Grid connection operation method for new energy power plants
The method enhances solar power plant-grid synchronization through data-driven prediction and phase-locked loop technology, ensuring stable and efficient grid connection by adjusting voltage, frequency, and phase, addressing prediction inaccuracies and synchronization challenges.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- HUANENG TAIYUAN DONGSHAN GAS TURBINE THERMAL POWER CO LTD
- Filing Date
- 2025-11-26
- Publication Date
- 2026-06-24
Smart Images
Figure 2026103836000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of power system operation, and particularly to a method for interconnected operation of a new energy power plant with the power system.
Background Art
[0002] With the increasing global demand for clean energy and the growing environmental awareness, solar power generation has been rapidly developing as a sustainable and renewable energy utilization method. In recent years, solar power generation technology has been continuously advancing, the conversion efficiency of solar cells has been gradually improved, and the cost has been continuously decreasing. Large-scale solar power plants have emerged one after another, not only playing an important role in distributed energy supply, but also occupying an increasingly large share in the centralized power generation field. For example, in areas with sufficient sunshine, solar power generation has already become an important component of the local power supply, greatly contributing to reducing the dependence on traditional fossil energy. At the same time, with the development of energy storage technology, the combination of solar power generation and energy storage systems also provides new solutions for improving the stability and reliability of energy, further promoting the popularization of solar power generation in the power field.
[0003] However, existing solar power generation power prediction methods often have lower prediction accuracy under complex operating conditions. If the power prediction is inaccurate, not only will the power system operation plan become unreasonable, but when the deviation between the actual solar power generation power and the predicted value is larger, there is also a risk of disrupting the power supply-demand balance of the power system.
[0004] At the same time, achieving phase synchronization between the solar power plant and the power grid is a crucial step in grid connection. However, conventional technologies are susceptible to interference from the power grid and the dynamic characteristics of the solar power plant itself during the phase synchronization process, resulting in a complex and unstable process. If the phase difference is not precisely controlled within a narrow range at the moment of grid connection, a large inrush current may occur, damaging the power grid and the solar power plant equipment, shortening the lifespan of the equipment, and potentially causing a power grid failure. For example, if the power grid fluctuations are relatively large, conventional phase synchronization methods may not be able to adjust the inverter output phase in a timely and accurate manner, resulting in grid connection failure or unstable system operation after grid connection.
[0005] Most existing grid connection operation methods lack the ability to adaptively adjust to changes in the operating conditions of the power grid and solar power plants. Power grid load demand, topology, and the performance of the solar power plants themselves can all change over time, but conventional technologies make it difficult to optimize grid connection operation strategies in real time based on these changes. As a result, solar power plants cannot always maintain optimal grid connection operation conditions during long-term operation, which affects the economics and reliability of the entire power grid.
[0006] Therefore, in this field, there is an urgent need for a method of operating new energy power plants in conjunction with the grid to solve the above problems. [Overview of the Initiative] [Problems that the invention aims to solve]
[0007] This invention provides a method for operating a new energy power plant in a grid, and aims to solve the problems of the prior art described above. By using an innovative grid connection method and a precise mathematical model, it ensures that solar power plants can be connected to the power grid smoothly and efficiently, while maintaining power quality and the stability of the power grid, and better meeting the operational needs of the power grid. [Means for solving the problem]
[0008] The present invention relates to a method for operating a new energy power plant in a grid-connected environment, Step 1 involves collecting data from a solar power plant and the power grid, wherein the solar power plant data includes solar irradiance, temperature, output voltage and current data of the solar cells, and the power grid data includes voltage, frequency and phase parameters. Step 2 predicts the future output power of the solar power plant based on collected solar power plant and power grid data, Step 3 involves combining future output power data from the solar power plant and the power grid to calculate the output voltage and frequency of the solar power plant's inverter, and then adjusting it to match the power grid. Step 4 involves using phase-locked loop technology to synchronize the output phase of the solar power plant's inverter with the phase of the power grid, based on the adjusted output voltage and frequency. The present invention provides a method for operating a new energy power plant in a grid connection, which includes step 5, after completing voltage, frequency, and phase matching and synchronization adjustments between the solar power plant and the power grid via steps 3 and 4, employing soft-start technology to switch the solar power plant to the power grid.
[0009] According to the grid connection operation method for a new energy power plant according to the present invention, in step 1, the process of collecting data from the solar power plant and the power grid is as follows: This includes acquiring solar radiation and temperature data by placing solar radiation sensors and temperature sensors at different locations in the solar power plant, acquiring output voltage and current data from solar cells by attaching instrument transformers and instrument current transformers to the combiner box and inverter of the solar power array, respectively, and acquiring voltage, frequency, and phase parameters from the power grid monitoring device.
[0010] According to the method for grid-connected operation of a new energy power plant according to the present invention, in step 2, the process of predicting the future output power of the solar power plant is as follows: Calculating the solar cell output current using a current simulation model
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[0011] According to the grid-connected operation method for a new energy power plant according to the present invention, in step 3, the process of calculating and adjusting the output voltage and frequency of the solar power plant by combining future output power based on solar power plant and power grid data is as follows: Using a voltage regulation model, the inverter output voltage reference value
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[0012] According to the grid connection operation method for a new energy power plant according to the present invention, the voltage adjustment coefficient
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[0013] According to the grid-connected operation method for a new energy power plant according to the present invention, in step 4, the process of synchronizing the output phase of the inverter of the solar power plant with the phase of the power grid by employing phase-locked loop technology is: Power system voltage phase angle
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[0014] According to the grid connection operation method for a new energy power plant according to the present invention, step 5 is the initial value of the soft start current in the grid connection switching process.
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[0015] According to the grid connection operation method for a new energy power plant according to the present invention, in step 5, grid connection switching is performed when the phase difference between the power grid voltage and the output voltage of the solar power plant is smaller than a first threshold, and the fluctuations in voltage and frequency are smaller than a second threshold.
[0016] The grid connection operation method for a new energy power plant according to the present invention further includes the step of increasing the grid connection current at a predetermined gradient during the soft start process, that is, increasing the corresponding ratio of the rated current at each sampling period until it reaches the rated current value for normal operation.
[0017] According to the grid connection operation method for a new energy power plant according to the present invention, after the grid connection switchover is completed, the results are fed back and a voltage adjustment coefficient is calculated based on the switchover results.
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[0018] Compared to the prior art, the beneficial effects of this invention are as follows:
[0019] This invention uses a power prediction model constructed based on the physical characteristics of solar cells to comprehensively consider the influence of important factors such as solar radiation and temperature on the output current of solar cells, and to accurately calculate the output power of a solar power plant. Furthermore, under different solar radiation and temperature conditions, factors such as the linear relationship between photogenerated current and solar radiation in the model, and the influence of temperature on the inverse saturation current, can more accurately reflect the actual power generation capacity of the solar cells.
[0020] This invention uses a directional voltage and frequency regulation model to calculate reference values for inverter output voltage and frequency based on the measured voltage and frequency of the power system and the actual operating conditions of the solar power plant (e.g., output power). Regarding voltage regulation, by rationally determining the voltage regulation coefficient, the inverter can more accurately adjust the output voltage and quickly and stably match it to the power system voltage. Regarding frequency regulation, by determining the frequency regulation coefficient based on factors such as the capacity of the solar power plant and the inertia of the power system, the solar power plant can immediately respond to changes in the power system frequency and effectively adjust the output power, thereby maintaining the stability of the power system frequency.
[0021] By utilizing phase-locked loop technology and combining it with an accurate phase-synchronization model, this invention enables accurate measurement of the phase angle of the power grid voltage and real-time adjustment of the output phase angle of the solar power plant's inverter. By rationally setting the proportional and integral gains, the phase-synchronization process has a rapid response speed and high accuracy. In the event of interference from the power grid or changes in the dynamic characteristics of the solar power plant itself, the effects of these unfavorable factors can be effectively overcome, ensuring that the phase difference between the solar power plant and the power grid is always controlled to be within an extremely small range at the moment of grid connection and during operation after grid connection.
[0022] Throughout the entire process of grid connection operation, the present invention can automatically adjust the grid connection strategy in response to changes in system operating conditions (e.g., changes in load demand of the power grid, changes in solar radiation and temperature of the solar power plant) by continuously collecting data and monitoring the operating status of the power grid and the solar power plant in real time.
[0023] Other features and advantages of the present invention are described in the following specification, some of which will become apparent from the specification or be understood by carrying out the invention. The object and other advantages of the present invention can be realized and obtained by the structures specifically shown in the described specification and drawings.
[0024] The technical solutions of the present invention will be described in more detail below with reference to the drawings and embodiments. [Brief explanation of the drawing]
[0025] The drawings are provided to further understand the present invention, constitute part of the specification, and are intended to be used in conjunction with the embodiments of the present invention to interpret the present invention, and are not intended to limit the present invention. In the drawings, [Figure 1] This is a schematic flowchart of a grid connection operation method for a new energy power plant according to an embodiment of the present invention. [Modes for carrying out the invention]
[0026] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. It should be understood that the preferred embodiments described herein are for illustrative and interpretive purposes only and are not intended to limit the present invention. [Examples]
[0027] An embodiment of the present invention provides a method for operating a new energy power plant in a grid-connected environment, referring to Figure 1. Step 1 involves collecting solar radiation, temperature, output voltage and current data from the solar power plant, as well as voltage, frequency, and phase parameters from the power grid. Step 2 predicts the future power output of the solar power plant based on the collected data, Step 3 involves calculating the output voltage and frequency of the solar power plant by combining future output power based on power grid and power plant parameters, and adjusting them to match the power grid. Step 4 involves using phase-locked loop technology to synchronize the output phase of the solar power plant's inverter with the phase of the power grid, Step 5 includes, after completing the matching and adjustments, employing soft-start technology to switch to the grid connection.
[0028] The principles and technical effects of this embodiment are as follows: By monitoring important parameters of the solar power plant and power grid in real time (e.g., solar radiation, temperature, voltage, current, frequency, phase, etc.), the system can be ensured to always have access to the latest operating conditions. Based on the collected data, an algorithm or model is used to predict the output power of the solar power plant for a certain period in the future, which is useful for pre-planning, provides accurate information for power grid operation, and helps to address potential power fluctuations. In order to match the output of the solar power plant to the requirements of the power grid, it is necessary to adjust the output voltage and frequency of the power plant according to the predicted output power and the current power grid and power plant parameters. This dynamic adjustment helps to minimize the impact on the power grid and ensure power quality. Phase-locked loop (PLL) technology is employed to synchronize the output phase of the solar power plant's inverter with the phase of the power grid. After all necessary adjustments are completed, soft-start technology is used to switch to the grid connection, and the output power can be gradually increased by soft-starting. This avoids the shock to the power grid caused by sudden load application, protects the equipment from damage, and reduces interference with the power grid.
[0029] Phase-locked loop technology is a control technology that achieves signal phase synchronization by matching the phase of the output signal with the input reference signal, and by stably tracking the output frequency to the reference frequency, thereby achieving high-precision signal phase locking and frequency tracking.
[0030] Soft-start technology is a technique for controlling the startup process of equipment (especially motors and high-power consumption equipment). It uses specific circuits or control algorithms to avoid excessive inrush current and torque at the moment the equipment is energized, achieving a smooth startup process that gradually increases from low voltage and low current to rated voltage and rated current. This protects the equipment and associated circuit systems, extends the service life of the equipment, and reduces the impact on the power grid.
[0031] To further optimize the above embodiment, the process for collecting data in step 1 is as follows: This includes acquiring solar radiation and solar cell temperature data by placing high-precision solar radiation sensors and temperature sensors at different locations on the power plant, acquiring output voltage and current data from solar cells by attaching instrument transformers and instrument current transformers to the combiner box and inverter of the photovoltaic array, and directly acquiring power grid voltage, frequency, and phase parameters from a power grid monitoring device.
[0032] Furthermore, it boasts high accuracy (for example, a measurement error of within ±2%) and a wide measurement range (solar radiation can be measured in a range of 0 to 2000 W / m²). 2 Select solar radiation sensors and temperature sensors that have a temperature measurement range of -40°C to 80°C and a fast response time (response time less than 1 second). When placing sensors at different locations within the power plant, ensure that the solar radiation and temperature changes within the entire power plant area are accurately reflected by adhering to the principle of uniform placement. For example, in the case of a large solar power plant, comprehensive and representative data can be obtained by placing sensors at specific intervals (e.g., one sensor per 100 square meters) in different arrays and areas with different orientations within the power plant.
[0033] Data collected by solar radiation sensors and temperature sensors is transmitted to the power plant's data collection center via wired (e.g., using shielded twisted-pair cables to reduce the impact of electromagnetic interference on data transmission) or wireless (e.g., using ZigBee or Wi-Fi communication technology to ensure the stability and timeliness of data transmission) communication methods. At the data collection center, the collected solar radiation and temperature data is pre-processed in real time, and this pre-processing includes data cleaning (removing outliers, such as obviously erroneous data caused by sensor failure or temporary shielding) and data calibration (periodically calibrating the sensors based on known standard solar radiation and temperature values to ensure measurement accuracy).
[0034] High-precision instrument transformers (e.g., accuracy class 0.2) and current transformers (e.g., accuracy class 0.5) should be installed in the combiner box and inverter of the photovoltaic array. The selection of instrument transformers and current transformers should be based on the rated voltage, current, and measurement accuracy requirements of the photovoltaic power plant, thereby ensuring that the output voltage and current of the photovoltaic array can be accurately measured. For example, in the case of a photovoltaic power plant with a rated voltage of 1000V and a rated current of 500A, selecting a transformer with an appropriate transformation ratio (e.g., 1000V / 100V, 500A / 5A) will convert the high-voltage, high-current signal into a low-voltage, low-current signal that can be processed by the data acquisition device.
[0035] Signals output from instrument transformers and instrument current transformers are collected by a data acquisition card (having a high sampling rate, for example, 10 kHz or higher, to accurately capture changes in voltage and current). The collected analog signals are converted into digital signals by an analog-to-digital converter (ADC) and used for subsequent data analysis and processing. During the data acquisition process, attention must be paid to signal isolation and interference prevention measures. For example, photoelectric isolation technology is employed to prevent interference from the power system and other electromagnetic interference from affecting data acquisition, ensuring that the collected voltage and current data are accurate and reliable.
[0036] When acquiring data directly from a power system monitoring device, ensure that the monitoring device has an appropriate communication interface (e.g., RS-485, Ethernet interface, etc.) and communication protocol (e.g., Modbus, IEC61850, etc.). Configure the power plant's data acquisition system with the corresponding communication module and software driver according to the communication interface and protocol requirements of the power system monitoring device to ensure a stable communication connection with the power system monitoring device. For example, if the power system monitoring device uses the Modbus communication protocol, install the Modbus communication driver in the power plant's data acquisition system and set the correct communication parameters (e.g., baud rate, data bits, stop bits, parity bits, etc.) to ensure that voltage, frequency, and phase parameters on the power system side can be accurately read.
[0037] The system verifies data acquired from power grid monitoring equipment, including data format verification (ensuring data meets specified format requirements) and data range verification (checking whether parameters such as voltage, frequency, and phase are within a reasonable range). Simultaneously, to ensure synchronization between power grid data and solar power plant data, time synchronization technology (e.g., NTP protocol) is employed to synchronize the data acquisition equipment within the power plant with the power grid monitoring equipment. This ensures that the various collected data coincide on the time axis, facilitating subsequent grid connection operation analysis and control operations.
[0038] To further optimize the above embodiment, in step 2, the process for predicting the future output power of the solar power plant is: Solar cell output current using a current simulation model
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[0039] Note that proportionality coefficient
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[0040]
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[0041] To further optimize the above embodiment, in step 3, the process of calculating and adjusting the output voltage and frequency of the solar power plant inverter by combining future output power based on the parameters of the power grid and the solar power plant is as follows: Using a voltage regulation model, the inverter output voltage reference value
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[0042] Voltage regulation coefficient
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[0043] In addition,
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[0044]
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[0045] The hardware characteristics and control capabilities of the inverter itself are:
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[0046] To further optimize the above embodiment, in step 4, the process of synchronizing the output phase of the inverter of the solar power plant with the phase of the power system by adopting the phase-locked loop technology is Power system voltage phase angle
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[0047] In an actual solar power plant grid connection system, the effects of different
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[0048] To further optimize the above embodiment, step 5 is performed during the grid connection switching process, the initial value of the soft start current
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[0049] Furthermore, parameter analysis will be performed on the equipment of the solar power plant (e.g., inverters, transformers, etc.) and the equipment on the power grid side (e.g., switching devices, cables, etc.) to determine the predetermined ratio β. Important parameters such as the rated current and short-time withstand current of these pieces of equipment will be identified. From the perspective of equipment safety, the predetermined ratio should be ensured so that the current does not cause an excessive shock to the equipment in the initial stage of soft start, thereby ensuring the insulation performance and service life of the equipment. For example, in the case of an inverter, the power semiconductor device (e.g., IGBT) inside has a specific current tolerance limit, and according to its databook, the allowable short-time overcurrent multiplier may be 1.2 to 1.5 times the rated current. Considering a specific safety margin (e.g., 80%), the predetermined ratio of the initial value of the soft start current can be provisionally determined in the range of 0.8 * 1.2 = 0.96 (i.e., 96%) to 0.8 * 1.5 = 1.2 (i.e., 120%).
[0050] To further optimize the above embodiment, in step 5, grid switching is performed when the phase difference between the power grid voltage and the output voltage of the solar power plant is smaller than the first threshold, and the voltage and frequency fluctuations are smaller than the second threshold.
[0051] Furthermore, voltage and frequency fluctuation data during the actual operation of the solar power plant, as well as related data during grid connection operations, will be collected. By analyzing this data, the characteristics and patterns of voltage and frequency fluctuations under different operating conditions (e.g., different solar radiation, different power grid loads) will be understood. Based on actual operating experience, a second threshold will be determined that not only ensures stable operation of the power grid but also adapts to changes in the normal operation of the solar power plant. For example, a statistical analysis of one year's operating data from a certain solar power plant revealed that under normal operation, voltage fluctuations are generally within ±3% of the rated voltage and frequency fluctuations are within ±0.1 Hz, but fluctuations may increase in the event of abnormal weather or a sudden change in the power grid load. Taking these circumstances into comprehensive consideration, the voltage fluctuation threshold was set at ±3.5% of the rated voltage, and the frequency fluctuation threshold was set at ±0.15 Hz. In this way, the stability of the power grid and the normal operation of the equipment can be ensured, while also adapting to the actual operating conditions of the solar power plant and improving the feasibility and reliability of grid connection operations.
[0052] To further optimize the above embodiment, the soft-start process further includes increasing the current at a predetermined gradient, i.e., increasing the corresponding ratio of the rated current with each sampling period until it reaches the rated current value for normal operation.
[0053] Furthermore, the predetermined gradient must be determined considering the characteristic that the output power of a solar power plant changes according to the amount of solar radiation. During the soft-start process, efficient energy conversion and stable grid-connected operation are achieved by making the increase in grid connection current follow the increase in the output power of the solar power plant. Based on the solar radiation change pattern at the installation site of the solar power plant (for example, solar radiation gradually increases from morning, is strongest around noon, and weakens in the evening) and the output characteristic curve of the solar cells, the rate of change of power at different amounts of solar radiation is analyzed. For example, if the amount of solar radiation increases slowly in the morning, the output power of the solar power plant also increases slowly, and in this case, the grid connection current can be increased slowly by setting the predetermined gradient to a smaller value. When the amount of solar radiation stabilizes and becomes stronger around noon, the power output is relatively stable, and the predetermined gradient can be appropriately adjusted to a value that matches the stable power output. When the amount of solar radiation weakens in the evening, the power decreases, and the predetermined gradient also decreases accordingly, avoiding a mismatch with power due to excessive current. By analyzing the relationship between solar radiation and power output, the predetermined gradient curve that changes according to time and solar radiation conditions is determined, thereby optimizing the soft-start process.
[0054] A solar power plant system itself possesses certain inertia, including the capacitance characteristics of the solar cells and the control response time of the inverter. If the predetermined gradient is too large, the solar power plant system may not be able to respond immediately to rapid current changes, potentially causing control instability. On the other hand, if the predetermined gradient is too small, the soft-start time becomes too long, affecting grid connection efficiency. By conducting tests and analyses on the inertia of the solar power plant system (e.g., measuring parameters such as the system's time constant), the predetermined gradient is determined by balancing the system's response capability and soft-start efficiency. For example, in a system with greater inertia and a longer response time, the predetermined gradient should be set smaller to ensure that the system can stably control the current. In a system with less inertia and a faster response speed, the predetermined gradient can be appropriately increased, but the constraints of the equipment and power grid must still be considered. At the same time, the predetermined gradient can be dynamically adjusted for different seasons and weather conditions according to actual operating conditions, thereby achieving the optimal soft-start effect and improving the overall performance of the solar power plant.
[0055] To further optimize the above embodiment, after the grid connection switchover is completed, the results are fed back and the voltage adjustment coefficient is adjusted based on the switchover results.
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[0056] Upon completion of the grid connection switchover, the solar power plant and related operational data of the power grid will be continuously collected. The collected data will include, but will not be limited to, the output voltage, output current, and output power of the solar power plant, the voltage, frequency, and phase of the power grid, as well as the magnitude of the inrush current at the moment of grid connection and after grid connection, and power quality indicators (e.g., harmonic content, voltage fluctuations, etc.). This data will serve as the basis for evaluating the grid connection effect and subsequent optimization adjustments. For example, the above data will be acquired in real time by high-precision sensors attached to the combiner box of the solar power array, the output terminals of the inverter, and the connection point of the power grid, and will be transmitted to a data processing unit for storage and analysis.
[0057] This involves determining key indicators for evaluating grid connection performance, such as the ratio of the peak inrush current value to the rated current during grid connection (inrush current ratio), the range of voltage and frequency fluctuations after grid connection (e.g., the percentage of the peak-to-peak voltage fluctuation to the rated voltage, and the percentage of the maximum deviation of the frequency fluctuation to the rated frequency), and whether the power quality indicators meet relevant standards (e.g., whether the harmonic content is lower than the specified limit).
[0058] The actual evaluation metrics calculated from the collected data are compared with the set ideal metrics. If all evaluation metrics for each item meet the requirements, the current grid connection operation parameters (voltage regulation coefficient and frequency regulation coefficient) are considered appropriate, and no provisional optimization adjustment is necessary. However, if any of the evaluation metrics do not meet the requirements, an iterative optimization process is initiated.
[0059] The iterative optimization process is similar to the gradient descent algorithm, so a detailed explanation is omitted here.
[0060] The above embodiments are merely for illustrating the technical solutions of the present invention and do not limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in each of the above embodiments can still be modified or some of the technical features can be substituted equally. Furthermore, these 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 each embodiment of the present invention.
Claims
1. A method for operating grid-connected new energy power plants, Step 1 involves collecting data from a solar power plant and the power grid, wherein the data from the solar power plant includes solar irradiance, temperature, output voltage and current data of the solar cells, and the data from the power grid includes voltage, frequency and phase parameters. Step 2 predicts the future output power of the solar power plant based on the collected solar power plant and power grid data, Step 3 involves combining future output power data from the solar power plant and the power grid to calculate the output voltage and frequency of the solar power plant's inverter, and then adjusting them to match the power grid. Step 4 involves using phase-locked loop technology to synchronize the output phase of the solar power plant's inverter with the phase of the power grid, based on the adjusted output voltage and frequency. A method for operating a new energy power plant in a grid connection, characterized by including step 5, which involves completing voltage, frequency, and phase matching and synchronization adjustments between the solar power plant and the power grid via steps 3 and 4, and then employing soft-start technology to switch the connection between the solar power plant and the power grid.
2. In Step 1, the process of collecting data from the solar power plant and the power grid is as follows: A method for operating a new energy power plant connected to a grid according to claim 1, characterized in that it includes obtaining solar radiation and temperature data by arranging solar radiation sensors and temperature sensors at different locations in the solar power plant, obtaining output voltage and current data of solar cells by attaching instrument transformers and instrument current transformers to the combiner box and inverter of the solar power generation array, respectively, and obtaining voltage, frequency, and phase parameters from the power grid monitoring device.
3. In step 2, the process for predicting the future output power of the solar power plant is: Solar cell output current using a current simulation model [Math 1] The calculation is performed, and the current simulation model is as follows: [Math 2] Here, [Math 3] This is the solar cell output current obtained by model simulation. [Math 4] This is the photogenerated current, [Math 5] This is the reverse saturation current, [Math 6] This is the amount of electron charge, [Number 7] This is the current output voltage of the solar cell. [Number 8] This is a series resistor, [Number 9] These are parallel resistors, [Number 10] This is the diode characteristic coefficient, [Math 11] This is the Boltzmann constant, [Math 12] This is the solar cell temperature, The aforementioned photogenerated current is [Number 13] And here, [Number 14] This is a proportionality constant, determined by the material and structural properties of the solar cell. [Number 15] This is solar radiation, The aforementioned reverse saturation current is [Number 16] And, Here, 【Number 17】 This is a pre-set reference temperature. [Number 18] is the reference temperature [Number 19] This is the reverse saturation current in the region, [Number 20] This is the band gap of the solar cell, and Initial output current of solar cells [Math 21] The values are set, substituted into the current simulation model, and iterative update calculations are performed, and the values obtained from two consecutive calculations are... [Number 22] Once the difference in values meets the specified accuracy requirements, the final solar cell output current [Number 23] To output, Solar cell output current based on series-parallel structure [Number 24] and solar cell output voltage [Number 25] Adjust as appropriate to control the total solar current [Number 26] and total solar voltage [Number 27] To obtain, Actual output power to the power grid [Number 28] This involves calculating the power [Number 29] This represents the future output power of the solar power plant, and the calculation formula is as follows: [Number 30] Here, [Number 31] The method for grid-connected operation of a new energy power plant according to claim 2, characterized in that is the inverter conversion efficiency, which belongs to the known parameters of the inverter device.
4. In step 3, the process of calculating and adjusting the output voltage and frequency of the solar power plant by combining future output power based on solar power plant and power grid data is as follows: Using a voltage regulation model, the inverter output voltage reference value [Number 32] The calculation is as follows, and the voltage adjustment model is as follows: [Number 33] Here, [Number 34] This is the measured value of the power system voltage. [Number 35] This is the rated value of the power system voltage, [Number 36] This is a voltage regulation coefficient, used to consider the voltage regulation capability of the inverter and the tolerance of voltage fluctuations in the power system. Inverter output frequency reference value using frequency adjustment model [Number 37] The calculation involves the frequency adjustment model being as follows: [Number 38] Here, [Number 39] This is the measured value of the power grid frequency, [Number 40] This is the desired output power of the solar power plant, and it belongs to the rated value. [Number 41] This is the actual output power to the power grid. [Number 42] This is a frequency adjustment coefficient, used to consider the capacity of the solar power plant, the inertia of the power grid, and the tolerance of the power grid for frequency fluctuations. The inverter's output voltage and output frequency are set to the output voltage reference value. [Number 43] and output frequency reference value [Number 44] A method for operating a grid-connected new energy power plant according to claim 3, characterized in that it includes adjusting in accordance with the following:
5. The voltage adjustment coefficient [Number 45] The formula for calculating this is as follows: [Number 46] Here, [Number 47] and [Number 48] These are the endpoint values, i.e., the maximum and minimum values, of the adjustable voltage range at the inverter's rated output power. [Number 49] This is an adjustable voltage range. [Number 50] The voltage fluctuation range specified in the power system is the rated voltage. [Number 51] ± [Number 52] It indicates that it is within [a certain limit]. [Number 53] This is the permissible fluctuation range of the power system voltage, [Number 54] This is an adjustment constant, [Number 55] It is used to limit the value range to between 0.1 and 0.
5. The frequency adjustment coefficient [Number 56] The formula for calculating this is as follows: [Number 57] Here, [Number 58] This is the inertia constant of a power system, and is used to reflect the power system's ability to resist frequency changes. [Number 59] The method for grid connection operation of a new energy power plant according to claim 4, characterized in that the capacity of the solar power plant is the capacity of the solar power plant and all of the values belong to the rated values of the power grid.
6. In step 4, the process of synchronizing the output phase of the solar power plant's inverter with the phase of the power grid using phase-locked loop technology is as follows: Power system voltage phase angle [Number 60] and the phase angle of the inverter output voltage after adjustment [Number 61] Error [Number 62] Calculate, that is [Number 63] That is, The process involves synchronizing the output phase of the inverter of a solar power plant with the phase of the power grid based on a synchronization model, wherein the synchronization model is as follows: [Number 64] Here, [Number 65] This is a proportional gain, [Number 66] This is the integral gain, which is determined based on the response speed and accuracy requirements of the phase-locked operation. The grid connection operation method for a new energy power plant according to claim 5, characterized in that it includes continuously adjusting the trigger pulse phase of the inverter to keep the phase difference between the two within a predetermined allowable range, thereby ensuring that current shock is minimized at the moment of grid connection.
7. Step 5 is the initial value of the soft start current in the grid connection switching process. [Number 67] a predetermined ratio [Number 68] Set as the rated current, i.e. [Number 69] A method for operating a grid-connected new energy power plant according to claim 6, further comprising the condition that...
8. The method for operating a new energy power plant in a grid connection according to claim 7, characterized in that in step 5, a grid connection switchover is performed when the phase difference between the power grid voltage and the output voltage of the solar power plant is smaller than a first threshold and the fluctuations in voltage and frequency are smaller than a second threshold.
9. The method for operating a grid-connected new energy power plant according to claim 8, further comprising the step of increasing the grid-connected current at a predetermined gradient in the soft-start process, that is, increasing the corresponding ratio of the rated current at each sampling period until it reaches the rated current value for normal operation.
10. After the grid connection switchover is complete, the results are fed back, and the voltage adjustment coefficient is determined based on the switchover results. [Number 70] and frequency adjustment coefficient [Number 71] The method for operating a grid-connected new energy power plant according to claim 9, further comprising the step of adjusting as appropriate and performing iterative optimization.