Low-voltage distribution network voltage control device based on charging station and gravity energy storage

Abstract

The invention discloses a low-voltage power distribution network voltage control device based on a charging station and gravity energy storage, relates to a voltage control device based on gravity energy storage, and aims to solve the problem that an existing regulation and control method is poor in regulation and control effect. A voltage deviation module is used for judging whether a low-voltage out-of-limit fault occurs in a target node or not, and if yes, a low-voltage deviation gap of the target node is determined; otherwise, the target node does not need voltage control; the reactive power demand quantity determination module is used for obtaining the reactive power demand quantity according to the low-voltage deviation gap; the first judgment and adjustment module, the second judgment and adjustment module and the third judgment and adjustment module start reactive power, active power and load removal in sequence to form a level progressive control system. The method has the beneficial effects that the target node voltage of the low-voltage distribution network is improved on the basis of the target node, so that the low-voltage problem of the low-voltage distribution network is relieved, and meanwhile, the voltage control efficiency of the low-voltage distribution network is improved.

Description

Technical Field

[0001] The invention relates to a voltage control device based on gravity energy storage. Background Art

[0002] The distribution network is composed of overhead lines, cables, towers, on-load tap-changing transformers, disconnectors, reactive power compensators and some ancillary facilities. The distribution network can be divided into high-voltage distribution network, medium-voltage distribution network and low-voltage distribution network according to the voltage level. The voltage range of the high-voltage distribution network is: 35KV to 110KV, the voltage range of the medium-voltage distribution network is: 6KV to 20KV, and the voltage of the low-voltage distribution network is: 220V or 380V. In the daily operation process, for the low-voltage distribution network, when a large number of power loads are connected to the end of the line, there is a risk of low voltage in the low-voltage distribution network. The existing voltage control method of the low-voltage distribution network is to use reactive power compensators to compensate for voltage fluctuations, but reactive power compensators can only adapt to a small range. When the voltage fluctuation range is large, on-load tap-changing transformers are used for regulation. However, on-load tap-changing transformers have disadvantages, that is, when the low-voltage distribution network has a reactive power shortage, the voltage characteristics of the load can make the low-voltage distribution network maintain stable operation at a lower voltage. However, if the reactive power shortage is large, in order to maintain the voltage level, the on-load tap-changing transformer will act, the voltage will temporarily rise, and the reactive power shortage will be transferred to the main grid, thereby gradually decreasing the main grid voltage. In severe cases, it may cause the voltage collapse of the power generation system, and a power outage will occur. Therefore, it is significantly necessary to seek suitable and feasible low-voltage distribution network voltage regulation means to deal with these voltage problems. The existing regulation methods have the problem of poor regulation effect. Summary of the invention

[0003] The purpose of the present invention is to solve the problem that the existing control method has poor control effect, and proposes a low-voltage distribution network voltage control device based on a charging station and gravity energy storage.

[0004] The present invention discloses a low-voltage distribution network voltage control device based on a charging station and gravity energy storage, the voltage control device comprising: a voltage deviation module, a reactive power demand determination module, a first judgment and adjustment module, a second judgment and adjustment module, and a third judgment and adjustment module;

[0005] A voltage deviation module is used to determine whether a low voltage over-limit fault occurs at a target node. If so, a low voltage deviation gap of the target node is determined; otherwise, the target node does not require voltage control;

[0006] A reactive power demand determination module, used for obtaining reactive power demand according to the low voltage deviation gap;

[0007] A first judgment and adjustment module is used to judge whether the reactive power demand is greater than the current maximum reactive power provided by the gravity energy storage in the power system; if so, the gravity energy storage has a low voltage deviation gap, and the active power demand is obtained according to the low voltage deviation gap and the current reactive power output of the gravity energy storage; otherwise, the gravity energy storage is controlled according to the reactive power demand to increase the reactive power output;

[0008] The second judgment and adjustment module is used to judge whether the active power demand is greater than the current maximum active power provided by the gravity energy storage in the power system; if so, the charging load removal demand is obtained according to the low voltage deviation gap, the current reactive power output and the current active power output of the gravity energy storage; otherwise, the reactive power output and the active power output of the gravity energy storage are increased according to the maximum reactive power provided and the active power demand;

[0009] The third judgment and adjustment module is used to judge whether the charging load cutting demand is greater than the current load of the charging station in the power system; if so, the reactive output and active output of the gravity energy storage are increased according to the maximum reactive power provided and the maximum active power provided, respectively, and all loads of the charging station are cut off; otherwise, the reactive output and active output of the gravity energy storage are increased according to the maximum reactive power provided and the maximum active power provided, respectively, and the load of the charging station is cut off according to the charging load cutting demand.

[0010] Furthermore, the voltage deviation module is also used to obtain the active offset, reactive offset and voltage offset of the target node in the power system in each collection interval of the previous preset period; according to each of the active offsets and the voltage offsets, an active voltage sensitivity factor is obtained, and according to each of the reactive offsets and the voltage offsets, a reactive voltage sensitivity factor is obtained; wherein, the active voltage sensitivity factor is used to determine the active power demand and the charging load removal demand, and the reactive voltage sensitivity factor is used to determine the reactive power demand, the active power demand and the charging load removal demand.

[0011] Furthermore, the voltage deviation module determines whether a low voltage over-limit fault occurs at the target node by means of a voltage comparison circuit;

[0012] The voltage comparison circuit includes resistors R1 to R6, capacitors C1, C2, a diode D1 and an amplifier T1;

[0013] One end of the resistor R1 is connected to the output end of the +5V power supply; the other end of the resistor R1 is connected to one end of the resistor R2, and the other end of the resistor R1 is connected to the inverting input end of the amplifier T1; the other end of the resistor R2 is grounded;

[0014] The positive input terminal of the amplifier T1 is connected to one end of the resistor R3 and one end of the resistor R4 at the same time; the other end of the resistor R3 is connected to one end of the capacitor C1, and the other end of the resistor R3 serves as the input terminal of the sampling signal;

[0015] The other end of the resistor R4 is connected to the other end of the capacitor C1 and is grounded;

[0016] The power supply terminal of the amplifier T1 is connected to the output terminal of the +5V power supply; the ground terminal of the amplifier T1 is grounded;

[0017] The output end of the amplifier T1 is connected to the anode of the diode D1 and one end of the resistor R5, and the other end of the resistor R5 is connected to the output end of the +5V power supply;

[0018] The cathode of the diode D1 is connected to one end of the resistor R6 and one end of the capacitor C1 at the same time, and the cathode of the diode D1 is the output end of the voltage comparison result;

[0019] The other end of the resistor R6 is connected to the other end of the capacitor C2 and is grounded.

[0020] Furthermore, the model of the amplifier T1 is LM2903.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The reactive power demand is calculated according to the voltage gap of the target node, and the voltage gap is gradually compensated based on the reactive power and active power of the gravity energy storage. If the gravity energy storage regulation still cannot completely solve the fault, the load shedding demand is further calculated to try to shear off the charging station load to continue to increase the voltage. In the whole process, the three means of reactive power, active power and load shedding are enabled in turn to form a hierarchical control system, which is based on the characteristics of the gravity energy storage charging station and coordinates to deal with low-voltage faults in the power grid in various ways. This method fully coordinates the active and reactive power control of gravity energy storage for coordinated regulation, and improves the voltage of the target node of the low-voltage distribution network based on the target node to alleviate the low-voltage problem of the low-voltage distribution network. In addition, the module of the device does not involve optimization solutions, model calculations, etc., which puts less pressure on software and hardware calculations and greatly improves the regulation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a structural block diagram of a low-voltage distribution network voltage control device based on a charging station and gravity energy storage as described in the first specific implementation mode;

[0024] Figure 2 Detailed description of the invention The figure is a circuit diagram of a voltage comparison circuit in a third specific implementation mode. DETAILED DESCRIPTION

[0025] Specific implementation method 1. Combination Figure 1 This embodiment is described. A low-voltage distribution network voltage control device based on a charging station and gravity energy storage is described in this embodiment. The voltage control device includes: a voltage deviation module 1, a reactive power demand determination module 2, a first judgment and adjustment module 3, a second judgment and adjustment module 4 and a third judgment and adjustment module 5;

[0026] Voltage deviation module 1, used to determine whether a low voltage over-limit fault occurs at a target node, and if so, determine a low voltage deviation gap of the target node; otherwise, the target node does not require voltage control;

[0027] A reactive power demand determination module 2 is used to obtain reactive power demand according to the low voltage deviation gap;

[0028] The first judgment and adjustment module 3 is used to judge whether the reactive power demand is greater than the current maximum reactive power provided by the gravity energy storage in the power system; if so, the gravity energy storage has a low voltage deviation gap, and the active power demand is obtained according to the low voltage deviation gap and the current reactive power output of the gravity energy storage; otherwise, the gravity energy storage is controlled according to the reactive power demand to increase the reactive power output;

[0029] The second judgment and adjustment module 4 is used to judge whether the active power demand is greater than the current maximum active power provided by the gravity energy storage in the power system; if so, the charging load removal demand is obtained according to the low voltage deviation gap, the current reactive power output and the current active power output of the gravity energy storage; otherwise, the reactive power output and the active power output of the gravity energy storage are increased according to the maximum reactive power provided and the active power demand;

[0030] The third judgment and adjustment module 5 is used to judge whether the charging load cutting demand is greater than the current load of the charging station in the power system; if so, the reactive output and active output of the gravity energy storage are increased according to the maximum reactive power provided and the maximum active power provided, respectively, and all the loads of the charging station are cut off; otherwise, the reactive output and active output of the gravity energy storage are increased according to the maximum reactive power provided and the maximum active power provided, respectively, and the load of the charging station is cut off according to the charging load cutting demand.

[0031] In this embodiment, firstly, whether the target node in the system has a low voltage limit is determined by real-time monitoring, so as to determine the voltage gap of the target node; then, the reactive power demand is calculated according to the voltage gap of the target node, and the voltage gap is gradually tried to be compensated based on the reactive power and active power of the gravity energy storage; if the gravity energy storage regulation still cannot completely solve the fault, the load removal demand is further calculated, and the charging station load is tried to be removed to continue to increase the voltage; in the whole process, the three means of reactive power, active power and load removal are enabled in turn, forming a hierarchical control system, based on the characteristics of gravity energy storage, and coordinating and responding to low-voltage faults in the low-voltage distribution network in various ways. This method makes full use of the active and reactive control of the coordinated gravity energy storage for coordinated regulation, and improves the voltage of the target node of the low-voltage distribution network based on the target node to alleviate the low-voltage problem of the low-voltage distribution network; and the device does not involve optimization solution, model calculation, etc., which has less pressure on software and hardware calculations, and greatly improves the regulation efficiency.

[0032] Active offset, reactive offset and voltage offset refer to the active power change, reactive power change and voltage change of the target node in the collection interval respectively; the power system will collect the active power, reactive power and voltage of each node at each collection time, and the time difference between the collection times is the collection interval; two adjacent collection times constitute the collection interval; by subtracting the data obtained at the latter collection time from the data obtained at the previous collection time, the change corresponding to the collection interval constituted by the two adjacent collection times can be obtained; and the preset period is the period for analyzing and monitoring the operation of the power system, generally with days as the period; here, the active offset, reactive offset and voltage offset of each collection interval are used to analyze the impact of active and reactive changes on voltage, and provide data support for subsequent processing;

[0033] Specific implementation method 2. This implementation method further limits the low-voltage distribution network voltage control device based on charging stations and gravity energy storage described in specific implementation method 1. In this implementation method, the voltage deviation module 1 is also used to obtain the active offset, reactive offset and voltage offset of the target node in the power system in each collection interval of the previous preset period; according to each active offset and the voltage offset, an active voltage sensitivity factor is obtained, and according to each reactive offset and the voltage offset, a reactive voltage sensitivity factor is obtained; wherein, the active voltage sensitivity factor is used to determine the active demand and the charging load removal demand, and the reactive voltage sensitivity factor is used to determine the reactive demand, the active demand and the charging load removal demand.

[0034] In this embodiment, an active voltage sensitivity factor is obtained according to each active offset and voltage offset, and a reactive voltage sensitivity factor is obtained according to each reactive offset and voltage offset. The active voltage sensitivity factor is used to determine the active power demand and the charging load removal demand, and the reactive voltage sensitivity factor is used to determine the reactive power demand, the active power demand, and the charging load removal demand.

[0035] The active voltage sensitivity factor reflects the degree of influence of the active power change of the power system on the voltage change. The reactive voltage sensitivity factor reflects the degree of influence of the reactive power change of the power system on the voltage change. Both the active demand and the charging load removal demand are related to the active power of the gravity energy storage component. When calculating, it is necessary to determine the influence of the current active output of the gravity energy storage component on the voltage. Therefore, the active voltage sensitivity factor is an important parameter in calculating the active demand and the charging load removal demand. In addition, the above-mentioned reactive demand, active demand and charging load removal demand are all related to the current reactive output of the gravity energy storage. When calculating, it is necessary to determine the influence of the current reactive output of the gravity energy storage on the voltage. Therefore, the reactive voltage sensitivity factor is an important parameter in calculating the reactive demand, active demand and charging load removal demand.

[0036] Specific implementation method 3: Combination Figure 2 This embodiment is described. This embodiment further limits the voltage control device for a low-voltage distribution network based on a charging station and gravity energy storage described in the specific embodiment 1. In this embodiment, the voltage deviation module 1 determines whether a low voltage over-limit fault occurs at a target node by a voltage comparison circuit.

[0037] The voltage comparison circuit includes resistors R1 to R6, capacitors C1, C2, a diode D1 and an amplifier T1;

[0038] One end of the resistor R1 is connected to the output end of the +5V power supply; the other end of the resistor R1 is connected to one end of the resistor R2, and the other end of the resistor R1 is connected to the inverting input end of the amplifier T1; the other end of the resistor R2 is grounded;

[0039] The positive input terminal of the amplifier T1 is connected to one end of the resistor R3 and one end of the resistor R4 at the same time; the other end of the resistor R3 is connected to one end of the capacitor C1, and the other end of the resistor R3 serves as the input terminal of the sampling signal;

[0040] The other end of the resistor R4 is connected to the other end of the capacitor C1 and is grounded;

[0041] The power supply terminal of the amplifier T1 is connected to the output terminal of the +5V power supply; the ground terminal of the amplifier T1 is grounded;

[0042] The output end of the amplifier T1 is connected to the anode of the diode D1 and one end of the resistor R5, and the other end of the resistor R5 is connected to the output end of the +5V power supply;

[0043] The cathode of the diode D1 is connected to one end of the resistor R6 and one end of the capacitor C1 at the same time, and the cathode of the diode D1 is the output end of the voltage comparison result;

[0044] The other end of the resistor R6 is connected to the other end of the capacitor C2 and is grounded.

[0045] In this embodiment, the resistor R1 and the resistor R2 are both voltage-dividing resistors, and the resistor R3 and the resistor R4 are also both voltage-dividing resistors; the voltage-dividing resistors R1, R2, R3, and R4 respectively constitute a voltage-dividing circuit, the input voltage at the reverse input terminal of the amplifier T1 is the voltage of the voltage-dividing resistor R2, and the input voltage at the forward input terminal of the amplifier T1 is the voltage of the voltage-dividing resistor R4. When the acquisition signal is input to the IN terminal and the voltage obtained on the voltage-dividing resistor R4 exceeds the voltage on the voltage-dividing resistor R2, the output terminal of the amplifier T1 is positive and is output to the OUT terminal through the diode D1, driving the voltage deviation module 1 to act; otherwise, the output terminal of the amplifier T1 is negative, driving the voltage deviation module 1 to act or not.

[0046] Specific implementation method 4: This implementation method further limits the low-voltage distribution network voltage control device based on charging station and gravity energy storage described in specific implementation method 1. In this implementation method, the model of the amplifier T1 is LM2903.

[0047] In this embodiment, the LM2903 amplifier T1 has a fast response speed and can improve the circuit operation reliability.

[0048] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A low-voltage distribution network voltage control device based on charging stations and gravity energy storage, characterized in that: The voltage control device comprises: a voltage deviation module (1), a reactive power demand determination module (2), a first judgment and adjustment module (3), a second judgment and adjustment module (4) and a third judgment and adjustment module (5); A voltage deviation module (1) is used to determine whether a low voltage over-limit fault occurs at a target node, and if so, determine a low voltage deviation gap of the target node; otherwise, the target node does not require voltage control; A reactive power demand determination module (2) is used to obtain reactive power demand according to the low voltage deviation gap; A first judgment and adjustment module (3) is used to judge whether the reactive power demand is greater than the current maximum reactive power provided by the gravity energy storage in the power system; if so, the gravity energy storage has a low voltage deviation gap, and the active power demand is obtained according to the low voltage deviation gap and the current reactive power output of the gravity energy storage; otherwise, the gravity energy storage is controlled according to the reactive power demand to increase the reactive power output; The second judgment and adjustment module (4) is used to judge whether the active power demand is greater than the current maximum active power provided by the gravity energy storage in the power system; if so, the charging load removal demand is obtained according to the low voltage deviation gap, the current reactive power output and the current active power output of the gravity energy storage; otherwise, the reactive power output and the active power output of the gravity energy storage are increased according to the maximum reactive power provided and the active power demand; The third judgment and adjustment module (5) is used to judge whether the charging load removal demand is greater than the current load of the charging station in the power system; if so, the reactive output and active output of the gravity energy storage are increased according to the maximum reactive power supply and the maximum active power supply, and all the loads of the charging station are removed; otherwise, the reactive output and active output of the gravity energy storage are increased according to the maximum reactive power supply and the maximum active power supply, and the load of the charging station is removed according to the charging load removal demand.

2. A low-voltage distribution network voltage control device based on a charging station and gravity energy storage according to claim 1, characterized in that: The voltage deviation module (1) is further used to obtain the active offset, reactive offset and voltage offset of the target node in the power system in each acquisition interval of the previous preset cycle; obtain an active voltage sensitivity factor based on each active offset and the voltage offset, and obtain a reactive voltage sensitivity factor based on each reactive offset and the voltage offset; wherein the active voltage sensitivity factor is used to determine the active power demand and the charging load removal demand, and the reactive voltage sensitivity factor is used to determine the reactive power demand, the active power demand and the charging load removal demand.

3. A low-voltage distribution network voltage control device based on a charging station and gravity energy storage according to claim 1, characterized in that: The voltage deviation module (1) determines whether a low voltage over-limit fault occurs at the target node by means of a voltage comparison circuit; The voltage comparison circuit includes resistors R1 to R6, capacitors C1, C2, a diode D1 and an amplifier T1; One end of the resistor R1 is connected to the output end of the +5V power supply; the other end of the resistor R1 is connected to one end of the resistor R2, and the other end of the resistor R1 is connected to the inverting input end of the amplifier T1; the other end of the resistor R2 is grounded; The positive input terminal of the amplifier T1 is connected to one end of the resistor R3 and one end of the resistor R4 at the same time; the other end of the resistor R3 is connected to one end of the capacitor C1, and the other end of the resistor R3 serves as the input terminal of the sampling signal; The other end of the resistor R4 is connected to the other end of the capacitor C1 and is grounded; The power supply terminal of the amplifier T1 is connected to the output terminal of the +5V power supply; the ground terminal of the amplifier T1 is grounded; The output end of the amplifier T1 is connected to the anode of the diode D1 and one end of the resistor R5, and the other end of the resistor R5 is connected to the output end of the +5V power supply; The cathode of the diode D1 is connected to one end of the resistor R6 and one end of the capacitor C1 at the same time, and the cathode of the diode D1 is the output end of the voltage comparison result; The other end of the resistor R6 is connected to the other end of the capacitor C2 and is grounded.

4. A low-voltage distribution network voltage control device based on a charging station and gravity energy storage according to claim 3, characterized in that: The model of the amplifier T1 is LM2903.

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