Power grid voltage control method and system based on cooperation of multiple reactive power devices

Abstract

The invention belongs to the technical field of power systems, and relates to a power grid voltage control method and system for cooperation of multiple reactive devices, and the method comprises the steps: obtaining the response time characteristics of each reactive device, and dividing the multiple reactive devices into a first type of devices and a second type of devices according to the response time characteristics; when the voltage offset is detected, the first type of equipment is preferentially controlled to execute initial voltage regulation, and the starting moment of the second type of equipment is determined according to the matching degree of the compensation capability of the first type of equipment and the voltage offset; and controlling the second type of equipment to execute supplementary voltage regulation according to the starting time, so that the reactive power output of the second type of equipment is staggered from the first type of equipment in time. According to the method, the equipment is divided into the fast equipment and the slow equipment, the fast equipment is preferentially used for initial adjustment, and the starting time of the slow equipment is dynamically determined according to the compensation capability of the fast equipment, so that reactive output of the two types of equipment is staggered in time, interference and conflicts generated by simultaneous adjustment are eliminated, and resource internal consumption is reduced; and the voltage recovery stability and the regulation efficiency are improved.

Description

Technical Field

[0001] This invention relates to the field of power system technology, and in particular to a power grid voltage control method and system for the coordinated operation of multiple reactive power devices. Background Technology

[0002] During power grid operation, precise voltage regulation is a crucial aspect of ensuring power quality, reducing grid losses, and enhancing system security. To address voltage fluctuations, various types of reactive power regulation equipment are deployed in the power grid, including static var generators, static var compensators, synchronous condensers, capacitor banks, and energy storage converters and renewable energy generating units with reactive power regulation capabilities.

[0003] Voltage control methods typically integrate various reactive power devices into an automatic voltage control system, uniformly allocating reactive power commands based on global optimization objectives. While this achieves optimized reactive power scheduling at the system level, it overlooks the fundamental differences in the time response scales of different devices. Specifically, power electronic devices, such as static var generators (SVMs), can adjust reactive power output within milliseconds, making them suitable for handling sudden voltage fluctuations, but their regulation capacity is relatively limited. Electromechanical devices, such as capacitor banks and synchronous condensers, have larger regulation capacity and higher steady-state regulation accuracy, but their response speed is slower, often requiring hundreds of milliseconds or even seconds from command issuance to output stabilization. When voltage deviations occur, if all devices are simultaneously regulated, the high-frequency dynamic adjustments of fast-moving devices and the low-frequency response cycles of slow-moving devices will create superimposed interference. This not only fails to achieve the expected regulation effect but may also cause system oscillations, resulting in wasted regulation resources and increased energy loss. Summary of the Invention

[0004] Therefore, the purpose of this invention is to overcome the problem that when various reactive power devices are uniformly included in an automatic voltage control system for simultaneous regulation, the essential differences in response time scale between fast and slow devices are ignored, leading to superimposed interference between the high-frequency dynamic adjustment of fast devices and the low-frequency response cycle of slow devices, causing system oscillations, wasted regulation resources, and increased energy loss. This invention provides a grid voltage control method and system for the coordinated operation of multiple reactive power devices. Based on response time characteristics, devices are divided into fast and slow categories. Fast devices are prioritized for initial regulation, and the start-up time of slow devices is dynamically determined based on the matching degree between the compensation capability of fast devices and voltage deviation. This ensures that the reactive power output of the two types of devices is staggered in time, thereby eliminating regulation conflicts, reducing resource consumption, reducing interference between devices with different response times, and improving the stability of voltage recovery and regulation efficiency.

[0005] In a first aspect, to solve the above-mentioned technical problems, the present invention provides a grid voltage control method for the coordinated operation of multiple reactive power devices, comprising: The response time characteristics of each reactive power device are obtained, and the reactive power devices are divided into a first category of devices and a second category of devices based on the response time characteristics; the response time of the first category of devices is shorter than the response time of the second category of devices. When a grid voltage deviation is detected, the first type of equipment is prioritized to perform initial voltage regulation, and the start-up time of the second type of equipment is determined based on the degree of matching between the compensation capability of the first type of equipment and the voltage deviation. According to the startup time, the second type of equipment is controlled to perform supplementary voltage regulation so that the reactive power output of the second type of equipment is staggered from that of the first type of equipment in time.

[0006] Preferably, controlling the first type of equipment to perform initial voltage regulation includes: obtaining the current output power and adjustable upper limit of power of each reactive power device in the first type of equipment; determining the remaining capacity of the reactive power device based on the current output power and adjustable upper limit of power; calculating the required compensation amount based on the voltage offset; determining whether there is a single reactive power device in the first type of equipment whose remaining capacity is greater than or equal to the required compensation amount; if so, selecting the reactive power device with the smallest remaining capacity from the reactive power devices whose remaining capacity is greater than or equal to the required compensation amount as the execution device, and performing initial voltage regulation through the execution device; if not, activating each reactive power device in descending order of remaining capacity.

[0007] Preferably, the initial voltage regulation performed by the actuator includes: determining the target output power Q of the actuator according to the following method: Q = Q0 + ΔQ; Q0 represents the current output power of the actuator; ΔQ represents the required compensation amount; determining whether the target output power Q is less than or equal to the adjustable upper limit of the actuator's power; if so, controlling the output power Q(t) of the actuator according to the following method: ; t represents the time elapsed since the control command was issued, and τ represents the response time constant of the executing device; If not, the target output power Q is corrected to the upper limit of the adjustable power of the actuator.

[0008] Preferably, activating reactive power devices in descending order of remaining capacity further includes: if the electrical distance between two reactive power devices in adjacent activation sequences is less than a threshold, then an activation time interval is inserted between them, wherein the activation time interval is positively correlated with the sum of the response time constants of the two reactive power devices.

[0009] Preferably, determining the start-up time of the second type of equipment based on the matching degree between the compensation capability and voltage offset of the first type of equipment includes: obtaining the continuous adjustment duration, adjustment accuracy level, and response time constant of each reactive power device in the second type of equipment; selecting candidate equipment from the second type of equipment based on the continuous adjustment duration; selecting target equipment from the candidate equipment based on the adjustment accuracy level; the target equipment has the highest adjustment accuracy level; and determining the start-up time of the target equipment based on the largest response time constant in the first type of equipment and the response time constant of the target equipment.

[0010] Preferably, determining the startup time of the target device includes: t0 = a × τ1 + β × τ2; t0 represents the start-up time of the target device; τ1 represents the maximum response time constant among the first type of devices; τ2 represents the response time constant of the target device; α represents the response completion coefficient of the first type of devices, with a value of 3 to 4, so that the reactive power output of the first type of devices approaches the steady-state value before starting the target device; β represents the response pre-compensation coefficient of the second type of devices, with a value of 0.5 to 1, so that the start-up time of the target device is earlier than its own response completion time, in order to compensate for its response lag.

[0011] Preferably, after determining the start-up time of the target device, the method further includes monitoring the voltage fluctuation frequency of the power grid. If the voltage fluctuation frequency exceeds a fluctuation frequency threshold, the value of the response completion coefficient α of the first type of device is shortened to advance the start-up time of the target device. If the voltage fluctuation frequency is lower than the fluctuation frequency threshold, the value of the response completion coefficient α of the first type of device is extended to delay the start-up time of the target device. The start-up time of the target device is updated according to the adjusted response completion coefficient of the first type of device.

[0012] Preferably, before determining the start-up time of the target device, the method further includes: calculating the electrical distance d between the target device and the voltage offset monitoring point; obtaining the minimum electrical distance dmin between all activated devices in the first type of device and the voltage offset monitoring point; calculating the electrical distance coefficient η: η = d / dmin; if the electrical distance coefficient is greater than the coefficient threshold, the start-up time of the target device is corrected to: t1 = t0 - λ × (d - dmin); t1 represents the corrected start-up time; λ represents the advance coefficient, which takes a value of 0~1×10 -3 Seconds per kilometer; the coefficient threshold is 1.0 to 1.6.

[0013] Preferably, classifying multiple reactive power devices into a first category and a second category based on the response time characteristics includes: obtaining the response delay time of each reactive power device, calculating the average response delay time of each reactive power device in multiple voltage disturbance events; and classifying the multiple reactive power devices into a first category and a second category based on the average response delay time.

[0014] Secondly, to solve the above-mentioned technical problems, the present invention provides a power grid voltage control system for the coordinated operation of multiple reactive power devices, comprising: The feature acquisition module is used to acquire the response time characteristics of each reactive power device; The device classification module is used to classify multiple reactive power devices into a first category of devices and a second category of devices based on the response time characteristics; the response time of the first category of devices is shorter than the response time of the second category of devices. The initial regulation control module is used to prioritize controlling the first type of equipment to perform initial voltage regulation when a grid voltage deviation is detected. The startup time determination module is used to determine the startup time of the second type of device based on the matching degree between the compensation capability and voltage offset of the first type of device. The supplementary adjustment control module is used to control the second type of equipment to perform supplementary voltage adjustment according to the startup time, so that the reactive power output of the second type of equipment is staggered from that of the first type of equipment in time.

[0015] Compared with the prior art, the above-described technical solution of the present invention has the following advantages: First, grouping based on response time characteristics enables the control strategy to objectively reflect the actual response capability of the equipment, avoiding the neglect of individual differences due to fixed grouping by equipment type. The grouping results can be dynamically adjusted as the operating data is updated, exhibiting strong adaptability.

[0016] Secondly, prioritize the use of fast-response equipment for initial adjustment, fully utilize the rapid response of the fast-response equipment to ensure timely response in the initial stage of voltage recovery and shorten the duration of voltage deviation.

[0017] Third, by matching the compensation capability with the voltage offset, the decision to call up slow equipment is based on quantitative assessment. Slow equipment is only activated when fast equipment is indeed insufficient to cope with the situation, thus avoiding repeated resource calls and internal consumption.

[0018] Fourth, by staggering the timing, the dynamic adjustment process of the fast equipment and the adjustment process of the slow equipment are relayed rather than superimposed in time, eliminating signal interference and system oscillation that may be caused by the simultaneous adjustment of the two types of equipment, making the voltage recovery process more stable.

[0019] In summary, the grid voltage control method and system for multi-reactive power equipment coordination described in this invention can effectively improve the efficiency of multi-reactive power equipment coordinated regulation and improve the grid voltage control quality by optimizing the control strategy without increasing hardware investment. Attached Figure Description

[0020] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 This is a flowchart of a grid voltage control method for coordinated operation of multiple reactive power devices in a preferred embodiment of the present invention; Figure 2 This is a flowchart illustrating the process of controlling the first type of device to perform initial voltage regulation in a preferred embodiment of the present invention; Figure 3 This is a flowchart illustrating the determination of the startup time of the second type of device in a preferred embodiment of the present invention; Figure 4 This is a flowchart illustrating the adjustment of the start-up time based on the voltage fluctuation frequency in a preferred embodiment of the present invention. Figure 5 This is a flowchart illustrating the correction of the start-up time based on electrical distance in a preferred embodiment of the present invention; Figure 6 This is a structural block diagram of a power grid voltage control method for coordinated operation of multiple reactive power devices in a preferred embodiment of the present invention. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0022] In power grid operation, precise voltage regulation is crucial for ensuring power quality, reducing grid losses, and improving system security. Traditional power grid voltage control methods, when uniformly dispatching multiple reactive power devices, neglect the differences in response time among these devices. When grid voltage deviates, if devices with varying response speeds are simultaneously put into regulation, the dynamic adjustments of fast-responding devices and the response cycles of slow-responding devices may cause superimposed interference, resulting in unsatisfactory regulation effects and potentially even system oscillations, leading to wasted regulation resources and energy losses.

[0023] In response, Embodiment 1 of the present invention provides a grid voltage control method for the coordinated operation of multiple reactive power devices. The method acquires the response time characteristics of each reactive power device and classifies them into a first category of devices with faster response times and a second category of devices with slower response times based on these characteristics. When a grid voltage deviation is detected, the method prioritizes controlling the first category of devices to perform initial voltage regulation. Based on the matching degree between the compensation capability of the first category of devices and the voltage deviation, the method determines the start-up time of the second category of devices. Subsequently, the method controls the second category of devices to perform supplementary voltage regulation according to the start-up time, ensuring that the reactive power output of the second category of devices is staggered from that of the first category of devices in time, thereby achieving coordinated and optimized control of reactive power devices with different response speeds.

[0024] For ease of understanding, the key terms in this embodiment are explained below: Reactive power equipment refers to various devices in the power grid that have reactive power regulation capabilities, such as static var generators, static var compensators, synchronous condensers, capacitor banks, energy storage converters with reactive power regulation capabilities, and new energy generating units. These devices support or suppress the grid voltage by changing their reactive power output.

[0025] Response time characteristic refers to the time required for reactive power equipment to reach a stable reactive power output value after receiving a control command. This characteristic is an important indicator for measuring the response speed of the equipment, and different types of reactive power equipment have significantly different response time characteristics.

[0026] The first type of equipment refers to reactive power equipment with a short response time, usually power electronic equipment, such as static var generators or static var compensators; this type of equipment can quickly respond to voltage changes in a short time and provide rapid reactive power support.

[0027] The second category of equipment refers to reactive power equipment with a long response time. These are usually electromechanical or traditional equipment, such as synchronous condensers, capacitor banks, or energy storage converters with large inertia. This type of equipment has a large regulation capacity and high steady-state regulation accuracy, but its response speed is relatively slow.

[0028] Initial voltage regulation refers to the voltage regulation action first performed by the first type of equipment with the fastest response speed when the grid voltage deviates; this regulation aims to quickly suppress the voltage deviation and prevent further voltage deterioration.

[0029] Supplementary voltage regulation refers to the voltage regulation action performed by a second type of equipment with a slower response speed after the initial voltage regulation; this regulation aims to further stabilize the grid voltage, provide continuous and precise reactive power support, and coordinate with the regulation of the first type of equipment in terms of time.

[0030] The start-up time refers to the point at which the second type of equipment begins to perform supplementary voltage regulation. The determination of this time is intended to ensure that the second type of equipment intervenes in regulation only after the regulation effect of the first type of equipment has stabilized, thus avoiding mutual interference between equipment with different response speeds.

[0031] The following is combined with Figure 1 The embodiments of the present invention will be described in detail below with reference to the specific implementation process.

[0032] In actual engineering, the response time of reactive power equipment is not a fixed nameplate parameter, but a dynamic characteristic affected by various factors such as equipment type, operating conditions, and degree of aging. For example, the internal capacitors of a static var generator that has been in operation for many years may age, resulting in an actual response speed slower than the factory nominal value; while the excitation system response speed of a synchronous condenser in the initial stage of low-temperature startup may be lower than the response speed at normal operating temperature.

[0033] To accurately obtain response time characteristics, this embodiment collects the operating data of each reactive power device during historical voltage disturbance events, extracts the response delay time from receiving the instruction to the output changing to a certain proportion of the target value in each disturbance event, and the stable response period from the start of output change to entering a steady state. The average response delay time in multiple disturbance events is used as the response delay characteristic value of the device, and the average stable response period is used as the response period characteristic value of the device, thereby obtaining response time characteristics that can reflect the actual operating characteristics of the device.

[0034] After obtaining the response time characteristics of each reactive power device, the devices are divided into Category 1 and Category 2 devices based on these characteristics. This embodiment uses a sorting method based on the average response delay time. Specifically, the reactive power devices are sorted from smallest to largest according to their average response delay time; the smaller the average response delay time, the faster the device's response speed. Since in voltage control practice, the devices with the fastest response speeds need to be grouped into a fast-response cluster, this embodiment classifies the devices that rank at the top (approximately one-third of the total) as Category 1 devices, and the remaining devices as Category 2 devices. This classification method does not rely on device type labels and can objectively reflect individual differences between devices of the same type. For example, if two identical static var generators have different response speeds due to different maintenance conditions, the one with the faster response speed will be classified as Category 1, and the one with the slower response speed will be classified as Category 2. The Category 1 devices, classified in this way, generally have faster overall response speeds and are suitable for priority use when voltage disturbances occur; the Category 2 devices generally have slower overall response speeds or poorer response stability and are suitable for supplementary use when the capabilities of Category 1 devices are deemed insufficient.

[0035] When a grid voltage deviation is detected, this invention prioritizes controlling the first type of devices to perform initial voltage regulation. Implementing this step requires addressing a key issue: when the first type of devices includes multiple devices, how to select the specific executing device and how to determine the output target of each device to avoid overload or resource waste due to individual device differences.

[0036] This embodiment solves the problem in the following way: First, obtain the current output power and the adjustable upper limit of power of each reactive power device in the first type of equipment. Then, determine the remaining capacity of each reactive power device based on the current output power and the adjustable upper limit of power. The remaining capacity is equal to the adjustable upper limit of power minus the current output power.

[0037] At the same time, the required compensation amount is calculated based on the detected voltage deviation. The required compensation amount is equal to the product of the voltage deviation and the voltage-reactive power sensitivity coefficient. This sensitivity coefficient reflects the reactive power change required per unit voltage change and can be obtained through grid state estimation results or offline power flow calculation.

[0038] Based on this, it is determined whether there is a single reactive power device in the first category whose remaining capacity is greater than or equal to the required compensation amount. If so, the device with the smallest remaining capacity among the devices that meet the conditions is selected as the execution device. The purpose of this is to retain as many devices with larger remaining capacity as possible to cope with possible voltage disturbances in the future, while meeting the current adjustment needs. If there is no single device that can independently meet the needs, multiple devices are activated in descending order of their remaining capacity, until the sum of the remaining capacities of the activated devices is greater than or equal to the required compensation amount.

[0039] After determining the executing device, it is necessary to control the device to output reactive power in a specific manner. This embodiment uses an exponential response function to simulate the dynamic process of the reactive power device transitioning from its current output to the target output.

[0040] Specifically, the target output power of the actuator is determined to be the sum of the current output power and the required compensation amount. It is then determined whether this target output power is less than or equal to the actuator's adjustable power limit. If it is less than or equal to the limit, the actuator's reactive power output is controlled according to an exponential response function, where the exponential response function takes the form: ; Q0 represents the current output power of the executing device, ΔQ represents the required compensation amount, t represents the time from the moment the control command is issued, and τ represents the response time constant of the executing device. This function enables the reactive power output of the executing device to smoothly approach the target output value exponentially from the current value, avoiding the impact of sudden output changes on the power grid.

[0041] If the target output power is greater than the adjustable power limit, the target output power will be corrected to the adjustable power limit, and an insufficient capacity alarm message will be generated to prompt maintenance personnel to pay attention to the operating status of the equipment.

[0042] While prioritizing the initial voltage regulation of the first type of equipment, this invention also determines the startup time of the second type of equipment based on the matching degree between the compensation capability and voltage offset of the first type of equipment. The key issue to be addressed in this step is: how to accurately determine when the second type of equipment should start when the capacity of the first type of equipment is insufficient, so that it neither interferes with the dynamic regulation process of the first type of equipment too early nor causes a delay in voltage recovery too late.

[0043] This embodiment addresses the problem as follows: First, the response time constants of each reactive power device in the first type of equipment are obtained, and the maximum value is determined as the maximum response time constant of the first type of equipment. This parameter reflects the response speed of the slowest device in the first type of equipment. Simultaneously, the continuous adjustment duration, adjustment accuracy level, and response time constant of each reactive power device in the second type of equipment are obtained. The continuous adjustment duration reflects the length of time the device can maintain reactive power output, the adjustment accuracy level reflects the degree of deviation between the device's output and the target value, and the response time constant reflects the speed at which the device reaches stable output from startup.

[0044] When selecting target devices in the second category, candidate devices that can meet the adjustment duration requirements are first selected based on the continuous adjustment duration. For example, if the current voltage disturbance is expected to require continuous adjustment for several seconds, devices with a continuous adjustment duration longer than the expected duration are selected as candidate devices. Then, the candidate devices are sorted from high to low according to the adjustment accuracy level, and the device with the highest adjustment accuracy level is selected as the target device to ensure the accuracy of the supplementary adjustment.

[0045] Based on this, the startup time of the target device is calculated according to the maximum response time constant of the first type of device and the response time constant of the target device. Specifically, the startup time is equal to the sum of three times the maximum response time constant of the first type of device and half the response time constant of the target device. Three times the maximum response time constant of the first type of device ensures that the main adjustment process of the first type of device has been completed, because for a first-order system, the output approaches a steady-state value after three times the response time constant, at which point the high-frequency dynamic adjustment of the first type of device is essentially complete. Half the response time constant of the target device is used to compensate for the target device's own response lag, enabling it to output reactive power promptly when the voltage is most needed after startup.

[0046] When controlling the second type of equipment to perform supplementary voltage regulation according to the determined start-up time, it is necessary to ensure that the reactive power output of the second type of equipment is staggered in time from that of the first type of equipment. This embodiment achieves this goal by comparing the start-up time with the waiting time for the first type of equipment to approach steady state.

[0047] Specifically, the waiting time is determined based on the largest response time constant in the first type of equipment. The waiting time is equal to three times the largest response time constant, representing the time required for the first type of equipment to complete the main adjustment process.

[0048] When the startup time is greater than or equal to the waiting time, it indicates that starting the second type of equipment at the original startup time ensures that its startup time is later than the time when the first type of equipment approaches steady state. In this case, the second type of equipment is started directly at the original startup time. When the startup time is less than the waiting time, it indicates that the original startup time may cause the second type of equipment to start too early, overlapping with the dynamic adjustment process of the first type of equipment. In this case, the startup time is corrected to the waiting time, and the second type of equipment is started according to the corrected startup time. Through this mechanism, it is ensured that the reactive power output of the second type of equipment is staggered in time with the dynamic adjustment process of the first type of equipment, and the adjustment behavior of the two types of equipment presents a relay relationship rather than an additive relationship.

[0049] This invention, through classifying the response times of multiple reactive power devices and implementing time-sharing and phased collaborative control, effectively solves the problem of mutual interference between devices with different response speeds in traditional methods. It prioritizes the use of fast-response devices for initial adjustment, followed by supplementary adjustment by slower-response devices. Furthermore, the start-up time of the slower-response devices is quantified and determined, ensuring that the reactive power output of various devices is staggered in time. This avoids system oscillations, improves the stability and accuracy of voltage regulation, and optimizes the utilization efficiency of regulation resources.

[0050] In the above embodiments of this application, it is proposed that when a grid voltage deviation is detected, the first type of equipment should be prioritized to perform initial voltage regulation. When the first type of equipment includes multiple reactive power devices, how can the executing equipment be reasonably selected and its output controlled while meeting the current voltage regulation requirements, so as to avoid overload risks or resource waste caused by individual differences in equipment? In actual engineering, although each reactive power device in the first type of equipment has a relatively fast response speed, their current operating states are different. Some devices may be close to full power generation with little remaining capacity, while others are under light load with a large remaining capacity. If all devices are simply activated at the same time, some devices may trigger overload protection, while others may be idle; if activated in a fixed order, the regulation capacity of each device may not be fully utilized.

[0051] In this regard, the present invention further provides a preferred embodiment, which is described below in conjunction with... Figure 2 The specific implementation process will be explained.

[0052] First, obtain the current output power and adjustable upper limit of power for each reactive power device in the first category of equipment. The current output power can be collected in real time through the device's local measurement device. The adjustable upper limit of power is determined based on the device's rated parameters and current operating conditions. For static var generators, the adjustable upper limit of power is limited by the DC bus voltage and output current, and is usually a certain percentage of the device's rated capacity. For energy storage converters, the adjustable upper limit of power is also affected by the current state of charge. Calculate the remaining capacity of each reactive power device based on the current output power and the adjustable upper limit of power. The remaining capacity equals the adjustable upper limit of power minus the current output power. This parameter reflects the additional reactive power that the device can output under the current condition.

[0053] Simultaneously, the required compensation is calculated based on the detected voltage deviation. Voltage deviation refers to the difference between the actual voltage and the target voltage. The required compensation equals the product of the voltage deviation and the voltage-reactive power sensitivity coefficient. The voltage-reactive power sensitivity coefficient reflects the amount of reactive power change required per unit voltage change. It can be calculated from grid state estimation results or calculated offline based on the grid topology and stored in the system. For example, when the voltage deviation is 0.02 times the rated voltage and the voltage-reactive power sensitivity coefficient is 10 Mvar reactive power compensation per unit voltage change, the required compensation is 0.2 Mvar.

[0054] After obtaining the remaining capacity and required compensation of each reactive power device, it is determined whether there is a single reactive power device in the first category whose remaining capacity is greater than or equal to the required compensation. The purpose of this determination is to prioritize the use of a single device to independently complete the adjustment task, and to avoid mutual interference that may occur when multiple devices are adjusted simultaneously.

[0055] If a device meets the requirements, the one with the smallest remaining capacity is selected as the executing device. For example, if there are three devices in the first category with remaining capacities of 0.3 Mvar, 0.5 Mvar, and 0.8 Mvar, respectively, and the required compensation is 0.25 Mvar, and the remaining capacity of all three devices is greater than or equal to the required compensation, then the device with the smallest remaining capacity of 0.3 Mvar is selected as the executing device. The purpose of selecting the device with the smallest remaining capacity is to retain as many devices as possible with larger remaining capacities as possible to cope with potential voltage disturbances, while meeting the current regulation requirements.

[0056] If no single device in the first category has a remaining capacity greater than or equal to the required compensation amount, it indicates that no single device can independently complete the adjustment task, and multiple devices need to work together. In this embodiment, devices are activated sequentially according to their remaining capacity from largest to smallest, until the sum of the remaining capacities of the activated devices is greater than or equal to the required compensation amount. For example, if the required compensation amount is 1 Mvar, and the remaining capacities of the three devices are 0.6 Mvar, 0.5 Mvar, and 0.2 Mvar, respectively, the device with the largest remaining capacity of 0.6 Mvar is activated first. At this point, the sum of the activated capacities is 0.6 Mvar, which is less than 1 Mvar. The device with the second largest remaining capacity of 0.5 Mvar is then activated, and the sum of the activated capacities is 1.1 Mvar, which is greater than or equal to 1 Mvar. Activation is then stopped, and these two devices jointly undertake the adjustment task. This activation method ensures that the adjustment requirements are met with the minimum number of devices, reducing the number of devices involved in the adjustment and lowering the coordination complexity between devices.

[0057] After determining the execution device, it is necessary to control the execution device to output reactive power in a specific manner. This embodiment uses an exponential response function to simulate the dynamic process of the reactive power device transitioning from the current output to the target output. This is because the actual reactive power device is affected by internal inductance, capacitance and control loop, and the output power cannot change instantaneously, but exhibits first-order inertial characteristics.

[0058] Specifically, the target output power of the actuator is determined based on the current output power and the required compensation amount. The target output power equals the sum of the current output power and the required compensation amount. It is then determined whether the target output power is less than or equal to the adjustable upper limit of the actuator's power. If it is, the actuator's output power is controlled according to an exponential response function, the form of which is: ; Where Q0 is the current output power, ΔQ is the required compensation amount, t is the time from the moment the control command is issued, and τ is the response time constant of the executing device.

[0059] When t=0, Q(0)=Q0, and the output power remains unchanged. When t=τ, Q(τ)=Q0+0.632ΔQ, completing 63.2% of the change. When t approaches infinity, Q(∞)=Q0+ΔQ, and the output power approaches the target value. This function allows the reactive power output of the actuator to smoothly approach the target value from the current value, avoiding the impact of sudden output changes on the power grid, and also matching the output trajectory of the actuator with its physical response characteristics.

[0060] If the target output power exceeds the adjustable power limit of the executing device, it indicates that the device cannot independently complete the required compensation. In this case, the target output power is adjusted to the adjustable power limit, allowing the device to output its maximum capacity, and a capacity shortage alarm message is generated. For example, if a device's current output is 0.3 Mvar, the adjustable power limit is 1 Mvar, and the required compensation is 0.8 Mvar, then the target output power is 1.1 Mvar, exceeding the adjustable power limit. In this case, the target output power is adjusted to 1 Mvar, and the device's actual output increases from 0.3 Mvar to 1 Mvar, an increase of 0.7 Mvar. This fails to fully compensate for the 0.8 Mvar requirement, and the remaining 0.1 Mvar shortfall needs to be supplemented through other means.

[0061] When activating multiple devices sequentially according to their remaining capacity from largest to smallest, this embodiment also provides a further optimized solution to address the power oscillation problem that may be caused by the close spatial coupling of multiple devices. When the electrical distance between two reactive power devices in an adjacent activation sequence is less than a preset threshold, for example, when the two devices are installed in the same substation or the line impedance between adjacent substations is very small, their electrical coupling is strong. If they are activated consecutively in a very short period of time, their reactive power output changes will have a superimposed effect in the power grid, which may cause local power oscillations.

[0062] This embodiment inserts an activation time interval between the two devices, which is positively correlated with the sum of the response time constants of the two devices. Specifically, the activation time interval is equal to a preset scaling factor multiplied by the sum of the response time constants of the two devices. For example, if the scaling factor is 0.5, the response time constant of the first device is 10 milliseconds, and the response time constant of the second device is 20 milliseconds, then the activation time interval is 15 milliseconds. This time interval ensures that the output of the first device has approached a steady state before starting the second device, avoiding oscillations caused by output superposition. Furthermore, because the time interval matches the device response characteristics, it avoids unnecessary delays.

[0063] To address the overload risk and resource waste caused by individual device differences during multi-device coordinated regulation, a preferred embodiment of this invention provides an activation strategy based on remaining capacity priority and a smooth output control method based on exponential response. This scheme prioritizes the single device with the smallest remaining capacity to meet current needs, reserving larger capacity devices to handle subsequent disturbances. When a single device's capacity is insufficient, multiple devices are activated sequentially according to their remaining capacity from largest to smallest to meet regulation requirements with the fewest possible devices. An exponential response function controls the output for smooth transition, avoiding the impact of sudden output changes on the power grid. Activation intervals related to the response time constant are inserted for devices with close electrical distances to prevent output superposition and oscillations.

[0064] In the above embodiment, determining the start-up time of the second device involves several considerations. In practice, the response speeds of different reactive power devices vary significantly. The first type of device, while fast-responding, has limited capacity; its output approaches the target value exponentially and requires time to reach a steady state. The second type of device, while having a large capacity, responds slowly, also requiring time from start-up to stable output. Furthermore, when voltage fluctuations are frequent, a faster adjustment response is needed; when the device is far from the voltage monitoring point, its reactive power output experiences transmission delays. Ignoring these factors, simple fixed delays or empirical judgments are insufficient to adapt to complex and ever-changing operating scenarios.

[0065] This embodiment provides a preferred implementation scheme to address the above-mentioned problems. The following is a detailed description... Figures 3-5 The specific implementation process will be explained in detail.

[0066] First, obtain the continuous adjustment duration, adjustment accuracy level, and response time constant of each reactive power device in the second category of equipment. Continuous adjustment duration refers to the length of time the equipment can maintain reactive power output. For capacitor banks, they can continue to operate after switching until the command is withdrawn, resulting in a relatively long continuous adjustment duration. For energy storage converters, the continuous adjustment duration is limited by the state of charge (SOC), and the adjustment capability is restricted when the SOC approaches its upper or lower limit. Adjustment accuracy level reflects the degree of deviation between the equipment's output and the target value. Static reactive power compensation equipment typically has high adjustment accuracy, enabling precise control of the output near the target value; while mechanically switched capacitor banks can only be adjusted discretely, resulting in relatively low adjustment accuracy. Response time constant reflects the speed at which the equipment reaches stable output and is a key parameter for measuring the equipment's dynamic response characteristics. It can be obtained through on-site step tests or historical data parameter identification.

[0067] Candidate devices are selected from the second category of devices based on the duration of continuous adjustment. This selection step aims to eliminate devices that cannot meet the current adjustment duration requirement, preventing premature termination of the adjustment process and resulting in adjustment failure. For example, if the current voltage disturbance is expected to require 10 seconds of continuous adjustment, but a device's continuous adjustment duration is only 5 seconds, then that device should not be selected as a candidate, as it may stop outputting due to its own limitations before the adjustment is completed, causing an interruption in the voltage recovery process. The selection criterion can be set to a continuous adjustment duration greater than a preset minimum adjustment duration threshold. This threshold can be dynamically set based on the predicted duration of the voltage disturbance, or it can be set to a fixed value, such as 10 seconds, based on historical experience.

[0068] The target device is selected from candidate devices based on its regulation accuracy level, with the highest regulation accuracy level being chosen. Regulation accuracy level reflects the degree of deviation between the device's output and the target value; the higher the regulation accuracy, the closer the reactive power output is to the target value, and the more precise the contribution to voltage recovery. Selecting the device with the highest regulation accuracy level from multiple candidate devices as the target device ensures the accuracy of supplementary regulation and avoids over- or under-regulation of voltage due to device output deviation. For example, if the candidate devices include a static var generator with a regulation accuracy level of 0.5% and a capacitor bank with a regulation accuracy level of 5%, the static var generator is preferentially selected as the target device.

[0069] After identifying the target equipment, the startup time of the target equipment is determined based on the largest response time constant among the first-class equipment and the response time constant of the target equipment. The largest response time constant among the first-class equipment reflects the response speed of the slowest equipment in the first-class equipment and is the basis for judging whether the first-class equipment has completed the main adjustment process.

[0070] The response time constant of the target device reflects its own response speed and is used to compensate for its response lag. The specific formula for calculating the start-up time is t0, which is equal to the largest response time constant of the first type of device multiplied by the response completion coefficient α of the first type of device, plus the response time constant of the target device multiplied by the response pre-compensation coefficient β of the second type of device, i.e., t0 = α × τ1 + β × τ2.

[0071] The response completion coefficient α for the first type of equipment is between 3 and 4. This is because for a first-order system, after 3 times the response time constant, the output has completed about 95% of the change, and after 4 times the response time constant, the output has completed about 98% of the change. At this point, the dynamic adjustment process of the first type of equipment has basically ended, and the output has approached the steady-state value. Starting the second type of equipment at this point can avoid the overlap of the dynamic adjustment processes of the two types of equipment.

[0072] The pre-compensation coefficient β for the second type of equipment is between 0.5 and 1. This is because the second type of equipment requires a certain amount of time from startup to output stabilization. If it is started only when supplementary adjustment is needed, the time for its output to reach the target value will lag behind the required time. By starting 0.5 to 1 times its own response time constant in advance, its output can intervene in time when the voltage most needs supplementary adjustment.

[0073] In actual operation, the voltage fluctuation frequency of the power grid will change with the changes in the output of new energy sources and load fluctuations. The fixed response completion coefficient of the first type of equipment is difficult to adapt to all scenarios.

[0074] Reference Figure 4As shown, this embodiment further monitors the voltage fluctuation frequency of the power grid after determining the startup time. The voltage fluctuation frequency is obtained by performing spectral analysis on the voltage time-series data, reflecting the rate of voltage change. When the voltage fluctuation frequency exceeds the fluctuation frequency threshold, it indicates that the power grid is in a state of frequent disturbances, requiring a faster adjustment response. In this case, the value of the response completion coefficient α of the first type of equipment is shortened, for example, from 3.5 to 3, so that the startup time of the target equipment is advanced, allowing slower equipment to intervene earlier and form a closer relay cooperation with faster equipment. When the voltage fluctuation frequency is lower than the preset fluctuation frequency threshold, it indicates that the power grid is in a relatively stable state with sufficient adjustment time. In this case, the value of the response completion coefficient α of the first type of equipment is extended, for example, from 3.5 to 4, so that the startup time of the target equipment is delayed, giving the first type of equipment more sufficient adjustment time and avoiding unnecessary resource consumption caused by the premature intervention of slower equipment. The startup time is recalculated based on the adjusted response completion coefficient of the first type of equipment, so that the startup time can adapt to changes in the operating state of the power grid.

[0075] Before determining the start-up time, this embodiment also considers the impact of differences in the electrical location of the equipment in the power grid topology on the regulation effect. For equipment with a long electrical distance, the regulation effect of its reactive power output on the voltage monitoring point is subject to transmission delay and amplitude attenuation.

[0076] Reference Figure 5 As shown, the implementation steps of this embodiment of the invention are as follows: The electrical distance between the target device and the voltage offset monitoring point is calculated. This distance is determined using the equivalent impedance magnitude between nodes; a larger impedance magnitude indicates a greater electrical distance. Simultaneously, the minimum electrical distance between all activated devices in the first category and the voltage offset monitoring point is obtained as a reference distance. An electrical distance coefficient η is calculated, which equals the electrical distance of the target device divided by the minimum electrical distance. When the electrical distance coefficient η exceeds a threshold, it indicates that the electrical distance of the target device is significantly greater than the reference distance, resulting in a noticeable delay in the adjustment effect. In this case, the startup time needs to be corrected, as follows: t1 = t0 - λ × (d - dmin); t1 represents the corrected start time; λ represents the advance coefficient.

[0077] The advance factor reflects the transmission delay time corresponding to a unit electrical distance. Based on the propagation speed of electromagnetic waves, which is approximately 3.33 microseconds per kilometer on overhead lines, the advance factor can be taken to be on this order of magnitude. The threshold value of the factor is between 1.0 and 1.6. This threshold reflects the acceptable range of electrical distance differences. When the distance to the target equipment does not exceed 1.6 times the reference distance, no correction is needed because the transmission delay is still within an acceptable range. When it exceeds 1.6 times, the transmission delay is no longer negligible and needs to be compensated for by advancing the start time. When the electrical distance factor is less than or equal to the threshold value, the original start time remains unchanged.

[0078] To address the problem of accurately determining the startup time of the second type of equipment when the capacity of the first type of equipment is insufficient, a preferred embodiment of the present invention provides a quantitative calculation method based on the response time constant, and introduces an adaptive adjustment mechanism for voltage fluctuation frequency and a spatial compensation mechanism for electrical distance. This method ensures that the second type of equipment starts only after the first type of equipment has completed its main adjustments by multiplying the maximum response time constant of the first type of equipment by the response completion coefficient. It compensates for the response lag of the target equipment by multiplying its response time constant by the pre-compensation coefficient. It achieves adaptive startup time to the grid operating state by dynamically adjusting the response completion coefficient by monitoring the voltage fluctuation frequency. Finally, it compensates for the transmission delay of long-distance equipment by comparing electrical distances and using an advance coefficient correction.

[0079] Example 2: Refer to Figure 6 As shown, this embodiment of the invention provides a power grid voltage control system for the coordinated operation of multiple reactive power devices, including: The feature acquisition module is used to acquire the response time characteristics of each reactive power device; The device classification module is used to classify multiple reactive power devices into a first category of devices and a second category of devices based on the response time characteristics; the response time of the first category of devices is shorter than the response time of the second category of devices. The initial regulation control module is used to prioritize controlling the first type of equipment to perform initial voltage regulation when a grid voltage deviation is detected. The startup time determination module is used to determine the startup time of the second type of device based on the matching degree between the compensation capability and voltage offset of the first type of device. The supplementary adjustment control module is used to control the second type of equipment to perform supplementary voltage adjustment according to the startup time, so that the reactive power output of the second type of equipment is staggered from that of the first type of equipment in time.

[0080] The embodiments of the present invention are used to implement the grid voltage control method for coordinated operation of multiple reactive power devices in Embodiment 1. Both belong to the same inventive concept, solve the same problem, and have the same beneficial effects, which will not be repeated here.

[0081] In summary, the grid voltage control method and system for multi-reactive power equipment coordination described in this invention can effectively improve the efficiency of multi-reactive power equipment coordinated regulation and improve the grid voltage control quality by optimizing the control strategy without increasing hardware investment.

[0082] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A grid voltage control method for coordinated operation of multiple reactive power devices, characterized in that, include: The response time characteristics of each reactive power device are obtained, and the reactive power devices are divided into a first category and a second category based on the response time characteristics; the response time of the first category of devices is shorter than that of the second category of devices. When a grid voltage deviation is detected, the first type of equipment is prioritized to perform initial voltage regulation, and the start-up time of the second type of equipment is determined based on the degree of matching between the compensation capability of the first type of equipment and the voltage deviation. According to the startup time, the second type of equipment is controlled to perform supplementary voltage regulation so that the reactive power output of the second type of equipment is staggered from that of the first type of equipment in time.

2. The grid voltage control method for coordinated operation of multiple reactive power devices according to claim 1, characterized in that, Controlling the first type of device to perform initial voltage regulation includes: Obtain the current output power and adjustable power limit of each reactive power device in the first type of equipment, and determine the remaining capacity of the reactive power device based on the current output power and adjustable power limit. Calculate the required compensation amount based on the voltage offset; Determine whether there is a single reactive power device in the first type of equipment whose remaining capacity is greater than or equal to the required compensation amount; If it exists, then select the reactive power device with the smallest remaining capacity from among the reactive power devices with a remaining capacity greater than or equal to the required compensation amount as the execution device, and perform the initial voltage regulation through the execution device; If none exist, then activate them in descending order of remaining capacity of each reactive power device.

3. The grid voltage control method for coordinated operation of multiple reactive power devices according to claim 2, characterized in that, Performing initial voltage regulation via the execution device includes: The target output power Q of the actuator is determined as follows: Q = Q0 + ΔQ; Q0 represents the current output power of the actuator; ΔQ represents the required compensation amount. Determine whether the target output power Q is less than or equal to the adjustable upper limit of the power of the execution device; If so, the output power Q(t) of the actuator shall be controlled in the following manner: ； t represents the time elapsed since the control command was issued, and τ represents the response time constant of the executing device; If not, the target output power Q is corrected to the upper limit of the adjustable power of the actuator.

4. The grid voltage control method for coordinated operation of multiple reactive power devices according to claim 2, characterized in that, The system activates reactive power devices sequentially from largest to smallest remaining capacity, and further includes: if the electrical distance between two reactive power devices in adjacent activation sequences is less than a threshold, an activation time interval is inserted between them, wherein the activation time interval is positively correlated with the sum of the response time constants of the two reactive power devices.

5. The grid voltage control method for coordinated operation of multiple reactive power devices according to claim 1, characterized in that, Based on the degree of matching between the compensation capability and voltage offset of the first type of equipment, the start-up time of the second type of equipment is determined, including: Obtain the continuous adjustment duration, adjustment accuracy level, and response time constant of each reactive power device in the second type of equipment; Candidate devices are selected from the second type of devices based on the continuous adjustment duration; A target device is selected from the candidate devices based on the adjustment accuracy level; the target device has the highest adjustment accuracy level. The start-up time of the target device is determined based on the largest response time constant among the first type of devices and the response time constant of the target device.

6. The grid voltage control method for coordinated operation of multiple reactive power devices according to claim 5, characterized in that, Determining the startup time of the target device includes: t0 = a × τ1 + β × τ2; t0 represents the start-up time of the target device; τ1 represents the maximum response time constant among the first type of devices; τ2 represents the response time constant of the target device; α represents the response completion coefficient of the first type of devices, with a value of 3 to 4, so that the reactive power output of the first type of devices approaches the steady-state value before starting the target device; β represents the response pre-compensation coefficient of the second type of devices, with a value of 0.5 to 1, so that the start-up time of the target device is earlier than its own response completion time, in order to compensate for its response lag.

7. The grid voltage control method for coordinated operation of multiple reactive power devices according to claim 6, characterized in that, After determining the start-up time of the target device, the method further includes monitoring the voltage fluctuation frequency of the power grid. If the voltage fluctuation frequency exceeds the fluctuation frequency threshold, the value of the response completion coefficient α of the first type of device is shortened to advance the start-up time of the target device. If the voltage fluctuation frequency is lower than the fluctuation frequency threshold, the value of the response completion coefficient α of the first type of device is extended to delay the start-up time of the target device. The start-up time of the target device is updated according to the adjusted response completion coefficient of the first type of device.

8. The grid voltage control method for coordinated operation of multiple reactive power devices according to claim 6, characterized in that, Before determining the startup time of the target device, the following steps are also included: Calculate the electrical distance d between the target device and the voltage offset monitoring point; Obtain the minimum electrical distance dmin between all activated devices in the first type of equipment and the voltage offset monitoring point; Calculate the electrical distance factor η: η = d / dmin; If the electrical distance coefficient is greater than the coefficient threshold, the start-up time of the target device is corrected as follows: t1 = t0 - λ × (d - dmin); t1 represents the corrected start-up time; λ represents the advance coefficient, which takes a value of 0 to 1 × 10. -3 Seconds per kilometer; the coefficient threshold is 1.0 to 1.

6.

9. The grid voltage control method for coordinated operation of multiple reactive power devices according to claim 1, characterized in that, Based on the aforementioned response time characteristics, multiple reactive power devices are divided into a first category and a second category, including: Obtain the response delay time of each reactive power device and calculate the average response delay time of each reactive power device in multiple voltage disturbance events; Based on the average response delay time, the reactive power devices are divided into Class I devices and Class II devices.

10. A power grid voltage control system for coordinated operation of multiple reactive power devices, characterized in that, include: The feature acquisition module is used to acquire the response time characteristics of each reactive power device; The device classification module is used to classify multiple reactive power devices into a first category of devices and a second category of devices based on the response time characteristics; the response time of the first category of devices is shorter than the response time of the second category of devices. The initial regulation control module is used to prioritize controlling the first type of equipment to perform initial voltage regulation when a grid voltage deviation is detected. The startup time determination module is used to determine the startup time of the second type of device based on the matching degree between the compensation capability and voltage offset of the first type of device; The supplementary adjustment control module is used to control the second type of equipment to perform supplementary voltage adjustment according to the startup time, so that the reactive power output of the second type of equipment is staggered from that of the first type of equipment in time.

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