between different control modes, this embodiment uses a linear weighting method to smoothly transition the control command. Within N control cycles of mode switching, typically N=5~10, the final control voltage reference value, i.e., the output control command, is determined. for:

[0109]

[0110] in, To switch the control command from the previous moment, The control command calculated for the new mode after switching, the optimal regulation voltage or voltage reference value calculated; transition coefficient. Decays linearly from 1 to 0: .

[0111] To adapt to different power grid operating modes, such as changes between strong and weak power grids, the parameter proportional coefficient of the UPFC inner loop current controller... Integral coefficient Online adjustments are required. This embodiment employs a pole placement method, based on the real-time estimated system equivalent impedance. The controller parameters are recalculated so that the closed-loop poles controlled by the inner-loop controller are always located in the desired region of the left half of the complex plane, thus ensuring the speed and stability of the control.

[0112] It should be noted that, based on the already defined operational status categories... During the actual execution phase, the current primary control objective of UPFC can be dynamically configured, that is, the controller can be given priority to trigger the control mechanism:

[0113] like The control objective is precise power flow tracking, i.e., minimizing... ;

[0114] like The control objective is to eliminate line overload, i.e., minimize it. ;

[0115] like The control objective is to suppress short-circuit current. ,in, To the maximum withstand value of the equipment and to support the bus voltage. .

[0116] Furthermore, step 105, followed by:

[0117] The control voltage reference value is input into the pulse width modulation unit of the UPFC for safe operation verification, and the verification result is obtained.

[0118] The control voltage reference value can be used as the output control command. A safety check is performed before the pulse width modulation (PWM) generator in the UPFC is input. The check process includes:

[0119] Does the voltage amplitude limit meet? ,in It is determined by the DC voltage of the UPFC converter and the turns ratio of the AC-side transformer.

[0120] Does the current limit meet? Through feedforward calculations, ensure the corresponding converter output current is met. satisfy ;in, This indicates the maximum safe operating current of the UPFC converter.

[0121] If any of the above conditions are not met, then for Amplitude limiting is applied.

[0122] Furthermore, step 105, followed by:

[0123] The UPFC controller sends the current operating mode of the system and the reference value of the control voltage to the relay protection information system.

[0124] The braking coefficient of the line longitudinal differential protection is dynamically adjusted by the relay protection information system based on the received information and the preset correlation matrix.

[0125] At the control implementation level, existing solutions mostly rely on threshold judgments of preset parameters, which are difficult to adapt to the time-varying operation mode of urban power grids and lack a coordination mechanism with local line protection, posing a risk of protection malfunction. Therefore, this embodiment provides a UPFC control method that can adaptively adjust control objectives and strategies according to the real-time operating status of the power grid and coordinate with system protection devices.

[0126] This embodiment forms a complete fault defense closed loop through deep coordination between UPFC control and relay protection, as well as a system recovery strategy after fault clearance. First, the UPFC controller sets its current operating mode... (For example, Trend control Overload elimination (Fault current limiting / voltage support) is transmitted in real time to the station control layer relay protection information substation via the communication gateway. This signal is related to key outputs of the UPFC, such as the control voltage reference value. They are encapsulated together in a GOOSE message to ensure transmission speed; end-to-end latency <10ms.

[0127] Then, the line protection device receives the UPFC operation mode signal. .when At this time, the protection device dynamically adjusts its longitudinal differential braking characteristics based on a preset correlation matrix. For example, it adjusts the braking coefficient... From normal values Temporarily adjusted to ,in For example, 1.2. This is because the UPFC changes the phase of the fault current in current-limiting mode, and increasing the braking coefficient can prevent the protection from maloperating due to current phase distortion when there is a fault outside the zone.

[0128] In addition, during UPFC operation, especially during bypass activation, auxiliary criteria are added to help the protection correctly determine the fault location; the differential value of the fault current can also be calculated. ,like Exceeding the set threshold and accompanied by a drastic change in the bus voltage phase θ This strengthens the judgment weight of faults within the zone, resulting in a newly adjusted weight value. This criterion, together with the aforementioned differential protection mechanism, forms an "AND" logic, enhancing the selectivity of the protection under complex operating conditions.

[0129] Furthermore, the short-circuit current of the system containing the UPFC can be continuously monitored. and bus voltage When the following conditions are met: ,in, This is the normal load current value; and If the short circuit fault persists for more than 100 milliseconds, it is considered cleared. UPFC then automatically exits fault current limiting mode. Disconnect the bypass switch and the current-limiting reactor. Exiting operation, the control mode is preparing to return to normal.

[0130] Furthermore, after the fault is cleared, the UPFC is not immediately restored to the optimal power flow point, but rather restored gradually. In the first recovery phase, typically within 1-2 seconds, the UPFC is controlled to increase the power of the non-faulty lines to the device's safe limit. Next, ensure the system is out of emergency mode. In the second recovery phase, which takes place over the next few tens of seconds or even minutes, optimized power flow instructions can be reissued from the dispatch center. Slowly adjust the UPFC output to gradually restore the system to a new optimal operating point. During this process, monitor the load rate of critical lines to prevent further overload.

[0131] Finally, after the UPFC control event ends, all key indicators of the control process can be recorded, and an evaluation report can be generated, such as voltage recovery time. From the time of fault clearing to The time taken for the load to remain stable above 0.95 PU; load recovery rate :

[0132]

[0133] in For loads whose power is restored after a fault, The power loss load is caused by a fault.

[0134] Alternatively, based on a historical event database, parameter self-learning methods, such as gradient descent-based optimization algorithms, can be used to fine-tune the threshold parameters throughout the process, thereby improving the system's performance when dealing with similar events. For the overall technical architecture of this embodiment, please refer to [link / reference needed]. Figure 3 The UPFC control and protection coordination and system recovery timing in this embodiment are as follows: Figure 4 As shown.

[0135] The UPFC control method considering line N-1 faults provided in this application analyzes and identifies the operating status of the UPFC system by collecting various real-time electrical quantities. This enables precise perception of the power grid operating conditions and rapid detection of N-1 faults. Then, targeted analysis is performed on different fault states to provide more accurate decision data for UPFC adaptive control, ensuring that each UPFC adjustment adapts to the actual power grid conditions and guarantees the stability of power system control. Simultaneously, targeted adjustment can coordinate the relationship between UPFC control and system short-circuit current limiting. Therefore, this application's embodiments can solve the technical problems of existing technologies lacking adaptive adjustment capabilities based on real-time electrical quantities and being unable to coordinate the relationship between UPFC control and system short-circuit current limiting.

[0136] For easier understanding, please refer to Figure 2 This application provides an embodiment of a UPFC control device that considers line N-1 faults, comprising:

[0137] The information acquisition unit 201 is used to collect real-time electrical quantities on the UPFC installation line, and at the same time acquire the status signals of the circuit breaker and disconnector. The real-time electrical quantities include line active power, line reactive power, current amplitude and bus voltage.

[0138] The status identification unit 202 is used to analyze and identify the operating status of the system where the UPFC is located based on real-time electrical quantities, and obtain the operating status category, which includes normal status, overload status and short circuit fault status.

[0139] The overload analysis unit 203 is used to calculate the optimal regulation voltage of the UPFC based on a preset power regulation model using a sensitivity analysis method if the operating state category is overload.

[0140] The short-circuit analysis unit 204 is used to adjust the equivalent impedance current limiting of the UPFC series transformer if the operating state is a short-circuit fault state, trigger the UPFC parallel converter to perform reactive power regulation, and output a voltage reference value.

[0141] The UPFC control unit 205 is used to achieve UPFC adaptive control based on the control coefficient of the inner loop controller and the linear weighting method, according to the optimal regulation voltage or voltage reference value.

[0142] Furthermore, the state recognition unit 202 is specifically used for:

[0143] Calculate the line power surge of UPFC based on real-time electrical quantities;

[0144] If the power surge of the line is greater than the power surge threshold, and the circuit breaker of the associated line is determined to be in the open state based on the status signal, then the operating status category is determined to be N-1 interruption overload.

[0145] Calculate the load rate of the critical line in UPFC based on real-time electrical quantities;

[0146] If the load rate of each critical UPFC line is less than the lower limit of the load rate and no N-1 interruption overload occurs, the operating status is determined to be normal.

[0147] If at least one UPFC critical path has a load rate greater than the lower load rate limit, and the total load rate of all UPFC critical paths is less than the upper load rate limit, then the operating state category is determined to be a normal overload state.

[0148] If the current amplitude is greater than the short-circuit current threshold, or if the load rate of at least one critical UPFC line is greater than the upper limit of the load rate, the operating status is determined to be a short-circuit fault state.

[0149] Furthermore, the overload analysis unit 203 is specifically used for:

[0150] If the operating status category is overload, calculate the power difference of the overloaded lines;

[0151] A preset power regulation model is constructed with the goal of minimizing the power difference.

[0152] The optimal regulation voltage of the UPFC is calculated based on a preset power regulation model using sensitivity analysis.

[0153] This application also provides a UPFC control device that considers line N-1 faults, the device including a processor and a memory;

[0154] The memory is used to store program code and transfer the program code to the processor;

[0155] The processor is used to execute the UPFC control method considering line N-1 faults in the above method embodiment according to the instructions in the program code.

[0156] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0157] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0158] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0159] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for executing all or part of the steps of the methods described in the various embodiments of this application through a computer device (which may be a personal computer, server, or network device, etc.). The aforementioned storage medium includes: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media capable of storing program code.

[0160] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A UPFC control method considering line N-1 failure, characterized in that, The application relates to a UPFC adaptive control method and device. Real-time electrical quantities on a UPFC installation line are collected, and state signals of circuit breakers and disconnectors are acquired, wherein the real-time electrical quantities include line active power, line reactive power, current amplitude and bus voltage; An operating state of a system where the UPFC is located is analyzed and identified according to the real-time electrical quantities, and an operating state category is obtained, wherein the operating state category includes a normal state, an overload state and a short-circuit fault state; If the operating state category is the overload state, the optimal regulation voltage of the UPFC is calculated according to a preset power regulation model through a sensitivity analysis method; If the operating state category is the short-circuit fault state, the equivalent impedance current limiting of a UPFC series transformer is adjusted, the UPFC parallel converter is triggered to perform reactive power regulation, and a voltage reference value is output; UPFC adaptive regulation and control are realized according to the optimal regulation voltage or the voltage reference value based on the control coefficient of an inner loop controller and a linear weighting method.

2. The UPFC control method considering line N-l failures according to claim 1, characterized in that, The operating state of the system where the UPFC is located is analyzed and identified according to the real-time electrical quantities, and the operating state category is obtained, and the method comprises the following steps: The line power mutation quantity of the UPFC is calculated according to the real-time electrical quantities; If the line power mutation quantity is greater than a power mutation threshold value, and the state signal indicates that the circuit breaker of the associated line is in an open state, it is determined that the operating state category is an N-1 open overload; The load rate of a UPFC key line is calculated according to the real-time electrical quantities; If the load rate of each UPFC key line is less than a load rate lower limit, and no N-1 open overload occurs, it is determined that the operating state category is a normal state; If the load rate of at least one UPFC key line is greater than the load rate upper limit, and the total load rate of all UPFC key lines is less than a load rate upper limit, it is determined that the operating state category is a regular overload state; If the current amplitude is greater than a short-circuit current threshold value, or the load rate of at least one UPFC key line is greater than the load rate upper limit, it is determined that the operating state category is a short-circuit fault state.

3. The UPFC control method considering line N-l failures according to claim 1, characterized in that, If the operating state category is the overload state, the optimal regulation voltage of the UPFC is calculated according to a preset power regulation model through a sensitivity analysis method, and the method comprises the following steps: If the operating state category is the overload state, the power difference value of the overload line is calculated; A preset power regulation model is constructed with the minimum regulation of the power difference value as the target; The optimal regulation voltage of the UPFC is calculated according to the preset power regulation model through a sensitivity analysis method.

4. The UPFC control method considering line N-l failures according to claim 1, characterized in that, UPFC adaptive regulation and control are realized according to the optimal regulation voltage or the voltage reference value based on the control coefficient of an inner loop controller and a linear weighting method, and the method comprises the following steps: The proportional coefficient and integral coefficient of the inner loop controller are dynamically adjusted by using a pole placement method to obtain a control coefficient; A smooth transition instruction is generated according to the optimal regulation voltage or the voltage reference value based on a linear weighting method to obtain a control voltage reference value; UPFC adaptive regulation and control are realized according to the control coefficient and the control voltage reference value.

5. The UPFC control method considering line N-l failures according to claim 4, characterized in that, The control coefficient and linear weighting method based on the inner loop controller realizes adaptive regulation and control of the UPFC according to the optimal regulation voltage or the voltage reference value, and further comprises the following steps: The control voltage reference value is input into a pulse width modulation unit of the UPFC for safe operation verification, and a verification result is obtained.

6. The UPFC control method considering line N-l failures according to claim 4, characterized in that, The control coefficient and linear weighting method based on the inner loop controller realizes adaptive regulation and control of the UPFC according to the optimal regulation voltage or the voltage reference value, and further comprises the following steps: The current operation mode of the system and the control voltage reference value are sent to a relay protection information system through the UPFC controller; The braking coefficient of the line pilot differential protection is dynamically adjusted by the relay protection information system according to the received information and a preset correlation matrix.

7. A UPFC control device considering line N-l failures, characterized in that, It comprises: An information acquisition unit is configured to collect real-time electrical quantities on a line where the UPFC is installed, and simultaneously acquire state signals of circuit breakers and disconnectors, wherein the real-time electrical quantities include line active power, line reactive power, current amplitude and bus voltage; A state identification unit is configured to analyze and identify the operation state of the system where the UPFC is located according to the real-time electrical quantities, and obtain an operation state category, wherein the operation state category includes a normal state, an overload state and a short-circuit fault state; An overload analysis unit is configured to, if the operation state category is the overload state, calculate an optimal regulation voltage of the UPFC according to a preset power regulation model through a sensitivity analysis method; A short-circuit analysis unit is configured to, if the operation state category is the short-circuit fault state, adjust the equivalent impedance current limiting of a series transformer of the UPFC, trigger a shunt current of the UPFC to perform reactive power regulation, and output a voltage reference value; A UPFC regulation and control unit is configured to realize adaptive regulation and control of the UPFC according to the optimal regulation voltage or the voltage reference value based on a control coefficient and linear weighting method of an inner loop controller.

8. The UPFC control device considering line N-l failures according to claim 7, characterized in that, The state identification unit is specifically configured to: calculate a line power mutation variable of the UPFC according to the real-time electrical quantities; if the line power mutation variable is greater than a power mutation threshold value, and it is determined from the state signals that the circuit breakers of the associated lines are in an open state, then it is determined that the operation state category is an N-1 open overload; calculate a load rate of a key line of the UPFC according to the real-time electrical quantities; if the load rate of each of the key lines of the UPFC is less than a lower load rate limit, and no N-1 open overload occurs, then it is determined that the operation state category is the normal state; if the load rate of at least one of the key lines of the UPFC is greater than the lower load rate limit, and the total load rate of all the key lines of the UPFC is less than an upper load rate limit, then it is determined that the operation state category is a regular overload state; if the current amplitude is greater than a short-circuit current threshold value, or the load rate of at least one of the key lines of the UPFC is greater than the upper load rate limit, then it is determined that the operation state category is the short-circuit fault state.

9. The UPFC control device considering line N-l failures according to claim 7, characterized in that, The overload analysis unit is specifically configured to: if the operation state category is the overload state, calculate a power difference value of an overload line; build a preset power regulation model with the objective of minimizing the power difference value; The optimal regulating voltage of the UPFC is calculated according to the preset power regulating model through a sensitivity analysis method.

10. A UPFC control device considering line N-l failures, characterized in that, The device comprises a processor and a memory; The memory is configured to store program code and transmit the program code to the processor; The processor is configured to execute the UPFC control method considering line N-1 fault according to instructions in the program code.

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