A distributed photovoltaic power station power compensation system and method

Abstract

The present invention discloses a distributed photovoltaic power station power compensation system and method. The reactive value issued by the dispatcher is initially compared with the total reactive value of the current power station and the dead zone range, so as to quickly and preliminarily determine whether reactive compensation is needed; and the difference between the two is compared with the dead zone range again, and the optimal selection of reactive compensation devices such as reactive compensation devices and inverters is made according to the relationship between the difference and the dead zone range. The system and method have certain advantages and provide a solid foundation for the stability and rapidity of subsequent power compensation adjustment; the reactive compensation target value is divided into a normal stable area and a variable area, and the inverter is preliminarily adjusted to the terminal value of the normal stable area, without the need to use a multi-stage step-by-step adjustment method to improve the adjustment efficiency, and the average value of the variable area is used as the secondary adjustment target to further improve the adjustment efficiency, and the reactive compensation device is subsequently used for fine adjustment, which greatly improves the efficiency of the inverter in reactive adjustment.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic power station power compensation, and in particular relates to a distributed photovoltaic power station power compensation system and method. Background Art

[0002] Since photovoltaic power stations have the characteristics of intermittent, random, volatile and periodic, these characteristics lead to unstable output power of photovoltaic power stations, which in turn affects the voltage stability of the power grid. In order to deal with these problems, photovoltaic power stations usually use static var generators (SVG), static var compensators (SVC) and inverters for synchronous real-time adjustment to perform reactive compensation adjustment of photovoltaic power stations; however, in the prior art, due to the relatively low cost of inverters, especially in photovoltaic and wind power systems, inverters, as the most common power compensation equipment, are often used in conjunction with static var generators (SVG) and static var compensators (SVC), but in the power compensation adjustment process of the inverter, a relatively multi-stage step-by-step adjustment method is often used for power adjustment, so that the corresponding speed of the inverter power adjustment still has room for improvement, so a distributed photovoltaic power station power compensation system is designed. Summary of the invention

[0003] The purpose of the present invention is to provide a distributed photovoltaic power station power compensation system and method to solve the problems raised in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solution: a distributed photovoltaic power station power compensation system, comprising:

[0005] Data acquisition module, used to collect voltage, current, power factor, active power and reactive power data of distributed photovoltaic power stations in real time;

[0006] A power compensation control module, used to generate a power compensation control signal according to the data collected by the data collection module;

[0007] The power compensation device includes a static VAR generator and a static VAR compensator, which adjusts active power and reactive power according to the control signal received from the power compensation control module.

[0008] Preferably, the power compensation control module includes a power compensation calculation unit, a dead zone judgment unit and a control signal generation unit. The power compensation calculation unit is used to calculate the required active power and reactive power according to the collected voltage and current data, as well as the difference between the reactive value issued by the dispatching center and the total reactive value of the power station; the dead zone judgment unit is used to compare the values ​​of the dead zone and judge the relationship between the input value and the dead zone; the control signal generation unit is used to generate a power compensation control signal according to the output of the optimization algorithm module.

[0009] A distributed photovoltaic power station power compensation method comprises the following steps:

[0010] 1) Compare the reactive power value issued by the power grid dispatching system and the total reactive power value of the current power station with the dead zone. If they are outside the dead zone, reactive power regulation is performed;

[0011] 2) Compare the reactive power value issued by the power grid dispatching system and the difference between the total reactive power value of the current power station and the dead zone;

[0012] 3) If the difference is within the dead zone, the issued reactive value is used as the reactive control target and reactive adjustment is performed through the reactive compensator;

[0013] 4) If the difference is outside the dead zone, the total reactive power value of the current power station is used as the reactive power control target, and the inverter is used for adjustment; the target value is divided into a normal stable area and a variable area, and the reactive power is adjusted to the end value of the normal stable area through the inverter, and then the average value of the variable area is obtained, and the reactive power is adjusted to the average value through the inverter;

[0014] 5) Turn on the automatic following mode of the reactive power compensation device, and adjust the reactive power to the accurate reactive power control target through the coordinated compensation of the reactive power compensation device;

[0015] 6) Obtaining the real-time reactive value of the reactive compensation device, reducing the real-time reactive value of the reactive compensation device working in real time, and increasing the reactive value adjusted by the inverter according to the reduced real-time reactive value.

[0016] Preferably, in the step 3), the reactive power compensation device cannot meet the required reactive power compensation demand, and supplementary regulation is performed by adjusting the inverter.

[0017] Preferably, the changing region in step 4) is the region between the maximum value and the minimum value within the changing range of the total reactive power value of the power station, and the normal stable region of the target value is the region within the minimum value within the changing range of the total reactive power value of the power station.

[0018] Preferably, if the reactive power compensation device does not have an automatic following function, the reactive power is adjusted to the end value of the normal stable area through the inverter. According to the numerical difference between the current reactive power and the end value, the numerical difference is adjusted in several steps until it is adjusted to the target reactive power value, thereby maintaining the dynamic stability of the total reactive power of the system.

[0019] Preferably, in the step 1), the reactive power value sent by the power grid dispatching system is obtained by calculating the sent voltage, reactive power or power factor.

[0020] Preferably, when the power grid dispatching system sends the voltage to calculate the reactive value, measure the current voltage; obtain the voltage target value, and obtain the voltage deviation ΔV by subtracting the voltage measurement value from the voltage target value; calculate the reactive adjustment amount ΔQ according to the proportional control; ΔQ=ΔV·K, K is the proportional coefficient; combined with the current total reactive value of the power station And the calculated reactive power regulation ΔQ, determine the final reactive power value , = +ΔQ.

[0021] Preferably, when the power grid dispatching system sends the power factor to calculate the reactive value, the active power P actually output by the power station is obtained; according to the definition of power factor: , where PF is the power factor target value issued by the dispatching system; the reactive power Q is calculated according to the relationship of the power triangle, , where the calculated reactive power is the converted reactive value.

[0022] Technical effects and advantages of the present invention:

[0023] 1. By initially comparing the reactive power value issued by the dispatcher with the total reactive power value of the current power station and the dead zone range, it is possible to quickly and preliminarily determine whether reactive power compensation is needed; and by comparing the difference between the two with the dead zone range again, the optimal selection of reactive power compensation devices and inverters and other power compensation equipment is made based on the relationship between the difference and the dead zone range. This has certain advantages and provides a solid foundation for the stability and rapidity of subsequent power compensation adjustment;

[0024] When the reactive power compensation device is given priority for reactive power compensation, the inverter is still retained as a backup option to avoid the problem that the reactive power compensation device cannot meet the reactive power regulation requirements;

[0025] The reactive power compensation target value is divided into a normal stable area and a variable area, and the inverter is initially adjusted to the terminal value of the normal stable area. There is no need to use a multi-stage step-by-step adjustment method to improve the adjustment efficiency. The average value of the variable area is used as the secondary adjustment target to further improve the adjustment efficiency. The reactive power compensation device is then used for fine adjustment, which greatly improves the efficiency of the inverter in reactive power regulation.

[0026] By reducing the real-time reactive value of the reactive compensation device and increasing the reactive value adjusted by the inverter, the occupation of the reactive compensation device can be reduced, avoiding the problem of insufficient reactive compensation devices for adjustment when the required reactive power is large, and ensuring the stability of the adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the system module of the present invention;

[0028] Figure 2 It is a schematic diagram of the method flow of the present invention. DETAILED DESCRIPTION

[0029] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] The present invention provides Figure 1 A distributed photovoltaic power station power compensation system shown includes:

[0031] The data acquisition module is used to collect the voltage, current, power factor, active power and reactive power data of the distributed photovoltaic power station in real time; the data acquisition module includes a voltage sensor, a current sensor and a power analyzer. The voltage sensor is used to measure the voltage of each node of the distributed photovoltaic power station; the current sensor is used to measure the current of each branch of the distributed photovoltaic power station; the power analyzer is used to calculate the active power, reactive power and power factor.

[0032] The power compensation control module is used to generate a power compensation control signal according to the data collected by the data acquisition module; the power compensation control module includes a power compensation calculation unit, a dead zone judgment unit and a control signal generation unit. The power compensation calculation unit is used to calculate the required active power and reactive power according to the collected voltage and current data, as well as the difference between the reactive value issued by the dispatching center and the total reactive value of the power station; the dead zone judgment unit is used to compare the values ​​of the dead zone and judge the relationship between the input value and the dead zone; the control signal generation unit is used to generate a power compensation control signal according to the output of the optimization algorithm module.

[0033] The power compensation device includes a static VAR generator (SVG) and a static VAR compensator (SVC), which adjusts active power and reactive power according to control signals received from a power compensation control module;

[0034] A communication module, used to realize data transmission between the data acquisition module, the power compensation control module, the power grid dispatching system and the power compensation device;

[0035] The power grid dispatching system is used to monitor, control and optimize the operation of the power grid. In reactive power control, the power grid dispatching system ensures the voltage stability and reactive power balance of the power grid by issuing target values ​​and coordinating equipment operation.

[0036] As an embodiment of the present invention, the present invention also provides Figure 2 A distributed photovoltaic power station power compensation method is shown;

[0037] Step 1: The power compensation control module obtains the target value issued by the power grid dispatching center, which includes voltage, reactive power or power factor, and is converted into a reactive value by the power compensation control module through calculation; obtains the total reactive value of the current power station; determines whether to perform reactive adjustment according to the dead zone condition, if the reactive value converted from the target value issued and the total reactive value of the current power station are both within the dead zone range, no adjustment is performed, and if they exceed the dead zone, the adjustment is started; the dead zone is the allowable error range;

[0038] Step 2: Compare the reactive value converted from the issued target value with the total reactive value of the current power station, calculate the difference, and determine whether to use the reactive compensation device or the inverter for reactive adjustment first according to the difference;

[0039] Step 3: If the difference is within the dead zone, and the reactive value converted from the target value is not much different from the total reactive value of the current power station, the reactive value converted from the target value is used as the reactive control target, and reactive power is adjusted through the reactive compensator, using its fast response and wide adjustment range to quickly reach the target. If the reactive compensation device SVC / SVG cannot meet the requirement, the inverter is adjusted;

[0040] Step 4: If the difference is outside the dead zone, it indicates that the reactive value converted from the target value issued is significantly different from the current total reactive value of the power station. The current total reactive value of the power station should be used as the reactive control target, the real-time reactive value of the reactive compensation device is obtained, the inverter is adjusted, and the target value is divided into a normal stable area and a variable area. First, the reactive power is adjusted to the end value of the normal stable area through the inverter. Secondly, the average value of the variable area is obtained, and the reactive power is adjusted to the average value through the inverter. At the same time, the real-time reactive value of the reactive compensation device working in real time is reduced, and the reactive value adjusted by the inverter is increased according to the reduced real-time reactive value, so as to reduce the occupation of the reactive compensation device and avoid the problem that there are not enough reactive compensation devices for adjustment when the required reactive power is large due to the large occupation of the reactive compensation device; the reactive compensation device is adjusted together based on the average value, and the reactive compensation device SVC / SVG is set to the automatic following mode. Through the coordinated compensation of the reactive compensation device, it is adjusted to the accurate reactive control target, and the total reactive value of the system can be ensured to remain unchanged.

[0041] The target value variation range is the area between the maximum and minimum values ​​within the variation range of the total reactive power value of the power station, that is, the total reactive power value of the power station is within and Changes between is the minimum value within the range of variation. is the maximum value within the range of variation, and the average value is and The target value is the average value of all the change values ​​between the target value and the normal stable area. The target value is the area within the minimum value of the total reactive power value change range of the power station. The total reactive power value of the power station will not change to this area. Therefore, it can be directly adjusted to ;

[0042] If there is no automatic follow-up function, the inverter is used to adjust the reactive power to the end value of the normal stable area. According to the numerical difference Δq between the current reactive power and the end value, the adjustment process of the numerical difference is divided into multiple stages, and each stage adopts a fixed step size of 20%, that is, each adjustment amount , until it is adjusted to the target reactive power value, keeping the total reactive power of the system dynamically stable.

[0043] As an embodiment of the present invention, the method of converting voltage into reactive value is:

[0044] Measure the current voltage;

[0045] Obtain a voltage target value, and obtain a voltage deviation ΔV by subtracting a voltage measurement value from the voltage target value;

[0046] Calculate the reactive power regulation ΔQ according to proportional control; ΔQ=ΔV·K, K is the proportional coefficient;

[0047] Combined with the current total reactive power value of the power station And the calculated reactive power regulation ΔQ, determine the final reactive power value , = +ΔQ.

[0048] As an embodiment of the present invention, the method of converting the power factor into the reactive value is:

[0049] Obtain the active power P actually output by the power station;

[0050] According to the definition of power factor: power , where PF is the power factor target value issued by the dispatching system;

[0051] Calculate the reactive power Q according to the relationship of the power triangle, , where the calculated reactive power is the converted reactive value.

[0052] As an embodiment of the present invention, the average value calculation method of adjusting the reactive power to the average value by the inverter is: the calculation formula of the reactive power with respect to time is obtained by using the least squares method fitting: , t is time, , , is the quadratic term coefficient, and the time corresponding to the maximum and minimum values ​​within the range of the total reactive power value of the power station is and , and integrate at the time corresponding to the maximum and minimum values ​​and calculate the average value, the formula is , so as to more accurately obtain the reactive power adjusted to the average value by the inverter.

[0053] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A distributed photovoltaic power station power compensation method, comprising a power compensation system, the power compensation system comprising: Data acquisition module, used to collect voltage, current, power factor, active power and reactive power data of distributed photovoltaic power stations in real time; A power compensation control module, used to generate a power compensation control signal according to the data collected by the data collection module; The power compensation device includes a static VAR generator and a static VAR compensator, which adjusts the active power and reactive power according to the control signal received from the power compensation control module; Characterized in that the power compensation method comprises the following steps: 1) Compare the reactive power value issued by the power grid dispatching system and the total reactive power value of the current power station with the dead zone. If they are outside the dead zone, reactive power regulation is performed; 2) Compare the reactive power value issued by the power grid dispatching system and the difference between the total reactive power value of the current power station and the dead zone; 3) If the difference is within the dead zone, the issued reactive value is used as the reactive control target and reactive adjustment is performed through the reactive compensator; 4) If the difference is outside the dead zone, the total reactive power value of the current power station is used as the reactive power control target, and the inverter is used for adjustment; the target value is divided into a normal stable area and a variable area, and the reactive power is adjusted to the end value of the normal stable area through the inverter, and then the average value of the variable area is obtained, and the reactive power is adjusted to the average value through the inverter; The change area is the area between the maximum value and the minimum value within the change range of the total reactive power value of the power station, and the normal stable area of ​​the target value is the area within the minimum value within the change range of the total reactive power value of the power station; The average value of reactive power adjusted by the inverter to the average value is calculated as follows: The calculation formula of reactive power with respect to time is obtained by least square fitting , t is time, , , is the quadratic term coefficient, and the time corresponding to the maximum and minimum values ​​within the range of the total reactive power value of the power station is and And integrate and average the moments corresponding to the maximum and minimum values, the formula is: , so as to more accurately obtain the reactive power adjusted to the average value by the inverter; 5) Turn on the automatic following mode of the reactive power compensation device, and adjust the reactive power to the accurate reactive power control target through the coordinated compensation of the reactive power compensation device; 6) Obtaining the real-time reactive value of the reactive compensation device, reducing the real-time reactive value of the reactive compensation device working in real time, and increasing the reactive value adjusted by the inverter according to the reduced real-time reactive value.

2. A distributed photovoltaic power station power compensation method according to claim 1, characterized in that: The power compensation control module includes a power compensation calculation unit, a dead zone judgment unit and a control signal generation unit. The power compensation calculation unit is used to calculate the required active power and reactive power according to the collected voltage and current data, as well as the difference between the reactive value issued by the dispatching center and the total reactive value of the power station; the dead zone judgment unit is used to compare the values ​​of the dead zone and judge the relationship between the input value and the dead zone; the control signal generation unit is used to generate a power compensation control signal according to the output of the optimization algorithm module.

3. A distributed photovoltaic power station power compensation method according to claim 1, characterized in that: In the step 3), the reactive power compensation device cannot meet the required reactive power compensation demand, and supplementary regulation is performed by adjusting the inverter.

4. A distributed photovoltaic power station power compensation method according to claim 1, characterized in that: If the reactive power compensation device does not have an automatic following function, the reactive power is adjusted to the end value of the normal stable area through the inverter. According to the numerical difference between the current reactive power and the end value, the numerical difference is adjusted in several steps until it is adjusted to the target reactive power value to maintain the dynamic stability of the total reactive power of the system.

5. A distributed photovoltaic power station power compensation method according to claim 1, characterized in that: In the step 1), the reactive power value sent by the power grid dispatching system is obtained by calculating the sent voltage, reactive power or power factor.

6. A distributed photovoltaic power station power compensation method according to claim 1, characterized in that: When the grid dispatching system sends the voltage to calculate the reactive value, measure the current voltage; obtain the voltage target value, and obtain the voltage deviation ΔV by subtracting the voltage measurement value from the voltage target value; calculate the reactive adjustment amount ΔQ according to the proportional control; ΔQ=ΔV·K, K is the proportional coefficient; combined with the current total reactive value of the power station And the calculated reactive power regulation ΔQ, determine the final reactive power value , = +ΔQ.

7. A distributed photovoltaic power station power compensation method according to claim 1, characterized in that: When the power grid dispatching system sends the power factor to calculate the reactive value, the actual active power P output of the power station is obtained; according to the definition of power factor: apparent power , where PF is the power factor target value issued by the dispatching system; the reactive power Q is calculated according to the relationship of the power triangle, , where the calculated reactive power is the converted reactive value.

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