CN107453373B - Reactive power compensation method - Google Patents
Reactive power compensation method Download PDFInfo
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- CN107453373B CN107453373B CN201710814976.6A CN201710814976A CN107453373B CN 107453373 B CN107453373 B CN 107453373B CN 201710814976 A CN201710814976 A CN 201710814976A CN 107453373 B CN107453373 B CN 107453373B
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- 238000005259 measurement Methods 0.000 claims abstract description 10
- 238000010276 construction Methods 0.000 abstract description 3
- 239000003990 capacitor Substances 0.000 description 6
- 230000005540 biological transmission Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
- H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
- H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
- H02J3/1864—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control wherein the stepless control of reactive power is obtained by at least one reactive element connected in series with a semiconductor switch
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
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Abstract
The reactive power compensation method provided by the invention comprises the following steps: reactive power compensators are respectively arranged at a plurality of load ends, and each reactive power compensator comprises a voltage measuring device, a control device and a reactive power compensating device; the reactive power compensation device is used for compensating reactive power, and the control device receives a voltage change signal of the voltage measurement device, calculates a compensation strategy and outputs a control signal to the reactive power compensation device; the control device starts the reactive power compensation device to compensate reactive power to the load end, meanwhile, the voltage measurement device measures the voltage change direction of the load end and outputs the voltage change direction to the control device, and the control device calculates a compensation strategy according to the voltage change direction and outputs a control signal to the reactive power compensation device. The method is convenient and quick, the construction cost is reduced, and the configuration is more convenient and flexible.
Description
Technical Field
The invention belongs to the field of electric power, and particularly relates to a reactive power compensation method.
Background
The electric power is divided into active power P, reactive power Q and apparent power S. Wherein, the active power p=uicos phi, the power unit representing actual absorption is represented by W; reactive power q=uisin phi, which energy is not consumed in the process of the reciprocating exchange in units denoted Var; apparent power S S = UI unit is denoted VA, mathematical relationship of apparent power and active and reactive power: s is S 2 ＝P 2 +Q 2 The method comprises the steps of carrying out a first treatment on the surface of the Wherein, phi: representing the phase angle difference of the voltage U and the current I. In practice, the device consumes active power and reactive power, while the data measured by the electric energy meter only calculate the active power.
The phase angle difference of the pure capacitor and the pure inductor current I and the voltage U is 90 °, one advanced by 90 °, one retarded by 90 °, so p=uicos phi=uicos (90 °) =0w for the pure capacitor and the pure inductor; that is, pure capacitors and pure inductors have an active power of 0 in the circuit and consume no active power, which is why they are called energy storage elements.
The power factor pf=p/S is an important technical and economic index of the power supply and utilization system, and when the electric equipment consumes active power, a great amount of reactive power is required to be sent to the load by the power supply, and the power factor reflects the reactive power required by the electric equipment when the electric equipment consumes a certain amount of active power. Reactive power consumption in the power grid is large, about 50% of the reactive power is consumed in transmission, transformation and distribution equipment, and 50% of the reactive power is consumed in power consumers. In order to reduce reactive power consumption and the active power loss of the power grid caused by the reactive power consumption, the flow of reactive power in the power grid must be reduced, namely the power factor of the power grid load is improved, so that the aims of saving electric energy and reducing loss are achieved.
Although reactive power is not charged, the reactive power is high, the PF is small, and the electric power company can pay fine. In addition, the smaller the PF is, the same active power is consumed, the absolute value of the current in the line is increased, the line loss is increased, and the line aging is accelerated. Reactive power is consumed by some equipment, which is not eliminated, but reactive power can be provided nearby, reducing the flow of reactive power in the grid, so-called reactive power compensation.
Disclosure of Invention
Technical problems: in order to solve the defects in the prior art, the invention provides a reactive power compensation method.
The technical scheme is as follows: the reactive power compensation method provided by the invention comprises the following steps:
(1) Reactive power compensators are respectively arranged at a plurality of load ends, and each reactive power compensator comprises a voltage measuring device, a control device and a reactive power compensating device; the reactive power compensation device is used for compensating reactive power, and the control device receives a voltage change signal of the voltage measurement device, calculates a compensation strategy and outputs a control signal to the reactive power compensation device;
(2) The control device starts the reactive power compensation device to compensate reactive power to the load end, meanwhile, the voltage measurement device measures the voltage change direction of the load end and outputs the voltage change direction to the control device, and the control device calculates a compensation strategy according to the voltage change direction and outputs a control signal to the reactive power compensation device: when the voltage of the load end rises, the compensation strategy is correct, and the compensation force is continuously increased; when the voltage of the load terminal is reduced, indicating that the compensation strategy is wrong, reducing the compensation force or compensating in the opposite direction; and continuously adjusting the compensation strategy until the voltage of the load terminal is maximum.
The invention also provides a reactive power compensator which comprises a voltage measuring device, a control device and a reactive power compensating device; the voltage measuring device is connected with the control device and outputs a voltage change signal to the control device; the control device is connected with the reactive power compensator and sends a control signal to the reactive power compensator.
The beneficial effects are that: the reactive power compensation method provided by the invention determines the compensation strategy by detecting the voltage change of the load end, thereby eliminating the use of the current transformer, avoiding a series of problems caused by adding the current transformer, being convenient and quick to install, reducing the construction cost and being more convenient and flexible to configure.
Drawings
Fig. 1 is a schematic diagram of a conventional reactive power compensation method.
Fig. 2 is a graph of active power, reactive power and apparent power of a load.
Fig. 3 is a schematic diagram of the reactive power compensation method of the present invention.
Detailed Description
The present invention will be further described below.
Comparative example
In practical application, in order to realize reactive power compensation, it is necessary to measure the phase angle difference between voltage and current, and then switch a proper capacitor or inductance according to the phase angle difference to achieve the purpose of compensating reactive power nearby, that is, the PF after compensation is as close to 1 as possible.
The phase angle difference between voltage and current is measured, a current transformer is required to be connected in series in the main loop, on one hand, inconvenience is brought to equipment processing, and the space requirement in the equipment is high; on the other hand, this method can only compensate the reactive power of the shunt measured by the current transformer.
Specifically, the reactive power compensator and the current transformer are configured at the load end, and two configuration methods can be adopted:
(1) And respectively configuring a reactive power compensator and a current transformer at a load 1, a load 2 and a load 3:
the advantages are that:
(a) The reactive power compensator is better when being closer to the load, so that the reactive power compensator is better in compensation effect when being respectively configured on the load 1, the load 2 and the load 3;
(b) When one reactive power compensator fails, only the nearby load is affected, and other loads are not affected;
(c) The load can be dynamically increased, and the reactive power compensator is added while the load is increased.
The disadvantages are: each load is provided with a reactive power compensator, so that the construction is inconvenient; meanwhile, since the current must be measured, the current transformer must be strung on the corresponding circuit, and maintenance is troublesome and dangerous once the current transformer fails.
(2) A large reactive power compensator and a current transformer are arranged behind the transformer:
the advantages are that: the initial configuration capacity is in place in one step, the back load is not compensated in the nearby place, and the load is convenient to install.
The disadvantages are: the worst is that once a failure occurs, the global is affected.
Example 1
The reactive power compensator comprises a voltage measuring device, a control device and a reactive power compensation device; the voltage measuring device is connected with the control device and outputs a voltage change signal to the control device; the control device is connected with the reactive power compensator and sends a control signal to the reactive power compensator.
Example 2
Reactive power compensation method, theoretical basis, see fig. 3:
assuming that the active power of the load is AB and the reactive power is BC, the apparent power is AC.
The corresponding amplitude relation ratio of active current (in phase with voltage), reactive current (90 ° out of phase with voltage), total current (actual current) is also AB: BC: an AC.
If BC can be compensated nearby, the current transmitted on the line will be changed from AC to AB. The current amplitude becomes smaller and the phase is also in phase with the voltage.
It is known that a transmission line is not an ideal line and is resistive, so that the voltage at the load end is reduced compared with the voltage of the power supply when the power supply supplies power to the load through the transmission line, and the larger the line resistance is, the larger the current is, and the more obvious the reduction is. At a certain line resistance, assuming that the supply voltage is unchanged, the change in current will result in a change in the load terminal voltage.
The method comprises the following specific steps:
(1) Reactive power compensators are respectively arranged at a plurality of load ends, and each reactive power compensator comprises a voltage measuring device, a control device and a reactive power compensating device; the reactive power compensation device is used for compensating reactive power, and the control device receives a voltage change signal of the voltage measurement device, calculates a compensation strategy and outputs a control signal to the reactive power compensation device;
(2) The control device starts the reactive power compensation device to compensate reactive power to the load end, meanwhile, the voltage measurement device measures the voltage change direction of the load end and outputs the voltage change direction to the control device, and the control device calculates a compensation strategy according to the voltage change direction and outputs a control signal to the reactive power compensation device: when the voltage of the load end rises, the compensation strategy is correct, and the compensation force is continuously increased; when the voltage of the load terminal is reduced, indicating that the compensation strategy is wrong, reducing the compensation force or compensating in the opposite direction; and continuously adjusting the compensation strategy until the voltage of the load terminal is maximum.
The method can complete the actions of compensation and measurement in a very short time by attempting compensation and then measurement, so that the voltage change in the very short time can be considered to be caused by compensation rather than the power supply voltage change; if the compensation is correct, the transmission current in the line becomes small, the voltage drop caused by the line becomes small, and the voltage at the load end rises; vice versa;
specifically, referring to fig. 3, a reactive power compensator, a voltage measuring device and a control device are respectively arranged on three loads, the reactive power compensator is used for compensating reactive power, and the voltage measuring device is used for measuring the voltage change direction of a load end; starting a reactive power compensator to compensate reactive power to a load end, and measuring the voltage change direction of the load end; when the voltage of the load end rises, the compensation strategy is correct, and the compensation force is continuously increased; when the voltage of the load terminal is reduced, indicating that the compensation strategy is wrong, reducing the compensation force or compensating in the opposite direction; and continuously adjusting the compensation strategy until the voltage of the load terminal is maximum.
Meanwhile, the reactive power compensators configured by the three loads are mutually shared as the voltages are basically consistent; in particular, when the load 1 is not operating, since the current in the line connecting the load 1 is almost lost, the line voltage drop is negligible, and the voltage measured by the reactive power compensator configured for the load 1 is actually the voltage of the load 2 or the load 3, and then the compensation behavior of the load is compensated for the load 2 or the load 3. In the conventional method, once the load is not operated, the reactive power compensator which is configured for the load is not subjected to any compensation operation, namely the equipment is idle because the measured current is 0 and the phase angle is 0. The reactive power compensator manufactured according to the invention can work all the time no matter whether the nearby load works or not after being installed. All reactive power compensators behind one transformer have the roles of capacity mutual support and function mutual backup. Therefore, the configuration scheme can be flexible and changeable; it is particularly important that they support each other's backup, and safety and economy are greatly improved.
In particular, the method comprises the steps of,
the power supply voltage 220V, the transmission line impedance 0.5 ohm, the inductive load pf=0.8, the load current 28.41a, the phase angle with the voltage phi (cos phi=0.8), with an active current of 22.73A and a reactive current of 17.04A.
When no compensation measures are taken, the voltage of the load terminal is 220V-28.41A 0.5Ω=205.8V; at this time, if the controller adopts to cut an inductance and connect it to the circuit in parallel, the reactive current on the line will increase, for example, it will become 18A, then the total current of the load will become 29A, at this time the voltage of the load terminal will be 220V-29A 0.5Ω=205.5v, and the strategy error will be explained. Instead, a capacitor is switched to be connected in parallel to the circuit, so that reactive current on the circuit is reduced, for example, 16A is changed, the total load current is changed to 27.8A, the voltage of the load terminal is 220V-27.8A 0.5Ω=206.1v, the strategy is correct, the capacity of the switched capacitor is continuously increased, reactive current on the circuit is continuously reduced, for example, 0A is changed, the total load current is changed to 22.73A, and the voltage of the load terminal is 220V-22.73A 0.5Ω=208.6v. If the capacitance is further increased, the reactive current on the line increases (direction changes from the lagging voltage of 90 ° to the leading voltage of 90 °), and the load terminal voltage decreases. From this process, 208.6V is the highest voltage value for this period, and a compensation strategy with a load voltage value of 208.6V should be adopted.
Claims (2)
1. A reactive power compensation method is characterized in that: comprising the following steps:
(1) Reactive power compensators are respectively arranged at a plurality of load ends, and each reactive power compensator comprises a voltage measuring device, a control device and a reactive power compensating device; the reactive power compensation device is used for compensating reactive power, and the control device receives a voltage change signal of the voltage measurement device, calculates a compensation strategy and outputs a control signal to the reactive power compensation device;
(2) The control device starts the reactive power compensation device to compensate reactive power to the load end, meanwhile, the voltage measurement device measures the voltage change direction of the load end and outputs the voltage change direction to the control device, and the control device calculates a compensation strategy according to the voltage change direction and outputs a control signal to the reactive power compensation device: when the voltage of the load end rises, the compensation strategy is correct, and the compensation force is continuously increased; when the voltage of the load terminal is reduced, indicating that the compensation strategy is wrong, reducing the compensation force or compensating in the opposite direction; and continuously adjusting the compensation strategy until the voltage of the load terminal is maximum.
2. A reactive power compensator comprises a voltage measuring device, a control device and a reactive power compensating device; the voltage measuring device is connected with the control device and outputs a voltage change signal to the control device; the control device is connected with the reactive power compensator and sends a control signal to the reactive power compensator; the method is characterized in that: the reactive power compensator performs reactive power compensation by adopting the reactive power compensation method of claim 1.
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| CN201710814976.6A CN107453373B (en) | 2017-09-12 | 2017-09-12 | Reactive power compensation method |
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| CN108599179A (en) * | 2018-06-15 | 2018-09-28 | 东北农业大学 | A kind of Non Power Compensation Process |
| CN109904859A (en) * | 2019-04-20 | 2019-06-18 | 江苏驭创高铁节能科技有限公司 | A kind of four-quadrant frequency converter realization line drop compensation control method |
| CN113346511A (en) * | 2021-06-11 | 2021-09-03 | 南京中探海洋物联网有限公司 | Correction method for reactive power compensation |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2278298Y (en) * | 1996-10-08 | 1998-04-08 | 邹瑞云 | Automatic compensator for lead end transforming |
| CN201805227U (en) * | 2010-06-04 | 2011-04-20 | 东莞市展圳节能环保设备有限公司 | Power energy-saving device |
| CN202309087U (en) * | 2011-11-02 | 2012-07-04 | 福建阳谷智能技术有限公司 | Single-phase voltage adjusting device with core controller and combination switch |
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- 2017-09-12 CN CN201710814976.6A patent/CN107453373B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2278298Y (en) * | 1996-10-08 | 1998-04-08 | 邹瑞云 | Automatic compensator for lead end transforming |
| CN201805227U (en) * | 2010-06-04 | 2011-04-20 | 东莞市展圳节能环保设备有限公司 | Power energy-saving device |
| CN202309087U (en) * | 2011-11-02 | 2012-07-04 | 福建阳谷智能技术有限公司 | Single-phase voltage adjusting device with core controller and combination switch |
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