JPH0345996B2

JPH0345996B2 -

Info

Publication number: JPH0345996B2
Application number: JP59010100A
Authority: JP
Inventors: Hisashi Sekine; Yasushi Momochi
Original assignee: Hitachi Ltd; Hitachi Electric Systems Co Ltd
Current assignee: Hitachi Ltd; Hitachi Electric Systems Co Ltd
Priority date: 1984-01-25
Filing date: 1984-01-25
Publication date: 1991-07-12
Also published as: JPS60156300A

Description

【発明の詳細な説明】〔発明の利用分野〕本発明は同期機の励磁制御装置に係り、特に、
リアクタンスの大きな送電線で系統に接続される
同期機の不足励磁制御回路を備えた励磁装置に関
する。[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an excitation control device for a synchronous machine, and in particular,
The present invention relates to an excitation device equipped with an under-excitation control circuit for a synchronous machine connected to a grid through a power transmission line with large reactance.

[Background of the invention]

同期機の励磁制御装置は第１図に示すようにサ
イリスタ励磁機２、励磁電源変圧器３、界磁開閉
器４、自動電圧調整器５から構成され、同期器の
出力電圧を電圧変成器６より検出し、電圧設定器
５ａの指令値との偏差を偏差電圧検出器５ｂで検
出する。その偏差信号は信号演算増幅器５ｃで増
幅され、ゲートパルス移送器５ｄに与えられサイ
リスタ２の点弧位相を制御して同期器の励磁電圧
を制御する。 As shown in FIG. 1, the excitation control device for a synchronous machine is composed of a thyristor exciter 2, an excitation power transformer 3, a field switch 4, and an automatic voltage regulator 5, and the output voltage of the synchronous machine is transferred to a voltage transformer 6. The deviation from the command value of the voltage setting device 5a is detected by the deviation voltage detector 5b. The deviation signal is amplified by the signal operational amplifier 5c and given to the gate pulse transfer device 5d to control the firing phase of the thyristor 2 and the excitation voltage of the synchronizer.

同期機１がしや断器９を介して電力系統１１に
接続されたときには、同期器と系統との関係は第
２図に示すように系統リアクタンス１２を介して
無限大母線１３に接続された一機一無限大系とし
て表わすことが出来る。 When the synchronous machine 1 is connected to the power grid 11 via the disconnector 9, the relationship between the synchronous machine and the grid is as shown in Figure 2, where it is connected to the infinite bus 13 via the grid reactance 12. Each machine can be expressed as an infinite system.

この一機無限大系の同期機の運転は、同期機自
身の許容容量特性である第３図中の過励磁限界Ｇ
１、出力電流限界Ｇ２、不足励磁限界Ｇ３内か、
又は、定態安定限界SL内で運転する必要がある。
一般に、この制限のために、励磁制御装置には低
励磁制限回路５ｆを設け、同期機の出力（有効電
力Ｐ、及び無効電力Ｑ）を検出して不足励磁制限
UELの励磁制限を設けている。 The operation of this single infinite system synchronous machine is based on the overexcitation limit G shown in Fig. 3, which is the permissible capacity characteristic of the synchronous machine itself.
1. Is the output current limit G2 or underexcitation limit G3?
Or, it is necessary to operate within the steady state stability limit SL.
Generally, in order to limit this, the excitation control device is provided with a low excitation limiting circuit 5f, which detects the output (active power P and reactive power Q) of the synchronous machine and limits the underexcitation.
UEL excitation limits are set.

しかし、この定態安定限界は系統のリアクタン
ス及び同期機の運転電圧によつて変化する。この
定態安定限界は非突極機の場合、次式で表わされ
る。 However, this steady-state stability limit changes depending on the reactance of the system and the operating voltage of the synchronous machine. This steady-state stability limit is expressed by the following equation in the case of a non-salient pole machine.

（Ｐ／et²）²＋〔Ｑ／et²−１／２（１／Xe−１／Xd
）〕² ＝〔１／２（１／Xe＋１／Xd）〕² この結果、系統リアクタンスが大きい場合で、
かつ、定格より低い電圧で運転する場合、たとえ
ば、定態安定限界は第３図中SL′のようになり、
系統リアクタンス小、定格電圧時の制限特性SL
に比べ定態安定限界が大幅に縮小される。 (P/et ² ) ² + [Q/et ² -1/2 (1/Xe-1/Xd
)] ² = [1/2 (1/Xe + 1/Xd)] ^2As a result, when the system reactance is large,
In addition, when operating at a voltage lower than the rated voltage, for example, the steady state stability limit becomes SL' in Figure 3,
Limiting characteristics SL at low system reactance and rated voltage
The steady-state stability limit is significantly reduced compared to .

このため、通常の低励磁制御回路のみで出力電
圧低下時にも定態安定限界内で運転しようとする
と、その整定をUSL′のようにせねばならず、こ
れでは励磁制限回路のために、同期機の定格出力
がとれないという欠点がある。 Therefore, if you try to operate within the steady-state stability limit even when the output voltage drops using only a normal low excitation control circuit, the setting must be set like USL'. The disadvantage is that the rated output cannot be obtained.

[Purpose of the invention]

本発明の目的は、系統リアクタンスの大きな送
電線に接続される同期機の定態安定限界に対し良
好な制御を行ないうる同期機の励磁制御装置を提
供するにある。 An object of the present invention is to provide an excitation control device for a synchronous machine that can perform good control over the steady-state stability limit of a synchronous machine connected to a power transmission line with a large system reactance.

[Summary of the invention]

本発明の要点は低励磁制限装置を二組（又はそ
れ以上）設け、OR回路によりその制限出力のい
ずれかで励磁制限を行ないうるものとし、かつ、
同期機出力点附近の制限特性に同期機出力電圧の
補償回路を附加することにより、同期機が定格電
圧では定格電圧による定態安定限界内で同期機が
最大出力を出しうるものとし、同期機出力電圧が
低下したときのみ定態安定限界の縮小に応じて低
励磁制限特性を変化させて、同期機に可能な最大
出力を出しうる制限特性を設けるにある。 The main point of the present invention is that two (or more) sets of low excitation limiting devices are provided, and excitation can be limited by one of the limiting outputs using an OR circuit, and
By adding a compensation circuit for the synchronous machine output voltage to the limiting characteristics near the synchronous machine output point, it is assumed that the synchronous machine can output the maximum output at the rated voltage within the steady-state stability limit due to the rated voltage. The purpose is to provide a limiting characteristic that allows the synchronous machine to output the maximum possible output by changing the low excitation limiting characteristic in accordance with the reduction of the steady-state stability limit only when the output voltage decreases.

[Embodiments of the invention]

同期機の有効電力Ｐ及び無効電力Ｑ検出回路の
出力を入力信号とし、制限特性をもつ制限回路を
第４図の５ｆ及び５ｇの二組を設け、低励磁制限
回路（第二段）５ｇには電圧補償回路５ｈの出力
を印加する。 Using the outputs of the active power P and reactive power Q detection circuits of the synchronous machine as input signals, two sets of limiting circuits with limiting characteristics, 5f and 5g in Fig. 4, are provided, and the low excitation limiting circuit (second stage) 5g is used. applies the output of the voltage compensation circuit 5h.

低励磁制限回路（第一段）５ｆには第６図中に
示す制限特性UEL1の切片a_1sを定める設定器a₁及
び制限特性の傾きb_1sを定める設定器b₁を設ける。 The low excitation limiting circuit (first stage) 5f is provided with a setting device a 1 that determines the intercept a _1s of the limiting characteristic UEL1 shown in FIG _. 6, and a setting device b ₁ that determines the slope b _1s of the limiting characteristic.

この他、電圧補償回路５ｈには電圧補償開始点
を定める設定器a₃を設け、同期機端子電圧信号
V_GSと補償開始点のバイアス信号V_Sとの信号演算
増巾器OA３を設ける。この演算回路にはダイオ
ードD^h ₁、D^h ₂を備え、同期機出力電圧が制限開
始電圧（一般には同期機定格電圧）以下になつた
ときのみ電圧補償信号V^CSを発生する。従つて、
低励磁制限（第一段）を電圧補償回路付低励磁制
限（第二段）に組合せると、総合の制限特性は同
期機出力電圧が電圧補償開始点の電圧範囲外の場
合には第６図中の−−となり、電圧補償開
始点以内では制限特性UEL2の制限値が変化し
て、総合の制限特性は−′−′となる。 In addition, the voltage compensation circuit 5h is provided with a setting device _a3 that determines the voltage compensation starting point, and the voltage compensation circuit 5h
A signal operation amplifier OA3 is provided for calculating V _GS and a bias signal V _S at the compensation start point. This arithmetic circuit includes diodes D ^h ₁ and D ^h ₂ , and generates a voltage compensation signal V ^CS only when the synchronous machine output voltage falls below the limit start voltage (generally the synchronous machine rated voltage). Therefore,
When the low excitation limit (first stage) is combined with the low excitation limit with voltage compensation circuit (second stage), the overall limit characteristic becomes - in the figure, the limit value of the limit characteristic UEL2 changes within the voltage compensation start point, and the overall limit characteristic becomes -'-'.

この制御特性を同期機容量390MVA Pf0.9、定
格出力350MW、同期リアクタンスX^d＝1.724PU、
系統リアクタンス0.66PUの例で計算すると、第
７図に示すようにQ_G＝168MVAR、P_R＝
350MWに対し、定格電圧時定態安定限界がＰ軸
を切る点、P_N＝365MWに対し、電圧が0.95PUに
低下すると、P_L＝325MWとなる。このため、単
に制限特性をUEL1とUEL2を組合わせただけと
した場合、P_L＜P_U2となり、低励磁制限の機能を
満たさなくなる。これに対し、制限特性UEL2に
電圧補償を行なうとUEL2（Ｖ）となり、同期機
は定態安全限界内で安全な運転が可能となる。 This control characteristic is defined as synchronous machine capacity 390MVA Pf0.9, rated output 350MW, synchronous reactance X ^d = 1.724PU,
Calculating using the example of system reactance 0.66 PU, as shown in Figure 7, Q _G = 168 MVAR, P _R =
For 350 MW, the point where the steady-state stability limit at rated voltage crosses the P axis, P _N =365 MW, becomes P _L =325 MW when the voltage decreases to 0.95 PU. For this reason, if the limiting characteristic is simply a combination of UEL1 and UEL2, P _L <P _U2 and the low excitation limiting function will not be satisfied. On the other hand, if voltage compensation is performed on the limiting characteristic UEL2, it becomes UEL2 (V), and the synchronous machine can operate safely within the steady-state safety limit.

〔Effect of the invention〕

本発明によれば系統リアクタンスの大きな送電
線に接続された同期機を定態安定限界内で最大の
不足励磁制限運転を可能とし、進相運転を要求さ
れる同期機の運転を容易にすることが出来る。 According to the present invention, it is possible to operate a synchronous machine connected to a power transmission line with a large system reactance under the maximum underexcitation limit within the steady-state stability limit, thereby facilitating the operation of a synchronous machine that requires phase advance operation. I can do it.

[Brief explanation of drawings]

第１図は従来の励磁制御装置のブロツク図、第
２図は同期機と系統の構成図、第３図は同期機の
許容出力特性と定態安定限界の説明図、第４図は
本発明の励磁制御装置のブロツク図、第５図は低
励磁制限装置の回路図、第６図は本発明の一実施
例の低励磁制限装置の整定説明図、第７図は定態
安定限界と低励磁制限時の詳細説明図である。５ａ……電圧設定器、５ｄ……ゲートパルス移
相器。 Fig. 1 is a block diagram of a conventional excitation control device, Fig. 2 is a configuration diagram of a synchronous machine and its system, Fig. 3 is an explanatory diagram of the allowable output characteristics and steady-state stability limit of the synchronous machine, and Fig. 4 is the invention of the present invention. 5 is a circuit diagram of the low excitation limiting device, FIG. 6 is an explanatory diagram of the setting of the low excitation limiting device according to an embodiment of the present invention, and FIG. 7 is a diagram showing the steady state stability limit and the low excitation limiting device. It is a detailed explanatory diagram at the time of excitation restriction. 5a... Voltage setting device, 5d... Gate pulse phase shifter.

Claims

[Scope of Claims] 1. An excitation control device that controls the excitation of a synchronous machine connected to an electric power system, the voltage control device controlling the voltage of the electric power system to a predetermined value, and the synchronous machine being operated at low excitation. In the excitation control device for a synchronous machine, the low excitation limiting device is provided with a leading reactive power setting value and a slope setting value, and is configured to control the allowable capacity of the synchronous machine itself. Among the characteristics, the first one that simulates the underexcitation magnetic field characteristics
and a leading reactive power and slope setting value greater than the leading reactive power and slope setting values in the first low excitation limiting circuit,
a second low excitation limit circuit that simulates the underexcitation limit characteristic when the synchronous machine operates near the rated active power; and a second low excitation limit circuit that detects that the synchronous machine is operated below the rated voltage. It is equipped with a voltage compensation circuit that corrects the circuit characteristics to the stable operation side of the allowable capacity characteristics of the synchronous machine itself, and in the region where the active power is large, a second low excitation limiting circuit performs low excitation limiting,
An excitation control device for a synchronous machine, characterized in that a first low excitation limiting circuit performs low excitation limitation in a region where active power is small.