Origin Electric Company, Limited

Ngk Insulators, Inc.

The Tokyo Electric Power Company, Incorporated

Tokyo Electric Co.

Masaaki Ohshima

Shuichi Ushiki

Jinbin Zhao

Hirokazu Shimizu

Jirou Fukui

Akira Kobayashi

Shuuichi Ushiki

Kiyomi Watanabe

Akihiko Yoshida

Senji Atsumi

Hiromi Shimada

Yasuhiro Genjima

A method of controlling a single-phase voltage source AC/DC converting circuit has internal equivalent impedance as seen from an AC terminal, for converting power from a DC voltage source connected to a DC terminal to single-phase AC power or for converting single-phase AC power from a single-phase AC source connected to the AC terminal to DC power in accordance with a pulse width of a gate signal generated based on a PWM command.

Method of controlling single-phase voltage source AC/DC converter and interconnection system

A static synchronous compensator that generates a second axis voltage command from the difference between the DC voltage converted by a single-phase voltage AC-DC conversion circuit and a set DC voltage command. When the voltage (the voltage of an AC terminal) of the single-phase AC power system increases, since the difference between the voltage of the AC terminal and an internal electromotive force increases, the static synchronous compensator carries out a PWM control to decreases the voltage of the AC terminal side of the single-phase voltage AC-DC conversion circuit. Since the voltage of the single-phase voltage AC-DC conversion circuit becomes lower than the voltage of the single-phase AC power system, an ineffective current flows from single-phase AC power system in the static synchronous compensator so that the voltage of the single-phase AC power system can be decreased.

Static synchronous compensator and voltage control method

A method and a single-phase voltage type AC/DC converting device and a three-phase voltage type AC/DC converting device arranged between a load and a distribution network. The converting devices are capable of contributing to stabilize a system frequency and a system voltage. By applying an autonomous parallel operation control technique of an AC/DC converter to a load, which receives power from a distribution network, drooping characteristics (governor-free characteristics) for a frequency of active power and voltage-maintaining characteristics (V-Q characteristics) may be obtained. The governor-free characteristics automatically decrease and increase received power when the system frequency decreases and increases, so that even the load may contribute to stabilize the system frequency. The V-Q characteristics generates/absorbs reactive power so as to maintain a voltage at a receiving end constant regardless of load power to further stabilize the system voltage.

Single-phase voltage type AC/DC converter, three-phase voltage type AC/DC converter, and stabilization control method

An automatic synchronous parallelization apparatus capable of suppressing an inrush current by automatically adjusting the magnitude, the frequency, and the phase of the voltage when a single-phase voltage-type DC-to-AC converting device performing an autonomous parallel operation is connected in parallel with an external single-phase AC voltage source. The automatic synchronous parallelization apparatus includes a synchronization detecting circuit, a voltage amplitude command value generating circuit, and a frequency command value generating circuit. The voltage amplitude command value generating circuit generates the 1st-axis voltage command value, and the frequency command value generating circuit generates the 2nd-axis voltage command value, based on a value relating to a frequency difference between an external single-phase AC voltage source and a single-phase voltage-type DC-to-AC converting device and an effective value of a voltage of the external single-phase AC voltage source that are detected by synchronization detecting circuit. By using such command values, an output of the single-phase voltage-type DC-to-AC converting device can be adjusted to as to coincide with a voltage waveform of the external single-phase AC voltage source.

Synchronization detecting circuit and automatic synchronous parallelization apparatus

A single-phase voltage source AC/DC converter according to the present invention generates a second axis voltage command from difference between a DC voltage detection value at a DC terminal and a DC voltage command value and controls a DC voltage by increasing and decreasing active power with the second axis voltage command. For example, the voltage at the DC terminal is increased by decreasing active power when the DC voltage detection value at the DC terminal is lower than the DC voltage command, while the DC voltage detection value at the DC terminal is decreased by increasing the active power when the DC voltage detection value at the DC terminal is higher than the DC voltage command.

Single-phase voltage source AC/DC converter and interconnection system

The present invention is a single-phase voltage source DC-AC power converter and a three-phase voltage source DC-AC power converter. Each of the single-phase voltage source DC-AC power converter and the three-phase voltage source DC-AC power converter includes a voltage source DC-AC power converting circuit that converts power from a DC voltage source into AC power to output the AC power from an AC terminal; and target current producing means that includes a filter voltage command device and a voltage controller, the filter voltage command device generating a filter voltage command value that becomes a reference of the AC power output from the AC terminal, the AC output voltage at the AC terminal being input as an input signal to the voltage controller, the voltage controller integrating a difference between the filter voltage command value from the filter voltage command device and the AC output voltage at the AC terminal, the target current producing means outputting a PWM command such that a DC component included in the AC output voltage at the AC terminal becomes zero.

Single-phase voltage source DC-AC power converter and three-phase voltage source DC-AC power converter

An electric power source in which a plurality of inverters operate on the same frequency and the plurality of inverters are connected in parallel so that a resistance value expressed by (1&#x2212;&#x3b2;&#xb7;G)/(&#x3b1;&#xb7;G) where &#x3b1; is the output voltage feedback gain, &#x3b2; is the output current feed forward gain, and G is the inverter current gain, is made to be the equivalent output impedance; and is an electrical power source in which the cross-current between the inverters are made to be an acceptable value or below by adjusting the output of each of the inverters by controlling the equivalent output impedance by modifying both or either one of the output voltage feedback gain &#x3b1; or the output current feed forward gain &#x3b2;.

Electrical power source, operational method of the same, inverter and operational method of the same

The present invention is an electric power source in which a plurality of inverters operate on the same frequency and the plurality of inverters are connected in parallel so that a resistance value expressed by (1&#x2212;&#x3b2;&#xb7;G)/(&#x3b1;&#xb7;G) where &#x3b1; is the output voltage feedback gain, &#x3b2; is the output current feed forward gain, and G is the inverter current gain, is made to be the equivalent output impedance; and is an electrical power source in which the cross-current between the inverters are made to be an acceptable value or below by adjusting the output of each of the inverters by controlling the equivalent output impedance by modifying both or either one of the output voltage feedback gain &#x3b1; or the output current feed forward gain &#x3b2;.

A three-phase voltage-fed AC/DC converter includes a conversion circuit which converts power from a DC voltage source to three-phase AC power. The converter further includes a UM conversion circuit which carries out dq conversion of the three-phase output voltage, a superior voltage control circuit which outputs a voltage reference vector based on a superior reference vector and an output voltage vector obtained by the UM conversion circuit, an inferior voltage control circuit which outputs a PWM reference based on the voltage reference vector and the output voltage vector, and a frequency control circuit which synchronizes a value generated based on a q-axis component from the UM conversion circuit with a rotation angle of a conversion matrix in the UM conversion circuit.

Three-phase voltage-fed AC/DC converter

To suppress a DC component in AC power in a power converter for converting DC power to AC power. DC power is converted to AC power by a converter, and the AC power is supplied to output terminals uand uvia an inductor. The converteris controlled based on an error &#x394;(t) between an output current i(t) outputted from the converterand a target current j(t) outputted from a target current generation meansas a target value for the output current i(t), and a DC component Vin an output terminal voltage v(t) is detected by a voltage detection means. A DC component Iis suppressed by correcting a target current j(t) by a DC component suppression means. Also, a DC component in the AC power is suppressed to prevent biased magnification of a transformerby calculating a correction amount j(t) for correcting the target current j(t) from the difference between a first instantaneous value dof a load current i(t) flowing to a loadat a first time point tand a second instantaneous value dof the load current i(t) at a second time point tthat is a half cycle after the first time point to correct the target current j(t).

Single-phase power conversion device and three-phase power conversion device

A sodium sulfur cell comprising an anode active material of metallic sodium, and a cathode active material of sulfur or sodium polysulfide, and a beta alumina solid electrolyte separator, the above active materials containing, as an impurity, calcium of at most 20 ppm and/or potassium of at most 200 ppm, by weight. The cell of the invention has excellent characteristics, particularly prolonged electromotive life.

Sodium sulfur cell and process of manufacturing the same

A solid electrolyte tube for sodium sulfur cells, having an outer surface of a roughness defined by an arithmetical mean deviation of the profile (R.sub.a) of not exceeding 2.0 .mu.m and a maximum height of the profile (R.sub.max) of not exceeding 15 .mu.m, is produced by leveling the outer surface of the solid electrolyte tube in a state of green body, bisque fired and calcined body, or fired body, by means of a finishing apparatus such as a centerless grinding machine, external cylindrical grinding machine, lathe, or the like. The solid electrolyte tube having a smooth and even surface can be prevented from crack formation due to local concentration of Na ion, S, sodium polysulfide and thermal stress thereon, so that it can improve durability and reliability.

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Tokyo, Japan

Masaaki Ohshima