California went to a competitive market structure to capture the efficiency benefits of supplier competition through lower prices. This worked when there was a surplus but the efficiency savings were overwhelmed by increased costs measured in tens of billions of dollars when the market stopped functioning. The government has stepped in to provide price stability and reliability. The new industry structure is still evolving. California's experience is a reminder that the physics of electricity, whereby production and consumption must be perfectly coordinated in real-time, is testing economics and free market principles. There must be flexibility and will to adjust market rules and operations in light of market performance. Competitive electric markets must be designed in recognition of the fact that electricity is different from other commodities (no storage, network effects, short time constants) and that market economics and engineering realities have to be harmonized.

https://users.ece.utexas.edu/~baldick/panels/Budhraja.pdf

California's Electricity Crisis

Voltage Sags in Three-Phase Systems

Subtransmission and distribution systems in large cities are often served by underground cable systems. Because of the compactness and the reduced cost of dc cable transmission lines, a Multi-Terminal HVDC system based on IGBT Voltage Source Converters (VSCs) can be an attractive alternative to an ac cable system. This paper draws attention to the added value which comes from the capability of Multi-Terminal HVDC (VSC-M-HVDC) system to ensure uninterrupted quality power to sensitive loads. The value of Premium Quality Power Park obtainable from a VSC-M-HVDC system should enhance its attractiveness.

Premium quality power park based on multi-terminal HVDC

For reasonable power quality assessment of transient disturbances in electric power systems, new transient power quality indices are developed based on a signal processing technique, time-frequency analysis. Based on the time-frequency distribution of a transient disturbance, a set of time-frequency based power quality indices are developed. In this paper, the instantaneous disturbance energy ratio, normalized instantaneous disturbance energy ratio, instantaneous frequency, and instantaneous K-factor are suggested for transient power quality assessment. Time-frequency based power quality indices allow one to quantify the effects of transient disturbances with high-resolution and accuracy.

Power quality indices for transient disturbances

With the deregulation of the electric power energy market, providing quality power has become an important concern of both power suppliers and customers. Efforts have been made to improve the power quality using passive filters, active power filters, hybrid filters and the new concept of custom power. This paper presents a comprehensive review of compensating custom power devices mainly DSTATCOM (distribution static compensator), DVR (dynamic voltage restorer) and UPQC (unified power quality compensator). It is aimed at providing a broad perspective on the status of compensating devices in electric power distribution system to researchers and application engineers dealing with power quality problems. Classified references presented in this paper would serve quick and useful applications.

A Review of Compensating Type Custom Power Devices for Power Quality Improvement

Several indices are in common use for the quantification of electric power quality. These indices are convenient for condensing complex time and frequency domain waveform phenomena into a number. However, a variety of commonly encountered circumstances are not readily accommodated (e.g. quasiperiodic and aperiodic signal components and noninteger multiples of the power frequency). Also, the power acceptability curves have been used as convenient measures of power quality and these curves do not capture three-phase detail of power quality problems. In this paper, the general subject of pitfalls of power quality indices is discussed and suggestions for alleviating these problems are made.

C.T. Heydt

Papers

Pitfalls of electric power quality indices