CN212543724U - PID effect suppression device and photovoltaic power generation system - Google Patents
PID effect suppression device and photovoltaic power generation system Download PDFInfo
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- CN212543724U CN212543724U CN202021105045.2U CN202021105045U CN212543724U CN 212543724 U CN212543724 U CN 212543724U CN 202021105045 U CN202021105045 U CN 202021105045U CN 212543724 U CN212543724 U CN 212543724U
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Abstract
The utility model discloses a PID effect suppression device and photovoltaic power generation system, the device includes: the power supply clamping circuit clamps the voltage of the negative terminals of the photovoltaic arrays; the voltage sampling circuit samples the voltage to the earth of the negative electrode of each photovoltaic array in the photovoltaic power generation system or samples the voltage to the earth of the positive electrode of each photovoltaic array in the photovoltaic power generation system through the power supply clamping circuit and outputs corresponding voltage sampling signals; the master control circuit outputs corresponding power switch control signals according to the voltage values of the negative electrodes in the photovoltaic arrays corresponding to the voltage sampling signals to the earth; and the controlled end of the PID effect suppression circuit is connected with the output end of the master control circuit, and the voltage of the negative electrode of each photovoltaic array to the earth is adjusted when the controlled end is started according to the power switch control signal so as to suppress the PID effect. The utility model provides a photovoltaic array negative pole nonzero value's problem among the photovoltaic system realizes PID effect suppression.
Description
Technical Field
The utility model relates to a photovoltaic power generation technical field, in particular to PID effect suppression device and photovoltaic power generation system.
Background
The PID (Potential Induced Degradation) effect refers to a phenomenon that a high-strength negative voltage is applied between a cell and a frame on a photovoltaic array to continuously degrade the performance of the photovoltaic array, and is a phenomenon that the output characteristics of certain types of photovoltaic cell panels degrade due to Potential induction, which leads to the decrease of the output power of a photovoltaic system, and how to effectively inhibit the PID effect.
SUMMERY OF THE UTILITY MODEL
The utility model mainly aims at providing a PID effect suppression device and photovoltaic power generation system aims at solving the PID effect and restraines.
In order to achieve the above object, the utility model provides a PID effect suppression device is applied to the photovoltaic power generation system who has a plurality of independent photovoltaic arrays, PID effect suppression device includes:
the power supply clamping circuits are connected with a plurality of output ends of the power supply clamping circuits in a one-to-one correspondence mode, and are used for clamping the voltage of negative terminals of the photovoltaic arrays;
the voltage sampling circuit is connected with the input end of the power supply clamping circuit and is used for sampling the voltage to the earth of the negative electrode of each photovoltaic array in the photovoltaic power generation system or sampling the voltage to the earth of the positive electrode of each photovoltaic array in the photovoltaic power generation system through the power supply clamping circuit and outputting a corresponding voltage sampling signal;
the master control circuit is connected with the output end of the voltage sampling circuit and is used for outputting corresponding power switch control signals according to the voltage values of the cathodes in the photovoltaic arrays corresponding to the voltage sampling signals to the earth;
and the controlled end of the PID effect suppression circuit is connected with the output end of the master control circuit, and the PID effect suppression circuit is used for turning on/off according to the power switch control signal and adjusting the voltage of the negative electrode of each photovoltaic array to the ground so as to suppress the PID effect.
Optionally, the PID effect suppression circuit includes:
the controlled end of the switch power supply is connected with the master control circuit, and the switch power supply outputs corresponding power supply voltage according to the power supply switch control signal; and the output end of the switching power supply is connected with the input end of the power supply clamping circuit.
Optionally, the PID effect suppression circuit further includes:
and the controlled end of the controllable switch is connected with the master control circuit, the input end of the controllable switch is connected with the switching power supply, and the output end of the controllable switch is connected with the output end of the power supply clamping circuit.
Optionally, the general control circuit is further configured to control the controllable switch to be turned off when the switching power supply failure or the inverter failure in the photovoltaic power generation system is detected.
Optionally, the controllable switch is any one or a combination of a MOSFET, an IGBT, a contactor, a relay and a breaker.
Optionally, the switching power supply is any one of BUCK, BOOST, BUCK-BOOST, CUK, forward, flyback, half bridge, full bridge, and push-pull topologies.
Optionally, the power supply clamping circuit includes a plurality of diodes, anodes of the plurality of diodes are respectively connected to the output end of the switching power supply, and cathodes of the plurality of diodes are connected to the negative ends of the plurality of photovoltaic arrays in a one-to-one correspondence.
Optionally, the PID effect suppression apparatus further includes:
and the current-limiting resistor is arranged between the switching power supply and the ground in series.
Optionally, the overall control circuit includes:
the voltage comparator is used for controlling the switching power supply to adjust the voltage to earth of the negative electrode of any one photovoltaic array in the sampled photovoltaic power generation system when the voltage to earth of the negative electrode of the photovoltaic array is smaller than the reference voltage value;
and the output end of the master control unit is connected with the enabling end of the switching power supply to control the switching power supply to work so as to inhibit the PID effect.
The utility model also provides a photovoltaic power generation system, including a plurality of independent photovoltaic arrays, an inverter and the PID effect suppression device as stated in the right;
the output ends of the photovoltaic arrays are respectively connected with the direct current sides of the inverters;
the PID effect suppression device is arranged between the output ends of the photovoltaic arrays and the direct current side of the inverter in parallel.
The utility model discloses PID effect suppression device is through setting up voltage sampling circuit, in order to sample each photovoltaic array's in the photovoltaic power generation system negative pole is to earth voltage, or positive pole is to earth voltage to output corresponding voltage sampling signal to total control circuit, be used for according to a plurality of in the photovoltaic array negative pole is to earth voltage value in voltage sampling signal with total control circuit, output corresponding switch control signal; the utility model discloses still through setting up PID effect suppression circuit, PID effect suppression circuit basis switch control signal opens/closes to when opening, PID effect suppression circuit can produce direct current voltage, and will produce direct current voltage output at most photovoltaic array's negative pole end with between the direct current side of dc-to-ac converter, thereby adjust respectively photovoltaic array's negative pole (anodal) is to earth voltage, when taking place the PID phenomenon, can force the output voltage with each photovoltaic power generation negative pole to be greater than 0, can realize solving photovoltaic system in the problem of photovoltaic array negative pole nonzero value like this to realize PID effect suppression.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
Fig. 1 is a functional structure diagram of an embodiment of the PID effect suppression apparatus of the present invention;
fig. 2 is a schematic circuit diagram of an embodiment of the PID effect suppression apparatus of the present invention.
The reference numbers illustrate:
the objects, features and advantages of the present invention will be further described with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
It should be noted that, if directional indications (such as upper, lower, left, right, front and rear … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative position relationship between the components, the motion situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indications are changed accordingly.
In addition, if there is a description relating to "first", "second", etc. in the embodiments of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions in the embodiments may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should not be considered to exist, and is not within the protection scope of the present invention.
The term "and/or" herein is merely an association describing an associated object, meaning that three relationships may exist, e.g., a and/or B, may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.
The utility model provides a PID effect suppression device is applied to in the photovoltaic power generation system that has a plurality of independent photovoltaic array.
The PID (Potential Induced Degradation) effect refers to a phenomenon that a high-strength negative voltage is applied between a cell and a frame on a photovoltaic array to continuously attenuate the performance of the photovoltaic array, and is a phenomenon that the output characteristics of certain types of photovoltaic cell panels are attenuated due to Potential induction, which causes the output power of a photovoltaic system to be reduced, and how to effectively inhibit the PID effect is an urgent problem to be solved in the photovoltaic industry.
The scheme for realizing PID suppression generally comprises prevention and repair, and PID prevention generally indirectly raises the negative electrode of the panel to the ground potential to be positive by raising the ground potential of the neutral point on the alternating current side when the inverter works. The PID repairing is usually implemented by using an off-line inverse PID technology, and the PID repairing device is generally installed at the positive pole (or negative pole) of the photovoltaic cell panel, and the potential of the photovoltaic cell panel to the ground is raised to be positive (or negative) by using a positive bias power supply (or a negative bias power supply) at night. At present, PID suppression is set for a single path, that is, when PID suppression is needed to be performed on an independent photovoltaic array, a controllable switch power supply is put into or taken off the grid, which inevitably needs to set a plurality of controllable switches and a plurality of switch power supplies, and a PID suppression is configured for each photovoltaic inverter in a photovoltaic grid-connected power generation system to avoid PID effect generated by the photovoltaic array connected to the direct current side of each photovoltaic inverter.
In order to solve the above problem, referring to fig. 1 and 2, in an embodiment of the present invention, the PID effect suppression apparatus includes:
a plurality of output ends of the power supply clamp circuit 10 are connected with the plurality of photovoltaic arrays in a one-to-one correspondence manner, and the power supply clamp circuit 10 is used for clamping the voltage of negative terminals of the plurality of photovoltaic arrays;
the voltage sampling circuit 20 is connected with the input end of the power supply clamping circuit 10, and is used for sampling the voltage to the earth of the negative electrode of each photovoltaic array in the photovoltaic power generation system or sampling the voltage to the earth of the positive electrode of each photovoltaic array in the photovoltaic power generation system through the power supply clamping circuit 10, and outputting a corresponding voltage sampling signal;
the master control circuit 30 is connected with the output end of the voltage sampling circuit 20, and the master control circuit 30 is configured to output a corresponding power switch control signal according to the voltage values of the negative electrodes of the plurality of photovoltaic arrays corresponding to the voltage sampling signal to the ground;
and the controlled end of the PID effect suppression circuit 40 is connected with the output end of the master control circuit 30, and the PID effect suppression circuit 40 is used for turning on/off according to the power switch control signal and adjusting the voltage of the negative electrode of each photovoltaic array to the earth voltage when the power switch is turned on so as to perform PID effect suppression.
In this embodiment, the number of the voltage sampling circuits 20 only needs to be set to one, the voltage sampling circuits 20 are connected to the input end of the power supply clamp circuit 10, the output end of the power supply clamp circuit 10 is correspondingly connected to the photovoltaic arrays, that is, each photovoltaic array is correspondingly provided with an output end of the power supply clamp circuit 10, the voltage sampling circuits 20 can sample the voltages to the large ground of the cathodes of multiple photovoltaic arrays or the voltages to the large ground of the anodes of multiple photovoltaic arrays through the power supply clamp circuit 10, and there is no need to set a sampling circuit for each photovoltaic array, which can effectively save the cost of the wide power generation system. For a clearer explanation, the following embodiments take the voltage sampling circuit 20 as an example to sample the voltage of the negative electrode of the multi-path photovoltaic array to the ground voltage. The voltage sampling circuit 20 can detect the voltage value between the negative electrode of each photovoltaic array and the ground by adopting a voltage division serial connection mode, the voltage of the input end PV-of the power supply clamping circuit 10 is equivalent to the voltage value of the negative electrode of each photovoltaic array to the ground PE, the voltage value sampled by the voltage sampling circuit 20 is clamped at the maximum value of the voltage absolute value of some negative electrode to the ground PE, and the detected voltage to the ground of the negative electrode of the photovoltaic array is converted into an equal proportion voltage sampling signal to be output.
The total control circuit 30 is provided with a preset reference low voltage threshold (a target value Vref (specifically, a target value Vref may be set to 0V)), the total control circuit 30 may compare a voltage value between the negative electrode of the sampled photovoltaic array and the ground with the preset reference low voltage threshold, when the voltage value between the negative electrode of the sampled photovoltaic array and the ground is smaller than the preset reference low voltage threshold, at this time, it may be determined that at least one of the photovoltaic arrays generates a PID phenomenon in the output of the plurality of photovoltaic arrays, the total control circuit 30 outputs a switch control signal to control the PID effect suppression circuit 40 to operate, and the switch control signal is connected between the output ends of the plurality of photovoltaic arrays and the DC sides of the inverters (DC/AC)1# -n # through the power supply clamp circuit 10 to achieve PID effect suppression. When the voltage value between the negative electrode of the sampled photovoltaic array and the ground is greater than or equal to the preset reference low-voltage threshold value, it can be determined that the output of each photovoltaic array is normal, the master control circuit 30 outputs a switch control signal to control the PID effect suppression circuit 40 to stop working, and the photovoltaic power generation system works normally.
The PID effect suppression circuit 40 is turned on or off based on the control of the overall control circuit 30, and when the overall control circuit 30 controls the PID effect suppression circuit 40 to be turned off, the PID effect suppression circuit 40 does not generate and output a dc voltage, and the PID effect suppression circuit 40 may be in an off state or a standby state. When the total control circuit 30 controls the PID effect suppression circuit 40 to be turned on, the PID effect suppression circuit 40 can generate a DC voltage, and the generated DC voltage is clamped by the power clamp circuit 10 and then output between the negative terminals of the plurality of photovoltaic arrays and the DC sides of the inverters (DC/AC)1# -n #, so as to raise the negative voltage of the photovoltaic arrays to a non-zero value, thereby avoiding the negative terminals of the photovoltaic arrays from generating a negative voltage to the ground, and further avoiding the negative terminals of the photovoltaic arrays from generating a negative voltage to the ground, which can effectively prevent the photovoltaic arrays from generating the PID effect.
It can be understood that the PID effect suppression circuit 40 is connected between each of the photovoltaic arrays 1# to n # and the inverters 1# to n #, and the voltages of the negative electrodes of the different photovoltaic arrays to the earth voltage are not necessarily equal in the plurality of photovoltaic arrays 1# to n #. In the embodiment, the voltage sampling circuit 20 samples the voltage at the input terminal PV of the power supply clamp circuit 10, so that the sampled voltage value is clamped at the maximum absolute value of the voltage of one of the negative electrodes to the ground PE, that is, the voltage sampling circuit 20 may perform screening through the power supply clamp circuit 10 to select the maximum absolute value of the voltage of one of the negative electrodes to the ground PE. When the voltage value between the negative electrode of the photovoltaic array and the ground in the voltage to ground of any one path of the negative electrodes of the photovoltaic arrays 1# -n # is smaller than the preset reference low-voltage threshold value, the clamping of the power supply clamping circuit 10 can effectively ensure that the other input negative electrodes are correspondingly lifted by lifting the path with the maximum absolute value of the voltage to ground of the negative electrode, and the voltage to the negative electrode of each photovoltaic array can be lifted. The lowest value of the negative voltage of the photovoltaic array 1# -n # to the earth voltage can be in a non-negative value, and therefore the PID effect of the photovoltaic array 1# -n # is effectively avoided. The utility model discloses a voltage sampling circuit 20 and a switching power supply 41 can accomplish and carry out PID effect to multichannel input direct current and restrain.
The utility model discloses PID effect suppression device is through setting up voltage sampling circuit 20 to the negative pole of each photovoltaic array in the sampling photovoltaic power generation system is to earth voltage, and output corresponding voltage sampling signal to total control circuit 30, is used for according to a plurality of in the photovoltaic array negative pole is to earth voltage value or anodal earth voltage value to earth voltage value in the voltage sampling signal corresponds with total control circuit 30, outputs corresponding switch control signal; the utility model also provides a PID effect suppression circuit 40, PID effect suppression circuit 40 is opened/closed according to the power switch control signal, and when opening, PID effect suppression circuit 40 can produce direct current voltage, and output the produced direct current voltage between the negative pole end of a plurality of photovoltaic arrays and the direct current side of inverter (DC/AC)1# -n #, thereby adjust the negative pole (positive pole) of each photovoltaic array to ground voltage, when PID phenomenon occurs, can force the output voltage of each photovoltaic power generation negative pole to be greater than 0, thus can realize solving the problem of photovoltaic array negative pole non-zero value in the photovoltaic system, thereby realize PID effect suppression, and can realize a plurality of PID effects of photovoltaic array output through a PID effect suppression circuit 40, a voltage sampling circuit 20, can save the cost, and raising the multipath voltage.
Referring to fig. 1 and 2, in one embodiment, the PID effect suppression circuit 40 includes:
and a controlled end of the switch power supply 41 is connected with the master control circuit 30, and the switch power supply 41 outputs corresponding power supply voltage according to the power supply switch control signal.
The input end of the power supply clamping circuit 10 is connected with the output end of the switching power supply 41, and a plurality of output ends of the power supply clamping circuit 10 are connected with the negative ends of the photovoltaic arrays in a one-to-one correspondence manner; the power supply clamping circuit 10 is used for clamping the voltage of the negative terminals of a plurality of photovoltaic arrays.
In this embodiment, the switching power supply 41 may be implemented by a dc output power supply, and may specifically be an isolated topology or a non-isolated topology such as BUCK, BOOST, BUCK-BOOST, CUK, forward, flyback, half bridge, full bridge, or push-pull. The switchable power supply 41 operates based on the control of the overall control circuit 30, operates when receiving the output enable signal of the overall control circuit 30, and generates a corresponding magnitude of dc power according to the PWM drive signal output by the overall control circuit 30. The direct current power supply generated by the switching power supply 41 is clamped by the power supply clamping circuit 10 and then output, the voltage of the negative electrode of the photovoltaic array to the ground is clamped to be a certain value, the voltage to the ground of the negative electrode of each photovoltaic array is adjusted to be a non-negative value by applying the voltage to the ground to the photovoltaic array through the switching power supply 41, and therefore the negative electrode of each photovoltaic array can be prevented from generating negative voltage to the ground, and the photovoltaic array is prevented from generating a PID effect.
Referring to fig. 1 and 2, in an embodiment, the PID effect suppression circuit 40 further includes:
a controllable switch K1, wherein a controlled terminal of the controllable switch K1 is connected to the overall control circuit 30, an input terminal of the controllable switch K1 is connected to the switching power supply 41, and an output terminal of the controllable switch K1 is connected to an output terminal of the power supply clamping circuit 10.
In this embodiment, the controllable switch K1 is any one or a combination of a MOSFET, an IGBT, a contactor, a relay, and a circuit breaker. When the photovoltaic power generation system needs to be subjected to PID effect suppression, the master control circuit 30 controls the controllable switch K1 to be closed, so that the switching power supply 41 is switched on. When PID effect suppression of the photovoltaic power generation system is not needed, the master control circuit 30 controls the controllable switch K1 to be switched off, so that the controllable switch K1 is disconnected from the power supply 41.
Referring to fig. 1 and 2, in an embodiment, the general control circuit 30 is further configured to control the controllable switch K1 to be turned off when detecting a failure of the switching power supply 41 or a failure of an inverter (DC/AC)1# -n # in the photovoltaic power generation system.
In this embodiment, the master control circuit 30 may further be in communication connection with the switching power supply 41 and the communication terminals of the inverters in the photovoltaic power generation system, and when one or more of the photovoltaic inverters 1# to n # fails and is off-grid or stopped, the master control circuit 30 does not receive the negative voltage sampling signal output by the negative voltage sampling circuit any more, and stops the lifting of the negative terminal voltage of the photovoltaic array by controlling the controllable switch K1 to be disconnected. And meanwhile, the power supply 41 of the controllable switch K1 stops working, so that the sampling result of the photovoltaic array to the earth voltage is prevented from being influenced, and the PID effect suppression effect of the whole PID effect suppression device is further influenced. When the switching power supply 41 fails and the required direct-current power supply cannot be generated, the master control circuit 30 also controls the controllable switch K1 to disconnect the switching power supply 41 from the clamping circuit so as to stop the voltage rise of the negative terminal of the photovoltaic array.
Moreover, when each photovoltaic inverter in the grid-connected operation state enters the standby state, the controllable switch K1 power supply 41 may be switched to the standby state to stop outputting the voltage to the ground, so as to reduce the self-loss. The main control circuit can automatically detect that each photovoltaic inverter in the grid-connected operation state enters the standby state, or receive indication information sent from the outside or manually trigger the standby controllable switch K1 and the like by workers as a trigger condition for controlling the PID prevention device to enter the standby state.
Referring to fig. 1 and 2, in an embodiment, the power clamp circuit 10 includes a plurality of diodes (D1, D2, … Dn), anodes of the plurality of diodes (D1, D2, … Dn) are respectively connected to the output terminal of the switching power supply 41, and cathodes of the plurality of diodes (D1, D2, … Dn) are connected to negative terminals of the plurality of photovoltaic arrays in a one-to-one correspondence.
In this embodiment, the diodes (D1, D2, … Dn) are connected in a common positive mode, the cathodes are respectively connected to the cathodes of one of the photovoltaic arrays, when a negative voltage occurs at the negative terminal of any one of the photovoltaic arrays in the plurality of photovoltaic arrays, the diodes (D1, D2, … Dn) are turned on, the negative voltage sampling circuit can sample the voltage at the anode point of the diodes (D1, D2, … Dn) and output the voltage to the overall control circuit 30, the overall control circuit 30 can know that the negative voltage of the photovoltaic array at this time is a non-zero value, so as to control the switching power supply 41 to operate, and output the voltage to the negative terminal of the photovoltaic array through the diodes (D1, D2, D6857 Dn), so that when the voltage value between the negative terminal of the photovoltaic array and the ground exists in the voltage-to-ground of any one of the negative terminals of the photovoltaic arrays 1# -n #, the voltage is smaller than the preset reference low voltage threshold value, the voltage between the negative terminal of the photovoltaic, … Dn), can be effectual guarantees through the lifting wherein the utmost point is the biggest all the way to the voltage absolute value of earth voltage, then other input negative poles also corresponding by the lifting to the voltage of earth, can all carry out the lifting to each photovoltaic array's negative pole voltage, the utility model discloses can lift multichannel voltage under the prerequisite of saving the cost.
Referring to fig. 1 and 2, in an embodiment, the PID effect suppression apparatus further includes:
and the current limiting resistor R1 is connected between the switching power supply 41 and the ground in series, and the current limiting resistor R1 is connected between the switching power supply 41 and the ground in series.
The current limiting resistor R1 can avoid the current flowing through the diodes (D1, D2, … Dn) from being too large to damage the diodes (D1, D2, … Dn), when the switching power supply 41 and the controllable switch K1 are closed, each path of PV 1-PVn-of direct current input respectively passes through the anti-series diode (D1, D2, … Dn) (D1-Dn) and is firstly connected in parallel to PV-, is connected in series with the controllable switch K1, then sequentially passes through the switching power supply 41 and the resistor, and finally is connected to the ground, and the lifting of the negative electrode voltage of the photovoltaic array is completed.
Referring to fig. 1 and 2, in one embodiment, the overall control circuit 30 includes:
a voltage comparator U1, a first input terminal of the voltage comparator U1 is connected to a reference voltage value, a second input terminal of the voltage comparator U1 is connected to an output terminal of the voltage sampling circuit 20, an output terminal of the voltage comparator U1 is connected to a controlled terminal of the switching power supply 41, and the voltage comparator U1 is configured to control the switching power supply 41 to adjust the negative-electrode-to-large-ground voltage of any one photovoltaic array in the sampled photovoltaic power generation system when the negative-electrode-to-large-ground voltage of the photovoltaic array is smaller than the reference voltage value;
and the output end of the general control unit U2 is connected with the enabling end of the switching power supply 41, and controls the switching power supply 41 to work so as to inhibit PID effect. The master control unit U2 can be realized by a single chip microcomputer, a DSP, an FPGA and other microprocessors, and can also be realized by a PLC and other controllers.
In this embodiment, the reference voltage value may be set to 0V or below 0V, and when the voltage comparator U1 detects that the voltage to ground of the negative electrode of any one of the photovoltaic arrays in the photovoltaic power generation system is smaller than the reference voltage value, the switching power supply 41 is controlled to operate, and a dc power supply with a corresponding magnitude is output, so as to achieve the purpose of controlling the voltage to ground of the negative electrode to be 0V in real time. The master control unit U2 controls the switching power supply 41 to start and stop, specifically, by obtaining a sampling value of the voltage to the earth of the negative electrode of the photovoltaic array in the photovoltaic power generation system, and enabling the switching power supply 41 to start when the voltage to the earth of the negative electrode of any one of the photovoltaic arrays in the photovoltaic power generation system is smaller than a reference voltage value, otherwise, enabling the switching power supply 41 to stop or be in a standby state.
The utility model also provides a photovoltaic power generation system, including a plurality of independent photovoltaic arrays, inverter (DC/AC)1# -n # and the PID effect suppression device as above;
the detailed structure of the PID effect suppressing apparatus can refer to the above embodiments, and is not described herein; it can be understood, because the utility model discloses above-mentioned PID effect suppression device has been used among the photovoltaic power generation system, consequently, the utility model discloses photovoltaic power generation system's embodiment includes all technical scheme of the whole embodiments of above-mentioned PID effect suppression device, and the technical effect that reaches is also identical, no longer gives unnecessary details here.
The output ends of the photovoltaic arrays are respectively connected with the direct current sides of the inverters (DC/AC)1# -n #;
the PID effect suppression device is arranged between the output ends of the photovoltaic arrays and the direct current sides of the inverters (DC/AC)1# -n #, in parallel.
In this embodiment, the photovoltaic power generation system includes a plurality of photovoltaic arrays and a plurality of photovoltaic inverters, and the dc side voltage ranges of the plurality of inverters are PV1+ -PV 1-, PV2+ -PV 2-, … -, and PVn + -PVn-. By controlling the PID effect suppression device to work, the direct-current voltage of the output voltage of the PID effect suppression device is output to the negative electrode of the photovoltaic array, so that the voltage of the negative electrode of the photovoltaic array to the earth is lifted, and the photovoltaic system is ensured to be completely positive in voltage to the earth. The ac side of the photovoltaic inverter may be connected with an isolation transformer to incorporate energy generated by the photovoltaic power generation system into the grid.
The above is only the optional embodiment of the present invention, and not therefore the limit of the patent scope of the present invention, all of which are in the concept of the present invention, the equivalent structure transformation of the content of the specification and the drawings is utilized, or the direct/indirect application is included in other related technical fields in the patent protection scope of the present invention.
Claims (10)
1. A PID effect suppression device applied to a photovoltaic power generation system with a plurality of independent photovoltaic arrays is characterized by comprising:
the power supply clamping circuits are connected with a plurality of output ends of the power supply clamping circuits in a one-to-one correspondence mode, and are used for clamping the voltage of negative terminals of the photovoltaic arrays;
the voltage sampling circuit is connected with the input end of the power supply clamping circuit and is used for sampling the voltage to the earth of the negative electrode of each photovoltaic array in the photovoltaic power generation system or sampling the voltage to the earth of the positive electrode of each photovoltaic array in the photovoltaic power generation system through the power supply clamping circuit and outputting a corresponding voltage sampling signal;
the master control circuit is connected with the output end of the voltage sampling circuit and is used for outputting corresponding power switch control signals according to the voltage values of the cathodes in the photovoltaic arrays corresponding to the voltage sampling signals to the earth;
and the controlled end of the PID effect suppression circuit is connected with the output end of the master control circuit, and the PID effect suppression circuit is used for turning on/off according to the power switch control signal and adjusting the voltage of the negative electrode of each photovoltaic array to the ground so as to suppress the PID effect.
2. The PID effect suppression device according to claim 1, wherein the PID effect suppression circuit comprises:
the controlled end of the switch power supply is connected with the master control circuit, and the switch power supply outputs corresponding power supply voltage according to the power supply switch control signal; and the output end of the switching power supply is connected with the input end of the power supply clamping circuit.
3. The PID effect suppression device according to claim 2, wherein the PID effect suppression circuit further comprises:
and the controlled end of the controllable switch is connected with the master control circuit, the input end of the controllable switch is connected with the switching power supply, and the output end of the controllable switch is connected with the output end of the power supply clamping circuit.
4. The PID effect suppression apparatus according to claim 3, wherein the general control circuit is further configured to control the controllable switch to be turned off when the switching power supply failure or the inverter failure in the photovoltaic power generation system is detected.
5. The PID effect suppression device according to claim 3, wherein the controllable switch is any one or more combination of a MOSFET, an IGBT, a contactor, a relay, and a breaker.
6. The PID effect suppression device according to claim 2, wherein the switching power supply is any one of BUCK, BOOST, BUCK-BOOST, CUK, forward, flyback, half bridge, full bridge, or push-pull topology.
7. The PID effect suppression device according to claim 2, wherein the power supply clamp circuit includes a plurality of diodes, anodes of the plurality of diodes are respectively connected to the output terminals of the switching power supply, and cathodes of the plurality of diodes are connected to the negative terminals of the plurality of photovoltaic arrays in a one-to-one correspondence.
8. The PID effect suppression device according to claim 2, wherein the PID effect suppression device further comprises:
and the current-limiting resistor is arranged between the switching power supply and the ground in series.
9. The PID effect suppression apparatus according to any one of claims 2 to 8, wherein the overall control circuit comprises:
the voltage comparator is used for controlling the switching power supply to adjust the voltage to earth of the negative electrode of any one photovoltaic array in the sampled photovoltaic power generation system when the voltage to earth of the negative electrode of the photovoltaic array is smaller than the reference voltage value;
and the output end of the master control unit is connected with the enabling end of the switching power supply to control the switching power supply to work so as to inhibit the PID effect.
10. A photovoltaic power generation system comprising a plurality of independent photovoltaic arrays, inverters and the PID effect suppression apparatus according to any one of claims 1 to 9;
the output ends of the photovoltaic arrays are respectively connected with the direct current sides of the inverters;
the PID effect suppression device is arranged between the output ends of the photovoltaic arrays and the direct current side of the inverter in parallel.
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