JPS62262618A - Method of controlling system interlinkage inverter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a voltage-type converter that is operated in connection with an electric power system. I have 1 child. Such a system responds stably and quickly to disturbances such as changes in active and reactive power settings, disturbances in the grid, and fluctuations in the DC N source, and achieves the desired effective power output without adversely affecting the grid. It is desirable to be able to control reactive power.

[Conventional technology]

FIG. 3 is a schematic diagram showing the basic configuration of the interconnected inverter system. In the figure, 11 is a DC voltage source, 12 is a voltage type self-excited inverter, 13 is a transformer, and 14 is a power system. This can be expressed as an equivalent model using an AC voltage source 20, 21 and an impedance X as shown in FIG. Note that 20 represents an equivalent model of the inverter, and 21 represents an equivalent model of the power system.

Control of active power P and reactive power Q in such a system is performed, for example, as follows.

FIG. 5 is a simplified diagram showing a conventional example of an effective/reactive power control method using an inverter. In the figure, 1 is an active power regulator (APR), 2 is a reactive power regulator (人Q几), and 4 is an active power regulator (APR).
is a firing angle calculator, 11 is a DC voltage source, 12 is a voltage type self-excited inverter, 13.15 is a transformer, 14 is a power system, 1
6 is a current transformer, and 17 is an active and reactive power detector (PQ detector).

This is done by treating the output of AP 1 and the output of AQ 2 as the phase component (IVi) and amplitude component (IVi I) of the inverter output voltage ti with respect to the grid voltage vs. The vector m is indicated by adding a dot "." to the symbol.

[Problem that the invention seeks to solve]

However, in the above method, IVil and lV
Since i does not have a one-to-one correspondence with P and Q, but is a function of both, lVi is affected by a change in the setting of P or Q, and this change in lVi changes both P and Q. A phenomenon occurs in which the this is,
As the capacity of grid-connected inverters becomes larger, it becomes a problem as a disturbance to the grid, and due to such interoperability, it becomes difficult to increase the responsiveness of the system, resulting in the problem of not being able to perform high-speed control. There is.

Accordingly, it is an object of the present invention to provide a stable, high-speed control system that can control effective and reactive powers while making them non-interfering with each other, and has excellent transient response characteristics.

[Means for solving problems]

valid,! target value generation means for obtaining target values of active and reactive current components of the inverter output current in one-to-one correspondence with the dynamic force; [Operation] The present invention provides a control system for a voltage-type self-excited inverter that operates in connection with a grid to control active power and reactive power. Active current components and reactive 1 that uniquely correspond to active power and reactive power, respectively! These are effective when considered separately from the flow components.

Inactive electricity b! The target value of the voltage to be output from the inverter with respect to the target value of the effective and reactive current is determined by a calculator that expands the relational expression between the effective and reactive current and the inverter output voltage. Inverter voltage regulation based? Enable by doing #.

To make it possible to control reactive power by making it non-interfering.

Now let's consider a grid-connected inverter system like the one shown in Figure 3 using the % formula. Now, let's examine the grid-connected inverter system! Think of it as shown in Figure 2 (a). Here, the impedance between the inverter and the grid is represented by an inductance L and a resistance r. Then, the inverter output voltage Vjs output current i is treated as a vector on the a-β coordinate as shown in FIG. At this time, each α−
The β component is as follows. In the interconnected system expressed in this manner, the relational expression between the inverter output voltage and current can be obtained as follows by solving a predetermined differential equation. Note that P is a differential operator (d/di).

...... (4) Also, the active power P and the reactive power Q are as follows from the in-phase component and cross-sectional component of the battery with the grid voltage. In other words, %1aeiβ are effective and reactive currents that correspond one-to-one to the effective and reactive energies, respectively.

Therefore, to control )', Q, these valid and
The effect [flow sound, iβ should be controlled. Since this iβ has the relationship of equation (4) with respect to the inverter output voltage, an arithmetic device or a current/pressure converter that actually develops this equation within the control system is required. If provided and controlled, ideal control performance can be obtained. ◇ [Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention based on the above idea. As is clear from the figure, this embodiment is characterized by the provision of an arithmetic unit (I/V conversion device) 3 indicated by a dashed line. In other words, this includes various computing units 31a, 31b, 32a, which perform calculations based on equation (4) above,
32b, 33a*33b are provided, a target value 1 of active and reactive currents, and a control signal va of the voltage that the inverter should output from the cage β.

v, *, is calculated. Then, from these V, .

In addition, in this embodiment, active power, reactive power and active power,
Since there is a one-to-one correspondence with the reactive currents, the respective outputs t-active'a of the active power regulator 1 and the reactive power regulator 2
It is treated as the target value of L current and reactive current, that is, regulators 1 and 2 are set to 1! Although it is used as a means of generating a death target value, it is not limited to this method in particular.If the system voltage is constant, a coefficient unit that simply proportionally multiplies the target values of active and reactive power is provided. In this way, target values of effective and reactive power may be obtained.

〔Effect of the invention〕

According to this invention, target values of effective vL current and reactive current, which uniquely correspond to active power and reactive power, are derived as control variables, and developed based on the relational expression between effective forward current and inverter output voltage. Performance! Since the output voltage is controlled by determining the target value of the voltage that the inverter should output using the I-device,
It is possible to control active power and reactive power so that they do not interfere with each other, and it is possible to significantly improve transient characteristics.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram for explaining the invention in detail, FIG. 3 is a schematic diagram showing the basic configuration of a grid-connected inverter system, and FIG. 4 is an equivalent block diagram of FIG. 3, and FIG. 5 is a configuration diagram showing a conventional example of an active/reactive power control method using an inverter. Description of symbols l... Active power regulator (APR), 2...
・・Invalid%lami(AQR), 3------ Hn
Device - (I/V converter), 4... Firing angle calculator, 11... DC NFEr2.12...
...Voltage type self-excited inverter, 13°15...
Transformer, 14...Power system, 16...
Current transformer, 17... Active, reactive power detector (PQ
detector), 20...Inverter equivalent model, 2
1... Power system equivalent model, 31a, 31b.
...differential calculator, 32a, 32b...
Proportional calculator, 33a. 33b... Addition/subtraction device. Agent Patent Attorney Akio Namiki Agent Patent Attorney Seishi Matsuzaki 1 Senjo 2 Diagram (a)

Claims (1)

[Scope of Claims] In a grid-connected inverter that is operated in connection with a power grid and controls active power and reactive power, an active current component and a reactive current component of an inverter output current that correspond one-to-one to the active and reactive powers. Target value generation means for obtaining each target value, and calculation means for calculating each corresponding target value of the inverter output voltage from each target value of the active and reactive currents, and based on the output from the calculation means. A control method for a grid-connected inverter, characterized in that active power and reactive power are controlled by controlling the output voltage of the inverter.