CN-121984144-A - Distributed photovoltaic voltage out-of-limit treatment method for calculating line loss

CN121984144ACN 121984144 ACN121984144 ACN 121984144ACN-121984144-A

Abstract

A distributed photovoltaic voltage out-of-limit treatment method for calculating line loss comprises the steps of calculating an active power instruction and a reactive power instruction of a grid-connected point when the grid-connected point voltage is in an out-of-limit value level when the voltage detection result of the grid-connected point is out of limit, carrying out coordinate transformation on a modulation signal, carrying out constant amplitude value transformation on the grid-connected point voltage, directionally synchronizing the grid-connected point voltage into a rotating coordinate system to obtain a current reference value on a d-q coordinate axis, carrying out difference processing on the current reference value and the actual value on the d-q coordinate axis, sending the current reference value and the actual value into a PI regulator, carrying out SVPWM (space vector pulse width modulation) on the modulation signal obtained after the coordinate system transformation, and using the modulated output signal as a control signal of a photovoltaic grid-connected inverter, so as to regulate the active power and the reactive power of the grid-connected point voltage, so that a power distribution network bus receives the maximum active power, thereby reducing the line loss and avoiding energy waste.

Inventors

FAN WENTAO

Assignees

山东斯木信息技术有限公司

Dates

Publication Date: 20260505
Application Date: 20260206

Claims (4)

1. The distributed photovoltaic voltage out-of-limit treatment method for calculating line loss is characterized by comprising the following steps of: s1, when a grid-connected point voltage detection result is out of limit, calculating an active power instruction and a reactive power instruction of the grid-connected point to be injected into the photovoltaic power generation system when the grid-connected point voltage is at an out-of-limit value level; S2, carrying out coordinate transformation on the modulation signal, carrying out constant amplitude transformation on the grid-connected point voltage, and directionally synchronizing the grid-connected point voltage into a rotating coordinate system to obtain a current reference value on a d-q coordinate axis; S3, performing difference processing on the current reference value and the actual value on the d-q coordinate axis, sending the current reference value and the actual value to a PI regulator, performing SVPWM (space vector pulse width modulation) on a modulation signal obtained after coordinate system conversion, and using the modulated output signal as a control signal of a photovoltaic grid-connected inverter, so as to adjust the active power and the reactive power of a photovoltaic injection grid-connected point to adjust the voltage of the grid-connected point, and enabling a power distribution network bus to receive the most active power, thereby reducing line loss and avoiding energy waste.
2. The method for distributed photovoltaic voltage out-of-limit management for calculating line losses according to claim 1, wherein the active power command P pv_ref and the reactive power command Q pv_ref defining the point of connection are: ; Wherein R is line resistance, X is line reactance, P L is local active load, Q L is local reactive load, U lim is grid-connected point voltage limit value, and U s is distribution network bus voltage.
3. The method for calculating line loss in distributed photovoltaic voltage out-of-limit management according to claim 1, wherein the current reference value on the d-q coordinate axis is defined as: ; Wherein i d_ref is a current reference value of d axis, i.e. an active current reference value, i q_ref is a current reference value of q axis, i.e. a reactive current reference value, and u d is a voltage component of a rotating coordinate system.
4. The method for calculating out-of-limit treatment of line loss of distributed photovoltaic voltage according to claim 3, wherein after the distributed photovoltaic power generation system injects active power under maximum power tracking into the grid-connected point, if out-of-limit of the grid-connected point voltage is detected, the grid-connected point voltage is adjusted by using the residual reactive capacity of the inverter, the grid-connected point voltage is maintained at an out-of-limit value level, the active power and the reactive power of the photovoltaic grid-connected point at the moment are calculated, an active current reference value and a reactive current reference value are calculated according to the power command, and then the active power and the reactive power of the photovoltaic grid-connected point are adjusted.

Description

Distributed photovoltaic voltage out-of-limit treatment method for calculating line loss Technical Field The invention relates to a distributed photovoltaic voltage out-of-limit treatment method for calculating line loss. Background In rural power distribution networks with fewer loads, the voltage rise phenomenon is more serious because the total load is less, the photovoltaic permeability is very high, the voltage rise at the tail end of the power distribution network can influence the stability of the power network, and when the voltage rise is too high, the damage of household appliances can be even caused, so that the voltage rise is one of the main reasons for preventing the proportion of renewable energy sources in the power network from being improved. In the prior art, when the voltage is out of limit, dynamic reactive power support is given to the system, so that the out-of-limit degree of the voltage of a grid-connected point can be effectively improved, the grid-connected safety and stability of the distributed photovoltaic power generation system are improved, and in general, the dynamic reactive power support is mainly concentrated on two aspects of reactive voltage regulating equipment and the residual capacity of a photovoltaic grid-connected inverter. The reactive voltage regulating equipment can be divided according to the time scale and dynamic response performance of various reactive voltage regulating equipment, reactive displacement among the reactive voltage regulating equipment is considered to ensure that the system obtains better dynamic voltage supporting capability, and the method can have stronger dynamic supporting capability in the process of meeting reactive power requirements of the system, but the use of a quick reactive compensation device increases the cost of the system and cannot realize quick reactive power treatment. Disclosure of Invention The embodiment of the invention provides a distributed photovoltaic voltage out-of-limit treatment method for calculating line loss, which is reasonable in design, is based on detection and operation of a plurality of electrical related parameters, and can be used for injecting reactive power into grid-connected points by using the residual capacity of a photovoltaic inverter to regulate the voltage of the grid-connected points when a photovoltaic power generation system outputs active power with maximum output, so that the photovoltaic active power is kept unchanged, the active power and the reactive power of the photovoltaic injection grid-connected points are regulated, the out-of-limit voltage of the grid-connected points is restrained, the integral loss of a line is reduced, the bus of a power distribution network receives the maximum active power, the waste of energy sources is avoided, and the problems in the prior art are solved. The technical scheme adopted by the invention for solving the technical problems is as follows: A distributed photovoltaic voltage out-of-limit treatment method for calculating line loss comprises the following steps: S1, detecting grid-connected point voltage, and stabilizing the detected grid-connected point voltage by adopting an average filter to eliminate grid-connected point voltage fluctuation so as to obtain an accurate grid-connected point voltage detection result; S2, when the voltage detection result of the grid-connected point is out of limit, calculating an active power instruction and a reactive power instruction of the grid-connected point, which are needed to be injected into the photovoltaic power generation system when the voltage of the grid-connected point is at an out-of-limit value level; s3, carrying out coordinate transformation on the modulation signal, carrying out constant amplitude transformation on the grid-connected point voltage, and directionally synchronizing the grid-connected point voltage into a rotating coordinate system to obtain a current reference value on a d-q coordinate axis; S4, performing difference processing on the current reference value and the actual value on the d-q coordinate axis, sending the current reference value and the actual value to a PI regulator, performing SVPWM (space vector pulse width modulation) on a modulation signal obtained after coordinate system conversion, and using the modulated output signal as a control signal of a photovoltaic grid-connected inverter, so as to adjust the active power and the reactive power of a photovoltaic injection grid-connected point to adjust the voltage of the grid-connected point, and enabling a power distribution network bus to receive the most active power, thereby reducing line loss and avoiding energy waste. The active power command P pv_ref and the reactive power command Q pv_ref defining the point of connection are: ; Wherein R is line resistance, X is line reactance, P L is local active load, Q L is local reactive load, U lim is grid-connected point voltage limit value, and U s is distributio