Wen-Chen Chu

Scheduling of direct load control to minimize load reduction for a utility suffering from generation shortage

This paper adopts the method of dynamic programming to optimally determine the schedule of the direct load control, but its objective function is to minimize the amount of load reduction with appropriate constraints. This approach is intended to solve the chronic problem of severe power shortage in the summer for the Taiwan Power Company (Taipower or TPC). This scheduling scheme is to reduce the resulting inconvenience to customers as well as the effects to the total income from electricity sales to the minimum under the particular management conditions the TPC finds itself in. >

Allocating the costs of reactive power purchased in an ancillary service market by modified Y-bus matrix method

In an open accessed transmission system, the costs of each ancillary service will be unbundled. This paper proposes a straightforward method of allocating the costs of reactive power purchased by contract or from a bidding market. This method uses basic circuit theory and partitions the Y-bus matrix to decompose the voltage of the load buses with a view to calculating the reactive power sharing. This method is derived from the system equations without such assumptions as the proportional flow or lossless transmission line.

Multi-region short-term load forecasting in consideration of Heat Index and load/weather diversity

This paper proposes a multi-region short-term load forecasting methodology, taking into account the Heat Index, a human-perceived equivalent temperature, to improve the load forecasting accuracy in Taiwan Power Companys (Taipowers) system. With the distinct climate characteristics due to Taiwans long and narrow topography, it is difficult to obtain satisfactory load forecasting results by treating the whole island as one single region. Therefore, the multi-region load forecasting that factors in the load/weather diversity is applied to enhance the forecasting accuracy. Besides, such weather factors as temperature, relative humidity, and the Heat Index are also considered to examine the prediction accuracy. The results show that adopting the Heat Index as a parameter can effectively improve the accuracy if the temperature of the region under investigation is above 27°C/80°F. By considering both the load/weather diversity and the Heat Index, the further improvement of the load forecasting for the Taipower system in summer can be effectively achieved.

The Economic Dispatch with Consideration of Transmission Service Charge for a Generation Company

This paper presents a novel economic dispatch strategy for a generation company that owns several units with different fuel costs, efficiency, and locations, and has a bilateral contract with several large customers. The proposed strategy not only considers the generation cost, but also takes into account the wheeling charge for the use of the transmission system. A modified megawatt-mile method is proposed to calculate the wheeling cost in this paper. Finally, the calculation results of economic dispatch for a generation company with two units and their loads in a real power system will be demonstrated.

Optimal operation strategy for cogeneration power plants

The electrical power system has been increased both in the size and complexity at a rapid rate in the last few decades. With the trend of deregulation, power systems are operated in a more stressed state. Since the establishment of the cogeneration promotion law in 1988, over one hundred cogeneration power plants with the total installation capacity about 16% of total Taiwan Power Company (TPC) system in Taiwan. Also, after TPC adopting the time-of-use (TOU) tariff rate schedule, electricity price of peak and semipeak period is higher than off-peak period. These factors promote greater incentives for more effective utilization of the current facilities. This paper uses genetic algorithms to develop an optimal operation strategy for the cogeneration power plant (CPP) to improve its competitiveness in the power market. A real cogeneration power plant is used to verify the feasibility of the proposed algorithm.

A program of computer-aided coordination analysis for an undergraduate course in protective relaying

The authors introduce a program used as a tool for protective relaying courses at the undergraduate level. This program allows students to practice protective devices coordination in power systems on a personal computer by representing the time-current curve with dynamic computer graphics. The program is provided with a debugging system that is designed to inform the user of any problem found in a protection scheme. To make students fully understand the dynamic performance of protective devices coordination, the program allows students to assign the location of a fault, and will display the operating time of the protective devices according to the tripping sequence. The program also has the function of automatic coordination analysis, the results of which can be compared with the users scheme and can also help the user to have a better understanding of what is actually used in industry today. >

Development of the multi-variable loss equation for a longitudinal power system

A method which divides a longitudinal transmission system into Northern, Central, and Southern regions of Taiwan is presented. A loss equation is developed to describe the system losses as a function of the three regional loads and the interchanged power flow among them. The coefficients of this multivariable equation can be determined by the use of a regression technique, and the losses calculated are more accurate than those derived from the single-variable equation for this particular system. >

Feasible Strategy for Allocating Cost of Primary Frequency Regulation

Among the ancillary services, a great number of cost allocation strategies have been broadly developed in the deregulated environment. Generally, the utilization of such services can be determined by directly evaluating the actual amount of the usage or by indirectly analyzing the fair/reasonable contribution/attribution to the market participants. In the case of the primary frequency regulation (PFR) service, which is operated by the participating generating units to maintain the real-time balance between the generation and load, the discussion of the PFR service attributed to the load side has still received relatively little attention. In this paper, a new strategy of the cost allocation of the PFR service from the customer side is proposed. Two main factors, the load fluctuation and the frequent demand change, are considered to figure out the PFR reaction relating to the different substations. The design of a scheme for determining the cost allocation index of the PFR service can be applied to the presently exiting power market. In addition, the actually load series recorded from the extra-high voltage (EHV) substations of the Taipower system located in northern, central, and southern Taiwan are meticulously analyzed and utilized to verify the feasibility and practicability of cost allocation.

Redistribution of transmission loss based on Z-bus method

This paper presents a procedure for redistributing the Z-bus loss allocation in the open access transmission system. The proposed improvement not only identifies the contribution/attribution of the current flow between generation and load, but also figures out the responsibility of loss for each generator-load pair. The redistribution of the transmission loss based on Z-bus method can both closely reflect the relationship between generation and load and flexibly assign the loss to the selected bus. Moreover, the merits of the Z-bus loss allocation, depending on the network topology and the current injection, are all preserved. Finally, a 6-bus system is given to demonstrate the proposed method.

The economic dispatch with consideration of transmission service charge for a generation company

Summary form only given, as follows. This paper presents a novel economic dispatch strategy for a generation company which owns several units with different fuel costs, efficiency, and locations, and has a bilateral contract with several large customers. The proposed strategy not only considers the generation cost, but also takes into account the wheeling charge for the use of the transmission system. A modified megawatt-mile method is proposed to calculate the wheeling cost in this paper. Finally, the calculation result of economic dispatch for a generation company with two units and their loads in a real power system is demonstrated.